Have any of you noticed a difference in how your LiPo packs are performing now that the weather has turned colder?

Seems like LiPos go high resistance in cold weather. I notice that when you go through the typical throttle setup, the controller cuts off the motor at about 75% power. When you measure the current with a wattmeter, the amp draw goes well over 40 when the same setup in the warm weather is about 30 amps max. Anybody else have any experience with this?

Nope, don't have any experience with that. But i do have experience with my fingers not moving or slowing down in the cold. would that be Temperature Sensitivity? 

I knew that I had read about temperature sensitivity somewhere:

" Lithium polymer battery packs are very temperature sensitive. If a fully charged three cell lithium pack is placed in the freezer and left there for an hour the pack voltage will be depressed and the pack will exhibit a very high resistance to both charging and discharging. When running your motor it will deliver low power for the first minute or so until it warms itself during discharge." Bob Boucher (On information sheet included with Astro 109 Lithium Battery Charger)

This explains the motor cut off and high amp readings we were getting yesterday in the cold air.

m...maybe we need some NiCads for those really cold days...or something to keep our LiPo's warm! 

I was just reading a pdf file on them. " i hate pdf, can't copy and paste from it" but it said once the battery was cold it would take about 1 hr at 80 degrees for it to produce correct. Might be right about keeping NiCads for cold days. 

Here is a thought. get one of those little insulated boxes that will refrigerate or heat. Thermostatically controlled and runs off a 12 volt batt. 


http://www.walmart.com/catalog/product. ... id=3942757

...cold drinks in the summer and warm batteries in the winter! Plus, if you get one...then all of the other kids will want one too! 

The two batteries that I had in question have both just tested out normal. I brought them home and warmed them up. Then they were charged (slowly at first) and brought to peak charge. They were allowed to rest over night and then this evening I discharged them on the Astro 109 and both tested at 98% of rated capacity. Looks like temperature is going to be a factor to consider for cold weather flying with LiPos.

Now what kind of nice Nicd plane do I want for winter???

That sounds like Receiver #23 is coming.... 

Between the two 9CAP transmitters that I have, I can store 28 models...must mean that I need more receivers? 

If you buy 2 new Futaba 9c you can store 36 models......not to give you any ideas 

Interesting point!

More on my batteries: After the discharge last night (charger cut off at 9.0 volts for 3-cell packs) I let the batteries sit over night. This morning, they had recovered to 10.0 volts each. I recharged them and both took a charge equal to the discharge capacity that I got last night. They seem healthy based on this. (All of this was done indoors at 70 degrees)

This is our first year flying indoors, since the state gave us the ok to use their abandoned warehouse. Its huge, but we did put a wood burner in it to huddle around and keep warm. Probably around 35/40 degrees. We all have noticed that our run time is only about 1/2 of what it normally is in the summer, and there does not seem to be as much power on a full charge. But we can live with it. It is better than not flying at all.