It seems that the point that the temps where damage can occur is far lower than most people would ever encounter. Yet, still there are people thinking that any lower than the freezing point of water is also the low point at which these LiPo batteries should not be exposed for fear of damage. If you think that 10 degrees is approaching the danger point that isn't near it either.

The recommendations for optimum storage temperatures are not taking into account the temperatures where batteries would be damaged. Thunderpower's recommendations are no different than the type of recommendations that ladder manufacturer's include with their products, or those recommendations to not exceed speed limits.
An over-riding recommendation should be to always use common sense but since that is not really "common" then manufacturers and others need to make very conservative stipulations that they hope will impress impressionable people enough that they will never encounter a problem, hopefully - and there is always that issue of COA that motivates manufacturers to be ultra conservative.

As far as I'm aware and concerned, batteries can be stored in a garage in winter without concern unless where you live temps commonly fall below the -10 degree range and can range below -20 and that's approaching polar temperatures. You can store them in refrigerators. You do not need to use heaters to keep them warm.

Of course if you are concerned about the limits of cold temperatures then maybe a sacrificial LiPo would be a good idea - It's not possible for where I live since it is rare to see temps lower than 0 F. None-the-less, I will place a battery in the garage with a thermometer that registers and stores minimum and maximum temps to verify what I expect. My expectations are that if the battery is kept at storage level (3.8 V per cell) that there will be no effect on the battery and it will survive the winter without issue. Naturally there will be a control battery stored in house at the same storage voltage level for comparison.

What we still need as I wanted initially is definitive information as to exactly what temperature a LiPo will "freeze".

Why not just use the fridge year round?
The temp control can be set higher for winter and the heavy insulation will go a long way to keeping the temp stable overnight. If your garage is like mine it is fairly warm during the day and bleeds heat all night. Mine is coldest in the early AM but warms very quickly once the sun hits it.

Originally Posted by flashburn

Why not just use the fridge year round?
The temp control can be set higher for winter and the heavy insulation will go a long way to keeping the temp stable overnight. If your garage is like mine it is fairly warm during the day and bleeds heat all night. Mine is coldest in the early AM but warms very quickly once the sun hits it.

Simple is good. Very good advice.

FYI, from Sony (the first makers of Lion batteries... so they should know the chemistry involved):
http://www.sony.com.cn/products/ed/battery/download.pdf

... lithium ion rechargeable batteries should be in the discharged state when stored for extended lengths of time, and it is desirable that they be stored in a low-temperature environment.

Throughout the document, they refer to -20C to 60C as the practical discharge temperature range. Note, must be above 0C for charging.

Originally Posted by midnite

As far as I'm aware and concerned, batteries can be stored in a garage in winter without concern unless where you live temps commonly fall below the -10 degree range and can range below -20 and that's approaching polar temperatures.

I don't know where you live midnite, but I think your idea of how cold -10 is is exaggerated. I grew up in western NY, currently live in eastern MA. It's a rare winter that doesn't have at least one night that goes down below -10. Temps get a bit colder than that in the interior of the country. Still not the same as polar temps though, where it's way colder than that even during the day.

One more refinement on my battery box. Rather than a 15W light bulb, I bought a 15W terrarium heater. It's a mat about 8"x12" with adhesive on one side, which I stuck onto a piece of ceramic tile. Full on, the picnic cooler with the heater inside is tracking the outside temperature plus 40 degrees. With the thermostat, it should do nicely. So all up, $20 for the cooler, $40 for the heater, and $20 for the thermostat.

The heater is a ReptiTherm 30-50 gal terrarium heater from ZooMed, which I got at Petco. The thermostat is a G1134156 from Zoro Tools: Columbus inline thermostat Open on Rise, 13.8 amp, control range -10 to 100 degrees F. It's mechanical, with a nice knob to turn, rather than digital, so no battery required.

I realize the chances of an adverse event are very small, but I will enjoy having the batteries out of the house, especially when I travel for some period. Maybe when I've had more experience with them, I will not be quite so nervous.

Now, can someone tell me how to learn pattern flying in 5 easy steps...?

Ask in the pattern forum.

i have a mortar case that i got for 28 bucks, i keep my lipos in it during the winter and just store them in the house..lipos are perefectly safe when not being charged or dischared.

Originally Posted by AeroKen

I don't know where you live midnite, but I think your idea of how cold -10 is is exaggerated. I grew up in western NY, currently live in eastern MA. It's a rare winter that doesn't have at least one night that goes down below -10. Temps get a bit colder than that in the interior of the country. Still not the same as polar temps though, where it's way colder than that even during the day.

