Winter "Li Poly" run time

[BuzzBoy]

Anyone noticed a reduced amount of flight time in cold weather over summer time. Its cold here and my flight times seem down from normal, BuzzBoy

[FlyguyXII]

Yep i have noticed the same thing ill go from ten minutes in my trex to around 5

[macanaw]

you loose about 30% when the temp goes below 35ish

[bodywerks]

If you warm them up first and install and use them right away, as well as block off some of the cooling airflow, they will perform much better. Cold packs have a lot of resistance to current flow, which causes the voltage to drop harder under a load. Your batteries aren't dying faster, they just can't hold the voltage as well.

[Team Astro]

Lipolys deliver best and are happiest around 100 degrees. The car heater vents have helped us to warm packs up to acceptiable temps. Even warming up to 70 or 80 is better than nothing. Steve and I enjoy flying all year round this way since we never have to tune our setups in different seasons. Be sure to charge and discharge packs if the sit longer than 4-6 weeks when winter storing. We made our first 30 minute flight on a 6c 2100 TP, 3 or 4 years ago in 6 inches of snow. It was so cold we pasted the transmitter back and forth 6 or 7 times. Can you say frostbite!Terry

[exeter_acres]

I don't use NiCd or NiMh any more.... but I miss them in the winter....

they made great hand warmers after a flight!!!!

[Bobbydog]

Yeah theres a huge difference from hot to cold. For reasons already gone over. A few other things to remember about lipos and cold weather.

1) Never charge a cold lipo. Why? I cant remember, but you end up damaging the cells for some reason. I bought a 12V power supply after reading that and I now charge them in my hobby room in a Pyrex baking dish.
2) If youve got to store them for more than a month or so, discharge them to 3.7-3.9 Volts and put them in the fridge or freezer. Lipos capacity drops about 10% a year at room temp but only 2% a year when discharged and cold.
3) I use Polyquests and LiPower in the winter because they have a little foam insulation on them. I keep my lipos in my inside jacket pocket and they are pretty warm when I'm ready to use them. I think the foam helps keep it in. Not scientifically tested!

Good luck!

Bob

[SargeNZ]

	Quote: Originally Posted by Bobbydog
	Yeah theres a huge difference from hot to cold. For reasons already gone over. A few other things to remember about lipos and cold weather. 1) Never charge a cold lipo. Why? I cant remember, but you end up damaging the cells for some reason.

That said, it's probably NOT a good idea to bung a lipo straight onto the charger after a flight if it's heated up. A lipo's heat will actually increase in the first few minutes after removing the pack as the heat from the inner cells starts to conduct through to the outside where you can feel it.

Sarge.