About once a week (or oftener) someone posts a question on how, or whether to, revive an over discharged Lipo battery or What is the best storage voltage. Here are some of the recent threads on that subject. I'm sure you will find an answer to your question in one of them.

Why LiPo Batteries Fail
https://www.mpoweruk.com/lithium_failures.htm#lowvolts

Safe Disposal of LiPo Batteries
Daedalus66 and jj604 have written an excellent simple language document on the preferred way to dispose of those old, dead, or mangled LIPo packs based on sound information and some current advice from someone who actually knows what he is talking about..
Link to article.


Lipo Storage Voltage

Safer Storage Voltage is 20-30% chargedl.
Tests showing why a low SOC is the key to safe storage. https://www.ifixit.com/News/69041/ho...ZunZiCXh6gI%3D

IATA Shipping regs.

Shippers Lithium ion batteries packed by themselves (Packing Instruction 965) (not contained
in or packed with equipment):
(a) must be shipped at a state of charge (SoC) not exceeding 30% of their rated
design capacity. Cells and/or batteries at a SoC of greater than 30% may only be
shipped with the approval of the State of Origin and the State of the Operator
under the written conditions established by those authorities, see Special
Provision A331; and
IATA Lithium Battery Guidance Document – 2017
APCS/Cargo Page 3 15/12/2016
(b) are forbidden for transport as cargo on passenger aircraft unless shipped under
exemption issued by all States concerned, see Special Provision A201

LiPo Storage Temperature
The optimum storage as determined by extensive experiments is with 20% to 30% capacity and at low temperatures, which should not drop below 0°C.
Storage at 5°C to 10°C is optimal. https://www.plarad.de/fileadmin/down...A1_en_0216.pdf




.

An excellent post by Jon58

Think of storage voltage as a golden mean that balances cell damage during storage, self discharge, and safety.
Getting below 3.9 makes the battery last longer.
Going lower increases safety. 50% charge in experiments with intentional damage still sometimes produced fire. 40% and below did not-hence changes to ICAO shipping rules and 30% or below the new shipping standard.

Your LiPo may self discharge over time. While a 3% charge might be extremely safe stored, it is not much of a self discharge buffer.
20-40% charge gives you some self discharge buffer, is still below where fire has been demonstrated intentionally, and is well below the high charge over time damage areas.

If you store your batteries outside in a fire safe place, nothing wrong with 3.85.
If you store where the cat might knock the battery off a book shelf, or you or someone else may have without knowledge damaged your LiPo, then 3.85 still has some fire risk and 3.75 much less fire risk

http://www.icao.int/safety/dangerous...p.008.5.en.pdf



Dead Battery Recovery

(Remember, overdischarged lipos are damaged goods and the safety precautions recommended for lipo packs should be followed. Using damaged packs is not recommended)
Over-discharging can cause internal damage to electrodes and current collectors
(i.e., dissolution of copper) , can lead to lithium plating if the cell is recharged
(particularly, if the cell is repeatedly over-discharged), and can ultimately lead to thermal runaway"

[B]Consider this before doing any recovery attempts.


(HOW TO) Recovering over discharged lipos
https://www.rcgroups.com/forums/show....php?t=1072324

How to charge or discharge SINGLE CELLS to balance a pack.
https://www.rcgroups.com/forums/show...89&postcount=2

Balancing your lipo battery more quickly (and how cheap chargers work) (16 min 36 sec)

How to dispose of a LIPO pack.
Short stories HERE. and HERE.


How long can I keep my LiPos charged - a scientific approach by Julian
Summary:

So, to sum things up: If you charged up the packs and do not get to fly the very same day, putting them back to storage voltage immediately is better than even leaving the packs fully charged for only a single day.

https://www.rcgroups.com/forums/show...93&postcount=1

Shipping Regulations
https://www.iata.org/whatwedo/cargo/...nt-2017-en.pdf

Popular Discharger
https://www.ebay.com/itm/172783649063
Many other stores carry this discharger. Some may be cheaper.

If you shop elsewhere, be sure and get the one that includes the discharger unit (3 bulbs and controller).

There will alway be people who will start a new thread even if the answer to their question is on the first page of this forum, but I think the stickys have helped A LOT. The "Complete Guide to Lithium Polymer Batteries and LiPo Failure Reports" has almost 1/3 million views. That's an average of about 147 views PER DAY. You have to think that many of those people found the answer to their questions, and as a result, did not start another thread.

I think that this thread would be a valuable sticky, and one specifically aimed at "What's the best charger" would be good too.

Dan

Those other threads recommend charging around 0.3C until the battery is above "too low" threshold for the LIPO charger. I found a manual for a LIPO cell once (but I've since lost it), and it recommended charging "really slow". I think it mentioned 0.1C, but can't be sure. Anyway
- Charge really slowly as long as they are below 3.0V. (0.1C recommended)
- Damage is done by TIME below 3.0V. So recharge with this procedure ASAP when you notice you've left your battery on.