Live in southern part of Ontario. Temps here usually range from about 10-90 degrees F over the course of a year - but a very cold winter day can go as low as -10, maybe to -15 but never lower. High temps can get to about 100.

Yes, certainly not the same as polar temps.

But now - are we ever going to get the answer to the question - at what temperature do LiPo batteries freeze?

Originally Posted by Neko

One more refinement on my battery box. Rather than a 15W light bulb, I bought a 15W terrarium heater. It's a mat about 8"x12" with adhesive on one side, which I stuck onto a piece of ceramic tile. Full on, the picnic cooler with the heater inside is tracking the outside temperature plus 40 degrees. With the thermostat, it should do nicely. So all up, $20 for the cooler, $40 for the heater, and $20 for the thermostat.

The picnic cooler itself would likely have been sufficient to keep the overnight minimum up considerably on the ambient. Without extra heating.

Originally Posted by midnite

But now - are we ever going to get the answer to the question - at what temperature do LiPo batteries freeze?

Beats me.

About seven years ago, I launched a search to find the answer to that question. One of the results of that search:

An undated Nokia cell phone review stated that Lithium Polymer will freeze at -15 to -20 and can not be restored. (I assume the figures were in C, as it was a European review) (-15C to -20C)(5F to -4F)

For many years I stored my LiPos year-round outdoors under a second story deck in metal boxes covered only with a piece of white coroplast. They survived temperatures in the low teens F.

Bill

Originally Posted by ebill3

Beats me.

About seven years ago, I launched a search to find the answer to that question. One of the results of that search:

An undated Nokia cell phone review stated that Lithium Polymer will freeze at -15 to -20 and can not be restored. (I assume the figures were in C, as it was a European review) (-15C to -20C)(5F to -4F)

For many years I stored my LiPos year-round outdoors under a second story deck in metal boxes covered only with a piece of white coroplast. They survived temperatures in the low teens F.

Bill

Yes, this year I will use a test battery leaving it outside and measuring the coldest day. It will start out at storage voltage. If it survives then there will be no issue leaving batteries in the cold for me.

So from your investigation 0 F should be the point of no return. I have read comments that storing them in -20 C (-4 F) did no harm.
The following reference states - http://www.aga-power.com/list-13-3.html?lang=en
"Do store batteries at a place with low-humidity and free from corrosive gas within the temperature ranged from -20℃to +40℃" and "At -20 °C charge speed will greatly slow down as electrolyte is at its freezing point."

This reference also indicates that the low point for storage is -20 C. http://www.ibt-power.com/Battery_pac...ymer_tech.html

It would appear then that indeed LiPos may very well be approaching the freezing point at -20 C or about -5 degrees F.

Hopefully anyone reading this thread will now recognize that the freezing point of their batteries has no relationship to the freezing point of water. And, that leaving them in the fridge or freezer (freezer temp is usually no lower than 0 F) can do them no harm.
Once again my point in pursuing this topic is to make it clear that warnings to not freeze LiPos have nothing to do with the temperature at which water freezes.
It is also meaningless to tell people to not freeze their batteries or to not store them in the cold without also providing temperature reference points.

Originally Posted by tacx

yes, there is a sticky called "Lipo fires are real".

We could also have stickies called:

1. Gas furnace fires are real.

2. Gas stove fires are real.

3. Gas hot water tank fires are real.

4. Clothes dryer fires are real. This is a biggy!

5. Bar-B-que fires are real.

And on and on and on.

You could have a sticky on just about a thousand things that could catch fire. Are you getting rid of these things in your home? No. Why? Because most of us properly maintain these things. It's no different with lipos. Treat them properly and you should not have a problem.

Can you be gauranteed you will not have a battery go bad? No, No more than you have a gaurantee that all those other things will not go bad.

101% totally agree .....

The paranoia that is created by some is amazing and unfortunately once it takes hold - its difficult to dislodge.

As to storing in a garage ... and in a Fridge ....

If the garage is anything like most peoples - it has more incendiary items in it than a military outpost ... the consequences of paint thinners, gasoline, oil, other combustibles could well remove any advantage of the separate storage by a serious fire spreading to the house anyway !

Second if the fridge is new or very recent then it's coolant is OK ... but you only need to go back a short while and the coolant used is hazardous ...

Any more for storing in garages ?

As another says ... you don't store your electronic items out there do you ? Where's your models / Tx for example ? Are you a LiPo Tx man ?

Nigel