# Review of / Measurement on 4Sevens Single Bay Charger V2



## HKJ (Jun 30, 2011)

[size=+3]Charger 4Sevens Single Bay V2[/size]







This charger was introduced in 2011 together with a new battery from 4Sevens, but due to a problem with the V1, it was recalled and later this V2 introduced. The charger has one bay and can only charge a single cell at a time, because the charge rate and voltage can be adjusted it can charge a large selection of different sizes cells.

I have listed the differences between the recalled charger and the new charger






The charger arrives in a white unmarked card board box.









Here the two switches can be seen. The voltage switch is used to select the correct charge voltage depending on chemistry, the current switch is used to select current, depending on cell size/capacity. The switches has a very short travel.
The charger has connectors for 12 volt DC and for USB power.













The charger is supplied with leads for 3 different power sources. The mains power supply is universal voltage (100-240 VAC, 50/60 Hz). The car adapter needs a socket with 21 to 24 mm diameter. Using the usb power adapter the charger cannot charge at 1 ampere, but at a lower rate.
The led is red when charging, both with 160 mA and 0.5A/1A and green at all other times.


























The charger can handle 70 mm long batteries, and both button and flat top cells. Due to the design of the slider it is possible to place a battery in the charger without it getting a connection, this is not a real problem, just check the led changes to red, if not move the battery a bit.


[size=+2]Measurements[/size]

At low voltages the charger will try a short pulse each second, this will reset any tripped protection.
Between 1.0 volt and 3.0 volt it charges with 170 mA.
Between 3.0 volt and 3.6/4.2 volt the charger is applying regular charge current with constant current (either 500 mA or 1 A), when 3.6/4.2 volt is reached it uses a constant voltage charge.
The charger stops when the current has dropped to about 160mA.
When the battery goes above 3.6/4.2 volt or the charge stops the current is turned off (discharges with up to 35 uA current).
The charger will restart if the battery voltage goes below 3.45/4.11 volt, the power has been interrupted or the battery is replaced.
When charger is disconnected from power, but with a battery in, it will draw below 35 uA from the battery.






Charging a 2000mAh cell with 0.5A takes about 4 hours, first 3 hour with constant current and then 1 hour with constant voltage. The high termination current makes the CV part faster.






Increasing the current to 1A reduces the charge time to a bit below 3 hours. The CC phase is faster. Here it can also be seen that the CC/CV regulation is done by a microprocessor and not with a analog chip. The steps is the processor adjusting, analog would have been smooth.






My old IMR cell is fast to charge on the 1A setting, but is not filled completely due to the high termination current.






Here I am using USB power to charge a cell, the current switch is in the 1A position. The charger starts with a charging current of 700mA and uses a little bit more from USB. After 10 to 15 minutes the current is down to 500mA. If I had uses the 0.5A ampere setting, the current would have started at 500mA.






The 4Sevens 26650 battery takes about 5 hour to charge.






When charging a LiFePO4 cell with 3.6 volt termination voltage the charger also does a very fine CC/CV profile. It starts slowly, until the battery is raised to 3 volt, then it goes to full charge current. *BUT* it cannot handle the termination, it will terminate at 3.6 volt, but because LiFePO4 cell drops in voltage when charging is stopped, the charger will restart charging again.






The pulses that will reset a protection circuit, measured without a battery in the charger. These pulses are limited to a peek current of around 180 mA.



[size=+2]Conclusion[/size]

This charger follows a CC/CV charging profile and also supports long 18650 cells and a lot of other cell types. This makes this charger a good charger, with only a few small detail, that could have been better. The high termination current does spoil it for cells with smaller capacity and LiFePo4 cells must be removed when they are charged.
For cells with more than 2000mAh capacity it is a very good charger, for cells with smaller capacity the high termination current will cost a few % in charged capacity, but give the cells a longer lifetime.


[size=+3]Notes[/size]

Here is an explanation on how I did the above charge curves: How do I test a charger

Some of the photos are from the V1 review, because I got the replacement charger without accessories.


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## 45/70 (Jun 30, 2011)

I read through the entire review quickly. I think most people could live with the minor problems you mention. With the exception of the LiFePO4 "recharging" problem, I'd say it looks pretty good to me.:thumbsup:

*EDIT:* Almost forgot! Another fine job HKJ, nice work!

Dave


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## jasonck08 (Jun 30, 2011)

Nice job! Looks like a pretty decent charger, probably #2 behind the Pila.

It would have been nice to see the termination current be about 10% of the start current, as recommended by most Li-ion cell companies.

Also the graphs done using USB power look goofy and not really CC/CV.


