Did I kill my lipo?

[Beemerider]

Flying yesterday in some fairly substantial winds (10-15 mph). I guess substantial for my skill level anyway. My grandsons and I were flying a lightweight foam plane using a 1200mAh 2S 20C lipo. Had my timer set for 10 minutes which typically leaves me with 30-40% battery life remaining. I'm fairly new at this but it's my understanding to not drain a pack below 30% remaining? Was fighting the wind more than I realized but got down without losing power(throttle).

Upon checking remaining battery life my meter said 3%. I'm using an inexpensive $20 RC watt/power meter. (most of the guys at my field use the same or similar)

When I got home I immediately put it on charge. I've run it thru a couple of charge/discharge cycles with my iMax B6 so far.

Have I cooked this lipo?

[xmech2k]

Someone more expert should chime in as well, but I think the meters vary a bit on their percentage readings, so I wouldn't go by that, but by how many volts in each cell. I think it's less than 2.5v/cell and it's pretty much toast, but some people know how to do some magic and bring them back to life sometimes. First check what each cell voltage is.

[MX5Seeker]

Does your charger tell you how many miliamps you put back into the battery with that first charge? The rule of thumb I heard was don't' go over 80%.

[flydiver]

Don't worry about. You merely kicked it in the knee a bit. To do that on a routine basis is to make a short life for it. Once in a while isn't a treat but it's not the death knell either.
I got some batteries I use for combat that I only make a minor effort to be 'nice' to. They get down there all the time. They'll make 50+ cycles but I doubt they'll see 100.

[JetPlaneFlyer]

Don't even give it a second thought. If the charger recognised the correct number of cells and charged it as normal then the voltage was above the minimum value of 3v per cell and no significant damage would have been caused. You don't want to do doing it regularly but don't sweat on it if it happens one or twice.

I've stupidly run a few of my batteries down to dead flat, as in zero volts (by inadvertently leaving them connected to the ESC for days). After charging they are performing perfectly well and show no detectable ill effects, internal resistance is the same as before the mishap... Some people are way too paranoid about LiPo's IMHO.

[Beemerider]

Thanks guys. You never know till you ask. I didn't pay much for the lipo so I wasn't going to lose sleep over it. I reckon now I can put it back into it's regular duty powering my pacemaker.

[hoghead5150]

Originally Posted by Beemerider

I've run it thru a couple of charge/discharge cycles with my iMax B6 so far.

this is one thing i've never done. i never run a lipo battery thru a DISCHARGE cycle.

was told a long time ago by a friend that races short course trucks that you should never discharge a lipo. they are not like the old nicad or nimh batteries and that if you run them thru a discharge cycle on your charger that you can damage the lipo really easily. he said that IF i ever had a lipo that was somehow overcharged, that i should put it in one of my trucks and run the rig to bring the voltage down.

not sure how true this is, but i've never done it, never had a lipo puff (yet). he has probably 50 lipo batteries for all his rc stuff, i have around 10.

just something to keep in mind.

[JetPlaneFlyer]

yes, there is no reason to cycle LiPo's as you might do with NiCd batteries. cycling LiPos doesn't harm them as such but it does use up some of their finite life.

As for discharging, it depends on how far you discharge. If I have a fully charged battery and I want to put it in storage for more than a day or two I discharge it down to about 3.8-3.9v per cell. Most chargers have a 'storage' setting that does this automatically.

[FlyWheel]

OK, not to hijack this thread, as my question is somewhat similar. I have been out of the hobby for 14 months now for a cross country bicycle tour; 7 months planning, another 7 riding it. When I got home and had finished overhauling the bike. I thought I had best check my LiPo packs to be sure they hadn'd dropped too low during the time I was away. Well they hadn't, in fact they were all holding a FULL charge of between 11.5 and 12, 2 volts (they're al three cell)! IOW, forgot to discharge them to the recommended storage voltage mentioned in the post above, so they have been sitting at full charge for over a year.

Are they fried? Or can they be salvaged? None of them show any sign of puffing.

As an aside, I was rather impressed at their ability to hold a charge over time.

[flydiver]

Try em. Some lipos will only take some level of performance hit. Some will be trashed. Either way, you have what you have and there is no 'make it better'.

[slipstick]

They may be fine. To some extent it depends how old they are....older, lower C batteries are far less affected by being left fully charged than newer high C batteries. Anyway 11.5V is fine, 12.2V less so. Charge 'em up, give 'em a try and see how they perform.

Steve

[dahawk]

I know on my Icharger 206B, sometimes I'll sometimes get an error that says "too low to charge". You can switch to NIMH for a short time throwing amps at it but keep a close eye. It then gets to a point where the charger will charge and balance normally.

[solentlife]

Originally Posted by FlyWheel

OK, not to hijack this thread, as my question is somewhat similar. I have been out of the hobby for 14 months now for a cross country bicycle tour; 7 months planning, another 7 riding it. When I got home and had finished overhauling the bike. I thought I had best check my LiPo packs to be sure they hadn'd dropped too low during the time I was away. Well they hadn't, in fact they were all holding a FULL charge of between 11.5 and 12, 2 volts (they're al three cell)! IOW, forgot to discharge them to the recommended storage voltage mentioned in the post above, so they have been sitting at full charge for over a year.

Are they fried? Or can they be salvaged? None of them show any sign of puffing.

As an aside, I was rather impressed at their ability to hold a charge over time.

I'm terrible and never storage charge my LiPo's .... and they sit full charged while I travel on work. They sit for 2 - 3 - 4 weeks at a time on the bench ... I get home ... check with Wattmeter ... any that are below 98% are put on charger and I go flying.
I have 9 lipo's that are basically unuseable out of a whole box load ...

2 are 1000 3S and they were subjected to excessive loads too often and puffed up.
4 are 2280 3S and were useless when I rec'd them of ebay ... but they fly my 450 heli as long as it's only hovering / light duty.
3 are where cells failed in various crashes etc.

The other box load are fine and some of those are years old.

(I left out the freebies from friends where they were shot !! )

I do not recc'd others to follow my example ...

Nigel

[rcers]

I agree with Nigel - fully charged storage kills packs overall life sometimes very dramatically. I am really diligent now and amazingly all my packs are lasting much longer - go figure.



I'm convinced.

Mike

[JetPlaneFlyer]

Originally Posted by solentlife

I'm terrible and never storage charge my LiPo's .... and they sit full charged while I travel on work. They sit for 2 - 3 - 4 weeks at a time on the bench ... I get home ... check with Wattmeter ... any that are below 98% are put on charger and I go flying.

Nigel,

You may recall a few weeks back we were chatting about some of your bench test results, and I commented on how the voltage on most of your batteries was sagging really badly under load?... Well now we know why

I guess one man's "this battery is fine" is another man's "this battery is junk".. It all depends on your needs and expectations.