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Old Oct 04, 2012, 12:51 PM
jy0933 is offline
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Discussion

fly with lipo in freezing winter


I have konwn the battery will become inefficient at low temperature... I wonder what heat insulation do you guys use to fly in winter to get the best performance out of them

location.... Minnesota.... the temp in winter is usually -20~-10 c


thx
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Old Oct 04, 2012, 01:04 PM
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Personally I don't fly just cause hands get way too cold. But I think I remember someone recommending keeping them warm in a cooler with a hand warmer pack or something and then I think a lot of people just put a sock on the battery when using it.
Old Oct 04, 2012, 01:51 PM
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I use a bag lined with polystyrene.
A small bag of rice grains is heated in the microwave for a few seconds so it is nice and warm when held in my hand. This is put in the insulated bag along with my lipos.

The heat is contained for a couple of hours or so and the lipos come out nice and warm.

A small plastic bag filled with rice grains is about as cheap as it gets, and is re-usable for months - years maybe ?
Old Oct 05, 2012, 12:16 AM
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Around here it doesn't get that cold, only 0 to -5c at worst in the winter.

Things I've done:
- charge somewhere warm (it's very important to only charge at positive battery temperatures, charging at too low of a temperature can damage lipos)
- keep batteries in warm car (or inside jacket pocket) just before use
- fly only planes where battery is inside plane
- close off all ventilation holes on fuselage with tape

Fly.

Seems to work okay. I give up before batteries do.

For colder temperatures, I think a onboard heater of some sort would be better. Ideally, someone could make a warming blanket that could be plugged into lipo and wrapped around battery with velcro during flight.
Old Oct 05, 2012, 11:00 AM
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Originally Posted by groundfx View Post
For colder temperatures, I think a onboard heater of some sort would be better. Ideally, someone could make a warming blanket that could be plugged into lipo and wrapped around battery with velcro during flight.
I don't think that would be worth the shortened flight time. Any kind of heater will really drain the battery. If anything buy lower C rated batteries so they generate more heat under load and keep themselves warm.
Old Oct 05, 2012, 11:06 AM
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How about hand warmer bags. The ones you smash and they generate heat. One bag can last for a few hours. Not sure how heavy they are though.
Old Oct 05, 2012, 11:09 AM
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Originally Posted by grimbeaver View Post
I don't think that would be worth the shortened flight time. Any kind of heater will really drain the battery. If anything buy lower C rated batteries so they generate more heat under load and keep themselves warm.
this sounds interesting to me... cuz meanwhile you will reach low volt faster than power drain. ?!
Old Oct 05, 2012, 11:25 AM
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Really I think the best idea for in the plane is to insulate the battery the best you can and try and trap any heat the battery generates to keep it warm. The battery itself is a heater (depending on amp draw) so why not utilize that heat.
Old Oct 05, 2012, 06:51 PM
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Really I think the best idea for in the plane is to insulate the battery the best you can and try and trap any heat the battery generates to keep it warm. The battery itself is a heater (depending on amp draw) so why not utilize that heat.
I tend to agree and it works for my modestly low temperatures. However, new modem high discharge rate lipos don't heat up much so at lower temperatures I think some sort of modest external heater inside an insulated blankest is needed.

A few watts of heat is all that's needed if the insulating blanket is good enough. After all, a 200 lb human can stay warm in cold temps with good clothing and we only give off about 100 watts of heat or so. So that's 0.5 watts per pound.

I'm thinking a little bit of this polymer heater material would work.
http://www.calescofoil.se/index.php?...d=53&Itemid=59
http://www.calescofoil.se/images/sto...nt_wattage.pdf

Anybody know where to buy a small quantity?

If on board heaters are good enough for warming space probe electronics, it should be good enough for R/Cers.
Old Oct 05, 2012, 10:30 PM
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When I charge in the winter I charge in a nice warm car. Then while charging I take a dis towel and lay it over the cars heater to get it nice and warm. Then I simply wrap the battery tightly in the towel making as many layers as possible. My plane gets roughly 10 mins and the bats always come out still warm but not hot.
Old Oct 05, 2012, 10:48 PM
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I made these little tea cozies out of that foam that electronic devises comes in. Scotch taped together with a velcro flap closure and a piece to hold it to the sides of the profile fuses. As mentioned above, I use the next sized bigger prop in the winter to help the batt. generate a little more heat. Big plus is a little more performance from your planes. We have a woodstove in our clubhouse so if it's sunny out, little wind and above 20F we'll be there. Skis are made from Depron with the bottom skinned with hockey tape for the smaller planes or Coroplast or aluminum for the larger ones.

Gord.
Old Oct 05, 2012, 11:34 PM
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Sweet clubhouse setup!
Old Oct 05, 2012, 11:42 PM
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Originally Posted by flypaper 2 View Post
I made these little tea cozies out of that foam that electronic devises comes in. Scotch taped together with a velcro flap closure and a piece to hold it to the sides of the profile fuses. As mentioned above, I use the next sized bigger prop in the winter to help the batt. generate a little more heat. Big plus is a little more performance from your planes. We have a woodstove in our clubhouse so if it's sunny out, little wind and above 20F we'll be there. Skis are made from Depron with the bottom skinned with hockey tape for the smaller planes or Coroplast or aluminum for the larger ones.

Gord.
sounds great.... I should probably collect the bubble wrap next time


cheers
Old Oct 06, 2012, 05:05 AM
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Bo Edström, Sweden
Hi,

I have been flying with my electric planes down to -20 Celsius (-4 F). The LiPo cell used have been ThunderPower 45C 3250 mAh 3 cell and DesirePower V8 35C 5200 mAh 6 cell.

On the plane You can tape air inlet a little to restrict airflow/cooling but I have not needed to do that.
I charge with 12 volt Pb (lead) 80Ah supply battery in winter (with a Hyperion charger today, before that I had a RC Logic Fusion charger).
I keep the LiPo batteries in my pocket (in jacket) when not in use when I'm out flying when it is cold as -20 C. When charging I let them be in a LiPo sack but You can use other methods to keep them warm but I usually start imediately to charge battery after landing and then the battery is handwarm so it is usually no problem to charge them in my experience (I charge at 2C in the field).

For the transmitter I use a Raydiowarm http://www.raydiowarm.com/
(I have both the older version and the newest version Mk IV and with Mk IV I use a Robbe red neckstrap instead of the original standard harness)

For little heating inside this case I use two Hot Rox http://www.thehotrox.co.uk/

Works fine.

/Bo
Last edited by bossee; Oct 06, 2012 at 05:42 AM.
Old Oct 06, 2012, 04:16 PM
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Beautiful setting!

I guess one good thing about cold is that every lake becomes a potentially huge flat area to fly at.


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