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## HKJ (Jun 30, 2011)

jasonck08 said:


> It would have been nice to see the termination current be about 10% of the start current, as recommended by most Li-ion cell companies.



I would say 2% to 5% of rated cell capacity.



jasonck08 said:


> Also the graphs done using USB power look goofy and not really CC/CV.


 
That is correct, but the curve is within the CC/CV envelope, i.e. it is slower than possible, but does not go outside any recommendation.


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## 45/70 (Jun 30, 2011)

jasonck08 said:


> ......Also the graphs done using USB power look goofy and not really CC/CV.





HKJ said:


> That is correct, but the curve is within the CC/CV envelope, i.e. it is slower than possible, but does not go outside any recommendation.


 
I was assuming that this was because the cell was nearly fully charged to start with. If so, this would likely represent part, or all, of the CV stage, _only_.:shrug:

Dave


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## HKJ (Jun 30, 2011)

45/70 said:


> I was assuming that this was because the cell was nearly fully charged to start with. If so, this would likely represent part, or all, of the CV stage, _only_.:shrug:



Look at the mAh scale, I do fill in just about the same amount of mAh as in the other curves. You can also see the V scale, I start below 3.6 volt.
The reason for this curve is probably because the current generator needs a bit more than 5 volt to generate full current up to 4.2 volt.


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## sirimaxi (Jun 30, 2011)

Great review!!! Thanks!


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## 45/70 (Jun 30, 2011)

HKJ said:


> Look at the mAh scale, I do fill in just about the same amount of mAh as in the other curves. You can also see the V scale, I start below 3.6 volt.



Ah yes, of course. That's what I get for commenting without looking at the graph again. For some reason, the first time I skimmed through your review, the numbers at the bottom (time) for that particular set, stuck in my head as mAh, perhaps because my CBA II is setup that way. Of course, it may actually be that it is my head, that is the problem. At any rate, I was multitasking at the time, so I'll just use that as my excuse.

Dave


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## brightnorm (Jul 1, 2011)

HJK,

Thank you for this helpful and useful review.

Brightnorm


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## Got Lumens? (Jul 1, 2011)

HJK,
Nice review. Thank You.

I have a question, were any comparisons of the two versions done using the same battery?
I have a 18650 that comes off Version1 charger at 4.19V. When charged using the Version2 it comes off the charger at 4.14V.
I have done two charging cycles from 3.8V-Full charge on each. Does anyone else have a simular experience?
Thanks
GL


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## HKJ (Jul 1, 2011)

Got Lumens? said:


> I have a question, were any comparisons of the two versions done using the same battery?
> I have a 18650 that comes off Version1 charger at 4.19V. When charged using the Version2 it comes off the charger at 4.14V.
> I have done two charging cycles from 3.8V-Full charge on each. Does anyone else have a simular experience?



The AW18650-22 and the AW16340-IMR are the same cells in both tests (These cells are a bit old).
It is no surprise that the final voltage is a bit lower, this is because the V2 stops charging at a higher current.


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## StillRC (Jul 3, 2011)

Just curious - if any one else has noticed the charge time for an 18650 in the V2 charger is any longer in USB mode. I was surprised, it seemed to take allot longer than my V1. I didn't do any state of charge, it just took over a day and a half, the 1st time I used the (v1 charger) it took 5 hrs, in USB mode again.


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## JA(me)S (Jul 4, 2011)

It is time to replace my Wf-139. The new charger will be used to charge protected 18650s almost exclusively (AW & Redilast 2900). If cost isn't a concern, what is the concensus recommendation between Pila and 4Sevens?

Excellent review HKJ - as usual!

- Jas.


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## purduephotog (Jul 4, 2011)

Sigh, so even my hopes of a well branded single cell LiFePO4 charger are dashed.

Are there *any* alternatives out there that don't rhyme with 'hobby charger' ?


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## 45/70 (Jul 4, 2011)

purduephotog said:


> Sigh, so even my hopes of a well branded single cell LiFePO4 charger are dashed.
> 
> Are there *any* alternatives out there that don't rhyme with 'hobby charger' ?



purdue, LiFePO4 cells are so much more forgiving when it comes to charging, that I wouldn't worry too much about what charger you use. Most of the "crap" chargers out there that have LiFe capability will work, OK.

I've been known to use a WF-138 from time to time myself, for 15266 and 17340 LiFe cells, as it's pretty much "plug and play". The only drawback with it, is that it approximates a "Fast Charge" using a hobby charger, that is, it is similar to stopping the charge at C/5 vs. C/10, when the LED(s) turn solid green. This results in a somewhat less fully charged cell, but other than that it works fine. I do not however, charge LiCo cells with it very often, only in a pinch.

