# Eneloop Charging Rate



## this_is_nascar (Feb 25, 2008)

Using my BC-900 (firmware version unknown), what's the best charging rate to use to charge (4) AA Eneloop cells at the same time? Same question while charging (4) AAA Eneloop cells. I've been using 500mA, but have only charged them twice.


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## cave dave (Feb 25, 2008)

SilverFox will tell you to charge between 1c and 1/2c for proper end of charge detection and termination with any NiMh. So I charge at 1/2 the capacity of the battery. 
1000mA for AA
500mA for AAA

My two yr old Eneloops still are remarkably consistent in performance.


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## this_is_nascar (Feb 25, 2008)

Thanks and I'm assuming I don't do damage if I go lower, it just adds time to the charging cycle, correct?


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## SilverFox (Feb 25, 2008)

Hello Ray,

The reason you charge in the 0.5 - 1.0C range is to make sure the charger gets a strong end of charge termination signal from the cell. When you charge at lower rates, you present the charger with a weaker signal. If the charger misses the termination signal, you overcharge the cell.

Overcharging = damage.

If you want to charge at a slow rate, charge at 0.1C for 16 hours. Overcharging at 0.1C is usually not much of a problem, however there have been some reports that the new low self discharge batteries are sensitive to any overcharging. If you want to do this, you may want to hedge your bet and set the timer for 14 - 15 hours when charging at 0.1C with these cells.

Tom


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## coppertrail (Feb 25, 2008)

I've been using the 1000 mA rate with all my eneloop cells and they've been working great.


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## Mr Happy (Feb 25, 2008)

SilverFox said:


> If you want to charge at a slow rate, charge at 0.1C for 16 hours. Overcharging at 0.1C is usually not much of a problem, however there have been some reports that the new low self discharge batteries are sensitive to any overcharging. If you want to do this, you may want to hedge your bet and set the timer for 14 - 15 hours when charging at 0.1C with these cells.


Can you elaborate on the overcharging issue? This is fresh news to me. Does it mean that running a C9000 break-in cycle on LSD cells should be avoided or minimized?


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## BabyDoc (Feb 26, 2008)

There was a previous thread which addressed the charging of Slow Discharge NIMH cells. 
https://www.candlepowerforums.com/threads/187884

According to Maha, makers of the Imedion SLD cells, a 0.1 mha charge for 16 hours should do no harm to the new cell, even if it has retained a significant factory charge before applying a "forming charge" to it. Good sense would suggest discharging the cell before doing this. However, Maha insists this isn't necessary. Although these batteries can be used right out of the package, Maha suggests running the breakin cycle initially for best battery performance. Will you have to do this breakin cycle again after 30 or so cycles as is suggested for conventional NIMH batteries in the Powerex MHC-9000 instructions? I would doubt it, unless the battery has been left idle for years.


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## VidPro (Feb 26, 2008)

i use 500-700-1000, they all work with healthy enloops, but 200, 200 is SOOO bad, it makes me wonder if i should put the charger on a UPS, because it will reset to 200 on a power outage (computer in it resets)

from my tests you can slowly overcharge a enloop in open air at 300ma for more than 100 hours without ruining it, using a constant non PWM method. in fact the cell displays MORE capacity after testing it, resting it and testing it again, even after charging it for the 100 hours. that test should give an idea that the enloops own charger should work just fine.

but in the 900 they totally baked at 200, hurt them worse than my torture test for some reason. they still are fine, but they got dang hot, and acted funkey for a while. (the 900 has less passive cooling than my test did, with its containment around the cells, and with the 900 the current is PWM Averaged not constant)

if i was making a recomendation of ONE setting, it would be 700, 200 is a disaster, 1000 is a bit hot, and 500 while it works ok, is below , and a cold room or a weak cell it could not terminate.


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## this_is_nascar (Feb 26, 2008)

Thanks guys. It sounds like I should stay with the recommendations posted, as opposed to what I've been using.

1000mA for AA
500mA for AAA


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## bob_ninja (Feb 26, 2008)

this_is_nascar said:


> ... the best charging rate to use ...



... is exactly the rate that is used by the Eneloop specific charger from Sanyo. I cannot remember what is was; probably less than 1A.
Anyway search for discussions about Eneloop charger.

BC900 is very good with termination. I haven't had a single miss yet, even when using the lowest 200 mA. So when charging reasonably healthy Eneloop cells any rate from 500 mA and higher is fine.


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## UnknownVT (Feb 26, 2008)

bob_ninja said:


> ... is exactly the rate that is used by the Eneloop specific charger from Sanyo. I cannot remember what is was; probably less than 1A.


 
er, I think there may be a _BIG caveat_ on that......

eneloop 4-position charger (original) -






eneloop 2-position charger -





This means the charging current for AA are either 300mA (0.15C) or 550mA (0.275C) -

So both the chargers are way off of the 0.5C to 1C, or 0.1C recommendations -
and more or less in the _WORST_ possible range of charging currents -
according to whom?

BatteryUniversity.com page on nickel based batteries
about 3/4 down that page under 
*Charging nickel-metal-hydride *-
" _It is difficult, if not impossible, to slow-charge a nickel-metal-hydride. At a C?rate of 0.1-0.3C, the voltage and temperature profiles fail to exhibit defined characteristics to measure the full charge state accurately and the charger must rely on a timer. Harmful overcharge can occur if a partially or fully charged battery is charged with a fixed timer. The same occurs if the battery has aged and can only hold 50 instead of 100% charge. Overcharge could occur even though the battery feels cool to the touch._ "

(Half a step back, eneloops although are LSD (Low Self-Discharge), are basically still NiMH, so the recommendations for NiMH applies.)

