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Old Dec 19, 2001, 06:18 PM
Liquid Fuel Rocket Engine
JensJakob68's Avatar
Copenhagen, Denmark, Europe
Joined Nov 2001
156 Posts
Lousy performance in cold weather?

Hello

Went flying yesterday and today with the wingo.

It seems to be that in temp. around freezing point, the batteries are really performing very lousy.

I had to give up on flying with the Nimh 1600ma. Could barely keep the plane up.

The 8x500AR packs did also deliver lousey performance.

Sigh....

Is this normal? (It is my first winter flying season.)

JJ
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Old Dec 19, 2001, 06:28 PM
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Sabrejock's Avatar
Winnipeg, MB Canada
Joined Jan 2000
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JJ: We have experience flying WELL below freezing and IMHO the planes perform better. Cold air is more dense, so props and wings perform better. If you're not getting it, there is something else wrong.

Give your pack a "kick" charge just before putting it in, to warm it up. NiCad's don't like being cold, just like pilots. Tex.
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Old Dec 19, 2001, 08:06 PM
small electrics r BIG FUN
Iowa
Joined Aug 2000
4,344 Posts
Right. My two different make of Nimh packs like to be flown warm right off the charger, even when it's nice out. They just perform better . Not sure about Nicds, but I would think they would perform better if around 50-70 degrees F.

Other than that, cooler temps mean cooler motors, esc's and packs run cooler which all means less resistance.
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Old Dec 19, 2001, 08:23 PM
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PaulF's Avatar
Twin Cities, MN
Joined Aug 2001
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There was a thread about this last month. I've actually propped down due to the denser air. Try to keep the packs in a warm car or something until you are ready to use them.
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Old Dec 19, 2001, 09:01 PM
Registered User
Green Bay, WI
Joined Dec 2000
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cold weather wingo

Last year I flew my wingo in weather down to -4 Deg. F. by chargeing batterys and flying immediately after. Should be able to fly in colder weather this year as I am getting a radio glove for my transmitter for Christmas!
Ed Mc
Green Bay WI
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Old Dec 19, 2001, 10:08 PM
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Chicagoland
Joined Feb 2000
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JJ the NiMH performance is poor due to the temperature. As the temperature of the pack dropps it's voltage drops and you have less power available. I have measured this on the bench at room temperature, at -4deg F it will be drastic. Why the NiCd pack doesn't works well? I'm not sure. Was it warm when you charged it? NiCd should not be fast charged when cell temp is below 32degF. They must be warmed first. Failure to do so will cause the cells to vent.

Greg
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Old Dec 20, 2001, 03:03 AM
Liquid Fuel Rocket Engine
JensJakob68's Avatar
Copenhagen, Denmark, Europe
Joined Nov 2001
156 Posts
Interesting

Hi

Very interesting.

Then I should have propped down, and maybe I have vented all my AR500 packs, since Ischarged them as usual on 2.50 amp.

It was snowing outside the hall when we left, and there is _no_ heating inside the hall.

I had to share my freq. with some other people, so I never got to fly with warm cells direct off the charger, they were cold when I got in the air.

Interesting was that when the cells couldnt keep the wingo in the air any more (6 volt spd.400, 2.33:1 GB, 9x5 Slimprop), and I put the cells on a discharge/charge cycle with 4 amp discharge current, there was 200-300 mA left in the packs every time.

Weird.

JJ
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Old Dec 20, 2001, 07:55 AM
Registered User
Northampton, UK
Joined Jan 2001
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When you take your batteries off charge put them in a Jiffy type padded bag or wrap in bubblewrap to keep them warm till you are ready to fly. Alternatively carry them inside your jacket for 10 mins or so before flying.

Brian
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Old Dec 20, 2001, 10:50 AM
Fixed Wing Fanatic
Jim Walker's Avatar
United States, TX, McKinney
Joined Jul 2001
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Everybody replying to this thread is right on track. What we're doing here is moving electrons around. We store electrons in materials encased in a cylindrical cell. The materials being Nickel/Cadmium and Nickel/Hydride. They use these materials because their atoms have an uneven amount of electrons in their outer shell. This allows the atoms to accept more electrons or pass them along in a "flow". It's a basic physics fact that the colder a material is, the slower it's atomic structure can and does move. The way electrons move is from being pushed (voltage) to break their bond with their parent atom and jumping to a neighboring atom. The colder the atoms, the harder it is to create this flow of electrons. Water makes a good analogy to this basic fact about batteries.

To summarize, batteries are most efficient within a certain temperature range (I'd guess between room and body temperature). Get colder and the electrons don't want to move, get hotter and the materials start venting out of the cell and/or the insulator is damaged by the excess heat.
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Old Dec 20, 2001, 04:59 PM
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Tom Smith's Avatar
New Bern, NC
Joined Mar 2001
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Yeah, right ! I didn't know what was doing it, but last year when the temp went below 45 my nimh packs were lousy. Indoors they were fine, but outside, even after a charge, the were not up to snuff. I now use nicads outside in the winter and keep the NIMH for indoor flying, or warmer weather outdoors. The nicads seem to tolerate the cold better. Tom
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Old Dec 21, 2001, 12:45 AM
Speed Demon
GregG's Avatar
Antioch,CA,USA
Joined Dec 1999
12,335 Posts
Thanks for your info Greg. I've also found Nimh cells and Nicd cells seem to work better when warm. I've actually placed my battery packs on a warm car engine just to get them heated up because I liked the warm performance better.
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Old Dec 21, 2001, 01:18 AM
Mie oo Karjala poikii
Tyson's Avatar
Ruokolahti, Finland
Joined Apr 2001
704 Posts
I've managed to get my 800mAh NiMH's work quite well even temperatures below -15C (about 0F) on my Speed 280 Rook. Long 10 to 15 minutes flights despite the coldness.

On the Rook battery is mounted inside depron fuselage near the motor. As motor (and pack) gets warmer, depron keeps the the heat inside the fuselage (is a problem in summer and indoors...) and makes it possible use NiMH batteries even in very cold conditions.

-27.5C and strong wind today... I don't know if it would be too cold for batteries (probably), but it _definitely_ is too cold for me

-=Mike=-
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Old Dec 21, 2001, 01:41 AM
Registered User
Claremont, SD, USA
Joined Sep 2001
124 Posts
Last year I did a lot of flying below zero, down to -24F with both Nicd and Nimh (RS-1600). The thing I noticed most was reduced run time, down about one third. This was in a Wingo so alot of power was not needed the way I fly, usually pretty slowly.
I do like flying in winter though, NO BUGS!!!
James
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