# Best rechargeable CR123A with 3V?



## rayman (Jun 11, 2008)

I searched the whole day for rechargeable for a Fenix P2D and now the only thing that I found out is that I only can use RCR123As with 3V otherwise I can only use the turbo mode. As I want to use it as a EDC flashlight I want to have all modes available.

I also found this possibilities:

Soshine 3.0V CR123A
with the
UltraFire 3.0V/3.6V CR123A Charger

or

4 Pack RCR123A 3.0V 900mAh Rechargeable Li-Ion Battery with Smart Charger

or

2 RCR123A 3.0V 750mAh Rechargeable LiFePO4 Li-Ion Batteries with AC/DC Smart Charger

The first combination was recommended on www.light-reviews.com. And what is it all about with the 'LiFePO4'?
So which one is the best for the P2D? Or do you have other rechargeable batteries which you can recommend me?

rayman


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## mdocod (Jun 11, 2008)

LiFeP04 will be the most reliable format with the lest capacity.
The voltage regulated versions (pretty much any 3.0V rechargable that does NOT mention LiFeP04 in the name or description or specifications) will usually have slightly better runtime, but have more components that can go wrong. (protection circuit, and voltage regulator, and all those connections in-between).

When it comes to rechargeable options for the P1D/P2D, the questions is not what's better, it's what's less bad.


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## rayman (Jun 11, 2008)

mdocod said:


> LiFeP04 will be the most reliable format with the lest capacity.
> The voltage regulated versions (pretty much any 3.0V rechargable that does NOT mention LiFeP04 in the name or description or specifications) will usually have slightly better runtime, but have more components that can go wrong. (protection circuit, and voltage regulator, and all those connections in-between).
> 
> When it comes to rechargeable options for the P1D/P2D, the questions is not what's better, it's what's less bad.



That does'nt sound very good . So the best would be the third option with the LiFeP04?

rayman


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## mdocod (Jun 11, 2008)

I don't know if I would call it the best option, but if I were in your shoes, I would go with the LiFeP04 cells because, while they may have pretty low capacity, they are hardy cells that can handle a lot of cycles and abuse. They are also very safe (they won't flame/explode). Li-ion in general has a pretty good track record, but taking a LiFeP04 over a LiCo02 (standard li-ion) in a situation where the LiFeP04 is a comparable option, is a good decision. Just try not to over-discharge em too often and you'll be fine. Charge frequently to prevent over-discharge. They do not need to be "deep-cycled" or anything. 

Oh, FYI: The label capacity of 750mAH is not true, expect around 300-400mAH at best. The "900mAH" listed on the other version is also untrue, they are probably closer to 500-600mAH.


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## flashy bazook (Jun 11, 2008)

I've used the LiFePo4's with the Fenix P2 and they work fine (other than the relatively low capacity issue).

The biggest problem is that they are unprotected.

I lost one pretty quick when I used it in a flashlight which is a 2x123A's, and found out that the batteries weren't working well in series. One was being drained but not the other one, with the result that the one that was being drained was driven down to near zero pretty quick and could not be revived by any means I could think of (and I experimented with a few).

Of course, the P2 doesn't have this particular problem but you still need to be careful with unprotected batteries and regulated lights.


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## rayman (Jun 12, 2008)

thank you both,

so the do I overdischarge them if the light is dimming?

rayman


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## Blindasabat (Jun 12, 2008)

As SOON as the light begins to dim or will not support the highest level, recharge IMMEDIATELY. Actually, it is best to recharge them after you think you have used them for more than 20 minutes on a high setting or a couple of hours on a low setting. Just recharge them a lot.


rayman said:


> thank you both,
> 
> so the do I overdischarge them if the light is dimming?
> 
> rayman


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## rayman (Jun 12, 2008)

Blindasabat said:


> As SOON as the light begins to dim or will not support the highest level, recharge IMMEDIATELY. Actually, it is best to recharge them after you think you have used them for more than 20 minutes on a high setting or a couple of hours on a low setting. Just recharge them a lot.



So it doesn't matter if I recharge them a lot? It's only not good if I discharge them?

rayman


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## mdocod (Jun 12, 2008)

The rule applies to most rechargeable cells, with the exception of NICDs (sometimes). You don't want to drain them down to the point that they are *way* below their normal voltage range as it causes internal hemorrhaging, so to speak. You wouldn't want to repeatedly put it on the charger if it hadn't been used any either as that would be wasteful "topping" of the cell that would just wear it out. But topping up frequently is far more healthy for these cells than allowing them to over-discharge.


