Do LiPO batteries have issues with heat?

[Rick]

The hot weather the last couple of days had me wondering-do Lipo batteries lose effectiveness when ambient temperature gets high? I was concerned about the effects of heat and sunlight during flight on the small cells used for the smaller helis.

Is anyone noticing a diminshed runtime or power output when flying outdoors with lipos, or has everyone been hiding inside flying their micros?:)

[G-MRM]

Hi Rick, I have run the Century Swift and T-Rex 600 in a rather hot UK summer. I have always found the FlightPower Li-Po's get rather warm. I have been told that they do warm up more than other makes. They become more efficent when warmer and thats how they get the better ratings! However, the cooler you run the pack the better the life will be !

In the 600 I run the Align packs and they just get warm, I have not seen any time change from a hot to a cold day yet.

You should protect them from the very cold to the very hot and I must say I did fly the little T Rex 450xl in the snow last year but the battery lasted the normal time however it is kept in a metal case in a garage that doesn't get that cold.

Hope that may help, it's just what I have found at the end of a warm summer :D

[swatson144]

It's a good point Rick. You shouldn't exceed 140F on lipos. When the temps get up above 100F it doesn't leave much to play with and packs that run acceptably in the 120F range @ 80F ambient may easily get too hot. I tried to test a new motor while it was 102F out and clear skys scorching sun. I took a temp on my RX (black 8chan hitec) after a flight and it was 117F! I gave up on the test as I was sweating all in my TX and temps were not based on any real scenario except worst case.

In the winter the packs are lame until they warm up some so I usually keep them in shirt pockets so they start out warmer.

As a side note I suspect a lot of the packs you see ballooned on the shelf at the LHS are because they got over heated in a dark brown truck during delivery.

Steve

[Ranger]

Steve,
you mentioned a ballooned lipo due to heat! my vortex battery has done just that. The temp here at the moment is 42deg C
Don't know how that converts. and has not been over or under charged.
Could it be just the heat?

[G-MRM]

Li-Pos do this if over charged, over discharged, get too hot or if they are used over their max ratings.... or in my case just with age or because it is just a cheap battery !!!

The new battery I bought for my twin rotor has just started to do this and has not seen more than 20 cycles !! Welcome to the LI-Po club !! I will say the more expencive ones I have bought have lasted a year in my T-Rex 450 (FlightPower). The 'No Name' ones, well..............

[Ranger]

Thanks Martin,
I think I will replace it with a better quality one

[swatson144]

42C is 107.6F! So if the pack gets pretty warm during comfortable temperatures I'd say it got too hot. 140F is 60C.

I've had good luck with reasonably cheap packs. In fact better luck than with the best packs. I use capacities/voltages that lower the need for high "C" ratings. On the other hand I don't usually bother with the cheapest. I suspect the packs that come with the RTFs is the very cheapest that will work like 6C.

Last year was a pretty good year for me with lipos the 6 or 7 packs I wore out only got "soft" no puffing and gave me good cycle life. I always use a lipo alarm and when they start getting soft the alarm starts going off during peak demands and within ~20 more cycles is on pretty much most of the flight.

Steve

Steve

[Ranger]

Thank's Steve,
I think I will have to invest in a lipo alarm as well. I'm still trying to learn the in's and out's of lipo's :D

[swatson144]

If you are into DIY electronics I can point you to a nice simple 5$ lipo alarm. If you aren't you can't do much better than the HRPoly-X for 1-4S lipo.

I use the alarms to protect me from me. I always use timers to limit my flights to 70% and 2nd timer at 80%. The alarms are there to make sure I don't stick a uncharged pack in and kill it. :oops: . Nothing like having an alarm go off 3 mins into a flight to bring home the fact that you'd be needing a new pack if you weren't alarmed.

http://www.customidea.com/hrpolyx.php is the manufacturer. They don't list any dealer in OZ but they don't list my LHS either. So I wouldn't be surprised if you couldn't find one domestic.

Steve

[Ranger]

I'll check out the link, but I'm not past having ago at doing anything myself!
I make all my own Nav and strobe lights

[swatson144]

I did a quick posting on the lipo alarm http://www.helitown.com/forum/viewtopic.php?p=4645#4645

Steve

[Ranger]

Thanks Steve.
I'll have a look.