These charge currents were so contrary to all the recommendations that our local battery guru SilverFox singled out the eneloop chargers in his thread -

A look at slow charging


SilverFox said:


> The questions remains, Why does Sanyo in the Eneloop site seem to contradict the recommendations in their main site? Perhaps the Eneloop chargers have changed from –dV termination to peak voltage termination. I think some testing may be in order…


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## this_is_nascar (Feb 26, 2008)

.... and people continue to wonder why I have issues/concerns with using rechargable cells and because of that, don't use them at all.


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## Bones (Feb 26, 2008)

More fodder:

Duracell is imprinting this phrase on the wrappers of their re-badged Eneloop and their RayOvac Hybrid clone:



> Standard charge 200mA for 16h


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## cave dave (Feb 26, 2008)

Ya, the latest version of the standard Eneloop charger is whatever the cheapest thing the marketing folks at Sanyo could come up with to include in the package. *NOT what the engineers would recommend.*


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## SilverFox (Feb 27, 2008)

Hello Bones,

I am shocked... Could you post a picture of that?

Duracell has taken the position that 16 hours is too long to charge a cell. They say, in their technical literature, that a cell can be fully charged (at 0.1C) in 14 hours. This is a major shift for them. I have had several "heated" discussions over this. It would be nice to have a little extra "ammunition" in my quiver for the next debate...

Tom


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## Mr Happy (Feb 27, 2008)

SilverFox said:


> I am shocked... Could you post a picture of that?


I can oblige with the picture, if I may:






The manufacturing code printed on the cell is 7F08 - L T, but I don't know how to interpret it.


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## TorchBoy (Feb 27, 2008)

Hold on, isn't "standard charge" a technical or historical phrase basically meaning a slow charge? It's been the "standard" way of charging a NiCd or NiMH battery since they were invented. That doesn't mean it's the best way to charge a modern NiMH.


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## Bones (Feb 27, 2008)

Mr Happy said:


> I can oblige with the picture, if I may:
> 
> ...



Many thanks for posting a most excellent photograph Mr. Happy.



Mr Happy said:


> ...
> 
> The manufacturing code printed on the cell is 7F08 - L T, but I don't know how to interpret it.



It appears that your cells were manufactured on 2007 June 08 (7=Year, F=Month, 08=Day, LT=?).



> On the back of American made packages of Duracells is a stamped date code. The first digit is the last digit of the year of manufacture. Next is a letter representing the the month, arranged alphabetically, A - L. The next two digits are the day of the month. The last letter represents the U.S. factory. Example: "4J08X" indicates Oct. 8, 1984 Gray market Duracells do not have a stamped code.
> 
> http://groups.google.co.ke/group/misc.consumers ...
> 
> ...


I don't consider any of these sources definitive, but would suggest that if someone does locate a definitive source, they post it in its own thread for future reference.

Being able to narrow the search down to thread titles will offer some hope of locating it again.

Incidentally, I have a set of these re-badged Eneloops bearing the code 7K07-HT.

If this interpretation is correct, they were manufactured 2007 November 07.

Being less than four months old, I believe this makes them easily the youngest Eneloops thus far reported to be in the wild.

I suppose I should go change their diapers and devise an investment strategy for their college funds ...


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## SilverFox (Feb 27, 2008)

Hello Mr Happy,

Thanks.

Tom


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## SilverFox (Feb 27, 2008)

Hello Ian,

There are standards that the battery manufacturers use to determine the capacity of a cell, as well as the cycle life that can be expected. 

These standards are under constant scrutiny and are occasionally revised. I can assure you that if a manufacturer was able to get better performance through a better charging protocol, it would find its way into the standard.

Duracell proposes a better charging protocol, but rates their cells according to the existing standards. If their better charging method was "better," I would expect them to show the difference in side to side comparisons. I have never been able to find that comparison. I would also expect them to market chargers that utilized their "better" charging method. When I run my own tests, their procedure seems to work for brand new cells, but falls short when the cell has been used for a few cycles. While their ideas on NiMh chemistry seem interesting in theory, then don't seem to prove out in actual practice.

Duracell is an excellent quality company and they have vast "expertise" in the primary battery field. I don't believe they manufacturer any of their NiMh cells. I am not sure if they do as much NiMh battery testing as the NiMh battery manufacturers do. Almost all of the information in their technical bulletin is very good, it's just this one part on standard charging that there are "issues" with. I have emailed them asking them if they could provide side by side comparisons that back up their claims and have received no replies from them. 

Instead of "standing up" for their improved charging method, they label their product according to the existing standard. On one hand I am a little disappointed, but on the other hand I guess I already knew that their idea was a little "shaky."

Tom


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## bob_ninja (Feb 27, 2008)

Thanks UnknownVT and MrHappy for the pics.

Now we have a range of values:
SivlerFox/Maha/general consensus: 0.5C - 1C
for Eneloop: 1A - 2A

(BTW Sanyo's quick charger also does 1A/2A and is packaged with Eneloops in Costco in my area)

Eneloop specific chargers: 0.3A & 0.55A

Duracell writing (highly controversial): 0.2A

Also we now that the top line is the most secure/safe regarding termination signal, so you can't go wrong with those. We also know that the bottom one is fine so long as you have a 16 hour limit, but is probably too slow for general charging. That leaves the middle, or Eneloop specific charger settings. I am guessing that the 0.3A rate was too conservative and they subsequently went up to 0.55A rate. According to the 0.5C-1C rule this rate (about 0.25C) is unsafe. However, one should remember that Eneloop cells are far more robust that your average Energizer so probably maintains a very strong termination signal for most of its lifespan. I haven't heard of missed terminations on Eneloop chargers so far.

So go with 1A if you want zero risk, or try 0.5A if you prefer a slower rare. I tend to use 0.5A on BC900 when I am around and can check the charger. Otherwise I often use 1A on C9000.