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## Niconical (Jun 12, 2008)

I've been reading various threads lately on rechargable CR123A. At first I didn't think I'd use any as it seemed complicated and I didn't want to lose the lower settings on the light. 

As far I know, regulated means the battery will cut out when it drops to a certain voltage, to stop it being over discharged, and you then need to charge it to reset that. What I don't really know is what protected means. Is it the same thing as regulated?

With that in mind, is it possible to get 3volt regulated and/or protected CR123A? 

I have looked in the MarketPlace threads for AW as they seem to be recommended all the time. The problem is that every time I read about rechargables over here, then go to that AW sales list, I just get daunted by all the numbers. 

I dont really mind about low capacity, I just want a 3volt CR123A that I can Charge, use a little, charge and repeat, without having to worry about draining the battery too low or anything else that can go wrong. 

If someone could tell me which ones to get and which charger, I'd be grateful. 

Thank you


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## mdocod (Jun 12, 2008)

Hi Niconical
Hopefully this will help clear up some confusion.

1. Protection circuitry can be found on many LiCoO2 cells. This circuit prevents the overcharging and over-discharging of the cell by opening the circuit when the voltage goes "out of bounds" so to speak (usually somewhere around 2.75V and 4.3V). Protection alone does not alter the voltage of the cell in any dramatic way. It is still, for all intents and purposes, going to be a 3.7V cell. 

2. Voltage "regulation" circuitry can be found on some RCR123 size (16340) LiCoO2 cells. It's basically just a diode, or configuration of a few diodes, that "knocks" the voltage down by ~0.7V, resulting in operating voltages *closer* to 3.0V. 

#1 and #2 above can be found in conjunction on some RCR123 size cells. 

Here's an example of a 3.7V LiCoO2 cell that has both #1 and #2 installed on it:
http://www.batteryjunction.com/rc390reliba.html

My personal feelings about cells like this is negative for several reasons:
A: The cell size has to be sacrificed to make room for the extra electronics, reducing available capacity. So the actual cell within is not the size of a CR123, but several mm shorter. This is sort-of a moot point because these types of cells still generally have slightly more capacity than a LiFeP04 cell. 
B: More components to fail: PCBs don't have the greatest track record in general, especially those on the cheaper brands of cells (like tenergy/ultrafire/superfire/trustfire/etc). Then stack another component (the voltage regulator) into the mix, and you have multiple failure opportunities before the power ever makes it to the flashlight.
C: The voltage regulator in the cell is not a 100% efficient device, no component ever is. Expect 15% or more of the available power to be wasted as heat in this component. Heat and Li-Ion cells do not mix well, so IMO, this is a poor arrangement. I have not heard of any cells like this exploding, but just going on my general gut instinct, I don't see this as a *good* setup.
D: The charger required to charge this type of cell actually has a 4.4V output. The reason for this, is to overcome the voltage regulators effect on the circuit in reverse. (Li-Ion cells are supposed to be charged to 4.20V, no higher). If for some reason the circuit in the cell were to short out and allow the charger direct access to the cell, the cell would likely explode/vent/leak. The other problem I see with this, is it can create additional confusion for owners of multiple types of RCR123 cells. Putting a standard 3.7V cell into the "3.0V" charger designed for these voltage regulated cells, would probably cause the cell to vent as it overcharged it. 

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Anyways, having said all this, lets get back to one of the original points you brought up:


> I dont really mind about low capacity, I just want a 3volt CR123A that I can Charge, use a little, charge and repeat, without having to worry about draining the battery too low or anything else that can go wrong.



As you may be able to deduce from the points made above, the possibility of having a cell that you simultaneously don't have to worry about over-discharging, while at the same time, not have anything else go wrong, is an exercise in futility as you kind of have to decide to have one or the other. My personal feeling is that, with user responsibility, a bare LiFeP04 cell (non-protected) is a safer choice with less potential for failure. However, if you think you might be forgetting to top up the cells a lot, it might be a smarter investment to go with the protected/regulated cells. 

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I see you have a list of various lights in your signature line that you are probably interested in running rechargeables in. Your collection represents a very common situation people run into after becoming a flashaholic, and that is, that there is not good solution to make everything rechargeable without getting specific sets of cells and chargers for different types of lights. 