Dave


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## samgab (Jul 7, 2011)

Excellent review, as are all of your reviews HKJ. As a result I've just gone and purchased one of these 4Sevens chargers from their website; and despite saying it was going to be on back order, they dispatched it right away. I think it uses a better charging method (CC/CV) than the stop-gap Cytac I have been using for my 14500's and 18650's and at a better price than the Pila, especially when shipping is factored in to New Zealand for a Pila ($40 for the Pila, $30 for the shipping).
Also, I want to thank you for the info about DMM use in your sig-line. It's very informative. I use my DMM a lot anyway, but there were a few uses explained in there that I hadn't thought of.


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## pblanch (Jul 7, 2011)

Anyone else had the extended time taken to recharge via USB. I intended to use in conjuction with a USB battery pack that recharges at 5.5V (3000mah) as per http://www.voltaicsystems.com/amp.shtml when away from power supply and just to do top up charges with my AW2900. And had gotten the 47s vertion as it could do USB. As I havent recieved the charger yet (has shipped) I am now starting to think will it work, and if it draws a higher that 5.5V initailly will it damage the voltaic battery. Any advice/experiance will be welcome.

Thanks for the great review and update.


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## JA(me)S (Jul 7, 2011)

Instead of asking this question in a review thread, should I have posted the query as a separate thread?

- Jas.


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## Got Lumens? (Jul 8, 2011)

Yes. Proper CandlePower etiquette helps everyone:thumbsup:


JA(me)S said:


> Instead of asking this question in a review thread, should I have posted the query as a separate thread?
> 
> - Jas.


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## 45/70 (Jul 8, 2011)

Got Lumens? said:


> Yes. Proper CandlePower etiquette helps everyone:thumbsup:



Oh, I don't know that there's been any violation of etiquette here. JA(me)S question is, at least in part, about the 4Sevens charger. I suppose it would be up to HKJ to determine.

As Far as his original question,



JA(me)S said:


> If cost isn't a concern, what is the concensus recommendation between Pila and 4Sevens?



As I said before, from HKJ's excellent and very detailed (as usual) review, the 4Sevens charger is looking pretty good. That said, it's only been out for a couple weeks or so, and there aren't many people that have them yet.

Also, the Pila has withstood the test of time. I remember when the Yugo was considered as a potential replacement for the VW Beetle, in each and every way, when first introduced. Unfortunately, it failed the test of time. I seriously doubt this will be the case here, but nonetheless, it's a bit early for any long term evaluation.

If I needed a "consumer type, plug and play" Li-Ion charger, I think I would definitely consider this one anyway. The only drawback for me is that it is only a single bay charger, therefore I'd probably be looking at buying two. In this case, for about the same investment, the Pila IBC would appear more attractive to me, due to it's proven track record.

Dave


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## pblanch (Jul 8, 2011)

My appologies to all. I have moved my query to Batteries section.


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## HKJ (Jul 10, 2011)

45/70 said:


> Oh, I don't know that there's been any violation of etiquette here. JA(me)S question is, at least in part, about the 4Sevens charger. I suppose it would be up to HKJ to determine.



The question was fine for me, but I has been on a weeks vacation with a bad internet connection and not been able to do much posting.

I agree with your answer, 4Sevens looks like a good charger, but we need more time to really know it.


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## pblanch (Jul 14, 2011)

Well received mine today. All bits and pieces present. 

Found that something that was rattling around inside the unit. Was a little surprised. I decided not to use the unit in case it was a piece of metal or something. Decided that it would cost more to send back than the unit, so opened it up. Found a 3mm piece of clear plastic in the unit. 

Little disappointed that quality control a little lacking. I hope 4 sevens gets onto the manufacturing and informs them no added extra's apart from those listed.

Haven't powered the unit yet and will charge a battery when my battery is a little lower. 

Will let you all know.


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## samgab (Jul 25, 2011)

Superb work HKJ. I'm glad there are people like you out there who do all this testing that people like me can benefit from. My 4Sevens single bay V2 arrived in the mail today, and I've put it into commission immediately. This must be one of the most affordable consumer "bay" chargers that uses the correct CC/CV method?


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## nobunaga88 (Sep 6, 2011)

Hello,
I just wondering what should i set for my AW 18650 2900mah?
let me say i set it for 1A, then for the best Voltages is it on 3.6V or 4.2V??
what is big deal if i set on 4.2V? is it gonna blow?

Sorry for my Totally noob question...and for my english... 