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## Anders (Feb 27, 2008)

And Shulze recommend 2C:twothumbs.

"Suitable charge currents may be selected by the following rule:
Charge current = 2 x C (C=nominal cell capacity)
Example: Cell capacity C = 1.2 Ah, charge current 2 x 1.2 = 2.4A. Selected charge current: 2.5A"

Another odd thing:
"For precise measuring of battery capacities a discharge current of 1/10 C is recommended,"

6.30-5, 7.36-8, 10.36-8
http://www.modelflight.com.au/manuals/pdf/schulze/nextGen-web_V100_english.pdf

Silverfox: I think you have memorized the earlier manuals from Shulze, did the earlier manuals also recommend 1/10 C when discharging?

The IEC standard is 1/5 C but if 1/10 C is used maybe the buyer think it is a better charger since the discharged ampere is more.

Anyone used 1/10 to see the difference between them?

Anders


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## Bones (Feb 27, 2008)

Courtesy of the good folks over at the Eneloop USA Facts & FAQs:



> 13. Can I use a "Quick Charger" to charge an eneloop battery?
> 
> Though it is possible to charge an eneloop battery in a "Quick Charger", it is not recommended. We recommend charging eneloop batteries in a NiMh charger that is 2 hours or more. Charging eneloop batteries in a "Quick Charger" can reduce the overall life of the battery. It is strongly recommended to use eneloop, GE/Sanyo or Sanyo NiMh battery chargers. We only warrant eneloop if used with an eneloop, GE/Sanyo or Sanyo NiMh battery charger.


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## bob_ninja (Feb 27, 2008)

Bones said:


> Courtesy of the good folks over at the Eneloop USA Facts & FAQs:



Interesting. This suggest the *MAXIMUM* rate of 0.5C (as opposed to conventional thinking being *MINIMUM* rate of 0.5C)

Hmmmm ....


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## SilverFox (Feb 27, 2008)

Hello Anders,

The formula you are referring to is for charging NiCd cells. I believe Schulze recommends charging NiMh cells at 1C.

The standard for determining capacity is to discharge at 0.2C. I don't think you can get much more precise than that. I was unable to find that statement in the link you provided. Where is it?

I actually have run some tests at 0.1C and there is very little difference between discharging at 0.1C or 0.2C. 

Tom


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## SilverFox (Feb 27, 2008)

Hello Bones,

It is good to know that my Sanyo charger that charges at 1.0 or 2.0 amps is fine to use with the Eneloop cells...

Tom


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## SilverFox (Feb 27, 2008)

Hello Bob,

Yet when you open up the Eneloop technical specifications on that page, you find that a fast charge is listed as 2000 mA for 1.1 hours...

Tom


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## Anders (Feb 27, 2008)

Hello Tom.


4.3 Nickel-Metal-Hydride batteries (NiMH)
"Charge current typical 1 C (never less!)"

This is what I also had read earlier in the manual.




8.1 Ni-Cd/Ni-MH charge program with manual charge current selection (fixC)
"Charge current = 2 x C (C=nominal cell capacity)
Example: Cell capacity C = 1.2 Ah, charge current 2 x 1.2 = 2.4A. Selected charge current: 2.5A"


8.3 Ni-Cd/Ni-MH discharge program with manual current selection (fix D)
"Note: For precise measuring of battery capacities a discharge current of 1/10 C is recommended,
i.e.: a 1000 mAh battery should be discharged with 100 mA"


I have not read all of it, I just found this when I was looking after the first chapter (4.3) because I remember that Schulze recommends a little bit more than 1C.

Thankyou Tom, :wave: I thought it was more difference between discharge at 0.1 C and 0.2 C.

Anders


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## bob_ninja (Feb 27, 2008)

SilverFox said:


> Hello Bob,
> 
> Yet when you open up the Eneloop technical specifications on that page, you find that a fast charge is listed as 2000 mA for 1.1 hours...
> 
> Tom



Yeah, you are right. I don't see any conflict between the 2.
FAQ simply states that is is "possible" and the spec defines their terminology being fast/quick charge at 1C. Presumably this would imply that even faster rates like 15min chargers are not even considered.

Then FAQ continues by offering a "recommendation"

Thus you have a range of values, from recommended 0.25C-0.5C range to possible 1C.

I suppose it makes sense that they should offer a range of values as there is no magic single charge rate. Someone who doesn't want to wait can use 1C and their information simply confirms that such a rate is "possible" and more importantly valid.


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## SilverFox (Feb 27, 2008)

Hello Anders,

The 8.1 reference is referring to NiCd cells. I believe it is a typo in that it references both chemistries. Look at the last paragraph just before section 8.1.

I am not sure what is going on in 8.3. The only thing I can think of could be that some transmitters run at around 100 mA, so your remaining runtime would be a closer estimate by using the same discharge rate that your transmitter does.

Tom


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## SilverFox (Feb 27, 2008)

Hello Bob,

Let's take this one step forward...

Let's suppose that you are a battery manufacturer. You are asked to produce a specification sheet that demonstrates the capabilities of your new battery. There are standards available for determining capacity, so you list capacities based on those standards.

The question is "What charge rate do you use to demonstrate your products capabilities?"

Next question, on the data sheet what charging rate did Sanyo use?

Tom


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## SilverFox (Feb 27, 2008)

Hello Bones,

I might also point out that Sanyo has a 15 minute charger as well. 

If Eneloop cells will only be warrantied when charged with Sanyo chargers, I wonder what they would say if you told them you have been charging the Eneloop cells on a Sanyo 15 minute charger.

Tom


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## Turak (Feb 27, 2008)

Sheesh.....this again!

I don't think the debate over the 'best' charging rates will ever end.

