All my lipos are dead!

[gazmk2]

The conservatory doesn't get any colder than the rest of the house. I have an oil filled radiator on a timer to stop it getting too cold and to keep damp out. It is just very weird how it is only the 8 lipos I use on my protos max that have gone this way. The other lipos go much longer than 2 months between cycles/use and they're all fine. Most of them are turnigy blues too.

Everything gets charged on my powerlab 8 too.

[trillian]

The conservatory doesn't get any colder than the rest of the house.
Everything gets charged on my powerlab 8 too.

Strange. Well this has made me go check mine as I also haven't flown at all this year and didn't get any flying in December either as I was moving house. So far all of mine seem OK. I had them at about 3.83-3.88 volts per cell storage charge and they're still in a pretty safe range. But in general it is a bit of a concern if LiPo prices went up very much because I've had the attitude for a while now that it's no biggie if a LiPo dies now and then because I could replace them so cheaply. (plus, money keeps getting tighter and tighter with the rising cost of living)

[Planehazza]

Bought !!!!!!!!!!!!!!!!! REMEMBER on my last thread !

That's a really bad habit of mine I must admit lol ! Say no more .

Hehe sorry, couldn't resist. It's been a while since I gave in to the urge to correct it

[waveydavey]

F.F.S Rob

[JamieD]

plus if you crash, accidentally over discharge them or leave them in the car or conservatory on a sunny day then it's half the cost to replace them and not such a big deal.

[horneteer]

If all 8 have puffed there must be something that caused it. I've been using the 5000mAh 40C variants of these batteries for years and while three failed after about 5 years of use, I have never had one visibly puff up at all. The three that failed basically dropped a cell. The faulty cells would slowly self discharge, presumably because of age-related crystalisation/degradation. Apart from the failed cells, all have very low internal resistance levels. Mine live a fridge in airtight bags at a constant 5 degrees and at around 3.8V per cell. They hardly ever get used these days, even in the summer because I prefer to fly IC when possible. So they are in storage for most of the time. Is there any green corrosion around the contacts on your balance plugs?

Edit: There is no visible corrosion product on the balance plug in the pic. Is it possible that a fox or cat might have had a piddle on the ammo box at some point? Of course it would stink if this had happened.

Also only one of the cells looks to have swollen in the pic - the one nearest to the camera. I wonder if just one or two cells have just failed and swollen in all 8, in the same way that mine did while sitting in storage. Worth checking the cell voltage levels. Possibly a bad batch. Wouldn't hurt to contact HK although I can't see them replacing them, particularly since they don't seem to be readily available these days in the UK.

Very odd.

[woodsta888]

Heat kills lipos. Worst thing you can do is store them at room temp and in a conservatory that will get hot when the sun is out. I have 12 5000 6s and 12 5000 7s all in ammo boxes and stored cold turnigy blues and zippys. And a few nanotechs. Still all going. Nanotechs most degredation. Store cold, use warm.

Heat will ruin any battery type.

[JamieD]

Heat kills lipos. Worst thing you can do is store them at room temp and in a conservatory that will get hot when the sun is out. I have 12 5000 6s and 12 5000 7s all in ammo boxes and stored cold turnigy blues and zippys. And a few nanotechs. Still all going. Nanotechs most degredation. Store cold, use warm.

Heat will ruin any battery type.

A few months back someone on RCHA quoted the Optipower guys saying that the cold will damage a discharged lipos as well. But then a lot of people seem to swear by freezing lipos on storage charge - I guess that's a little more voltage than fully discharged.

[woodsta888]

A few months back someone on RCHA quoted the Optipower guys saying that the cold will damage a discharged lipos as well. But then a lot of people seem to swear by freezing lipos on storage charge - I guess that's a little more voltage than fully discharged.

Leaving lipos discharged will degrade them anyway. So cold may exacerbate that. But we are talking about lipos looked after correctly left for periods at storage charge.

I think a high variance in temps may not be good either. and a conservatory would to me have the highest fluctuation in temp anywhere in a house.

[mahbouni]

A few months back someone on RCHA quoted the Optipower guys saying that the cold will damage a discharged lipos as well. But then a lot of people seem to swear by freezing lipos on storage charge - I guess that's a little more voltage than fully discharged.

It was me but that's not exactly what Andy from OptiPower said at HeliFest. It was about fully charged LiPo's being damaged by cold. The CellPro chargers he sells have a Cold Weather balancing mode, which will charge the cells to only 4.1V in cold weather. I'm sure there are people who will argue against this and quote websites but they will not honour your warranty on your batteries. So if you have any doubts then contact the LiPo manufacturer and ask them if they will replace your batteries under warranty if damaged when left fully charged in the cold. If they say yes then you have nothing to lose.

[PeteStewardson]

It was me but that's not exactly what Andy from OptiPower said at HeliFest. It was about fully charged LiPo's being damaged by cold. The CellPro chargers he sells have a Cold Weather balancing mode, which will charge the cells to only 4.1V in cold weather. I'm sure there are people who will argue against this and quote websites but they will not honour your warranty on your batteries. So if you have any doubts then contact the LiPo manufacturer and ask them if they will replace your batteries under warranty if damaged when left fully charged in the cold. If they say yes then you have nothing to lose.

The issue isn't with the lipo being damaged by being fully charged when cold exactly. The main issue is that when you warm the lipo up the voltage goes up. So you charge to 4.1v when cold, because then when warmed up it will still only be at a safe 4.2v. If you charged to 4.2v in the cold, then took it into a warm room the voltage would rise above 4.2v and so cause damage.

[mahbouni]

Explanation makes sense. So I guess if you charge it in a warm room and let it get cold then no problem but if you charge to 4.2V outside in the cold, don't fly all your batteries and then bring them home in a warm car or into a warm house then damage can be done.

[PeteStewardson]

Yep that's exactly the issue.

[acidla]

It is like catching a cold when there is sudden change of temps

[Grumpy]

Theissue isn't with the lipo being damaged by being fully charged when coldexactly. The main issue is that when you warm the lipo up the voltage goes up.So you charge to 4.1v when cold, because then when warmed up it will still onlybe at a safe 4.2v. If you charged to 4.2v in the cold, then took it into a warmroom the voltage would rise above 4.2v and so cause damage.

That's what I used to think, and it seems logical, but it's not actually the case. The resting voltage of a LiPo doesn't actually increase to any significant extent when it warms up. You can easily test this yourself if you have doubts.

The real argument against chilling them when fully charged is that a LiPo has a critical voltage above which it will be damaged and may even fail catastrophically. At room temperature this voltage is around4.35V per cell for a standard LiPo. Charging to 4.2V therefore gives a safe margin. As the battery is cooled it's critical voltage reduces and the 'safety margin' is reduced. The likes of Revolectrix have their chargers set to lower the charge voltage in low ambient temperatures and so maintain the safety margin below the critical voltage.

Personally while I don't have the expertise to argue with the ‘battery boffins’on this I know from experience that chilling to around 4 deg. C (fridge temperature) has never harmed any of my fully charged batteries. Also some very authoritative sources such as Batteryuniversity have data published that shows battery life is increased if stored chilled. So while it may reduce safety margins is also seems to reduce rate of degradation.