Thanks Guys :naughty:


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## HKJ (Sep 6, 2011)

nobunaga88 said:


> Hello,
> I just wondering what should i set for my AW 18650 2900mah?
> let me say i set it for 1A, then for the best Voltages is it on 3.6V or 4.2V??
> what is big deal if i set on 4.2V? is it gonna blow?
> ...


 
These batteries (like most LiIon we use here) are ICR or LiCoO2 cells, i.e. you must use 4.2 volt. Using 3.6 volt would not damage the cell, but you would not get any charge in it either. If you charger a 3.6 volt cell on 4.2 volt you might get trouble!

All 18650 batteries can be charger on the 1A setting, the 0.5A setting is for smaller batteries. You can see my table "Supported battery sizes" for some recommendations on current switch setting vs. cell size.


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## nobunaga88 (Sep 6, 2011)

HKJ said:


> These batteries (like most LiIon we use here) are ICR or LiCoO2 cells, i.e. you must use 4.2 volt. Using 3.6 volt would not damage the cell, but you would not get any charge in it either. If you charger a 3.6 volt cell on 4.2 volt you might get trouble!
> 
> All 18650 batteries can be charger on the 1A setting, the 0.5A setting is for smaller batteries. You can see my table "Supported battery sizes" for some recommendations on current switch setting vs. cell size.


 
Thanks HKJ for your Fast reply 

anyway,
i got an email from Ryan from Going****.com, that if i want to match the voltage. So charge the 18650 on 3.6V (On this 47 Charger V2)

in that case, i must charge on 3.6V?
Then you say that i must charge my AW 2900Mah on 4.2V?

i'm Little bit confused here (maybe because my english very poor) 
Maybe i Need 2nd Opinion here 

Greatly Thanks
Kindly Regards


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## samgab (Sep 6, 2011)

You are confused by two different things.
3.6V is the _nominal_ voltage, but you have to _charge_ it at 4.2V.
Have a look at the data sheet for the cell you're asking about.
The answer, as HKJ said, is set it to 4.2V for the AW2900.


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## Stephen Wallace (Sep 6, 2011)

As stated, you will see that LiCo and LiMn cells are marked as having a 'nominal' voltage of 3.6 or 3.7v. Broadly speaking, this refers to a midway point in the cells voltage between being fully charged and discharged. The voltage of the cell is highest when freshly charged, and as the energy in the cell is depleted, the voltage will drop. So, the fully charged voltage will be higher than the nominal voltage. 

The nominal voltage is also round about the voltage that the cell will return to after discharging it, once the load is removed. So for instance, you start with a charged battery, discharge at 1A, and when the cell voltage *under that 1A load* drops to 3v, the discharge is terminated. Without the 1A current draw, the voltage will rise again, despite the fact that the battery is for all intents and purposes drained. If you then installed that cell in a charger set to 3.6v, then the charger would sense that the battery already read at 3.6v, and so would think that the battery were fully charged even though it wasn't. The 3.6v setting is for LiFe cells, which have as lower nominal voltage (normally stated as 3.2v if memory serves), which rises to 3.6v when fully charged. 

As both HKJ and samgab have stated, LiCo and LiMn cells have a nominal voltage of 3.6 or 3.7v, but this increases to 4.2v when fully charged, so you need to use the 4.2v setting on the charger.


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## nobunaga88 (Sep 6, 2011)

i see,,
Now i do really understand... 

Thanks HKJ,Samgab, and Stephen :wave: for enlightment :twothumbs

I Hope 4sevens charger coming soon on dual bay


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## Rexlion (Sep 10, 2011)

I just received my 4Sevens charger and tried it out. Charged 4 IMR 26650 cells from Lighthound and they all terminated at 4.20v or 4.19v. Then I switched the charger to .5A and put in an AW IMR 16340, and it finished at 4.16v. I'm happy with it.

Thanks for the review HKJ!

_Edit:_ This a.m. an older (gray) Trustfire 16340 charged for a while and then the charger began blinking, alternating between red and green lights! Checked the cell, it's at 4.05v. The cell might be getting too old to accept a full charge. But I don't recall seeing any reference to flashing lights anywhere about this charger, so I thought I'd bring it up.


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## tony22 (Sep 11, 2011)

HKJ (and 45/70) what's your sense of the pros and cons of this charger vs. the XTAR MP2? Not counting that the MP2 can do 2 batteries of course.


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## HKJ (Sep 11, 2011)

tony22 said:


> HKJ (and 45/70) what's your sense of the pros and cons of this charger vs. the XTAR MP2? Not counting that the MP2 can do 2 batteries of course.