It seems that many are looking at the charts produced by the battery manufacturers, etc. and just because the charts show certain rates....these are interpretted to be the 'recommended' rates....which typically THEY ARE NOT THE 'RECOMMENDED' rates. They are usually the two extremes that happened to perform reasonably well, just to show what is 'possible', not what is best for the battery.

Others look at what the charger manufacturers are recommending and seem to take them as gospel. The charger manufacturers are generally going to recommend whatever works best for 'their' particular charger design. They generally ARE NOT necessarily recommending what is best for the battery......just what works best with their charger.

How many FAST chargers actually say right on their packages that using the higher charging rates will lower the number of cycles that you get out of the battery?......ummmmm NONE. The marketing department would have a cow if you actually told the consumers the complete truth.


I myself have taken a slightly different tact.....

First understand that I have worked as an electronics technician, engineer, designer, tester, and QA for over 20 years.....with one of my last projects that lasted almost 3 years being designing and testing battery chargers for D size sealed Lead acid battery packs along with designing and testing DC Lighting Ballasts for automotive uses. Just so you understand I do have a fair understanding of all this.

I use whatever the LOWEST charge rate I can get away with, that DOES NOT miss the end-of-charge termination. This may be 200mA, 500mA, 1A, etc. Generally speaking newer batteries get lower rates, as they age, I up the rate a bit to ensure the end-of-charge signal is seen.

I have most of the MAHA chargers including the MH-9000, along with a couple BC-900, a RipVan charger, a couple older energizer chargers, one of the newer Energizer 15 minute chargers (got rid of it right away- battery killers) etc.

The bottom line when it comes to the NiMH cells is that ANY charging rate can be used to charge the batteries. BUT, you have take that with a grain of salt and understand the following;

1. The more heat the battery generates, the faster the battery is going to wear out. Basically meaning, don't count on getting 500 or a 1000 cycles out of it. Especially as you move to higher charge rates. KEEP IN MIND that just because the battery does not 'feel' warm, does not mean that you are not damaging it.the temperature at the center of the battery can be as much as 10-15'C higher than the surface temperature. This is especially true if you are trying to use fans to keep them cool while charging.

2. The characteristics of the battery are going to change as it ages, generally meaning that the typical way the chargers terminate (via -delta V) is going to get harder and harder to detect as the internal resistance builds with battery age. Which means you may need to up the rate a bit to get a good end-of-charge signal.

3. There is NO SINGLE CHARGE RATE that is ideal for every battery.


We can go on and on and on about this, but it will never end. Seems you are going to always have;

people that prefer slower gentle charging
people that prefer fast charging
people that don't care about getting the maximum life out of the battery
people that just don't know any better
people that keep on misinterpretting things they are reading
AND OF COURSE, people that simply are going to think whatever they want no matter how much proof you put in front of them.

Ummm....oh yeah.... don't believe everything you read on the Internet.


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## TorchBoy (Feb 27, 2008)

Turak said:


> don't believe everything you read on the Internet.


I don't believe you.


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## Turak (Feb 27, 2008)

TorchBoy said:


> I don't believe you.


 

:twothumbs Hehehe.....EXACTLY!

Take the time and test a few of your particular battery with your particular charger and see what works best for you......


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## Bones (Feb 27, 2008)

SilverFox said:


> It is good to know that my Sanyo charger that charges at 1.0 or 2.0 amps is fine to use with the Eneloop cells...



Hello SilverFox,

You appear to interpret the fact that Sanyo has chargers capable of charging at 1C as an inferred recommendation to charge the Eneloop at that rate regardless of their specific recommendation against charging it at rates higher than .5C in the Eneloop Facts and FAQs.

I interpret the fact that Sanyo doesn't recommend charging the Eneloop at rates higher than .5C as a specific recommendation against charging it at a higher rate regardless of the fact they make chargers capable of charging at 1C.

I also don't view this as an either/or situation. To me, the recommendation against charging it at rates higher than .5C just better enables me to choose the best charger for my Eneloops from the array that Sanyo has available.

An interesting difference in perspectives though ...


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## SilverFox (Feb 27, 2008)

Hello Turak,

It appears that you and I have been talking to different people at the battery manufacturers… Every chemical engineer involved with testing has told me that overcharging kills NiMh chemistry, and the quickest way to overcharge is to use a charge rate below 0.5C. The preferred rate is 1C.

I have also been involved with using and testing batteries over the last 20 years. I have found that the technical papers are quite often very good, and following them gives you good performance from your cells.

Now, almost all of my involvement in batteries has been with NiCd and NiMh chemistries. Although I have had to deal with some lead acid batteries. In the case of lead acid chemistry, slower charging is preferred.

I, like you, viewed the manufacturers charts with a grain of salt, and still do a little, however I have confirmed their results with my own testing. All of the sudden, I am looking at things from a little bit different perspective.

How many cycles do you get out of a set of batteries with your charging method?

I set out to see if I could get 500 cycles from a set of batteries. I took 9 cells in a battery holder and ran a test. The cells were 2400 mAh capacity. I charged them at 2.5 amps and discharged them at 1.0 amps down to 1.0 volts per cell. Every 50 cycles, I ran a 16 hour balancing charge. The cells barely warmed up during charging. The charger never missed a termination because I had the charge quantity set to 2650 and the charger never terminated on quantity. At 653 cycles I terminated the test. The capacity had dropped below 80% of its initial capacity, and that is my criteria for termination.

I followed the manufacturers recommendation and charged at 1C. I got more than the advertised 500 cycles from my set of 9 cells. I think charging at 1C works well, and I highly recommend it.

