My 14500 bats keep dying.

[magus7091]

I've made a couple nicosticks, but in the past 2 days, 5 14500 bats have died on me. Am I doing something wrong? Here's what I've been using:
batteries: DealExtreme: $5.64 TrustFire Protected 3.7V 900mAh 14500 Lithium Battery (2-Pack)
Charger: DealExtreme: $12.30 UltraFire 3.6/3.7V Battery Charger

They seem to work ok for a while but then all the sudden, poof, no power. No nothing. Any idea what's killing them?

 

[morphector]

Try cutting the plastic on the battery and remove the protection circuit, check with a voltmeter if you see any voltage that way. Several of my 14500 protection circuit blew up...

 

[bigozone]

gotta love those proteceted batteries

 

[WillyB]

2 days, 5 14500 bats have died on me

Replace the charger.

 

[magus7091]

I had a feeling that might come up... I'll try it, but a question, what about buying unprotected batteries, & a protection circuit, and wiring it in series with the battery in my box? Would this work?

 

[RjG]

I had a feeling that might come up... I'll try it, but a question, what about buying unprotected batteries, & a protection circuit, and wiring it in series with the battery in my box? Would this work?

Dropping them kills the protect circuit, or maybe your charger clamps them too tight. It's pretty easy to mechanically damage them.

On the other side of the metal plate on the bottom of protected batteries are SMD components for the protection.
They are flimsey, and not soldered well. I have a stack of dead DX 14500's as well, lol

Your batteries will probably work if you cut the protection off. Problem is, there is a POSITIVE flat metal ribbon that runs down to the bottom from the top of the battery for it to work.

To remove the protection, you have to rip that strip off too, since you can't have the postive lead just laying around the bottom of an unprotected battery. So you have to cut / remove the battery wrap, remove all that stuff, and re-cover the battery with shrink tube, or tape or something.

I did that with a couple, and even replaced the protection board on some of them.... but you are 100% correct. The "protection" board alone is cheap @ dx. Buy a few of those (one and a couple spares) and wire it into your mod with unprotected batteries. Just be VERY SURE than your charger cuts off properly somewhere under 4.25 volts, since you won't have the "double safety" any more.

 

[magus7091]

I'm thinking, from what you said, that it's the bat box itself that's damaging them. It's a tight fit to get them in there and they kinda snap in once I insert them. The box I'm using is one of the ones from digi-key and even with moving the positive terminal back it's a tight fit. I can't really make the neg terminal more loose with the way the box is set up, so that's probably what's causing the damage. Do you think it would be safe to remove the protection circuit? Is it possible that they're actually at risk of thermal runaway and not just a malfunctioning circuit... I don't really know if I should trust Li-ion batteries in a nicostick, without protection. If they do rupture it could cause serious harm to myself and my stuff.

 

[crashtestjeep]

cut some of the spring off to help them fit better

 

[magus7091]

Already did, unfortunately it didn't help much.

 

[WillyB]

Do you use a meter? What kind of voltage were you getting with the batts right off the charger?

 

[magus7091]

I've never checked them right off the charger...

 

[New_World]

i use those also.

I've had only a couple die on me in a couple months though.

check the charger.

Also a multimeter is an essential tool to have.

 

[magus7091]

I use one, just never bothered to test off the charger until I go "WTF is this thing dead??!?!" I'll get a new charger and a couple protection circuits, along with some unprotected 14500s when I do my next DX order.

 

[Ez Duzit]

Maybe try some batteries from a different supplier. High Tech DealZ, has DX like prices but is stateside. So besides his great prices, and good customer service, you also get much faster shipping, (which is free, and you'll have it in 4-5 days).

 

[magus7091]

OK.... More battery woes.... I don't know wth is wrong but I'm getting ridiculously frustrated with this. Just got a couple bats from madvapes... One of them is on charge right now... The other one? Well, it won't charge. Multimeter shows it to be at approximately 2.8 volts. Is it dead? Am I doing something wrong?

