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Old Jan 31, 2007, 12:46 PM
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Lipo's and REALLY COLD Weather

A friend of mine told me that you can't use Lipos in cold weather 30 degrees and colder Fahrenheit.That the plane will take off fine, but after a very short while, the plane will just drop out of the sky .... no warning ..... no control.

Of course that scares the heck out of me, cause I use a vid cam in my Easy Star all the time.

Here's my experience ....... I have noticed absolutely bad habits using my lipos in the cold weather. They seem to work ecactly as they do when it's 70 degrees, and when it's 20 degrees, and I have had absolutely NO PROBLEMS at all.

Well, this Saturday I plan on flying while filming video, and pulling a banner, but it's going to be REALLY COLD out (like 0 or 5 degrees). I don't want my plane to drop out of the sky like a rock, and destroy all my electronics.

Is there anything to worry about here?

I have had no ill effects at 15 to 20 degrees, and I need to know if I will have any problems with zero to 10 degrees (all temps discussed are in Fahrenheit.

Thanks
Jim
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Old Jan 31, 2007, 01:22 PM
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Finland
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Had to chime in as it was just -28 degrees celsius this morning.. Didn't fly though
Lipo-batteries certainly don't like the cold weather, but if protected (by for example a Formosa) from the draft -10 or even -15 shouldn't pose much of a threat. Just make sure to keep them in your *krhm* pocket right 'till the last minute.
A separate NICD receiver battery is a cheap, but heavy insurance.

-M
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Old Jan 31, 2007, 01:25 PM
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Son, Norway
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We fly below zero most of the winter. The only problem is that we might hit LVC before the lipos warm up as a result of the load. Lipos mounted on the outside of planes will have problems though, because of extensive cooling during flight.
Try to keep the pack warm before the flight to avoid the problems early in the flight.

Fred
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Old Jan 31, 2007, 01:25 PM
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Greensboro, NC
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First of all, cold air is denser than hot air, so your plane will have more lift flying in cold weather. It will actually fly better than on a hot day.

As for the batteries suddenly ceasing to discharge any current, I can't see how that could happen, either.
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Old Jan 31, 2007, 01:33 PM
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Chicago, IL
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I meant Fahrenheit

I'm an idiot I live in the Burbs of Chicago, and it's cold !!!

I flew a 3cell 1000 on the outside of a foamy p-51 the first time is was cold (begin of Dec - like 15 or 20 degrees) and had no ill effects (while nerviously waiting the whole time for it to drop out of the sky like a rock, as my friend said)

I just recently was out on a frozen lake Ice fishing sun 27th at about 20 degrees. I did NOT keep the batts anywhere warm or in my pocket, left them sitting on the ice all morning in a plastic tuppaware container. Popped an ice cold batt in the Easy Star ( a DN 3 cell 2000), and flew all over in heavy wind (15 to 20). I had NO PROBLEMS with the batt, and was able to land nicely with no damage to my radio/video gear. Oh btw- here is a vid of my Pike Seminar that I put on. Enjoy !!!

http://angling101.com/images/jimvid/pikeseminar.wmv

Now it's going to be about zero degrees this Sat morning, but I really NEED to fly the plane and get some more video of yet another ice event.


I do not want to risk the embarrassment of my plane dropping out of the sky in front of everyone, and my equipment getting smashed to pieces.

Anyone in the cold weather climates ever use your lipos at or below zero?

(ps .... don't some people store alkalines in the fridge or freezer?.......... and ...........what about the nicad in my radio?)