The next project is to do the same thing with Eneloop cells…

I may be the only one that actually believes and acts upon the information provided in the technical bulletins, but I am probably one of the very few that actually get more than 500 cycles from a NiMh battery pack too…

I will also say that 15 minute charging is a little too fast. I was able to get 150 cycles from my Sanyo 2500 mAh cells, but they were pretty much done after that. However when I switched to some 2000 mAh cells, they were still going strong after 150 cycles on the 15 minute charger. They were down around 10% on capacity, but I believe they would probably go another 100 – 150 cycles before crapping out. The next step is to see how the Eneloop cells perform with the 15 minute charger. This should be interesting.

I also have tried your system. It actually works pretty well, however it is difficult to know when to increase the charge rate to the next level. I would end up with an overcharge before realizing that I needed to increase the charge current. I would get “acceptable” performance, but never had cells actually exceed their advertised cycle life. 

I should point out that most of this discussion involves NiMh chemistry. NiCd chemistry seems to handle abuse much better. I have had, and still have some NiCd packs that are still going strong after hundreds of cycles. My NiCd packs have two different chargers. One charges at around 0.1C for 15 hours, the other charges a pack in 1 hour. I mostly use the 1 hour charger, but try to balance the cells in the pack frequently.

You are correct in that people will hold to their own “truths” and charge at whatever rate they feel comfortable with. I think it is OK to revisit this from time to time and let people know what works. With diligence in tracking a cells internal resistance, your method may work fine, however, I know mine works well enough to meet the advertised specifications.

The low self discharge chemistry is new. I have been using my Eneloop cells for around 2 years now. I charge them at 1.5 amps and they are still going strong. Occasionally, I charge my Eneloop cells on the 15 minute charger too. So far there are very few Eneloop cells that have died. When we get more information on how they die, we will be able to form better conclusions as to what is the best range to charge them at.

I agree that you shouldn’t believe everything you read on the Internet. Take what you read and test it. If it tests true, then you can believe it.

Tom


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## SilverFox (Feb 27, 2008)

Hello Bones,

Yes, it is an interesting difference in perspective... I wonder how things will play out.

Tom


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## VidPro (Feb 27, 2008)

Turak said:


> The charger manufacturers are generally going to recommend whatever works best for 'their' particular charger design. They generally ARE NOT necessarily recommending what is best for the battery......just what works best with their charger.
> 
> I use whatever the LOWEST charge rate I can get away with, that DOES NOT miss the end-of-charge termination.
> 
> ...


 
and 2b. the characteristsics of the battery change when its just parked for a long time, and has not been cycled.

3b. there is no single charge rate for all CHARGERs, because the design of the charger makes huge differences in how it works at that rate.
most (consumer locked in) chargers WILL charge an enloop just fine, as they have been designed FOR the rate they are used at.

i would bet that even the 2 sanyo chargers (300 and 500) have different termination methodology.

i (basically) agree with all of what you said.
it is better to understand what the battery wants, and how the charger is designed to operate, than to have some set of numbers sloshing around in your head that wont mean a dang thing when you use a different charger , and charging alogrythm.

my recomendation was ONLY based on the one charger the 900 , and it probably wouldnt even apply to the 9000, and i have many chargers which dont AT ALL work at those rates , i still love my 10X 230ma charger, it has never treated my batteries poorly, it cant  even when it misses.


I will even use a LOWER rate than what will terminate  when the rate is low enough that termination is not a nessisty.

-----------------

the battery university and "shultz triton" recomendations are specific TO a specific TYPE of charging alogrythm, thier statements would go 100% wrong if you used a .5-1C on a dumb charge that had no termination method. 
and visa versa, without a fast rate on a "smart charger" a battery that had not been cycled for a LONG time, will not show a visable termination as strongly as is needed on those chargers. and even how YOU set the chargers settings.

all this talk of "termination" nessisty, is "newer" type info, back 20 years ago nobody gave a flying leap that anything terminated, because they didnt put "smart" computers in, just logical alogrythms and slow charging. dont be confused by HIGH charge rates, if you have NO TERMINATION method, that is the Last thing you want.
and they still have MANY consumer devices that last for eons without any human interaction that use slow dumb $5 charger rates. they usually slow down as the voltage gets higher, Simplicity in a dumb charger can be smarter than a smart charge if you have the time.

Charger alogrythms can be broken down into catagories much easier than remembering some set Numbers junk.

things you can ask yourself to determine what the battery gets:
1) is it Pulsing for averaged current control or actually AT that current rate
2) does it have any termination or reduction in rate when it reaches some voltage
3) does it terminate based on a V-0 flatening, a hard V-Drop, soft v-drop, or at voltages
4) how much heat does the charger electronics contribute TO the battery, does it heat the battery with itself, also the ones with lids :-(
5) how much free-flow of air does the battery have (not to assume that a fan wont change how the chargers functions)
6) is it a slow dumb charger that is low rate
7) what method does it top-off with when the battery is alegedly charged, and is that Averaged high current or a lower current rate
8) does it have a timer
9) does the temperature probe have any usefull value.
10) will it destroy your wee little AAAs because aaa function was tossed in the side , and dont work for poop

it is stuff like that that can make better determinations for how you act with the items, than some set number for "all" chargers.

even the 15 minute charger :devil: has a "way" of doing its damage that attempts to be controlled differently than other chargers. 
EX: forcing a 15 min charge to work with a battery the charger rejected, because its alogrythm would fail then, is a bad idea.


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## Bones (Feb 28, 2008)

SilverFox said:


> Yes, it is an interesting difference in perspective... I wonder how things will play out.



Me too.

I must also admit that I find the difference in our perspectives especially curious considering that virtually everything I know about batteries and charging, I learned from your missives.

The only thing I can come up with is that you're really a .5C charger in the guise of a 1C, and I picked this up subliminally ...


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## SilverFox (Feb 28, 2008)

Hello Bones,

 

Tom


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## Anders (Feb 28, 2008)

Hello Tom.

You are probably right about the Typo in the manual.

