Originally Posted by RC Man

What is the freezing temperature of lithium?

Lithium is a metal, perhaps the question should be at what temperature it will melt.

Dennis

Rather than using a bird-bath heater, I found this nice line-voltage thermostat for under $30.

http://www.zorotools.com/g/Portable%...tats/00053176/

I plan to put that in a picnic cooler connected to a drug-store heating pad. Set to 45 degrees it should keep the batteries very comfortable indeed.

Now, keeping them cool in the summertime, when the garage can reach 95-plus, is a different story. I guess a small fridge will be in order.

Let me get this right.

You are going to purchase a cooler, a heating pad, and a thermostat. You are then going to assemble all this stuff, in a safe manner I assume, so you can keep your batteries warm during the winter?

Then you are going to buy a refrigerator to keep them cool in the summer?

I think you should just switch to fuel. Allot less hassel, and appearently allot safer.

Originally Posted by Neko

Rather than using a bird-bath heater, I found this nice line-voltage thermostat for under $30.

http://www.zorotools.com/g/Portable%...tats/00053176/

I plan to put that in a picnic cooler connected to a drug-store heating pad. Set to 45 degrees it should keep the batteries very comfortable indeed.

Now, keeping them cool in the summertime, when the garage can reach 95-plus, is a different story. I guess a small fridge will be in order.

I'd say the real weak link is that heating pad, much less reliable, IMHO, than the lipo you are worried about.

If it fails, good-bye garage!

Originally Posted by RC Man

What is the freezing temperature of lithium?

~180 deg C

Not that that is relevent since there is no metallic Li in a Li battery, only Li ions stored in a different substrate. The freezing a battery can do is the electrolyte.

Originally Posted by tacx

Let me get this right.

You are going to purchase a cooler, a heating pad, and a thermostat. You are then going to assemble all this stuff, in a safe manner I assume, so you can keep your batteries warm during the winter?

Then you are going to buy a refrigerator to keep them cool in the summer?

I think you should just switch to fuel. Allot less hassel, and appearently allot safer.

Not comparable. A small fridge costs much less one plane. Buy it, plug it in, forget it. Not only will it give peace of mind (priceless), but part of this discussion is just for the fun of figuring out how to do this.

Originally Posted by Alan Hahn

I'd say the real weak link is that heating pad, much less reliable, IMHO, than the lipo you are worried about.

If it fails, good-bye garage!

I'd much rather have that go than the house. But the possible failure of the heating pad is a good point. How about something a little more robust:

http://www.oreillyauto.com/site/c/de...0649&ppt=C0076

And these "Battery box heaters"

http://www.oreillyauto.com/site/c/de...0651&ppt=C0076
http://www.autopartsandstuff.com/zer...rywarmer2.aspx

If it matters at all ThunderPower says store at 40F-70F:
http://thunderpowerrc.com/documents/Winter.pdf

If you are going to keep them in the garage at least make sure you keep them on the opposite side from all the flammable stuff normally in a garage.

If you're going through all that trouble why not just bury them under ground below the frost line?

A very low wattage light bulb in the cooler with two thermostats with the apropiate temperature range in series. Just in case one sticks. This is unlikely with a device drawing so little current. Not new thermostats unless cheap either. Plenty of good used ones should be out there. Actually in this application I would never rely on just one thermostat.

Be nice to know where the OP lives, or did I miss that information?

Since he talks about temperatures using F, I assume the USA. I rather doubt there are many, if any, US locations where LiPos stored in an unheated garage would suffer damage from cold temperatures.

Chicago area. We get down to the teens (F) almost every winter and occasionally much lower.

Originally Posted by Neko

Chicago area. We get down to the teens (F) almost every winter and occasionally much lower.

Not cold enough... as stated previously.

Originally Posted by desertstalker

Not cold enough... as stated previously.

Here in eastern Massachusetts we occasionally get nights down below -10F. A garage attached to a house will stay a bit warmer than that, if the doors seal well. But it is getting down to questionable range. And if your garage is attached to your house, you're not really helping by putting the lipos in the garage anyway.

Hi Guys,
I can get rather "anal" about things also and was worried about where to store and charge lipo batteries from the day 6 years ago when I got into RC electric airplanes. At first, I charged them in my house, on some ceramic floor tiles, which are obviously fireproof. Then, a very informed guy on this forum mentioned to me that my charging method would prevent a possible fire, but he pointed out that the bigger problem if a lipo should "blow" is the toxic fumes that are emitted. Obviously, I don't want to kill my little dog and wife with toxic smoke (okay, at least not the dog). So, I began charging on my workbench in my garage, again on ceramic floor tiles (and the lipos in a fireproof "Lipo Sack"). With the garage door open, along with the back door out to the yard, at least if a battery "blew", the smoke would exit harmlessly out of the garage.

Now, regarding storage. Two years ago, I bought 10 high-quality lipos, again recommeded by a very informed forum member and stored them in Lipo Sacks in my garage, on top of my workbench covered with tiles. I stored them fully charged so they'd be ready whenever I went flying....and sometimes they would sit there for days or weeks, fully charged. Temperatures here in Connecticut can be very warm in the summer and cold in the winter. After 2 years of storing them in my garage and with over 200 cycles on each battery, they only recently were retired...mostly due to them swelling and losing some of their "strength". I feel I got my monies worth out of them at this point anyway.

Now, going forward, I've been convinced that I should change my storage procedure. I'm going to store them at 50% charge and only charge them as I need them. I bought a deep cycle battery that I can bring to the field and charge my batteries as I fly. I can also charge some before I leave for the field using house current from my 10amp power supply. I've been convinced that while 2 years and hundreds of cycles was a good "return on my investment", that with my new procedure, I may get even more cycles and years out of my new batch of batteries. I'll definitely let everyone know the results of my experince in a couple to three years. Obviously, it was easier to just fully charge a battery after a flight and store them fully charged. It takes a little more planning and thought to be sure to only charge what you need and sometimes, I end up having to wait for a battery to charge at the field because I didn't plan properly or I've decided to get "one last flight in". I'll see if the new procedure, with its new complications, is worth the effort.

I hope this helps,
Mondo

Originally Posted by barrymore

A very low wattage light bulb in the cooler with two thermostats with the apropiate temperature range in series. Just in case one sticks. This is unlikely with a device drawing so little current. Not new thermostats unless cheap either. Plenty of good used ones should be out there. Actually in this application I would never rely on just one thermostat.

Perfect, Barrymore! I've got a 15W bulb in a trouble-light in the cooler, and the temperature has plateaued at 40 F degrees above ambient. So even if the thermostat fails on, it shouldn't be a problem.

AeroKen, the garage is detached. A car returning from a trip will keep it reasonably warm for a while, but not something to rely on here on the prairies.

Ebill3, I would also have thought cold temps would not be a problem, but as I wrote a few posts back, the ThunderPower guys said not to let them get below 32. Perhaps they are doing a COA for lawsuits.