 

[caesar]

Your problem comes from the cheap charger.
The batts were fine when you first started using them but these cheap chinese chargers kill them slowly in time.

Buying batts from china is ok but chargers should be better quality.
Best method is to buy some Li-Ion charger boards based on MAX1811 and make your own charger.

 

[Kurt]

OK.... More battery woes.... I don't know wth is wrong but I'm getting ridiculously frustrated with this. Just got a couple bats from madvapes... One of them is on charge right now... The other one? Well, it won't charge. Multimeter shows it to be at approximately 2.8 volts. Is it dead? Am I doing something wrong?

2.8V is likely below what is necessary to fire up the coil.

Thanks for the link, Caesar! My charger is this one the site you linked has (but bought from DX):

TrustFire MultiFunctional TR-001 Lithium Battery Charger [TrustFire] - $11.83 : High Tech DealZ, Simplifying the LASER Hobby!

I take it this is a "cheap charger". Are there good ones out there? I don't have time or the knowledge to make my own charger...yet.

 

[WillyB]

The other one? Well, it won't charge. Multimeter shows it to be at approximately 2.8 volts. Is it dead?

Assuming your meter is correct that battery should charge, but it is bit too low as most Li-ions ship and should always be at 3+V.

From Battery University:

[FONT=Verdana, Arial, Helvetica, sans-serif]Some lithium-ion batteries fail due to excessive low discharge. If discharged below 2.5 volts per cell, the internal safety circuit opens and the battery appears dead. A charge with the original charger is no longer possible. Some battery analyzers (Cadex) feature a boost function that reactivates the protection circuit of a failed battery and enables a recharge.

[/FONT][FONT=Verdana, Arial, Helvetica, sans-serif]This may be what has happened and why your charger won't accept it.[/FONT] A new cell should not come in this condition. Consider it junk and ask for a replacement.

2.8V is likely below what is necessary to fire up the coil.

Thanks for the link, Caesar! My charger is this one the site you linked has (but bought from DX):

TrustFire MultiFunctional TR-001 Lithium Battery Charger [TrustFire] - $11.83 : High Tech DealZ, Simplifying the LASER Hobby!

I take it this is a "cheap charger". Are there good ones out there? I don't have time or the knowledge to make my own charger...yet.

I believe your charger may be better than the OP's as it at least seems to charge at a slower rate in real world testing. Many of the Chinese chargers basic designs are OK but the problem seems to be the inexpensive parts and their high 5% tolerance figures, which can swing in either direction. In other words depending on the 5% 'swing' of numerous components there can be major sample to sample differences. You'll never see 5% tolerances used in Military Spec devices.

For the most part though overcharging seems to be the biggest enemy of li-ion. Looking at this chart you'll note that charging to 4.3V will significantly lower a batteries longevity.

If you have decent meter check your batts when they come off the charger. Many folks don't own a precision meter, but something like 4.14-4.18V is problem a safe result.

You can go nuts and do some reading here, these folks are true fanatics. There are also diagrams on tweaking cheap chargers to get them in spec.

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FWIW this seems to be the fanatics choice.

Pretty much the standard of excellence

Buy Pila IBC™ 4-stage Charger, AC Adapter, Carrying Case | Pila BC01-AC01

 

[bigozone]

i saw an awesome Li-Ion charger at the local hobby shop...

IIRC the charger was for those RC cars but can charge any battery as long as you know the specs of the battery, now if i could justify dropping >$100 on a charger.

 

[magus7091]

FWIW this seems to be the fanatics choice.

Pretty much the standard of excellence

Buy Pila IBC™ 4-stage Charger, AC Adapter, Carrying Case | Pila BC01-AC01

Will this charger work for 14500 bats? The ones listed don't say that but it just may be the company's name for the same bats, i.e. a ford taurus and mercury sable. I realize it's not a perfect analogy but I think it gets the point across....