 
It does follow a true CC/CV charge profile, making it the fastest charger (But only with one battery at a time), but sadly it terminates charging before the battery is full (This is mostly a problem with small cells). If you plan on getting any light with 26650 cells, the 4Sevens also has the advantage, it can directly fit the cell, you do not need to make some sort of connection from charger to battery. The placement and marking of the switch is also much better on the 4Sevens charger. The support for LiFePO4 batteries may also matter to some people.


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## tony22 (Sep 11, 2011)

Thanks. Which one would be a better solution for a proper charging of RCR123?


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## HKJ (Sep 11, 2011)

tony22 said:


> Thanks. Which one would be a better solution for a proper charging of RCR123?


 
For 16340 (RCR123) I would use the WP2 V2, due to its lower termination current.


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## tony22 (Sep 11, 2011)

Okay. I found a U.S. based seller on eBay with perfect Feedback so I just picked one up.


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## 45/70 (Sep 11, 2011)

tony22 said:


> Thanks. Which one would be a better solution for a proper charging of RCR123?



Although it has not been around very long and is basically as of yet, unproven, as it stands now, I would pick the 4Sevens charger, regardless of the termination current.

The XTAR just has too many "quirks" for my taste. The XTAR chargers are improving, and are probably better than most "consumer type" Li-Ion chargers out there, but IMO, they still "ain't quite right". They appear to use many "shortcuts" to achieve a charger that "almost" qualifies as a proper charger. Maybe someday......

Dave


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## tony22 (Sep 11, 2011)

Well, I like the idea of being able to do two batteries at once so I'm going to give the XTAR a try. I was also just a little concerned about the data seeming to indicate the 4sevens didn't quite get the battery up to it's full specified voltage (I guess because of the higher termination current?). Why can't anyone get one of these things right?


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## Acid87 (Sep 11, 2011)

Sold. I've always been a bit wary/lazy with Li ion cells this makes it easier so think I'll maybe pop on one. Only downside by the sounds is the charging of RCR123s.

Cheers for the review HKJ as usual


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## 45/70 (Sep 11, 2011)

tony22 said:


> Why can't anyone get one of these things right?



Heh, I've been asking this question for years. The only proper "consumer type" chargers that have come about so far, are the Pila IBC, and it looks like the 4Sevens. Neither one of them are perfect, but are very close.

A few years ago I was told by those with more expertise in electronics than I, that it would actually be easy and not cost all that much to make a charger that worked as the Li-Ion cell manufacturers recommend. I had originally suggested that it might be more expensive to make one, but they all said no, it wouldn't. Now they are suggesting that a charger that charges cells using the proper algorithm would be too cumbersome and expensive. So anyway, I'm not sure which is correct, but I would prefer a charger that charges cells properly, regardless of the cost.

I think you'll be fine with the XTAR. As I mentioned before though, it (they) just has too many "quirks" for me. I think the cost cutting measures must have something to do with this. It seems though that if you did away with the whole voltage checking thing, which is not part of a proper charging algorithm, nor even necessary, that you could come up with a charger that actually worked correctly, for the same cost. Then again, maybe not.....:shrug:

Dave


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## 45/70 (Sep 11, 2011)

tony22 said:


> I was also just a little concerned about the data seeming to indicate the 4sevens didn't quite get the battery up to it's full specified voltage (I guess because of the higher termination current?). Why can't anyone get one of these things right?



I should have mentioned this, there is no specified charged voltage for any type of Li-Ion cell. There is only a maximum voltage specification which the cell may be exposed to during charging. For LiCo and LiMn cells, this specification is 4.20 Volts +/- 0.05 Volt (or +/- 1%). This is a common misunderstanding here on the Forum.

In the case of LiCo cells, _they are not supposed to be charged to 4.20 Volts_. In fact, unless the cell is very new and mostly unused, a charger that charges cells to 4.20 Volts, is likely a charger using an improper charging algorithm. Also, this type of charger is harder on cells, as this overcharging causes unnecessary damage, particularly to older cells.

Dave


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## Black Rose (Oct 18, 2011)

Thanks for the review and information on this charger. Just ordered one.


