Quick battery safety question

[motigg]

Hello everyone. I just ordered one Panasonic protected 18650 (3100) and one AW RCR123, and one of the Jetbeam Intellicharge chargers. This is my first foray into rechargeable lithiums. I've read around but this stuff is complicated. From what I can gather, given that I'm not running any lights with multiple rechargeables (the RCR123 is for my HDS, the 18650 for my Peak Night Patrol), I should be ok in terms of safety. I need to 1. monitor the charger when charging and 2. keep a close eye on my batteries, watch the temperature, etc. If I do this, I should be safe, as far as these things go. Am I right, or am I missing something?

One other question: can I run the lights until the they go dark, that is, until the batteries die, or do I need to be constantly topping the batteries off after significant use, even if they aren't run down, to avoid overdischarging them? I think with protected cells I can do the former (if I need to, that is, or if by accident a light stays on and I don't know it), but am not sure.

Thanks!

 

[archimedes]

Sounds like you have a good start on battery safety habits :)

Don't run 'em dry, though, even if they are protected cells ... I would think of the "protection" circuit as a last-ditch safety feature that shouldn't have to kick in unless at least one thing has already gone wrong.

You wouldn't constantly run your engine right up to the redline, just because there was a rev-limiter that "should" prevent a blown engine, right?

Frankly, the advantage of rechargeables is that you can easily and cheaply fill 'em up.

The HDS is a "smart" torch that will monitor the voltage of a Li-Ion and should also prevent over-discharge, but that is a feature lacking in most other lights.

Always a good idea to check voltage before & after charging, and before & after use.

 

[snakyjake]

1. monitor the charger when charging

2. keep a close eye on my batteries, watch the temperature...

3. can I run the lights until the they go dark, that is, until the batteries die, or do I need to be constantly topping the batteries off after significant use, even if they aren't run down, to avoid overdischarging them?

1. Good, but I don't like having my eyes on my batteries for hours? Not something I want to do, and have better things to do. I rely on a good quality charger and protection circuit.

2. I don't like watching batteries. I rely on protection circuit.

3. Better to top of batteries before over discharging, but again, I don't like watching batteries. I rely on protection circuit.

4. Lockout your light so it doesn't accidentally turn on.

5. Don't loan your light out to anyone who doesn't know how to safely operate the light (especially kids).

If you can do everything you said you are going to do, you should be safe.

It would be nice if there were some good tests on protection circuits, since are safety relies on them. But there isn't (at least none I've seen).
I'm considering LiFePO4 for better safety than a protection circuit. I'm also back to considering a optimized NiMH light because I don't like my lights cutting off on me and leaving me in the dark (which is what a protection circuit will do when discharged).

Jake

 

[motigg]

Thanks for responding. Since I'm getting protected cells, it sounds like I just need to watch the charging and top the batteries off regularly. I don't have an instrument to check voltage, so I'll be better off not running them dry.

 

[archimedes]

I'm sorry, but my opinion is that some way to check voltage is an absolute necessity to use Li-Ion cells safely.

It need not be an expensive Fluke DMM, but they make reasonable voltmeters for this purpose for just a few dollars....

The cottonpickers charger even includes a built-in voltmeter :)

 

[motigg]

I may have to pick up a cheap voltmeter at some point. I opted against the cottonpicker charger because I don't want to rely on USB ports and because the Intellicharger can handle my Eneloops as well. But mostly because I don't want to use USB.

 

[SemiMan]

You can make yourself crazy worrying about things that realistically you don't have to.

Does it hurt a Lithium-Ion running it down to the protection circuit? No not really. That is what it is there for. Keep in mind the protection is for deep discharge because there comes a point where you can't charge them any more. This is what it prevents. Yes running down to the protection circuit will reduce the life of the battery, but time is money and I being able to only get 250 cycles instead of 500 is likely not an issue for most people. The way most people use flashlights, float life, i.e. just sitting there with lithium ions will kill them quicker.

The charger you have picked charges each battery seperately. It has diagnostics as well. To that end, you will know when each battery is charged properly and it should indicate when a battery cannot be charged properly.

