Lipo warm-up?

Hi, I would like to ask opinions about lipo temperature management. It is getting cold now, but how cold is too cold for lipo batteries?
When to warm up the batteries and how you guys do it?

i am very interesed as well , i have heard that many are pre-heating there batteries , but to what temp and how?


i try and not let my batteries get below 40*f , which is easy , i just dont store them in my car( but i run them very easy for 5 min. to get some heat in them when it is cold outside)

Shawn Palmer, when he was still with CC, wrote a lipo FAQ on RCCA forums and he addressed this to some extent - only time I've seen it mentioned. Here's some of that work -

"Lipo Tweaks
-----------------------

Starting Temperature
Here's one for the real tech heads! Like most batteries, lipos all have an "ideal output temperature". When run with a starting temperature of around 100degF, the internal resistance is at it's lowest. So you get best voltage under load AND least amount of heat built up during the run. When I fly (small) lipo-powered planes in the winter, I put the packs in my jeans pocket for about 1/2 hour before I go fly them. The initial performance is WAY better than starting them at either room temp (60-70degF) or the garage temp (35-45degF). The really telling point comes when a few minutes into the flight when it's very cold outside, the pack starts to cool from the airflow and the performance drops drastically."

[redshift]

Ok guys, what's the minimum ambient temperature for lipos?

My FlightPower packs say "AVOID CHARGING IN FREEZING TEMPERATURES"-- well I won't be doing that, however I will be running in 20F or lower, add in the windchill factor at say 30 mph.

Will this damage lipos?

Do I need to make some self-powered electric blankets for them lol

Or will the cold merely reduce performance?

What's your experience?

[Gee]

I used my lipos all last winter almost on a daily basis. Temps were down to 0 a couple of times but mostly between 25-35 I would guess. Didn't have any problems and they are still going strong (except one) so this will be winter number two for them. They held up better then the plastic parts did in those temps. We had a lot of snow last year and it stayed around for what seemed like all winter. So the lipos and all the electronic were all enclosed in one way or another with plastic wrap or a baggy that wrapped around everything. They seemed to get enough work that they were warm when I was done running. Actually had problems keeping the Novak HV ESC cool enough while all was wrapped up. Had to use extra fans to ciruculate air in the contained area. Guess I really never thought about a minumum temp for them. I really didn't pay much attention to any performace difference.

[redshift]

Aww well you just totally destroyed my idea for a toaster with a 'lipo' setting.

We're at roughly the same latitute Gee, so I'll take your word, and you'd agree the hardest part is keeping the fingers warm. 10 minutes may be all I can take some days, I've tried gloves, and even those thin brown cotton ones make inputs on the TX kinda vague and not right, and they don't keep hands real warm either.

I guess I'll just have the packs at room temp when I put them in, I'm running a 9XL with 2 4900s and 2 6000s, they barely crack 100 degrees even when it's 95 ambient, so I don't think they will generate any heat during use.

Man I'm still trying to wrap my head around this batteries "too cold" thing. my problem up til a few months ago was trying to keep my Nimh stick packs from turning into molten ingots!

I'll certainly take this problem over that...

Thanks for the reply.

[JERRY2KONE]

As for the hands and fingers you can try putting some of those hand warmers inside your gloves to aid in keeping your apendages warm. You can get them at most hardware stores or even on line from The Bass Pro Shop/Great Outdoor World. I use them and they really do help. I also purchase a pair of socks there that have "D" battery packs attached to them, with an electric element like an electric blanket. I am wearing them now for around the house. It is like 20 to 30F here in Korea this week.

[lincpimp]

A lipo at 100f seems to work best. Now the 30c enerland cells like to be warmer than that, like 120f. I would warm them up before use.

[BL_RV0]

I use sport chalet hand warmers inside wool socks. Not cold here yet, but when it deos get chilly (40*) I use them.

[Gee]

40* is about the temp to break out the cutoff up here. Gotten use to the cold weather but still don't care for it. The bummer up here is the lack of daylight. Go to work in the dark and get home in the dark. This is the time of year I start trying to figure out lights for all the RCs.

I guess if your going to the track and need the best performance it would make sense to get a toaster they use for beagles and keep them warm. Just bashing they do fine. I went to REI (outdoor sports store) here in town last fall and spent close to 50.00 on some nice gloves. Wanted the thinnest they had but the warmest. They do real well except for the finger tips can get cold.

The other problem I ran into last year was loosing the LCD on my DX3R transmitter when it got real cold. Still worked fine but nothing on the screen would show up until it got warm. If you are worried about the lipos getting too cold maybe throw them in a wool sock before you strap them in. One nice thing about winter is you can gear it up a bit higher and do some experimenting without worry to much about thermalling your ESC or batteries.

[JThiessen]

Originally Posted by BL_RV0

I use sport chalet hand warmers inside wool socks. Not cold here yet, but when it deos get chilly (40*) I use them.

wusssyyyyy!

[lincpimp]

Originally Posted by Gee

... it would make sense to get a toaster they use for beagles and keep them warm...

I hope that no one from the aspca reads this. And it must be a big toaster to get a beagle in it. Those dogs get decent sized...

Originally Posted by JThiessen

wusssyyyyy!

My thoughts exactly....

[redshift]

I'll take cream cheese on my beagle lol.

Good point about the plastic parts also, they do tend to get brittle, I really only have A-arms to be concerned with tho.

And go easy on the Californians, you can't be truly hardened (by which I mean frozen stiff) until you've dealt with negative 40 a few days in a row, which is usually the high temp here in February ;)

I saw a few years ago a 'TransMitt' for use with a stick TX, think they advertised it on RCGroups. I may make something like that. As I said, the real problem with gloves for me is the throttle/brake feel. Steering is no problem but I have large hands and my digits don't fit well with gloves in the trigger notch.

This thread was about batteries tho wasn't it lol. I don't care if the batts don't have maximum punch, just wondered if it's possible to do damage in extreme cold, I guess if it's too cold for the hands it's probably borderline too cold for the lipos, maybe I'll just use that as the determining factor.

But I did build my Mute to be fairly weather resistant with no additional protection needed, and while it's of course not waterproof, it does work fabulously well. And BrianG, I have removed my fans for the season. Time to get it sloppy!

:)

[JThiessen]

My senior year in high school, we played the state championship football game and it was 30 below, with a 20 mph "breeze"....I didn't really feel the cold until I snapped my ankle and had to sit the rest of the game. At least I didnt have to put ice on it.....

FWIW on the batteries. What happens in cold is that molecules dont move as fast, and you just see fewer amps out of it. Hence why in cold weather people buy batteries for thier cars with a higher cold cranking amperage. So I highly doubt you'll damage a battery. You may end up having false low voltage shut down, though.

[redshift]

Having a blast here tonight- we got snow!

Normally I don't much care for it, but ya gotta make the best of it right?

Gotta say the Zombie Max tires hook pretty good, but what fun is that right.. howbout a few hundred feet sideways?

Packs were about 70F, ambient temp about 20-25F, 10 minutes of full throttle and packs dropped about 10 down to 60F,

I ran my MA 2S 6000s that were at 7.8, ran down to about 7.4 after the 10 or 15 minutes, no noticeable lack of juice.

I look forward to some serious snow hill climbing and speed runs on hardpack!