The fenix lights you have would all run fine on any 3.0V rechargeables you decide on, but the TK10 would run better on a pair of 3.7V protected cells as it will accept the higher voltage without any problems, The combination of higher voltage and higher capacity available in the protected 3.7V cells would net better runtimes.


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## Niconical (Jun 13, 2008)

*To mdocod...*

Thanks for all that. Not only have you answered my questions, you’ve given me more than I needed, which has now moved me from just “tell me what to buy and why” up to “I’m gonna learn more to make my own choices”. 

Of course, this therefore means I have even more questions, if you don’t mind. 

So. Protected. The charger won’t overcharge it, and when it’s in a light and it drops to a certain voltage it will cut off so as to not damage itself. It will however be at 3.7v or even more when fresh from a charger. I won’t have access to the lower settings on a multilevel light. 

Regulated. It will operate at 3v, apart from a few milliseconds of first use while the regulation kicks in. However, if you let that voltage drop too much, it will damage or ruin the battery. I will have access to the lower settings on a multilevel light. 

In your reply above you linked to some batteries that are both regulated and protected. You also mentioned further on that...
_“the possibility of having a cell that you simultaneously don't have to worry about over-discharging, while at the same time, not have anything else go wrong, is an exercise in futility as you kind of have to decide to have one or the other.”_ 
I have to be honest and say that I still don’t really understand that. If it’s regulated I can’t damage the light, and if it’s protected I can’t damage the battery, so what else is there to go wrong? I will freely admit though that there is no doubt a lot more to it, and I will hopefully learn more about the why and how in the future. 

There is also another aspect that I don’t understand. I have read numerous references about single CR123A lights being a lot brighter when used with a 3.7v rechargeable instead of a 3v primary. My understanding is that the LED needs 3.6v (correct me if I’m wrong) to function. The circuit in a single battery light therefore boosts the 3v up to 3.6v to get the LED to work. Assuming that’s true, why then is there such a big difference when using a 3.7v battery? If a light using a primary is running the LED at 3.6v, how much difference can an extra 0.1v make, and why do I see these claims of them being much brighter with rechargables?

Moving on to my situation. For reasons of who will use the lights, where and how, it would be good for me to have regulated 3v batteries for the P2D, and unregulated but protected batteries for the Romisen. This is because I don’t want to lose the lower settings on the Fenix, and the Romisen only has 1 setting anyway so nothing to lose. Based on what I wrote above about the difference between a 3v primary and a 3.7v rechargeable, I assume the Romisen will therefore be brighter, but as mentioned, I still don’t understand why. 
Although I’ve written a lot here (sorry about that BTW, I’m sure you all have better things to do, but if you’re reading it in daylight hours, at least I haven’t wasted good flashlighting time), I only really have 3 main questions, and here they are...

1. P2D with regulated batteries, not protected. Good for me, 3v, keeping my lower settings, but be careful not to over discharge. However, other than me needing to be careful not to over discharge the battery, what is the downside? I know there must be one, I’m just not really sure what it is. 

2. Romisen with protected batteries, not regulated. Good for me, don’t have to worry about over discharging, and there are no lower settings to lose anyway. Again, same question. What’s the downside?

3. I’ve read that some rechargeables are slightly longer. Is there a way to tell before, or do I just have to look for brands that others have confirmed are a fitting length for my lights?

For the first 2 questions when I ask “what is the downside” I mean purely from a safety point of view. I don’t know much about batteries, but I do understand words like vent, explode, overheat, leak, etc. Any downside that involves more cost to get the batteries, or less capacity in them, isn’t such an issue, it’s those worrying words I want avoid, not cost or low capacity. 

Finally, encompassing all that I have written, my requirements and the safety aspects. I read that LiFeP04 is a lot safer than other forms of lithium rechargeable, but with a lower capacity. I’m no doubt over simplifying things, but can I not just get batteries that are LiFeP04, _AND_ regulated, _AND_ protected, even if they do have a low capacity?

Well, that’s all, thanks again for your time. 