What you should not do is operate lithium-ion batteries with different charge levels. This is a definite no-no. That results in charge reversal, etc. and likely a short end to your battery(ies). If you always charge and discharge the same set together, then this is not a big deal. This would be my primary recommendation. Always keep lithium ions together as a set.

There you go ... no real worries. If you had a cheap charger I would be more concerned but you will not so don't be.

Semiman

 

[archimedes]

Respectfully, I disagree.

Although there are others on this board much more expert in batteries and chemistry than I, my understanding is that overcharging of lithium ion cells (ICR-type) results in plating the lithium ions into highly reactive lithium metal, while deep discharge causes metallic copper shunts to develop (risking internal short circuits).

Either situation compromises the integrity and proper safe functioning of these cells, which may then suffer thermal runaway (1000 degree Celcius flames and toxic fumes).

Protection circuits can fail. Chargers can fail. Multiple layers of redundancy are helpful in managing risks and reducing the chances of a catastrophic event.

This board is testament to the overwhelmingly safe overall use of Li-Ion power for flashlights, as well as the rare but spectacular failures.

Nothing in life is totally safe and risk-free, and people do choose to accept different levels of risk with various activities.

My main point is that it is quick, easy, cheap, and sensible to check voltages before & after, and make sure not to overcharge or deep discharge Li-Ion cells, without simply relying on a couple of hair-thin wires to cut off the power before there's a problem :)

 

[snakyjake]

Protection circuits can fail.

If you know of any quality protection circuits that have failed, please post. These protection circuits are like mini circuit breakers. I trust circuits in all my electronic devices, and the circuit breakers for my house. Why not trust a battery circuit breaker?

main point is that it is quick, easy, cheap, and sensible to check voltages before & after

What about during usage?

 

[archimedes]

If you know of any quality protection circuits that have failed, please post.

http://www.congrex.nl/08a11/presentations/day1_S08/S08_04_Jeevarajan.pdf

http://www.battcon.com/PapersFinal2011/AroraPaperDONE2011_17.pdf

http://www.candlepowerforums.com/vb/showthread.php?326898-My-house-almost-burned-down-today

http://www.candlepowerforums.com/vb/showthread.php?296907-My-Maha-MH-C808M-Charger-Melted!-What-Now

http://www.candlepowerforums.com/vb/showthread.php?280909-Ultrafire-18650-3000mA-exploded

These protection circuits are like mini circuit breakers. I trust circuits in all my electronic devices, and the circuit breakers for my house. Why not trust a battery circuit breaker?

Well, just for example, maybe flashlights and batteries could occasionally get dropped and banged up ... which might "break stuff inside" like delicate wires and such. Circuit breakers in a house don't usually get dropped on the ground or physically banged around too often ? They may also be made of sturdier materials (heavier gauge wires, etc), too. As I mentioned, I'm not an electrician or expert, however.

What about during usage?

If voltage is within proper ranges before and after charging, and before and after discharge, most likely it will be within the proper range during usage. Although some lights (such as HDS) do in fact monitor voltage during usage, I agree that for many/most lights, that would be impractical.

 

[snakyjake]

Thanks archimedes. It will take me some time to digest the report (not the easiest for me to understand). Couldn't get the second link to work.

From the first report:
"Tests were carried out with cells in series and cells in parallel".

I wish someone with the knowledge would do a test for single cell AW (or other high quality battery). Doesn't even have to be a battery, could be just the protection cell.

 

[archimedes]

Thanks archimedes. It will take me some time to digest the report (not the easiest for me to understand). Couldn't get the second link to work.

From the first report:
"Tests were carried out with cells in series and cells in parallel".

I wish someone with the knowledge would do a test for single cell AW (or other high quality battery). Doesn't even have to be a battery, could be just the protection cell.

