Lipos in winter

[Hernthehunter]

I live in the Midwest and just want to know what do I need to be concerned about regarding lipo batteries and electric motors in winter?

[cliffh]

Nothing for the motors if stored indoors in a dry area.

Lipos should be stored with approximately 40% charge on them.

I have lots of lipos since my wife also flies. To keep track of charge status, we put a regular rubber band around all fully charged batteries. Band off to fly, so battery with no band is discharged.

We put orange rubber bands around batteries partially discharged for storage. That way, we don't accidently mix up a "storage charge" battery and think it is fully charged.

At any rate, find a way to keep fully and your 40% charge batteries separate.

Cliff

[newjak]

One other thing to consider when out at the field in cold weather. Lipos like to be kept warm. So keep them as warm as possible right before use.

[MaxAdventure]

When you fly in below freezing temperatures, be sure to keep the LiPo out of the air flow. Usually just wrapping a 'blanket' around them allows the heat they generate during use to keep them warm enough from dropping the voltage. Keep them at room temperature until ready for use.

[Alaska]

What about use at sub-zero temperatures? Will I need to completely insulate the battery from exposure to the outside air?

[newjak]

Originally Posted by Alaska

What about use at sub-zero temperatures? Will I need to completely insulate the battery from exposure to the outside air?

I've never flown in sub-zero weather, but check this out
http://www.horizonhobby.com/Products...rodID=TRI20235

[Alaska]

I was thinking about the need to keep the batteries warm during flight. I can keep them in my truck with the heater running before flying, and I will definitely leave the truck running and the heater on so I can warm up between flights.

Or... I may just not fly when it gets below 10-15 degrees, but that's going to limit my flying time considerably. The nice clear sunny days here in the winter typically are around zero. It usually doesn't warm up above 10-15 unless it's overcast and a lot of times it's snowing then.

[newjak]

Originally Posted by Alaska

I was thinking about the need to keep the batteries warm during flight. I can keep them in my truck with the heater running before flying, and I will definitely leave the truck running and the heater on so I can warm up between flights.

Or... I may just not fly when it gets below 10-15 degrees, but that's going to limit my flying time considerably. The nice clear sunny days here in the winter typically are around zero. It usually doesn't warm up above 10-15 unless it's overcast and a lot of times it's snowing then.

Your lipos will get warm during use. Exactly how warm they get under extreme cold conditions I don't know.

[MaxAdventure]

ALASKA - I did answer your question above, before you posted. Did you see?

Freezing temps - keep the lipo warm until use, then wrap it to keep it out of the air flow. They generate heat while being used and that's usually enough to keep them warm.

You'll have to see just how warm/wrapped for your packs/plane and temps.

[Alaska]

Thanks MaxAdventure. I'll try wrapping them in some foam and see how it works out.

[JetPlaneFlyer]

I can confirm that low temps are a problem for Lipo's. I've attempted to fly in temps around -5C and the voltage dropped so low that the low voltage cut out on the ESC was tripping after a few seconds of run.

These were small cells in a micro size model and i found even if i pre warmed them did not keep warm long enough for more than a few seconds of flight... larger cells may do better.

[Lieutenant Loughead]

I fly every day. I fly in 110F heat, and in 10F cold. There is a SMALL difference in the flight times of my aircraft on the cold weather, but we are talking about 18 minute flghts in the cold versus 20 minute flights in the heat. (Both are not good for LiPos, by the way!)

It all boils down to your amp draw, the battery used, and the ambient temperature. If you use a 10C, 1000mAH LiPo and draw 10 amps, you are going to have problems in the winter because the cold LiPo will not hold that full throttle voltage for long!

However, if you have an airplane which uses LiPos which regularly come down warm, that is a perfect airplane to fly in the winter time! The airplane warms the LiPo, and the outside air keeps it cooler than in the summer time!

[SARG 5]

Sarg5 here
Hernthehunter. Where do you live. I live 10miles north of Russell, Ks. Always looking for E-flite folks, not many around here. Just trying to get started in elec.
FLYING THE COUNTRY WE DEFEND

[Hernthehunter]

Live in Columbus, OH. Flying an electric Big Stik 60, Eflite pulse 25, MS Composit Bulldog, and a MS Composit Citabria presently.

[Hernthehunter]

I think I will wrap the lipos in foam to keep warm enough. Charging will be fun when it drops down. All our charging equipment is outside under our shelter. Read that the lipos shouldnt get below 55 degrees F to charge. Maybe a heating pad under the lipo bag would be good enough. I am stubborn mutt and really want my flight time.

GOOD FLYING!!