*EDIT: I've just seen some more info in another thread you replied to. *
*It relates to the LiFePO4. You wrote....*

_they are closer to the operating voltage of CR123 primary cells, so can often act as direct replacements for CR123 primaries in devices that don't tolerate the higher voltage of LiCoO2 cells. they are "safe" chemistry cells, they can be abused, overcharged, over-discharged, overheated, punctured, smashed, etc, without much risk of flame or explosion.......The simplicity of the LiFeP04 cell, even though it has less capacity, is often worth the tradeoff for it's reliability."_

I think that answers my final paragraph. LiFPO4, near 3v, can't be overcharged or discharged. As far as I can tell, they're the ones for me, but please do feel free to correct me if I'm wrong!

*Sorry, 1 more edit:* In the other thread you replied to I looked at the LiFePO4 you linked to. They state “Discharge cut-off voltage: 2.2V”. They also state “Please never overdischarge battery below 2.2V/cell”. 

What am I missing? “cut off voltage at 2.2V”. How can you discharge it lower than 2.2V if it cuts off at 2.2V? I know I’m missing something, but I just don’t know what. 

OK, no more edits now....


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## rayman (Jun 13, 2008)

Niconical said:


> Finally, encompassing all that I have written, my requirements and the safety aspects. I read that LiFeP04 is a lot safer than other forms of lithium rechargeable, but with a lower capacity. I’m no doubt over simplifying things, but can I not just get batteries that are LiFeP04, _AND_ regulated, _AND_ protected, even if they do have a low capacity?



I'm relativly new in this forum. But as I told you before I search for some reachargeable CR123As for the P2D for some days now. All I know is that there are no CR123As that are LiFeP04, _AND_ regulated, _AND_ protected, unfortunatley . At the moment I think I'm going to buy this.

rayman


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## mdocod (Jun 13, 2008)

Hi Niconical!
I'm going to quote sections of your reply to respond to reach individually as best I can..



> So. Protected. The charger won’t overcharge it, and when it’s in a light and it drops to a certain voltage it will cut off so as to not damage itself. It will however be at 3.7v or even more when fresh from a charger. I won’t have access to the lower settings on a multilevel light.




I should clarify this further. 
A protected cell prevents the voltage of the cell from being pushed dangerously out of bounds, but does not protect it from accelerated wear that can occur with minor overcharging or over-discharging. Ideally speaking, charging should be terminated at or below 4.20V, charging as high as 4.30V is usually *safe* on a new healthy cell, but it will DRAMATICALLY reduce the number of charge/discharge cycles the cell will last. Some cheap chargers are known to charge to above 4.20V if the cells are left on the charger too long. Even after the light goes "green" many of these chargers continue to trickle charge the cell, which is bad for li-ion. Ideally speaking, discharging should be terminated at ~3.0-3.5V under a load, depending on the severity of the load in question. The built in protection will allow the cell to be dragged down to ~2.5-2.75V in most cases, which, in a slow drain device, or a device set on "low," can result in open circuit voltages down around or below 3.0V, which isn't all that great for the cell. (but isn't really dangerous).

A bare unprotected cell, could be dragged down to well below 1V with the regulation circuitry found in many lights, this would almost certainly spell the death of the cell. If not on that cycle, within a few cycles. Trying to recharge a cell that has been repeatedly over-discharged can cause explosion. The protection is there to keep things safer, but not necessarily "perfect."

As far as having access to multi-levels on a multi-level light, it depends on the light itself. The P1D and P2D will loose those lower settings as the driver basically goes into "direct drive" mode when the voltage of the cell is higher than the voltage needed to accomplish the desired level of operation. There are a number of multi-level lights on the market that will operate from 0.9-4.2V and still run in low modes properly.



> Regulated. It will operate at 3v, apart from a few milliseconds of first use while the regulation kicks in. However, if you let that voltage drop too much, it will damage or ruin the battery. I will have access to the lower settings on a multilevel light.



In this case, on P1D/P2Ds, the reduced voltage of the cell should give access to all modes, though the lowest settings may behave slightly different than they do on a CR123 as these 3.0V regulated cells still tend to run higher voltage than their primary brothers. Under a load, these often still deliver 3.2V give or take, while CR123s generally deliver ~2.5-2.75V under a load. 



> In your reply above you linked to some batteries that are both regulated and protected. You also mentioned further on that...
> “the possibility of having a cell that you simultaneously don't have to worry about over-discharging, while at the same time, not have anything else go wrong, is an exercise in futility as you kind of have to decide to have one or the other.”
> I have to be honest and say that I still don’t really understand that. If it’s regulated I can’t damage the light, and if it’s protected I can’t damage the battery, so what else is there to go wrong? I will freely admit though that there is no doubt a lot more to it, and I will hopefully learn more about the why and how in the future.