Sorry about the link formatting, should be fixed now :)

Also from the first report:
"Tests also included determination of PTC (Positive Temperature Coefficient) limitations for cells from different manufacturers, CID (Current Interrupt Device) tests in header assemblies as well as single cells and choice of diode for prevention of catastrophic hazards in multi-cell strings." (emphasis added)

 

[motigg]

It's true that one takes all sorts of risks in daily life. The worry I have regarding these flashlights/chargers/batteries in particular, however, is that the technology is being pushed to the limit, and I'm not sure we have the same safeguards in the flashlight world that we have with respect to the e.g., circuit breakers in our homes. Electricians must be licensed, there are building codes, etc. Much of what goes on in the flashlight world seems to me to be the equivalent of letting "some guy who another guy you know knows" work on the electrical system of your home--maybe he knows what he's doing, maybe he doesn't. Cheap consumer electronics (e.g., stereos, TVs, cell phones, etc.) fail all the time, and when you add the power that these lithiums hold, and the fact that the high-end flashlight world is relatively insular and hence not subject to same kind of broad public scrutiny that provides a safety incentive to manufacturers of more popular goods, there is the potential for serious harm. This doesn't mean that rechargeable lithiums are the most dangerous things around or that the risks outweigh the benefits. It just means that because I'm not in a position to understand the complex issues myself, and because there is no authoritative licensing board (or something equivalent) to which I can defer, it makes sense (for me) to be as careful as I can be while still enjoying the benefits of this technology.

 

[archimedes]

It's true that one takes all sorts of risks in daily life. The worry I have regarding these flashlights/chargers/batteries in particular, however, is that the technology is being pushed to the limit, and I'm not sure we have the same safeguards in the flashlight world that we have with respect to the e.g., circuit breakers in our homes. Electricians must be licensed, there are building codes, etc. Much of what goes on in the flashlight world seems to me to be the equivalent of letting "some guy who another guy you know knows" work on the electrical system of your home--maybe he knows what he's doing, maybe he doesn't. Cheap consumer electronics (e.g., stereos, TVs, cell phones, etc.) fail all the time, and when you add the power that these lithiums hold, and the fact that the high-end flashlight world is relatively insular and hence not subject to same kind of broad public scrutiny that provides a safety incentive to manufacturers of more popular goods, there is the potential for serious harm. This doesn't mean that rechargeable lithiums are the most dangerous things around or that the risks outweigh the benefits. It just means that because I'm not in a position to understand the complex issues myself, and because there is no authoritative licensing board (or something equivalent) to which I can defer, it makes sense (for me) to be as careful as I can be while still enjoying the benefits of this technology.

Yes. Well said ... very much so.

 

[tandem]

My prescription for hobbyist / experimental use of li-ion cells in flashlights with a reasonable amount of safety:

1. Invest in a known good charger with a good track record

2. Purchase an inexpensive voltmeter

3. Invest in known good cells with a track record of good, safe, service (bye-bye Ultrafire and other HouseFire brands)

4. Purchase well made lights with solid engineering that either have internal protection against over-discharge or have well understood runtime characteristics and get to know how the light behaves. With every new light I've ever bought (Li-ion powered or otherwise) I do a runtime test at the levels I'll use most. This helps me to understand how the light will behave as cells are drained. Documentation (manuals) are worth reading too.

5. Don't charge cells unattended. For some this may be the most difficult rule to follow, but probably most of us have three or four hours of "awake" time at our home or place of employment. A 3100 mAh cell which has not been fully depleted will often be fully charged in 3 or 4 hours or much less depending on how the light was used, perhaps as long as 5 or 6 hours if it is fairly fully depleted.

6. Measure cell voltage before they go into the charger, off the charger, and - if you have a large or not well organized collection of cells - measure voltage before they go into your light. It is always good for our sanity to know that we are putting a cell into our light that has a charge, and that our charger isn't over-charging our cells. Performing these tests takes a couple seconds and is no imposition on my time.

7. Use the light responsibly. Don't loan powerful lights to those that won't practice safe use. Don't leave powerful lights lying around for children to discover. Many lights can be damaged by incorrect polarity (cell inserted backwards) so train potential users. If your light is powerful, consider locking it out when it is in a pocket or backpack or briefcase. Some li-ion powered lights, particularly the XM-L and multi-emitter XP-G lights, are capable of generating tremendous heat and certainly do present a fire risk if they are activated in an enclosed space like your jacket pocket or a briefcase full of easily ignitable paper.