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## ALWZWFO (Oct 20, 2011)

I just rececently recieved two 4sevens chargers and charged up 3 different fairly new AW17670's. Both chargers CV phase was 4.24 volts at the end of the charge. Batteries read 4.21 volts hot off the chargers. I tried 0.5A and 1.0A with nearly the same readings. This is basically what my WF-139 does voltage wise, so no improvement there. I had to raise up the rear of the batteries to the upper knob to make contact, a little effort required as the slider spring is pretty strong. Obviously it is much speedier than my 139, even at the half amp setting. I got one to keep up at my vacation cabin so I wouldn't have to lug a charger up with me every trip. I really got these hoping they would be closer to 4.20 volts. I was hoping one would be ok, Should I live with the shortened battery life? I could have gotten another 139 for a third the price. My 18650 lights are up at the cabin, so I couln't test the batteries fit or voltage.

(Measured with Fluke 87V)


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## HKJ (Oct 20, 2011)

The usual manufacturer specification says 4.2 volt +/- 0.05 volt, i.e. 4.24 volt is within acceptable limits.

But the big difference between WF139 and 4Sevens is not the voltage, but the way it charges, the WF139 does always force batteries to 4.2 volt, the 4Sevens uses a voltage of 4.2 volt, but stops charging when the current is below some limit.
This difference in charging methode will be more obvious with older cells, the WF139 will charge them to 4.2, the 4Sevens will not.
You can try comparing the charge curves around the yellow line (Where the charger turns of) and you will see the difference, especially if you compare the curves for my old 16340 imr cell. The WF-139 review is here.


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## light36 (Oct 20, 2011)

*Thanks HKJ , your review has been very helpfull . Keep up the good work !! .*


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## ALWZWFO (Oct 20, 2011)

HKJ said:


> The usual manufacturer specification says 4.2 volt +/- 0.05 volt, i.e. 4.24 volt is within acceptable limits.
> 
> But the big difference between WF139 and 4Sevens is not the voltage, but the way it charges, the WF139 does always force batteries to 4.2 volt, the 4Sevens uses a voltage of 4.2 volt, but stops charging when the current is below some limit.
> This difference in charging methode will be more obvious with older cells, the WF139 will charge them to 4.2, the 4Sevens will not.
> You can try comparing the charge curves around the yellow line (Where the charger turns of) and you will see the difference, especially if you compare the curves for my old 16340 imr cell. The WF-139 review is here.



I am aware the max recommended voltage is 4.25. I think my 4sevens chargers will force older batteries to at least 4.22 volts, as that is where the voltage slowed climbing as the CV stage seemed to kick in, especially at 0.5A setting and continued climbing, maybe not to 4.24 with an older cell though. I was hoping for more battery life at the approximate 4.21 terminating volts which your graph shows.


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## Black Rose (Oct 25, 2011)

ALWZWFO said:


> I just rececently recieved two 4sevens chargers .


What version are yours?

I received one yesterday and it was version 3 (V3).


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## Stephen Wallace (Oct 25, 2011)

I had a couple a V2 chargers, but one broke - the post to which the sliding negative terminal's spring was attached snapped. The replacement I was sent was a V3. Not used it enough to tell if there is really any difference in performance, but one obvious difference is that the power supply has changed. The new power pack has 5v, 1.5A output, rather than 12v 1A.


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## Black Rose (Oct 26, 2011)

As I mentioned in the V3 thread, the V1 and V2 chargers both used 12.0v 1.0A inputs and the wall wart and car charger provided the same power.

The V3 charger uses 5.0V and 1.0A input and the wall wart and car charger have been updated to produce reduced voltage (5.0V 1.5A) for the V3 charger.

I would assume that the wall warts and car chargers from V1 & V2 cannot be used with the V3 charger.

You'd risk a  of the charger itself feeding 12.0V into a device only expecting 5.0V.


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## ALWZWFO (Oct 26, 2011)

Both of mine are V3


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## snakyjake (Oct 28, 2011)

HKJ said:


> For 16340 (RCR123) I would use the WP2 V2, due to its lower termination current.



Between the WP2v2 and 4Sevens, what differences will I notice charging and running 16340 (RCR123) and 18650? Or the Pila?

If I interpret the graphs correctly:
*16340 (RCR123):*
WP2v2 ~ 310 mAh
4Sevens ~325+ mAh
I would presume 4Sevens would give a longer runtime, but not sure what 15 mAh translates into actual runtime. 

*18650:
*WP2v2 ~1750+
4Seven ~1750+
Tie.

I'm leaning towards 4Sevens because of the simplicity. Because of safety concerns, I don't charge use multiple cells, so singe bay is good. Plus I don't need spacers to lose with 4Sevens. 

Jake


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## HKJ (Oct 28, 2011)

snakyjake said:


> If I interpret the graphs correctly:
> *16340 (RCR123):*
> WP2v2 ~ 310 mAh
> 4Sevens ~325+ mAh
> I would presume 4Sevens would give a longer runtime, but not sure what 15 mAh translates into actual runtime.