What I meant by this, is that, those extra components within the regulated/protected cell, are more possible failure points. So while they are supposed to "protect" you from anything "going wrong" if they themselves "go wrong" then something has gone wrong. Point being that the cell with the most complexity has the most opportunity to fail in some way or another. 



> There is also another aspect that I don’t understand. I have read numerous references about single CR123A lights being a lot brighter when used with a 3.7v rechargeable instead of a 3v primary. My understanding is that the LED needs 3.6v (correct me if I’m wrong) to function. The circuit in a single battery light therefore boosts the 3v up to 3.6v to get the LED to work. Assuming that’s true, why then is there such a big difference when using a 3.7v battery? If a light using a primary is running the LED at 3.6v, how much difference can an extra 0.1v make, and why do I see these claims of them being much brighter with rechargables?



Every LED is different. to say they they need 3.6V to run is a gross generalization. For years around here we have talked about the "LED Lottery," we used to call it the "Luxeon Lottery" when Luxeon was the only big game in town for high power LEDs. 

What I mean by lottery here, is that not every LED requires the same voltage. If you had 10 Q5 emitters in front of you, and you wanted to run 700mA across each of them in a different device, every one of them would require a different voltage to achieve this current. 

Regulated lights, like the P1D, do not regulate based on voltage at all, they shoot for a particular forward current across the diode. They automatically, instantly, ramp voltage (up or down, depending on the light and power source available), to whatever voltage is needed to maintain that set current. As the LED warms up and cools down that voltage requirement changes some. As the LED ages, it changes some, but the driver is always shooting to meet a certain current goal, and just modifies voltage to achieve this goal.

The voltage required to achieve a particular common forward current, is called the "Vf" of the LED. LEDs within certain ranges of Vf are grouped together and sold as a particular part number. This is known as the "binning" of the LEDs. You'll find long part numbers used to describe an LED, one section of that part number describes it's color tint, one part describes it's Vf, another part might describe what family of LEDs it belongs to, while another part describes it's luminous intensity range when driven to specified forward current. 

Anyways, the point being, that if you buy a bunch of P1Ds all at different times, you are likely to have a wide variety of LED Vfs in the batch. If one of them requires 3.5V to achieve 700mA (or whatever the "high" setting on a P1D is), and another requires 3.7V, then the amount of "overdrive" would be much different for these two lights when driven by the same 3.7V cell.

Keep in mind, that a 3.7V li-ion cell, actually comes fresh off the charger at 4.20V, under the load of direct driving a LED, the voltage of the cell will sag and find equilibrium with the LED at some forward current. For the 3.7V Vf LED, that might happen at 3.85V with a overdriven forward current of 1100mA. For the 3.5V Vf LED, that might happen at 3.75V with a forward current of 1800mA. In the case of the 3.7V Vf LED, the overdrive would probably be pretty tolerable provided it wasn't run for excessive lengths of time, while the 3.5V Vf LED would probably suffer more substantial damage from heat even in the short term. Knowing which Vf LED you have is only possibly by running your own tests on the LED with a good bench power supply and a good amp meter.

So, back to the original question, how much could that 0.1V difference really have on the LED?
Sometimes, a LOT. Diodes are not like regular resistive loads. Increasing the voltage even SLIGHTly on a semiconductor can have dramatic effects on current flow. For most popular high current LEDs like the Crees, 2.5V is not enough to get hardly any electrons to flow across the diode, while increasing to 3V will start to get a few flowing, increasing to 3.5V will get a LOT flowing, and 4V+ will often allow so much current to flow (several amps) that it will fry the LED. The behavior of semi-conductors as it is related to voltage input is measured on a logarithmic scale, not linear. 



> Moving on to my situation. For reasons of who will use the lights, where and how, it would be good for me to have regulated 3v batteries for the P2D, and unregulated but protected batteries for the Romisen. This is because I don’t want to lose the lower settings on the Fenix, and the Romisen only has 1 setting anyway so nothing to lose. Based on what I wrote above about the difference between a 3v primary and a 3.7v rechargeable, I assume the Romisen will therefore be brighter, but as mentioned, I still don’t understand why.
> Although I’ve written a lot here (sorry about that BTW, I’m sure you all have better things to do, but if you’re reading it in daylight hours, at least I haven’t wasted good flashlighting time), I only really have 3 main questions, and here they are...



