Reviving a Dead Lipo... Need Some Facts

[Greatscott]

I was at a scaler get-together a couple of weekends ago and forgot to unplug the lipo alarm on my battery (unplugged the battery from the ESCs, neither have LVC), as a result, the battery ran down to zero. So, did some research and did this to revive it:

1. Tried charging it normally, didn't work.
2. Place the charger in NiMH mode, plug in the main leads and the balance leads.
3. Charge at 1amp until the battery reads just over 6VDC. This took my charger about 4 minutes to do, I let it get to 6.15V.
- While charging, the battery voltage would bounce about 100 mv - 300mv. I made sure that it was stable above 6VDC before proceeding.
4. Switch the charger to Lipo mode and charge normally.
5. Once charged, do a balanced discharge at 3 amps. The cells were about 500mvDC apart at the end of the charge cycle.
6. I let the pack get to about 3.7vDC per cell, then I balanced charged again. Checking the batteries showed they were within 100mv from each other. Finished this around 8 pm and let the pack sit over night. After work the following day I checked the voltage and it was the same as the night before.
7. Testing...
- I put the pack in my 4WD Slash, it has a CC 4-pole 3800 system in it, and will discharge a battery faster than my other RCs.
- The pack had great power and run time. I did not take any quantitative measurements, but the truck seemed just as fast as it usually is, had a good amount of power (enough to pop wheelies when the stock tires hooked up just right), and ran for about 20 minutes before I checked the battery. It was still at 3.8vDC per cell. There is no sign of swelling and my temp gun couldn't pick up any extra heat coming off of the battery.
- I have recharged the battery and voltages look great.

Honestly, I am really surprised this worked. But, I figured I had little to lose, the pack was functionally dead. The thing I was really worried about was my charger, so I kept a sharper eye than usual on it just in case. For me, charging lipos is kind of like going to the ocean: Never turn your back in it...

I am pretty sure the pack suffered some damage, shortened its life in some way, but for now it looks like it is fine. I will keep a close eye on it when running and recharging for the next few cycles though.

NEED SOME FACTS...
While researching how to do this I ran across a lot of posts and comments in videos that said, "REVIVING AN UNDER VOLTAGE LIPO PACK IS DANGEROUS!!!!", but I have been able to find nothing that actually supports this. Or, anything to support it is any more dangerous that just charging a lipo period. From everything that I researched, it seems like the most dangerous part was running the lipo all of the way down, causing heat and chemical stress on the battery. If the battery survives this, it should be ok. Of course, having to go through this process is to be avoided. I understand that one of the cells might have been damaged while being discharged, causing an unbalanced condition, but that would be caught when checking the battery during and after changing in NiMH mode. At which point the battery is truly dead and we take a little trip to Best Buy's battery recycle bin.

So, looking for some facts, some hard evidence that reviving packs that are under-voltage is "VERY DANGEROUS".

[SINister]

Nice lipo fire caused by undamaged batts under normal charging conditions -

I've recovered a couple lipos using the method you described but never used them again. For what new ones cost it's simply not worth it to me.

[S1NN3R]

Originally Posted by Greatscott

So, looking for some facts, some hard evidence that reviving packs that are under-voltage is "VERY DANGEROUS".

I work at a hobby shop, and we "boost" batteries like this numerous times a week for customers that don't RTFM. Not one of the batteries we've done this to has ever had a melt-down after doing so. Take from that what you will. They're not always good after doing it, sometimes they come back and sometimes they're done, but after doing it minimum 300-400 times over the years, if it increased the likelihood of a fire, we probably would have seen it by now. So personally, I don't think you're at any increased risk using a lipo that has been dead.

That said, it shouldn't really matter if it makes it more likely to catch fire, because you already should be observing reasonable precautions anyway. Don't put them on the charger and leave the house, use a lipo bag for charging and storage, or at the very least put them in a terra cotta pot on a concrete floor to charge/store them.

Originally Posted by Greatscott

At which point the battery is truly dead and we take a little trip to Best Buy's battery recycle bin.

As an aside, there are no heavy metals or other environmentally hazardous chemicals in lipos, and no material to reclaim and reuse. Putting them in the battery recycling bin just means the guy at the recycling plant has to find it and throw it away when sorting through the regular batteries. Just toss em in the dumpster, soak em in salt water overnight beforehand if you want to be extra cautious.

[Johnnysplits]

Originally Posted by S1NN3R

use a lipo bag for charging and storage, or at the very least put them in a terra cotta pot on a concrete floor to charge/store them

Ah, that's not even necessary. I've been charging my lipo's at 2C to 3C rates in the open on the bench for years and storing them in a fireproof bag inside my apartment for just as long. Unless you REALLY damage the battery (by many means), they're perfectly safe. The chemical composition has changed from the early lipo's. If they were such a high risk of fire, no airline carrier would transport them. A lot of people are afraid of them and I can't imagine why. They are the best thing to happen to the battery world!!

[JeepinDoug]

I've revived LiPos many times but it's not worth the effort.
The danger outweighs the benefits.
When the LiPo does come back, much of the mAh capacity is damaged.
So not only is it dangerous to try to Nimh charge it back up to voltage because of fire possibilities but charging and using thereafter are also subject to fire.
And BTW, LiPos don't extinguish with with water or fire extinguishers. They generate their own oxygen and will keep burning no matter what you try.

24hr Salt water and toss.