Charging of a LiIon is useal done in two phases, a CC (constant current) where the current is constant (Big surprise ).

Followed by the CV (Constant voltage) where the current is slowly reduced, while the voltage is constant. This phase can easily take an hour, but the actual time depends very much on the final current, how much energy you get into the battery also depends on the final current. A low final current will take a long time and fill more energy into the cell.

Usual the LiIon cell manufacturers recommends a final current about c/30 to c/50, i.e. capacity divided by 30 to 50, that would be 2500/50 to 2500/30 or 50 to 83 mA for a 2500 mAh cell. A higher termination current will not have any bad effect on the cell, but will not fill it completely. 

For 16340 cells both the chargers has a rather high termination current, the 4Sevens much higher than WP2, i.e. you will get more energy into the cell by using the WP2.


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## snakyjake (Oct 28, 2011)

HKJ said:


> ...you will get more energy into the cell by using the WP2.



How does that translate into mAh or runtime (perhaps from a benchmark flashlight that you have)?
Am I losing seconds, minutes, lots of minutes? 
AW16340 is 750mAh...how many amp hours do I lose with 4Sevens vs. WP2?


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## HKJ (Oct 28, 2011)

snakyjake said:


> How does that translate into mAh or runtime (perhaps from a benchmark flashlight that you have)?
> Am I losing seconds, minutes, lots of minutes?
> AW16340 is 750mAh...how many amp hours do I lose with 4Sevens vs. WP2?



Probably only a few percent (i.e. less than 10%).
I am thinking about doing some tests for this, not with a specific charger but more generally, but it will have to wait until my new automatic battery test system is ready.


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## snakyjake (Oct 28, 2011)

Still trying to make the right interpretations of the graph...

Capacity for 16340 for Xtar is ~310 mAh.
Capacity for 16340 for 4Sevens is 325 mAh.

325 > 310 = 4Sevens > Xtar = 4Sevens charges to higher capacity.

Other observations: 4Sevens charges faster. Test shows 4Sevens charging at 1A instead of 0.5A like the manual recommends.


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## HKJ (Oct 28, 2011)

snakyjake said:


> Still trying to make the right interpretations of the graph...
> 
> Capacity for 16340 for Xtar is ~310 mAh.
> Capacity for 16340 for 4Sevens is 325 mAh.
> ...



With chargers that is pulsing the charge current, there is a high tolerance on the summation of the charge current, i.e. you cannot trust the mAh for the Xtar. Even if it is corrent, a 15 mAh differens might be due different starting conditions on the cell (I do always discharge the cell to 3 volt at 100 mA, before starting the test, but depending on rest time from discharge to charge test the cell will recover some mAh).

I uses this cell to see if the charger does "funny" thing while charging, i.e. how does it handle the termination current and voltage. Because it is an IMR cells it can easily take the 1A charge rate (it is rated for up to 1.5 A charge rate).

Because the tested WP2 has a lower termination voltage than the 4Sevens, the 4Sevens might put more energy into the cell, than the WP2 in my test, but looking at the cell voltage 10 minutes after termination of charge, it looks to be about the same, i.e. same amount of energy in the cell.

Not all WP2 has the lower termination voltage and if it has same termination voltage as the 4Sevens, it will put more energy into the cell (due to the lower termination current).


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## snakyjake (Dec 1, 2011)

Does the charger have reverse polarity protection, like Pila?

Any issues if I charge a 3100 mAh capacity battery at 0.5 amps, instead of 1.0A?

...just how smart is a smart charger?


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## HKJ (Dec 2, 2011)

snakyjake said:


> Does the charger have reverse polarity protection, like Pila?



I do not test for it and according to 4Sevens specifications it does not look like it has it.



snakyjake said:


> Any issues if I charge a 3100 mAh capacity battery at 0.5 amps, instead of 1.0A?




The charge will take longer time, but because the termination current is the same, you will get the same energy in the cell.



snakyjake said:


> ...just how smart is a smart charger?



I would say it is about average for a good cradle charger. To get a really smart charger you need a hobby charger.


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## BrittOmnRex (Dec 28, 2011)

Hello,
I'm totally new to this, but I received this charger for Christmas, along with some AW RCR123A batteries.

I have a question, and I've tried to find an answer on the forums, but didn't have much luck.

I see the recommendation to charge on the 0.5A setting, but what happens if the switch were to be set to the 1.0A setting? Could it cause damage to the battery or to my charger?

Thanks for any help that can be provided!


