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Inadvertantly Overdischarged Lipo

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Tosh McCaber27/09/2020 12:04:58
237 forum posts
28 photos

Hmm- Just found that I'd left my 1300mah 3s lipo battery still plugged inside one of my planes, for the past 5-6 days! Surprise surprise- it's reading about 11/2 volts!

Do I ditch it out of hand, or try to charge it to see if it will come back up? Don't want any explosions or fire!

Has anyone any thoughts, through previous experience?

leccyflyer27/09/2020 12:13:57
1760 forum posts
349 photos

Hi "Tosh"

You don;t say if that is under load or not but 11.5v for a 3s1p pack is 3.8v per cell, which some folks use as storage voltage, so it should be fine to balance charge normally, keeping an eye on it. Does your charger have the capability to show the voltage of individual cells?

Frank Skilbeck27/09/2020 12:15:57
4935 forum posts
114 photos

You can try it, but your charger will probably not recognise it on the Lipo setting due to the low voltage. So set your charger to Nimh and charge rate to say 0.5A and watch the voltage until it gets above 9v, then you can charge it on the lipo setting, do not leave it unattended.

But even if it comes back, the capacity and performance will probably be reduced based on my previous experience.

Peter Miller27/09/2020 12:22:35
11780 forum posts
1416 photos
10 articles

My 1300 Lipos are regularly down at that level as are some of my larger ones.

I just charge them up as normal with no problems and some are years old

Alan Gorham_27/09/2020 12:25:03
1415 forum posts
147 photos
Posted by leccyflyer on 27/09/2020 12:13:57:

Hi "Tosh"

You don;t say if that is under load or not but 11.5v for a 3s1p pack is 3.8v per cell, which some folks use as storage voltage, so it should be fine to balance charge normally, keeping an eye on it. Does your charger have the capability to show the voltage of individual cells?

The OP didn't say 11.5V....He said 1 1/2 which is either 1.5V or 5.5V depending on what he meant! Either way it's flat and will have lost significant capacity. Best to chalk it up to experience and buy a new one.

Caveman27/09/2020 12:26:09
334 forum posts
245 photos

Tosh, I think you should clarify whether your 11/2volts means:

11 1/2 i.e. 11.5volts


1 1/2 i.e. 1.5volts

It makes a massive difference!!


leccyflyer27/09/2020 12:29:22
1760 forum posts
349 photos

I read it as 11 1/2 volts - the joy of fractions.

It; it really is 1.5v then it;s toast.

Tom Gaskin 127/09/2020 12:29:37
50 forum posts
5 photos

+1 for Frank's explanation.


Ben B27/09/2020 12:33:58
1475 forum posts
4 photos

I'd ditch it. No lipos last forever and it's a relatively cheap type to replace. I once did this to a very high C rating (ie expensive) 3300mah 6s battery- chucking that one hurt. Even if it was possible to resurrect it, the IR will likely be very high which risks all kinds of issues when charging and / or discharging.

Tosh McCaber27/09/2020 12:50:55
237 forum posts
28 photos

Thanks for all the replies guys!

You're right Ben. I was going to order up some replacement batteries anyway- I needed more anyway. I posted to see whether there was any way, and how dangerous it was, to give recharging a try- I'm new to this electric business! I didn't want a fire in my workshop- the wife would kill me!!

Tried your suggestion Frank- unfortunately- the battery isn't recognised, even on the Nimh setting on the charger (Sky D100 v2- excellent charger).

For clarification- the voltage is1.5v, as opposed to 11.5v!!

Edited By Tosh McCaber on 27/09/2020 12:51:32

leccyflyer27/09/2020 12:58:55
1760 forum posts
349 photos

Thanks for the clarification Tosh - if the voltage is that low, I'd just Tosh it. It's only a 1300mah pack so you can just put it down to experience.

Up to you whether to discharge it down to zero or not. Personally I use a 12v auto bulb with a couple of fly leads soldered on, which are connected to my usual connectors. Once the bulb ceases to glow, you can put a meter on the battery and it's completely flat. I then clip the leads, one at a time, and put some heatshrink over the end of shortened leads and then take it to the local recycling centre. Don't bother with all the salt water bath stuff that you might read on the internet.

MattyB27/09/2020 15:36:21
2437 forum posts
47 photos

No need to discharge that one any further before disposal - 0.5V/cell is well toasted but perfectly safe!

Tosh McCaber27/09/2020 18:10:47
237 forum posts
28 photos

Thx for that Leccy, see you on the field! With a new Lipo!

leccyflyer28/09/2020 08:11:02
1760 forum posts
349 photos

Hope so Tosh -take care yes

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