My 10440 battery overdrained?

[Ragdoll]

I used an unprotected 10440 rechargeable battery (AAA) for my LODce and when I found the light intensity dropped I pulled it out and checked it.
It only has 1.58V left.
My 10440 was newly bought and it had 3.6V in it and so I didn't bother to charge it since LODce only needs 1.5 V (single AAA cell). I only used it for trial for a couple of times and max for couple of minutes!

What should I do now? Should I put it in my charger and see if it can be charged or not? Would it explode if it is dead and not chargeable already?

Thanks for your advices.

 

[LukeA]

My 10440 was newly bought and it had 3.6V in it and so I didn't bother to charge it since LODce only needs 1.5 V (single AAA cell). I only used it for trial for a couple of times and max for couple of minutes!

That's dangerous and a very bad idea. Lithium cells top off at around 4.2V. They're drained when they hit their rated voltage. You've seriousyl overdischarged the cell. I think it would be dangerous to try to charge or use the cell.

 

[legtu]

**edited. Rule 7 issue**

 

[mchlwise]

I think it's been pretty well-established that the L0DCE will be just fine on a 10440... but unless you're really careful the lithium cell will not.

The new L0D Rebels are even worse, and will just about certainly make your battery go

I reviewed both the Cree and Rebel L0Ds here:

http://www.candlepowerforums.com/vb/showthread.php?t=174561

I won't be using the 10440 in either light (assuming it's even still viable).

:sigh:

 

[selfbuilt]

That's dangerous and a very bad idea. Lithium cells top off at around 4.2V. They're drained when they hit their rated voltage. You've seriousyl overdischarged the cell. I think it would be dangerous to try to charge or use the cell.

Agreed, it's not worth the risk in my opinion either. Charging an overdischarged li-ion is just too dangerous.

The problem with the L0D-CE is that by the time the L0D-CE even *starts* to dim, you have drained the battery too low. If you look at the last runtime graph in my Jet-u vs L0D-CE thread, you'll see when I stopped the 10440 run at the very beginning of the L0D-CE downward slope in output, it was already at 2.84V.

I would recommend periodically taking the 10440 out of the L0D-CE and measuring voltage, rather than waiting for the light to dim.

 

[Patriot]

I'm of the same opinion as the rest. Why cause yourself a worry for 3 or 4 bucks. Even if you're able to charge it this time without issue, you'll never trust it again after knowing that the voltage was that low. A replacement is cheap insurance.

 

[FlashCrazy]

Same here, I wouldn't chance it. If the battery showed 1.58V when you checked it, then it was probably 1.2V or less under load in the LOD-CE...not good. The minimum recommended voltage of 2.7V to 3.0V is under load. Many people think that it's open circuit or "resting" voltage that counts, but it's not. You can drain a Li-Ion to 1.5V, and then let it rest for awhile...then it may show 2.8V or so. One would think "Hey, it's 2.8V...no damage was done!" Not quite...it's the loaded voltage that matters. Yeah, you can charge at a really low current to bring the battery back up, and may only notice reduced capacity, but I still wouldn't be comfortable with that. You can't be sure that no internal changes occurred...changes that could lead to problems down the road. The cells are cheap enough to replace. Cheap insurance if you ask me.

 

[Fallingwater]

It's one thing if it's discharged to zero, it's another if it's discharged to 1.58.
It's well below its healthy minimum limit, but it's not a surefire explosion guarantee. It can probably be rescued. I would at least try charging it outdoors, or in a fire-safe container just to be sure.

 

[SilverFox]

Hello Ragdoll,

I consider a Li-Ion cell with a nominal voltage of 3.7 volts completely discharged when the resting, open circuit voltage reads 3.5 volts. When you get voltages below that, the cell is over discharged.

When a cell is over discharged, the electrolyte dissolves the electrodes and you end up with contamination within the cell. The contamination gives you reduced performance, and can lead to dangers while charging.

The key seems to be the amount of time spent in an over discharged state, but there are also a number of other things that influence the ability of the cell to be recovered.

It can be dangerous to try to recover an over discharged Li-Ion cell. Make sure you attend to the attempt and it is best to try the recovery outside.

The recovery involves charging at around 100 mA (or a maximum of 0.1C) until the voltage gets up over 3.5 volts. Then you check the cell for any signs of warming or heat. If things look good, you can then do a normal charge. After charging, you need to do a discharge test to see the change in capacity. If the capacity drops to below 80% of your initial capacity, the cell has been damaged and should be recycled. If you are above 80% you move on to the next step. The next step is to store the cell, fully charged, for a few days and check for any indication of self discharge. There is some danger during this test, so it is best to store in an non combustible area. To check this, check the voltage of the cell around an hour after charging and compare that voltage to what you get a few days later. If you observe very little, or no change in voltage over 5 days, mark the cell and put it back in service. If the voltage drops off, the cell is damaged and should be recycled.

Sometimes recovery works, and sometimes it doesn't. With individual cells I don't feel it is worth the effort, but with an expensive battery pack it may be worth a try.

Tom

 

[Ragdoll]

Thanks a lot everybody.
This to me is a good learning experience (or bad, considering losing the battery:mecry
of handling non protected batteries. Guess I have to buy a new one to save all the hazzles.
Anybody used a Nimh battery for LODce before? Would there be much difference comparing with li on rechargeables or primary alkaline/ lithium batteries?

 

[moon lander]

Same here, I wouldn't chance it. If the battery showed 1.58V when you checked it, then it was probably 1.2V or less under load in the LOD-CE...not good. The minimum recommended voltage of 2.7V to 3.0V is under load. Many people think that it's open circuit or "resting" voltage that counts, but it's not. You can drain a Li-Ion to 1.5V, and then let it rest for awhile...then it may show 2.8V or so. One would think "Hey, it's 2.8V...no damage was done!" Not quite...it's the loaded voltage that matters.

yikes! i asked about that a few months ago and was told it was the resting voltage that mattered. i guess im lucky to be alive right now, as ive been overdischarging all of my cells by at least a little and recharging those that recover to 3v or above.

rule of thumb: switch to alkaline or nimh for reading in bed. thrice i fell asleep with my light on and drained the li-ion down to almost nothing. obviously i retired those ones.

protected cells dont seem to be a solution as the protection circuits sometimes dont catch a slow drain. too bad more lights dont have the low voltage indicator like the lightflux lights.

thanks for the valuable information.

 

[SilverFox]

Hello Moon Lander,

Keep in mind that there are several parameters that matter...

Resting voltage is a very good indicator, but it has to be taken in context with the rest of the parameters.

If you discharge a Li-Ion cell at 5 amps down to 2 volts, and when you remove the load the voltage rebounds to 3.5 volts, or higher, you will have done less damage than if you had discharged the cell at 200 mA down to the same 2 volts. In the latter case the cell may slowly rebound to 2.5 or 3 volts.

In both cases damaged is being done, but in the first case the damage is minimized because of the minimum time spent at low voltage.

Tom