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## HKJ (Dec 29, 2011)

BrittOmnRex said:


> Hello,
> I see the recommendation to charge on the 0.5A setting, but what happens if the switch were to be set to the 1.0A setting? Could it cause damage to the battery or to my charger?



Using to high charge rate (i.e. 1A on 16340) will increase the wear on the battery and in extreme cases it might make the battery exploded.


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## BrittOmnRex (Dec 29, 2011)

HKJ said:


> Using to high charge rate (i.e. 1A on 16340) will increase the wear on the battery and in extreme cases it might make the battery exploded.



Many thanks for that answer. I was afraid that was what could happen, so I'll be sure to double-check the switch every time!


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## jayflash (Jan 21, 2012)

Two questions: Will this charger support AAA 10440 LiIon cells? It wasn't in the list.

Is .5A too high a charge rate for that small cell?

Thanks!


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## HKJ (Jan 21, 2012)

jayflash said:


> Two questions: Will this charger support AAA 10440 LiIon cells? It wasn't in the list.
> 
> Is .5A too high a charge rate for that small cell?
> 
> Thanks!



A 10440 will fit in the charger, but the charge rate is to high. 
Charging 10440 in the charger will probably reduce the lifetime of the batteries and will slightly increase the risk for accidents.
Due to the high termination current of the charger, the battery will not be completely filled!


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## jayflash (Jan 22, 2012)

Thanks HKJ. Have you any preferences for charging small LiIon cells? Is the best charge rate .5C or less. If charge time isn't a constraint will a low charge rate result in longer cell life without other negative effects?

I may still consider the 47 unit if it'll charge to about 90% and let the cells live for a couple years. I don't recharge often.

Once again, thanks for your time and help.


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## HKJ (Jan 22, 2012)

jayflash said:


> Thanks HKJ. Have you any preferences for charging small LiIon cells? Is the best charge rate .5C or less. If charge time isn't a constraint will a low charge rate result in longer cell life without other negative effects?
> 
> I may still consider the 47 unit if it'll charge to about 90% and let the cells live for a couple years. I don't recharge often.



When charging there are 3 parameters that is important, maximum charger current, termination current and charge voltage. Voltage is seldom a problem, most cells needs 4.2 volt.
For the small batteries I usual uses a hobby charger where I can adjust the charge rate and the termination current is 1/10 of the charge rate.
You can also get a CottonPickers charger, I have looked at one of the larger models, but a smaller model can easily be used.

For charge rate I would go after 1C or lower, using 0.5C is probably a good idea, but you have to watch the termination current, it is probably not a good idea if it gets below 0.01C (The usual rating is between 0.02C and 0.05C).


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## DavidMB (Jan 26, 2012)

Will a cell be damaged if its left in the charger after the light is green and it's finished charging?


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## HKJ (Jan 26, 2012)

DavidMB said:


> Will a cell be damaged if its left in the charger after the light is green and it's finished charging?



Usual not, but small or old cell might wear down faster, this has to do with the automatic restart of the charger. If you can see the charger starts charging again (i.e. change to red), it is a extra bad idea to leave the cells in the charger.


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## 45/70 (Jan 26, 2012)

Hi David. For reasons as HKJ suggested, as well as others, it is never a good idea to leave charged cells of _any_ chemistry in _any_ Li-Ion charger designed for charging individual, or "loose" Li-Ion cells. This is not the same as charging your cell phone, or a laptop.

The margin of safety when charging loose Li-Ion cells (a practice not supported by Li-Ion cell manufacturers) is at a much lower level, and in a whole different league than that encountered when charging a laptop. It is recommended to always monitor the charging of loose Li-Ion cells closely, and remove cells from the charger as soon as the charge is complete. This applies whether you are using a $350 Schulze, or a $6 DSD charger.

As far as the answer to your question, technically, yes you can, but it's a bit like carrying a single action auto pistol "cocked", _but not_ "locked". Don't do it. If using a good charger, probably nothing will happen to the cell. This is true also of the pistol, but......

Dave


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## snakyjake (Jan 26, 2012)

I think the main reason for not leaving the cells in the charger is because the charger may be trickle charging or the green light might run the battery down over long periods....right?


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## 45/70 (Jan 26, 2012)

Hi Jake. That's probably two of the primary reasons, yes. On the other hand, you have to look at charging loose Li-Ion cells as still being in the experimental stage, which it is, actually. As I've said, Li-Ion cell manufacturers do not approve of nor sell Li-Ion cells to consumers. This is for liability reasons. There are just too any things that can/could go wrong, not to keep a close eye on the charging process of loose Li-Ion cells.

Dave


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