Just a couple of months back and plus being new to any type of elec. flying except for a GWS Tiger Moth that was all stock with no upgrades I had went on the battery section of the forums and ask if there was anyway at all I could save my Brand New Lipo that I had left plugged in to the plane by mistake and it drained the battery to the point to where it showed zero voltage. The answer I got was to cut the plugs off and disgard the new pack (3 cell) and that''s just what I did. Being my very first Lipo and brushless set-up that really hurt!! If I had read this post in time just maybe I could have saved the pack? It was just a 20.00 pack but just being a week old and now was told it was junk kinda hurt a little. I sure hated cutting those plugs off that new pack but that's what I was told to do and that's what I did. Thanks for this info and maybe next time it happens (Which I don't think it will) as now atleast I know and very careful about leaving one pluged up!! Now if I'm very careful just maybe I can save a pack or atleast have a chance...

Again, Thanks for the info and instrutions on how to do this! VERY good informantion that I will not forget and you can take that to the BANK!!

Best Regards,
Ben Morrow

Ben,
Tossing a pack that had been under load for 1 week and was at 0V was not a bad thing to do.
Once the cells go below 2.5V the battery starts to undergo permanent damage which can not be undone.
Here's a reference on what happens inside the pack once the voltage/temp goes outside the safe operating window. http://www.mpoweruk.com/lithium_failures.htm
Running the pack below 2.5V/cell causes the copper anode to dissolve.

The best hope for "saving" cells is when the pack has gone just a little under the range where the charger won't turn on and it hasn't been at that low level for very long.

I don't remmember recommending any units from 2dodrc but that's neither here nor there.
I suggest you post this question as a new thread in the forum, you'll probably get more responses.
Cell checkers will work with any manufacturers pack - the only "but" is that the connectors must match up.
For instance, Polyquest uses a 5 pin connector for 3s packs using pins 1,3,4,5 as I recall whereas Hobbyking and many others use a 4 pin connector in a 1,2,3,4 combo for 3 cells. TP uses a smaller 4 pin connector using pins 1,2,3,4. If all your packs match the pin wiring on your tester, no problem. Otherwise you'll need adapters to match them up.

Originally Posted by rewolff

Those other threads recommend charging around 0.3C until the battery is above "too low" threshold for the LIPO charger. I found a manual for a LIPO cell once (but I've since lost it), and it recommended charging "really slow". I think it mentioned 0.1C, but can't be sure. Anyway
- Charge really slowly as long as they are below 3.0V. (0.1C recommended)
- Damage is done by TIME below 3.0V. So recharge with this procedure ASAP when you notice you've left your battery on.

I've revived a few turnigy and Rhino packs by charging them at 100ma.

I sat the batteries in a lipo safe during the charge. i once upon a time tried to revive a lipo by charging it at 2c.......there was a fire.

100ma worked for me

This is great battery info... i think there is almost impossible to charge a dead lipo, should try the info, tks

Can anyone advise me on the correct and safe procedure for re-soldering a charger lead to a cell?

Thanks,

Picture?

thanks for putting this info together in one place. very helppful

my situation is a little different than the links you posted.

I have that parkzone ulta micro 4 battery charger. I had 4 charging at the time i bought my wildcat. then i left them sit in the charger for a month or two :|

My carger things they are charged. yet my blade msr and pz p-51 disagree. the life on them is very short. some are seconds. others a minute or so at WOT.

I plug them in. some charge solid for a few minutes then start to blink which means they are "almost full". my charger reconizes all them. they just have a very small winndow. VERY small. i tried charging with my hyperion charger with similar results. I keep discharging and recharging which may have helped a little. not much. Am i just screwed? these 1s batteries seem very delicate. im going to try a hyperion 130 and 160mah. maybe pz batteries just suck?

They probably discharged while sitting in the charger. Many (most) chargers do not completely disconnect from the battery when turned off. They will continuously suck a little bit out of the pack when unpowered. I'm guessing you over-discharged them which can permanently damage them.

hi and happy new year
i have a problem with a 11.1v 3 cell battery because the older charger walkera ga-002 was charging just 2cells.
so yesterday i got a new imax b6 , it says 4.20v for the 2 cells and 1.9v for the last one .
when try charging or balancing it goes 1mn than shows a full battery message , i tried discharging but its only the 1.9v cell that goes to 0.8v the others lows to 4.12v i couldn`t get lower voltage ...

what do you advise me to do? is it possible that the battery is dead ?

li po 4000mah 11.1v + imax b6
thanks for help

The battery is probably a candidate for a 2-cell pack or the garbage. Cells under 2.5V for any length of time can be permanently damaged. The only thing you could try is charging the 1.9V cell up to 4.2V by charging that one through the balance tap by itself.

Beware! Damaged packs like this one can be unsafe. I'd treat this one especially like a fire ready to happen. If you do anything, I'd recommend doing it outside in a fire safe place and always storing it in a fire safe place.

Thanks for help Hopy , im going to buy a new one , best thing to do