Cold Weather and Lipos

[Harvo]

I have some Krawler Hobbies 850mah 3s lipos that are great batteries. They always charge close to 830 mah.

The truck I use them on is a berg with 2 BRXL's.

A couple of nights ago, it was about 40 degrees out and I ran the battery to cutoff. When I charged it, it only took 630mah. I thought the battery might be failing. Used different but identical battery next, and the same thing happened... about 610 mah.

Oddly...the charge time is about the same.

Now I am wondering if it is the BRXLs cutting off too early for some reason.

Any ideas? Could it be the cooler weather?

Thanks

[squatch71]

theres another thread on this somewhere...but first thing I would check is what is your ESC cut off set to?? mines at 3.2/cell..just incase

*edit*
Found it
Either need suggestions or answers

[Harvo]

Just recharged my gens ace 450 that I drained in the same truck. It took a full charge. So maybe both Krawler Hobbies batteries are going bad at the exact same time?

Or something about those batteries make them more snsitive to cold?

I'm at a loss

[YYCADM]

Did yo get the batteries at the same time? do you cycle through them both regularly? it's certainly possible they could both be failing at the same time if they've had an equal number of charge-discharge cycles through them.
Lipos are no different than any other battery; they do have a finite number of charge cycles available before they die. You may have just reached that point with them if you've used them equally.
Cold and batteries is never a great combination anyway and lipos in my experience don't care much for cold weather.

[soutthpaw]

I know cold makes a big difference on traditional lead acid batteries such as use in automobiles, Hadn't thought about it for Lipo's.

[JeremyH]

Originally Posted by Harvo

Or something about those batteries make them more snsitive to cold?

That is certainly possible....but to my understanding, most cells are made by the same places so they should be relatively the same.

Are the KH packs the same age as the GenAce packs?

[KBrog]

Ive noticed that cold weather has more of an effect on my higher performing lipo's than on my low priced hobbyking lipo's.

But then again, my hobbyking batteries are what I call "cold conditioned".
I leave them in the cold garage where they are stored, and charged. So they dont really go through a drastic temp. change all of a sudden.

My other batteries have not been conditioned in the same manner.

[hbj069]

Hey Harvo, I had this happen also on the KH batteries, I let them set overnight and return to room temp (about 60 degrees in the man cave) and all was good. They charged fine the next day. I also recall last year using the truck heater to warm them up before crawling.

[Harvo]

Originally Posted by JeremyH

That is certainly possible....but to my understanding, most cells are made by the same places so they should be relatively the same.

Are the KH packs the same age as the GenAce packs?

No the gens ace are newer. Did get the KH packs all at the same time though.

Originally Posted by hbj069

Hey Harvo, I had this happen also on the KH batteries, I let them set overnight and return to room temp (about 60 degrees in the man cave) and all was good. They charged fine the next day. I also recall last year using the truck heater to warm them up before crawling.

Thanks. I'll try that. I'm also going to drain them in a different rig to see if it still happens.

[ram_tough]

I seem to remember a thread from last fall about lipos in the cold weather. Chris the battery man had some graphs (I think) and mentioned about runtimes decreasing and cell performance dropping in the lower temps. I started last year keeping a hothands in my pocket with my lipos on those cold comp days; to keep some normal temp to the cells.

Found It: http://www.rccrawler.com/forum/elect...mance-***.html

I love the search button

[JeremyH]

Originally Posted by Harvo

No the gens ace are newer. Did get the KH packs all at the same time though.

Then I suppose it is possible that they are going bad.

I've been running the same packs (only 4s) in my super for quite some time (since they came out) and had good luck with them. No puffing and no drop in runtime.

[Charlie-III]

Originally Posted by ram_tough

I seem to remember a thread from last fall about lipos in the cold weather. Chris the battery man had some graphs (I think) and mentioned about runtimes decreasing and cell performance dropping in the lower temps. I started last year keeping a hothands in my pocket with my lipos on those cold comp days; to keep some normal temp to the cells.

Found It: http://www.rccrawler.com/forum/elect...mance-***.html

I love the search button

Absolutely, low temps kill battery performance, ANY kind of battery. Since pulling power from a battery is a chemical reaction, most of them work better the warmer you get them (short of overheating the pack).
I would be a bit leery of keeping LiPO's in my pockets, but keeping them warm is highly recommended. This is a good reason to have a way to charge them onsite, the charging also adds some heat to the pack.

BTW, nice use of the search button ram_tough!