[Greatscott]

Thanks to a poster on another forum, I did find some information about why not to revive lithium-based cells:

How to Awaken Sleeping Li-ion - Battery University

[scalerbob]

Had the same happen to me this past weekend. Left my scx10 on. Oops. Brand new 3s 5000mah. I was pissed. We went to our lhs. He did what he called bump charged it. It worked great. Went from 0volts to 3.8 in a few minutes. I had to leave. So it set for hours till I hooked it up to charge again. It charged up. I had to balance it with my cell match for a couple hours. Then re charged it. Worked like a charm. He used the new venom charger. Red one. Costs $64. New.

[JeepinDoug]

Let us know either how much run time you get or, if your charger has the capability, how many mah it accepts on the charge.
Ill will guess you see a big loss in both.

[gunder463]

i have revived lipos this way a couple times and watched how much mah they take afterwards and it dosent seem to be huge but it will never go to its posted capacity again and every time it happens it takes less and less till its just dead. thats what ive seen with my lipos, however my revtech formulax 2s came to life fully after being left on all night and discharged to nearly zero,

[z50king]

You are going to burn down your house. Don't do this. It's a bad idea

[Greatscott]

Originally Posted by z50king

You are going to burn down your house. Don't do this. It's a bad idea

But here is the point of this thread. A lot of people say this, but provide no reason why. Or they can spout some stuff they heard, but have no evidence to support it. Some have conjured up lipo fire videos from 5 years ago as proof, but we know the the chemistry has changed, and most of those lipos in the videos where purposely stressed to make them go nuclear.

Aside from the one article from Battery U, I can't find anything else that says it is a bad idea. Plus, that article says that 90% of over-discharged ( < 1.5VDC/cell) will be revived with not problems.

With that, I am watching this pack like a hawk with I run or charge it for a few cycles, just in case (have the face shield and welding gloves standing by).

[djjiz]

I work at a hobby shop and we do this all the time. Most recover and hold the rated mah.

A good charger shows us everything we need to know and constantly checking temps confirms what we find.

If you are afraid of a little lipo feel free to send them my way.

[slimfire]

It happened to me with a 3s 2250 mAh of my TX...I left it on for 3 weeks......:(

I simply tried to charge it at 1C (only lipo mode, no NiMh) and checked the charger all the time long, cells voltage is perfectly balanced, mAh seems to be as before...

The only thing is the battery has got some swelling

Do u think I should worry?


- Slim -

[djjiz]

Never attempt to recover them for more than 15 or 20 minutes. That's my opinion anyways. If it takes longer than that they are for sure junk

[winnerone23]

I do it.. Haven't had any issues..

To go even further.. I have stabbed, shot, smashed, twisted wires together, etc.. All trying to get a lipo to smoke or catch fire..

The worst I have come across is a dropped cell that couldn't be recovered.. Then I throw it in the rock pile for a day or 2 until I dispose of it in a safe manner

[The Violator]

You could revive a Lipo battery, just like you could drive a car down the freeway with your feet on the wheel and your hands on the brake and gas. The question being is it worth the risk. I have had a lipo explode hours after being charged, just sitting in a car not even plugged in. I also have jammed a large nail through a 3s 5000 lipo to see if it would explode, and got nothing more than a lot of hissing and smoke.

Is it worth the risk to you, your stuff, your family to save $30 on a new lipo.

[z50king]

Originally Posted by Greatscott

But here is the point of this thread. A lot of people say this, but provide no reason why. Or they can spout some stuff they heard, but have no evidence to support it. Some have conjured up lipo fire videos from 5 years ago as proof, but we know the the chemistry has changed, and most of those lipos in the videos where purposely stressed to make them go nuclear.

Aside from the one article from Battery U, I can't find anything else that says it is a bad idea. Plus, that article says that 90% of over-discharged ( < 1.5VDC/cell) will be revived with not problems.

With that, I am watching this pack like a hawk with I run or charge it for a few cycles, just in case (have the face shield and welding gloves standing by).

It's a bad idea. I know it in my soul. I can feel it. I have faith. Learn it; live it; love it.

Sent from my SPH-L720 using Tapatalk

[djjiz]

I have faith that batteries don't explode when you look at them funny.

Send your packs to me when you're done wrapping them in tinfoil.

[S1NN3R]

Originally Posted by The Violator

You could revive a Lipo battery, just like you could drive a car down the freeway with your feet on the wheel and your hands on the brake and gas. The question being is it worth the risk. I have had a lipo explode hours after being charged, just sitting in a car not even plugged in. I also have jammed a large nail through a 3s 5000 lipo to see if it would explode, and got nothing more than a lot of hissing and smoke.

Is it worth the risk to you, your stuff, your family to save $30 on a new lipo.

The question isn't whether bad things can happen with lipo batteries, we all know that while it's rare, yes bad things can happen. The question is whether boosting them in the manner described makes it any more likely for bad things to happen. My experience, and again that experience entails working at a hobby shop where we charge dozens and boost handfuls of batteries every single week for years, is that no, the battery or a single cell being below voltage by itself doesn't increase the likelihood of catastrophic failure by any measurable amount.

It's a different story if there's physical damage to the cell or it's poofy, we won't try to boost those because we have seen an increase in volatility in those cases.

[The Violator]

Originally Posted by S1NN3R

The question is whether boosting them in the manner described makes it any more likely for bad things to happen. My experience, and again that experience entails working at a hobby shop where we charge dozens and boost handfuls of batteries every single week for years, is that no, the battery or a single cell being below voltage by itself doesn't increase the likelihood of catastrophic failure by any measurable amount.
.

Could you name the hobby store you work at, so everyone knows where to absolutely never go.