[barrie6313]

Hi guys l have been reading your comments on keeping lipo's warm and thought you might be interested in what l have been working on .i started this project last winter and designed a heated pad which went inside a transmitter muff ( not sure if you use these in the states ) which worked very well and recently i have used the same idea and made an insulated box with a heated pad in to keep my lipo's warm the heat is controlled by an adjustable thermostate up to a maximum of 30 degrees c and requires only a 12 volt supply.My box takes about 30 mins to warm up as there are 13 lipo's in it but once warm the thermostate keeps the temperature to 27-29 degrees C .the way l intend to use it is to connect it up the night before l go flying to a car battery and then in the morning swap to a small 12volt 7AMP sealed lead acid battery which is more portable and will last several hours. the pad runs at 1.25 amps and has a 2 amp fuse in line l have made several of these and have had no problems with any of them.

[flypaper 2]

For my profile planes where the batt' Velcros to the side, I make an envelope out of that 1/8 in. thick foam that electronics comes wrapped in. Scotch taped together with a piece of velcro for the closure. The batt. is slid in, velcroed shut then velcroed to the side of the plane. Don't need to take the envelope off the side of the plane. Take the batt. out, slide another in and go. With the colder air, you can put on the next sized bigger prop. Gives you more poop, batt has to work harder so keeps itself warmer. We fly down to about 20 F. Gets a little uncomfortable below that. We fly all winter in a woodstove heated clubhouse.

Gord.

[Lieutenant Loughead]

Personally, I would not feel comfortable putting my LiPos in a "warming oven" as suggested in post number 16. Heating LiPos is really a very bad idea, since heat actually kills LiPos. I understand that the idea of your "warming oven" is to gently warm them to a "safe operating temperature", but warming them to 27-29C (80-84F) is much too warm for a LiPo.

A LiPo's temperature should probably be closer to 18-20C (65-68F) on a cold day -- but even then, I would not chance my expensive LiPos to a "warming oven" that may malfunction, or cause "hot spots".

Just my two cents...

EDIT --> I just realized that was your first post on WattFlyer. My apologies if I did not make you feel welcome. The above post is my personal opinion -- others may be interested in your idea. Best of luck!

[Hernthehunter]

Thanks Lieutenant. I agree with keeping the lipos warm to a lower temp when charging. So I thought an adjustable temp heating pad under the lipo bag would be of the most benefit. I caught a posting saying not to charge your battery if its temp is under 55 degrees F. So with an adjustable temp heating pad I thought I could keep it about 60 degrees F in the charging bag.

Thanks to flypaper too on the prop size idea. Hadn't thought about that.

GOOD FLYING!!

[flypaper 2]

The FMA Cellpro 4 has a built in temp. sensor where, if it drops below, I think it's around 55F, it charges to a lower cell voltage. Had that happen in the winter in the clubhouse with a woodfire going. Charger and batt. were being charged sitting on one of the chairs when the screen said cold charge. I put the charger and batt. on top of a table where the temp was a bit higher and about 15 mins later it went to normal charge. I think the problem is, if it's charged to 4.2 volts at low temp, as it warms up the voltage keeps climbing to the overvoltage dangerous state. I may be wrong but that's my take on it.

Gord.

[jjw]

There are issues with lithium chemistry batteries when charging at cold temperatures, but so are there with older tech. nickel cells. The problem specific to lithium is that the susceptibility of the anode to be plated (with lithium metal) goes up as the battery temperature goes down.

If the bat. temp. is below 45F then charge rates should be dropped below 1C. If cell temps are below freezing (32F/0C) then its probably a good idea not to attempt charging at all. Note that I stated cell temps and not air temp.

-Jim.

[barrie6313]

I have took all your comments on board and made another heated pad for my warm box (its no longer an oven )this time drawing less amps for a more slower heat build up, the thermostat is now set to 16-18C l have also put a thermal cut out between the pad and the thermostat in case the thermostat malfunctions (l could make it belt and bracers and put 2 thermal cutouts in) l take enough charged batteries to fly without having to charge any at the flying field so all of them fit in my warm box and with the added security of the thermal cutout its a lot safer ,please let me know if you can think of anything l have missed

[Lieutenant Loughead]

Originally Posted by barrie6313

I have took all your comments on board and made another heated pad for my warm box (its no longer an oven )this time drawing less amps for a more slower heat build up, the thermostat is now set to 16-18C l have also put a thermal cut out between the pad and the thermostat in case the thermostat malfunctions (l could make it belt and bracers and put 2 thermal cutouts in) l take enough charged batteries to fly without having to charge any at the flying field so all of them fit in my warm box and with the added security of the thermal cutout its a lot safer ,please let me know if you can think of anything l have missed

That sounds like a much better plan. Thank you for taking my comments as constructive criticism.

Hey -- you should start a thread of your own, and let everyone know of your invention. You might just sell a bunch of them!

On another note -- where can I get one of those big gloves for my hands and transmitter (for flying in cold weather)?