Good cells, good chargers, good lights - used responsibly - should be as safe to use as any consumer device powered by li-ion or li-po portable power technologies.

 

[snakyjake]

http://www.congrex.nl/08a11/presentations/day1_S08/S08_04_Jeevarajan.pdf

Not seeing over discharge test.

http://www.battcon.com/PapersFinal2011/AroraPaperDONE2011_17.pdf

Good information.

http://www.candlepowerforums.com/vb/showthread.php?326898-My-house-almost-burned-down-today

4Sevens charger issue, not battery. I think 4Sevens had a history of this, and that's why there is V3 now...same with Intellicharger. I'd only trust Pila. Hobby charger isn't automatic enough for me.

http://www.candlepowerforums.com/vb/showthread.php?296907-My-Maha-MH-C808M-Charger-Melted!-What-Now

NiMH charger issue.

http://www.candlepowerforums.com/vb/showthread.php?280909-Ultrafire-18650-3000mA-exploded

Ultrafire is a cheap low quality battery. Stick with AW, Redilast, or Callies Kustoms.


Over-charge isn't a problem with Pila or a hobby charger. Intellicharger is showing promise. 4Sevens v3 might be okay.
Over-discharge risk can be solved by checking voltage before charging. I don't think over-discharge while in-use is going to cause a thermal runaway, as long as you don't recharge it.

Good info!

 

[motigg]

snakyjake, you said "I don't think over-discharge while in-use is going to cause a thermal runaway, as long as you don't recharge it." Does this mean that if I run an 18650 down until the battery runs dry--the light goes black--then I should not recharge that cell?


edit: tandem--thanks--this sounds like sensible advice and I think it's consistent with my approach. I just need to get a voltmeter--I'm going to see if I can get one of the cottonpicker mini-voltmeters. I've also emailed Peak to ask about the electronics in the Night Patrol, specifically if it has internal protection against over-discharge.

 

[snakyjake]

snakyjake, you said "I don't think over-discharge while in-use is going to cause a thermal runaway, as long as you don't recharge it." Does this mean that if I run an 18650 down until the battery runs dry--the light goes black--then I should not recharge that cell?

Remember I'm not an expert, as I'm trying to understand the risks just like everyone else is. I just think when the battery is over-discharged there won't be enough energy/voltage to produce a thermal runaway (and this is where I might be wrong). But the over-discharge damages the battery. The risk for a thermal runaway is when the damaged battery is recharged.

To eliminate this risk, check the battery before charging. If the battery is over-discharged, discard the battery at a hazardous waste facility.

Jake

 

[snakyjake]

You could always look at LiFePO4 batteries. These are the "safe" lithium chemistry...safe enough that Surefire will stand behind them.

 

[Viking]

http://www.candlepowerforums.com/vb/showthread.php?280909-Ultrafire-18650-3000mA-exploded

Ultrafire is a cheap low quality battery. Stick with AW, Redilast, or Callies Kustoms.

Actually it turned out later , that it was in fact UNPROTECTED cells that exploded in that last thread.

Quote from post 48:

He received cells which where marked as protected cells but in fact there was no protection circuit :thumbsdow He was not experienced enough to difference between protected and unprotected cells ... The cells where over-discharged the day before. That's the reason why they got warm during the charging time. They where already damaged at that point.

[FONT=arial, sans-serif]But there was another example mentioned in post 92

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A friend of mine had a single battery 18650 protected cell flashlight running a single P7 LED (Aurora AK-P7) explode/catch fire while in his flashlight holster. When it blew there was a loud pop, the tailcap blew out and caused a small second degree burn to the inside of his forearm. I don't know the brand of the battery (came with the flashlight-marked ICR 18650 2400 mah), but disecting another identical battery showed it did have a protection circuit at the base of the battery. The battery was charged with an inexpensive single cell Li-Ion charger that came with the flashlight. What would have caused a single cell protected battery to explode? Seems to me the protection circuit must have failed in this case? Still, what would be the explosion mechanism?

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