Anders


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## bob_ninja (Feb 28, 2008)

SilverFox said:


> .... Every chemical engineer involved with testing has told me that overcharging kills NiMh chemistry, and the quickest way to overcharge is to use a charge rate below 0.5C.....



I will interpret "quickest" as meaning the most frequent cause of overcharge, or the most likely. My experience and that of other BC900/C9K users is that there are almost no missed terminations well below 0.5C, even as low as 0.1C
How would those "chemical engineers" explain the lack of overcharging when using below 0.5C on decent quality chargers?

I think a better measure would be the specific odds of missing termination. Something like "for BC900 using 0.1C the odds of missed termination is X"
That would be much more useful than vague statements like the one above. How quick is quick??????

Between engineers and the reality I'll always go with the reality 

P.S.: That being said, I do keep this warning in mind and use 0.5C and higher for older cells. My problem is generalization of a rule that doesn't really apply to sophisticated chargers we use and newer higher quality cells like Eneloop.


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## bob_ninja (Feb 28, 2008)

SilverFox said:


> ...
> I also have tried your system. It actually works pretty well, however it is difficult to know when to increase the charge rate to the next level. I would end up with an overcharge before realizing that I needed to increase the charge current. I would get “acceptable” performance, but never had cells actually exceed their advertised cycle life. ...



Well that is simple. Based on time (say after 5 years) and based on diminished capacity (say after 10% capacity loss) - whichever occurs first - you switch to a higher rate. The actual numbers differ based on cell quality. In the worst case when in doubt simply go to 1C as you said.


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## SilverFox (Feb 28, 2008)

Hello Bob,

And how many cycles do your get from your batteries...?

Tom


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## bob_ninja (Feb 28, 2008)

Hello Tom,

To be honest I had only dumb chargers and huge memory problems with NiCd before finding this site. So I only started using NiMH and better chargers in the past 5ish years, hence haven't really thrown away many cells by now. Mostly older NiCds that go down to 0V.

I still use junk NiMH cells in my wireless mouse and other similar low drain apps. When I charge those (below 80% of original capacity) I follow your advice of using 0.5C or more *AND* am present to be able to check on charging and cell temp. Actually I avoid charging in general during night.

I haven't had a single missed termination on BC900 and C9K yet.

Yes, my experience is short so you and others likely have much more experience.

P.S.: I should have said with the exception of Energizers. I threw away all AAs, still have a couple of Cs. But that is a different story, nothing to do with charger.


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## SilverFox (Feb 28, 2008)

Hello Bob,

It is funny you should bring up the old NiCd cells. I am working with some 12 year old Eveready D cells, seeing if I can bring them back to life. They are only 1200 mAh. Scott from Tektite sent them to me after we were discussing the techniques used to recover NiCd cells after long storage. These cells are "new old stock," and are sealed in the package. Some of them actually came back to nearly 1200 mAh after a few cycles. Others are being more stubborn.

Back to the discussion...

I have had missed terminations on all of the chargers that I have used. Most of these have been when using charging rates less than 0.5C. Schulze advises you to set the charge quantity only slightly above the capacity of your battery pack with the idea that in the event of a missed termination, the charger will time out on quantity and only minimal damage will be done.

Handlobraesing sent me some "used" Eneloop cells. I think I will charge them on the BC-900 at 200 mA and see what happens. I believe the efficiency of NiMh chemistry at lower charge rates is around 66%, so the charge should end when I have put around 3000 mAh into the cell. I believe the BC-900 actually times out somewhere around there, so I will have to pre-charge them with around 1000 mAh on the C9000, then move them over to the BC-900.

Tom


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## Gene (Feb 29, 2008)

Ray,
Even though I use some rechargeables, I understand where you're coming from! All this technical stuff about this and that and charge them at this rate and buy this charger and buy the next great charger that has that rate and this rate and store your cells at 40% percent charge or you will kill them. It's too much!!! If I had the funds, I would buy primaries for everything!

That being said, I really do appreciate the amount of effort that has gone into all this research.

Tom, (SilverFox), has done a considerable service to these forums but says USE THOSE CELLS! Tom, most flashlights sit and are used for emergencies. I realize that these same cells are used for different applications but we are talking about lights here.

MY lights are used for maybe an hour to 1 1/2 hours of continues use to change a tire or dig out of a snow hole. I realize that your expertise will expand the realms of useage and I thank you for it.

I live in a very rural area that gets a good foot of snow or two on a good winter night and I still have an old 1W Luxeon that runs for 1 1/2-2 hours on a primary 123 cell. I have many other lights with P4's, Q this or that and they all are used primarily for emergencies. 

I think all this spending for cells and chargers is too much!


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## Mr Happy (Feb 29, 2008)

Gene, I think you're right. What many people seem to overlook around here, especially when advising newcomers, is that the kind of spending many people make on all sorts of chargers and batteries (and flashlights) is spending for fun, not for practicality. Why is it that so many people recommend the Maha C9000? That is not a charger for ordinary people. What should be recommended is a basic consumer charger like the Duracell Power Gauge at $19.99 including 4 batteries. You put the batteries in it, wait until they are charged, and use them. Nothing more is needed.

When I am considering advice to non-techy people, one of the good questions I find to ask myself is, would I recommend this to my mother? (To put this in context, I bought my mother the simplest of point and shoot digital cameras, and still had to spend hours and hours explaining to her how to switch between picture mode and playback mode. She said, "why did you buy me a computer when all I need is a camera?")


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## tygger (Feb 29, 2008)

Bones said:


> The only thing I can come up with is that you're really a .5C charger in the guise of a 1C, and I picked this up subliminally ...




So 1C is not the consensus for eneloops? Sorry, for my


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## SilverFox (Mar 1, 2008)

Hello Gene,

With rechargeable cells you basically have two options…

1.	Use your cells up, or
2.	Store them “to death.”

Not only do I embrace the first option, but also while I am using them up, I want them to be “vibrant” and give me good performance.

