Lipo's & Cold Weather ?
 

When is it to cold to use your lipo's safely ?.

Not sure on the exact temp, but I was running my E-Revo in the snow when I went to the mountains last week and it was about 15* - 20*F. I didn't notice any performance loss either..... well besides for having no traction. :wink:

Ran my buggy todat at -2* ran good no issues. I do recall that if you charge your lipo's at a low temp then take them to a high temp without discharge they can technically be overcharged?

I think that sounds familiar- cold temps reduce the capacity/capabilty of a battery. A bit like petrol- it expands in warm weather, and can overflow from a fuel tank if you filled it right up (fill up in the morning, then you will have more fuel later in the day!).

i remember i had serious issues with the cold on my mini-t on 3S lipo's. An eagletree will tell you what the loss is. normally lipo's deliver a lower voltage (under load too) when it's cold. so the LVC will kick in sooner, and you won't be able to use their full capacity.

You could warm your lipos, most perform best around 100 degrees

Whats considered cold, also what if i warm them up with a hair dryer first to around 80 or 85 degrees give of take ?.

I would say cold was anything below 10-15*C, and the hairdrier trick should work fine, if you set it to a gentle setting.

Well, have a definate awnser on this. Before I was running fine above 0*, well last night we ran the cars (lipo&nimh) out in the extreme cold -5* and they both ran about 10min and kicked out. My son has no lvc on his setup (nimh) and the car just slowed like the batts were dead.

Today we plugged them in to charge after sitting in the warm house last night, mine (lipo) only took 1200mah in a 5000mah 3S batt and his came off the charger just as quick.

So, +5*f was fine -5* was definatley not.

As for warming with a hair drier, I would think you'd have to cook it for some time before the center of the pack was warm... You could nuke it in the microwave, just use a friends microwave and video tape it for me ;) JK

You could also simple hook up the red to the black wire. they tend to heat up pretty easy that way.

:lol::lol::lol::lol::lol::lol:

If you're really in a hurry, you could hook the red wire to the black then throw it in the micowave for a min or so. That should def get the temps up in a hurry :lol:

I'd say any temp below 50F is going to noticeably degrade the Lipo performance. I keep my Lipo's in my pockets when at the track when its that cold and then use a heat gun for a min to warm em up a bit before the race.

I called flightpower today & got the answer i was looking for. They said they do not recomend use a lipo when the core temp of the lipo is below 40 degress. They also said if it's that cold when your done using it they said put it right back on the charger as long as your pack is not over 100 or 110 degress, to keep the core temp up. They said this will also help lower the over all temp of your lipo in the charging process.

Well, I run a mm5700 on 3s in my losi xxx-s. It was about 40*f when I decided to go do some speed runs at the local(not really) huge parking lot. Just starting off my lipo(maxamps 3s 4k) was at 67*f. I radar-ed in at 33mph; then ran slowly tried to warm up the lipo and gradually hit 40mph. After, I decided to chuck the lipo on the windshield defroster in my car. Warmed it up to a nice 95*f then clocked in at a nice 57mph. Warming the lipos really do help.

I was talking to one of my boat racing friends(brushless of course) and he preheats his lipos to about 110*f before starting, supposedly it helps the electricity flow better....

Bye:mdr:

Careful with preheating though. If I'm not mistaken, voltage climbs as well, so if you have a freshly peaked pack at ~70* (room temp) and then you heat it up, it may push the voltage above the 4.2v per cell mark and cause damage.

According to certain specs I've seen, the cells can tolerate ~4.25 for short periods without any damage, so it leaves a bit of a buffer, but I thought it was something that should be mentioned.