Thanks Jim
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Old Jan 31, 2007, 02:20 PM
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Haralson County GA. USA
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Simple answer is that LiPolys provide less voltage and less power when they are below 90F or so. Ideal temp. range for the battery is 90 to 125F.
How much performance youu lose depends on the degree they are pushed.
If you have a battery capable of delivering 20A at 10.5V in 70F ambient temperature however you only use 2C aveage current (30 minute flights) then the cold would not have much of a noticeable effect.
I fly flat plate foamies and when the temp. is below 50F I warm the LiPolys to 85-90F . wrap them in a 1/16 thich layer of foam and they are approx. 115F at the end of a 8 min. flight . The planes performs just like it does durning the summer.
If on the other hand I take a LiPoly from a 55F room and fly it unprotected the palne flys poorely and I must be very careful not to use WOT or the LVC point will be reached.

Charles.
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Old Jan 31, 2007, 03:06 PM
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Finland
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Quote:
Originally Posted by Jim Kachel
(ps .... don't some people store alkalines in the fridge or freezer?.......... and ...........what about the nicad in my radio?)
Storing is a whole different issue than using

Nicads still have the best tolerance for cold (vs. lipo / nimh) so you shouldn't have to worry about the radio.
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Old Jan 31, 2007, 03:15 PM
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Chicago, IL
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Quote:
Originally Posted by Bondi
Nicads still have the best tolerance for cold (vs. lipo / nimh) so you shouldn't have to worry about the radio.
Thanks for easing my mind with the radio issue

What about wrapping the batt in foil to help retain the heat? (I am one of many who are already squeezing their batts in, with no room to wrap them in foam).

What are your guys thoughts about that?

Is that nutz, or doable?
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Old Jan 31, 2007, 03:25 PM
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Walled 'tucky, MI. USA
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Wrap em in a peice of brown paper bag. It's thin and insulates well for what it is.

I was worried my lipos would freeze or get damaged if left in the car or an unheated room. Is that possible?
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Old Jan 31, 2007, 06:49 PM
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United States, WA, Puyallup
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Quote:
Originally Posted by roosevelt
I was worried my lipos would freeze or get damaged if left in the car or an unheated room. Is that possible?
Possible, but doubtful. This reference says you can store lipos as low as -20 C.

Bill
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Old Jan 31, 2007, 08:03 PM
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Wow. That's neat. It even shows the loss in disharge capacity relative to the outside temperature. Thanks.
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Old Jan 31, 2007, 10:55 PM
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Gaithersburg, MD, USA
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Li Pos lose some capacity when cold.

Quote:
Originally Posted by Jim Kachel
I meant Fahrenheit


Anyone in the cold weather climates ever use your lipos at or below zero?





Thanks Jim
Jim,

Li Pos do lose capacity when cold. See attachment. However, this is one of the beauties of Li Po: They are so light that you can parallel packs to make up for lost capacity and still not add enough weight to compromise flight performance unless the airplane is marginal to begin with.

Good luck,
Fred@fmadirect.com
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Old Jan 31, 2007, 11:15 PM
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Jim K.'s Avatar
Chicago, IL
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Quote:
Originally Posted by flarssen
We fly below zero most of the winter. The only problem is that we might hit LVC before the lipos warm up as a result of the load. Lipos mounted on the outside of planes will have problems though, because of extensive cooling during flight.
Try to keep the pack warm before the flight to avoid the problems early in the flight.

Fred


Below zeroC or zeroF Fred?

Also, anyone think about putting one of those hand warmer packets (you get at the hardware stores) in the fuse w/ the batt and radio gear? If there was room, that should end all concerns w/ below zero temps F for us Midwest guys.

What do you guys think of that idea ...... Good.......... or a waste of time?


Jim
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Old Feb 01, 2007, 12:41 AM
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Son, Norway
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Quote:
Originally Posted by Jim Kachel
Below zeroC or zeroF Fred?

Also, anyone think about putting one of those hand warmer packets (you get at the hardware stores) in the fuse w/ the batt and radio gear? If there was room, that should end all concerns w/ below zero temps F for us Midwest guys.

What do you guys think of that idea ...... Good.......... or a waste of time?


Jim
Zero C for me, Zero F for others .
You could use those hand warmers to keep them warm before flying, and maybe while charging. Charging cold lipos is not good either...

Fred
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