Over the years, I have learned how to do that, and I pass that information on.

I have lights that I don’t use as much as others. Those lights have primary cells in them. I find that a “brick” of AA cells from Costco lasts me about a year. The “brick” of AAA cells last a couple of years. I try to keep around 100 CR123 cells on hand, and generally go through around 50 a year. I also have a few C and D cells that I rarely use.

The lights that I use a lot all have rechargeable cells in them.

If you aren’t using your lights a lot, I think primary cells are the way to go. However, there are some lights that don’t perform well on primary cells (the variations of the Mag85 comes to mind immediately), and when you invest in those types of lights, you have to realize that you will also have to take care of the batteries used in them.

If you don’t take care of your rechargeable batteries, your lights will under perform, and you won’t be happy with either the light or the batteries. I may be so bold to suggest that if you don’t want to properly take care of your batteries, you should probably sell the light and let someone else have a go at it.

In your case where you are only using your lights for a few hours a year, I totally agree. Primary cells are the way to go.

Tom


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## SilverFox (Mar 1, 2008)

Hello Mr Happy,

The C9000 is a recommended charger for several reasons. The first is the Break-In function. Another is that its default charging rate is suitable for most of the cells we use. Another is that its trickle charge rate, after completing the charge, is low enough to not “cook” cells that are inadvertently left in it.

In addition to all of this, it can also discharge a cell for storage, and it allows you to play with some advanced features if you are so inclined to do so.

I am not aware of any other consumer grade charger that does all of this and also offers easy to use default settings.

If you get one for your mom, this is how to explain it to her…

“Hello Mom,

I am sending you a battery charger. Plug it in. When you need to charge your batteries, put them in the slots. When “Done” is displayed, use them.

Love,
Your Son”

Now, once or twice a year when you go to visit her, you can run a Break-In on her cells for her, or you can get in touch with the person that mows the lawn and talk them through the process over the phone.

When she calls you complaining about only being able to get a few pictures with her camera before the low battery warning comes on, you now have a tool available to help her, and you, figure out what the problem is. This trouble shooting will take some extended phone work, and you may have to go over the menu selection a few times, but you should be able to resolve the problem with a test or two. 

Your mother will think you are “absolutely brilliant.”  

Tom


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## SilverFox (Mar 1, 2008)

Hello Tygger,

The recommended range is 0.5 - 1.0C...

Tom


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## Mr Happy (Mar 1, 2008)

Tom,

The weak link in your scenario is that the C9000 costs $60.

If instead one buys the Eneloop pack from Costco for $25 they get a charger and 8 AA cells. Someone can charge and use the Eneloops in that charger and probably get at least 1 - 2 years good performance out of each cell (assume 20 charges per year max with 2-3 weeks between charges). When the cells stop performing, buy more Eneloops at $15/4 and go on for another 1-2 years.

I reckon that would keep someone going for 8 - 10 years before they have spent the $60 that the C9000 costs. And in 10 years time technology will be so different that the camera will be out of date, and who knows, battery technology may have moved on to something new as well.

So really, I do believe the C9000 is for heavy users who run through 100's of charge cycles per year, and especially for people who have a technical bent.

For myself, I have a C9000; I had the money to spend on it, and it is fun. But I really don't kid myself that I bought anything other than a "cool gadget" for its entertainment value. If I were short of cash, there is no way it would have been a rational purchase.


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## SilverFox (Mar 1, 2008)

Hello Mr Happy,

:devil: :devil: Are you saying that you won't spend $60 on your dear mother? :devil: :devil:

Gee whiz...  

No, I totally understand your argument.

However, as you are well aware by now, I tend to put performance and reliability ahead of cost. Does that make me a person of "technical bent?"

Tom


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## Mitch470 (Mar 1, 2008)

I've been using the LaCrosse BC-900 and charging Eneloop AA's at 500 mAh and AAA's at 200 mAh. I've been doing this for 6 months and so far everything is perfect.

I have a hunch it really doesn't matter which charger you use or what the charge rate is. In 2 years or less new technology will explode again and we will throw away our present chargers and batteries and buy the latest and the greatest AGAIN.

I am eagerly awaiting 9V Eneloops.


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## SilverFox (Mar 1, 2008)

Hello Mitch,

Just a minute now... The BC-900 is over 2 years old...

Tom


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## TorchBoy (Mar 2, 2008)

Mitch470 said:


> In 2 years or less new technology will explode again ...


I use Eneloop because they _don't_ explode - in whatever sense.


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## brightnorm (Mar 2, 2008)

As a non-electronic dummy I got a MaHa 204 for my eneloops because the proprietary charger was so slow. When I read the fine print and saw the 2A charging rate for 4 batteries it scared me enough to go back to the Sanyo. Having been in an apartment building fire I'm very cautious when it comes to battery overheating, probably too cautious. 

Then, at the recommendation of a well-known CPF'r I got the MaHa 9000. Even though it's overkill for me I use it all the time. I put the batteries in and wait until "done". At some point I'll try some of its advanced features. I am reassured by the design that puts space between all four batteries. 

Brightnorm


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## Yoda4561 (Mar 2, 2008)

As a user of both the 204w and the C9000 I have to say you've made a good choice. The 204w always made my powerex 2500's really hot and within a year they all started underperforming, the classic 1 week self discharge. The c9000 runs the batteries much cooler at its default charge rate, barely warm to the touch after a full charge. The 204 is a faster charger but I found that with some of those 2500's that were going bad it would sometimes miss termination and the batteries would get blistering hot.(my c9000 has never missed a charge termination, even on those bad batteries, though now it just tells me they're bad and refuses to charge them) Ever since I've made it a habit to be home or at least not be gone long when charging batteries, so I can check on them once in a while to make sure they haven't missed termination. I still use the 204 as a travel charger as it's more compact, and a few fast charges don't really hurt batteries in the long run.


