lipos and cold weather
 

Is it safe to run lipos like in 20deg and 30deg weather i race in ohio in a dome type thing in the winter any feed back would be great thanks

It is safe, but performance won't be the greatest. Lipos don't like low temps. The plane guys have known this for a while - even when they warm their lipos, the air flow cools them back down and they see a loss of performance.

About all you can do is start them off from a warm temp and see how badly performace drops off when they cool. This is one case where you don't want a lot of cooling air flow. Maybe you can insulate them to help keep them warm.

I went looking for specs and Kokam says their operating temp range is from
-20C to +60C. The low side is -4F if I converted right - I was worried that there was a lower temp limit below which they did't recommenmd running. Looks like you're ok there. I've never used mine in low temps - I just don't get into being cold while trying to have fun running an rc.

thanks alot for the info i will try to see if there is drop

The big CellPro charger has a Cold Weather Mode, that limits the maximum charge voltage when it’s cold. Supposedly a full charge when cold degrades the battery.

From the manual:

 In Cold Weather Balancing Mode, charging automatically stops at 4.10V/cell when temperature
is below 55°F to prevent cell damage.

Lipo supposedly has an optimum discharge temp of 100F. I read of some who warm their lipos so when they start a race, they do not have to wait for the discharge itself to warm the lipo up - they start right off with optimum amps at the highest volts.

Some elec plane guys I occassionally hang with put the packs in their shirt pocket an hr or so before they're going to use them if its cold and bring them up to near body temp. They're the ones telling me they can see a drop when flying when the lipo gets cooled down - speed drops and they can't fly as long as in warmer weather.

I didn't know about limiting the charge if temp was low. Its not much of a prob where I live.

I race a big local race this weekend and it was about 50 deg. outside. I put a Lipo in my inside coat pocket after I charged it for about an hour. When I put it in my truck it was body heat warm, which was alot warmer than the outside temp. The car had loads more punch and speed down the straight. SMC has posted that the batteries take a better charge when about 140 deg. I am going to pick up a heating pad for the next race.:nod: I hear tire warmers work well also but not as nice to sit on when your not racing. :lol:

I'd be careful at anything approaching 140F. Thats usually the threshold where they start warning about lipo damage.

I contacted the manufacturer of my lipo's about the best temp in cold weather and they said.
On a race day in the winter you should pre-heat them for two hours to between 70* & 80* before charging them. keep them at that temperature for the entire race day and your lipo's will last longer.

thanks guys for the help i was just wonderin cause they say never store ur lipo in cold weather but they dont say anything about using them in cold weather:confused:

You def want to keep your lipos stored inside when its cold outside! Too expensive to degrade from something thats so easy to prevent.

guess I have to brake out the 3300s, the temp never got above 30 yesterday:cry:

So I guess there are reasons not to get completely rid of them...

Okay I was going to get lipos for my kids to run in the slashs I'm getting them. If they charge them inside then take them out, then bring them back in to charge again are we looking at problems and shortened battery life? At $100 or so a pop I can't afford to be replacing lipos.

Yeah 140*F is WAY to warm. My Duratrax/checkpoint charger temp alarm is set at about 95*F. Good to know about the cold weather thing though

Jay

If you store your lipos inside where its heated to start with, unless its way below freezing (too cold for kids to go out anyway), think you'll be fine. I would wait in between charges until they are warmed back up if they come in and are cold from running. If the lipos are warm when they come in, its not a prob - charge 'em and go run again!