I'm not totally familiar with the Romensen, but keep in mind that just because the P1D/P2D tend to be a bit brighter on a 3.7V cell, does not mean this will hold true for all lights. Since some can buck or boost voltage as necessary to accommodate a wider range of voltage input.



> 1. P2D with regulated batteries, not protected. Good for me, 3v, keeping my lower settings, but be careful not to over discharge. However, other than me needing to be careful not to over discharge the battery, what is the downside? I know there must be one, I’m just not really sure what it is.



actually, as it stand currently, I am not aware of any voltage regulated 3.0V cell that is also not protected. I don't think such a cell is available. For any 3.7V cell, you want to have a PCB (protection circuit) onboard. The regulated 3.0V cells are just 3.7V cells under the skin, so having the protection is the most important part. The reason I lean towards LiFeP04 cells is that they remain safe regardless of how you abuse them. While they can be abused to the point of not recovering (no longer taking a charge), they will not become unsafe when this happens.



> 2. Romisen with protected batteries, not regulated. Good for me, don’t have to worry about over discharging, and there are no lower settings to lose anyway. Again, same question. What’s the downside?



Provided the rominsen support the 3.7V cells, then the protected version of these cells is the best option as you will get the most available capacity. The protection keeps the cell in check. The protection can fail, but I'd say it's worth the better capacity in this case. 



> but can I not just get batteries that are LiFeP04, AND regulated, AND protected, even if they do have a low capacity?


I have not seen any such cell. There isn't really much good reason for them to put a regulator on a cell that is already naturally ~3V operation, it would just be a wasteful component. Adding protection to a LiFeP04 cell would be similar to putting it on a NIMH cell, it's just not needed for safety purposes as the cell will not become volatile if it is overcharged or over-discharged. 



> Sorry, 1 more edit: In the other thread you replied to I looked at the LiFePO4 you linked to. They state “Discharge cut-off voltage: 2.2V”. They also state “Please never overdischarge battery below 2.2V/cell”.
> 
> What am I missing? “cut off voltage at 2.2V”. How can you discharge it lower than 2.2V if it cuts off at 2.2V? I know I’m missing something, but I just don’t know what.



The LiFeP04 cells do not do this themselves, it's just a "warning" to the user that discharging below 2.2V can cause advanced/premature/accelerated wear on the cell. Discharging to below 2.2V and holding the voltage down with a slow drain for an extended period of time would probably "kill" the cell, making it impossible to take a useful charge again. But the cell would still be safe.


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## tricker (Jun 13, 2008)

http://www.all-battery.com/index.asp?PageAction=VIEWPROD&ProdID=1877

atleast consider this with free shipping +4 more batteries


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## rayman (Jun 13, 2008)

tricker said:


> http://www.all-battery.com/index.asp?PageAction=VIEWPROD&ProdID=1877
> 
> atleast consider this with free shipping +4 more batteries



Thanks alot but there is no free shipping to Germany. I think there is a mistake because the shipping cost are $75.70 . That would be three times the price of the charger + batteries. And with this money I could buy me another P2D.

Sometimes I really hate it to live in Germany :sigh:.

rayman


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## winston (Jun 13, 2008)

Niconical said:


> *To mdocod...*
> 
> Thanks for all that. Not only have you answered my questions, you’ve given me more than I needed, which has now moved me from just “tell me what to buy and why” up to “I’m gonna learn more to make my own choices”.


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## mdocod (Jun 13, 2008)

responded in post #14


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## Niconical (Jun 14, 2008)

*Mdocod...*

I really can’t thank you enough for taking the time to write your replies. I had picked up lots of individual bits of info from trawling through other posts and just general reading, but certainly not enough to actually make a choice on rechargables, or know why I’m making that choice. I now feel like I am firmly on the first rung of the battery knowledge ladder. 

I obviously have a lot further to go up that ladder, and I will probably make mistakes at some point, but now I can choose my own and use my own, based on what I want and what I know, rather than just standing at the base of the ladder shouting up at people saying “what do I buy, how ‘bout this one, how ‘bout that one?” 