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## Bones (Mar 2, 2008)

SilverFox said:


> Just a minute now... The BC-900 is over 2 years old...



As is the Eneloop, time doeth fly ...


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## Gene (Mar 2, 2008)

Hi Mr. Happy,
I'm with you and I like simple. I love the anology concerning your mom!  Digital cameras are fine as long as I can point and shoot. Don't even mention complex cell phones. I don't own a cell phone and never will. I even have trouble with those supposedly "simple" UIs in all the lights nowadays. I want low/med/high. That's it!

My father was an electrical engineer but I didn't get the genes. I was even a motorcycle mechanic for years and can do wiring but this new stuff is beyond my understanding.

Hi Tom,
I do use some of my lights everyday. You can't live as rural as I do and not. It's DARK around here!  However, I don't use them nearly as much as you use yours. I was stating that I only use my lights for maybe 1 hour to 1 1/2 hours in ONE USEAGE. I do use them a lot but normally for only 5-10 minutes at a time.

I have trimmed down my rechargeable usage for some of the reasons you state. I've also trimmed down the amount of lights I own. 

When I use rechargeables, I prefer AW's unprotected cells as they stay charged seemingly almost forever and I've been using them for years and have never had a problem. I also still have a few of the old protected Pila 168S cells that I've had for years. I'm sure their capacity has been reduced some because I store them with a full charge but they still continue to work wonderfully for me. 

I guess what I'm trying to say is I have enough stuff to babysit in my life without adding a bunch of chargers and cells to the list. I'm just not going to take the time to make sure every rechargeable cell I have is at 40% or whatever before I store it for awhile. As Mr. Happy alluded to, I AM "Mr. Happy" if I can pop whatever rechargeable cells I have into a charger, get the green and I'm good to go. 

As always though, thanks for your expertise and enlightenment on these subjects as they are fascinating to read.


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## bob_ninja (Mar 3, 2008)

Good arguments on both sides.

I DID send my mother home with a charger and batteries. I gave her a Sanyo quick charger (default 1A rate) and a bunch of Eneloops. The charger is very simple, single light and no buttons. My parents are old and I am afraid C9K would confuse them, although I agree it would be a fine charger even for non-experts. The Sanyo will charger Eneloops at 0.5C which is a middle of the road rate, so I am fine with that.

Her problem was camera, so I gave them Eneloops. They should be safe and I hope not have much of a memory effect.

As for lights, I also have a few sitting in the garage and at the door. Now that I use LEDs I find batteries last too long and I always end up recharging before empty. As I was collecting Eneloops for my mom, I realized I can use a smaller capacity NiCd in the lights as they use so little anyway. That way I should be able to recharge them more often as they have less than half the capacity of Eneloops.

So if you find that your batteries last too long in your lights, downgrade to smaller NiCds (that you may have kicking around) or primaries.

Another trick is to rotate them. Say I have a set of 4 cells sitting in the radio for 6 months, still not empty. I would swap them out into a higher drain device that will empty them sooner. Or I may simply recharge before empty. It is perfectly fine to recharge before empty. It should actually provide you with a longer lifespan.

Finally, if you still find that you have too many cells and cannot use them on a regular basis then just give extras to your mom


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## VidPro (Mar 4, 2008)

Mr Happy said:


> . Why is it that so many people recommend the Maha C9000? That is not a charger for ordinary people.


 
good question, Why do people have Quad core $1900 computers to get E_mail , and viruses ONLY , when you could get e-mail on an ol 233PII. and heck they can get viruses with anything 

I think the BEST reason for getting a charger that not only shows your charging amps that were put in, but in some way can test when Discharging capacity. some way to KNOW if the cell is still a viable usefull item.
for most toys and lights and many things that your at home using, where just shoving another cell that works in it, you really dont NEED some high faluting computerised thing.

but when the application is more critical, anything that can determine the total Usable NOW capacity of the cell, is the key to knowing if its going to work. if its balanced with the other cells your using, if it will make the TIME you need it to make. for me many uses are Job critical, and tossing out alkalines like they were water sucks.

when you use enough ni-??? things, and have used them for LONG enough, its nice to know which ones are Crap, and only causing you grief. you know after you have had them for 4-5 YEars, and have 200 cycles on them or so. 

there are tons of NEW cells you couldnt count on at all. Still today tons of JUNK being sold on (lets call them) auction sites, that a quick test with some computerised thing, and you realise your better off with Alaklines  how much does knowing capacity help the foo who bought $30 worth of 3600ma AA batteries off of e-bay :laughing: (that might be good for 1/2 that)

so nobody NEEDS that stuff, untill you need that stuff, and you know when YOU DO. if you dont know you need that, and what your getting out of rechargables is "Doing the Job" then you dont need it.

as for the price, heck that is almost as much as a CBA  which could really test.

(of course add that to what silverfox said, about functions available to get the MOST out of the cell)

Use it or lose it, if you are going to go rechargable, you lose a lot of Start Up money, if you are only going to NEED to recharge it $5 worth, then you dont need a $60 charger. but if you were going to try and squeese the life out of the cell in cycles and time, you need to know when the cell is trash.
we have saved hundreds of dollers and have a more reliable usable cell with rechargables, even after the startup costs, adding in another $60 really isnt that much compared to a pallette of kirklands


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## Mitch470 (Mar 4, 2008)

*FUN*

Rechargeable batteries are simply more fun than discardable batteries. The same with complex chargers. We get fun watching all the numbers go up and down.

Same with computers. I use a computer for my spreadsheets rather than a 13 column analysis pad because it is more FUN.


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