So again, thank you, it is really appreciated


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## mdocod (Jun 14, 2008)

A lot of my long winded responses, while often helpful, can often throw more monkey wrenches into the situation. So in conclusion to previous thoughts, I think I should say the following:

Lets say you buy a set of rechargeables, and a charger, and use em for awhile and decide you'd like to try something different. As long as you cycle those cells a few dozen times, and take advantage of the flashlight at every opportunity thinking in terms of "guilt free rechargeable lumens," then you will likely overcome the cost of using primary cells and generated a lot less toxic waste in the process. So even if a particular rechargeable decision doesn't pull through for the long term, you can still justify it if you use it for a little while. In my experience, I'm more likely to turn on a flashlight when I know it can be recharged later. With flashlights that have primaries in them, I'm constantly fretting over whether to even turn it on or not. This is why pretty much everything I ever use on a regular basis has a rechargeable cell of some sort in it 

Oh, and, you are very welcome  It's my pleasure. I owe this forum for the opportunities and knowledge it has provided for me, the least I can do is share knowledge and continue the cycle. I've always been of the belief that information should be free. 

Eric


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## rayman (Jun 14, 2008)

Thank you very much mdocod. What Niconical said it the same with me. Now I can make my own choice and don't have to ask every time which batteries I should take. It's long to read but it's really not wasted time. Now I have that kind of basic knowledge I need for this forum .

rayman


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## Niconical (Jun 16, 2008)

To Mdocod (or anyone else who can help  )

I'm back!

I've finally decided on the LiFeP04. I think there is a lot to be said for the others, but the safety of the LiFeP04 swings it for me. I'm going to get some from AW on the marketplace, but I just have 1 more issue first. 

If I run the LiFeP04 low enough that it goes past its minimum voltage, I could probably ruin the battery. Maybe if it only goes a little past it will be fine, but drain it too far and it's game over for that battery. My question is this. How am I supposed to know? I read somewhere that it's when the light gets less bright, but I don't know the lights that well. If it is actually getting dimmer as I look at it then yes, I can see that, but if I turn on high and it's fine then I put it on medium for a few minutes, then back to high but the high has dimmed a little, I'm not going to notice that. 

So assuming you do really need to get it back in the charger as soon as it starts to dim, and assuming I'm not going to notice that, can I just charge it as often as I want? Use it for 20 mins or so, stick it in the charger, just based on time?

I'll still be getting them anyway, but I'd like to know this, otherwise I can see myself pointing it at the wall every 2 minutes wondering if it's less bright than 2 minutes ago.


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## mdocod (Jun 16, 2008)

yep, just slap it on the charger whenever you feel like it's a good time. The cell does not need to be drained down before being charged back up. It'll be most healthy for the cell to keep it somewhat topped up rather than risk it sitting in a pretty discharged state...

I'm pretty sure that the P1D/P2D boost regulators are based on similar circuitry as the boost regulators in the L series (AA powered) lights, so I'm betting these things will stay at near full brightness all the way down to around 1.5V or less. You probably won't be able to notice sudden dimming unless you are in the highest most and the voltage of the cell drops to less than 1.2V. 

Sounds bad right?

Well, not so fast. The cell drops down there very suddenly on turbo mode, it's not like a slow dragging downward. The cell probably is holding above 2.5V through most of the run, then all of the sudden takes a nose dive under the load to ~1V when you see it dimming, shut it down, then, since it was only being discharged below 2.2V for a few seconds, the voltage of the cell rebounds back over 2V after sitting for a minute or so. Very little harm done. Now, on the other hand, if the light is in it's lowest mode and left on for really long periods of time, it would be possible to be dragging the voltage down below that minimum recommended ~2.2V and hold it there for a long time not seeing any difference in output. So the low mode running for a LONG time might be the most likely to ruin the cell.

Try not to worry about ruining a cell to much. Charge it frequently like you were saying and you'll likely not have any problems. Buy a few extra cells, they're only a few dollars each.


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## Niconical (Jun 16, 2008)

That's cleared it up for me. Thank you, as always


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## Niconical (Jun 17, 2008)

Just a comment this time, not a question. 

Just in the last few days I've noticed 2 lights, a new Dereelight model and a Liteflux, that both have listed the option to have the light set to automatically power off at a certain voltage. I don't know if this is a new thing, or if lights have had that option for a while, but if I were choosing a new light now, that would be a main deciding factor. 

I'll certainly be looking into the 2 listed above when it comes to my next light. 

Oh, and BTW, 6 LiFePO4s and charger ordered from AW, mission accomplished


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