Storing RC Lipo in the desert

desert_triker

desert_triker

1 mW
Joined
Sep 8, 2013
Messages
17
Location
Tucson, AZ
New member here, in the process of putting a Friction Drive on my recumbent Catrike. It's a runner with a servo tester for a throttle, lots more to do. I'll post pics when I get it running. I promise!

I'm getting up to speed on Lipo and my question is: Is it necessary or beneficial to store (a month or more) Lipo in a chilled environment when the outdoor ambient daily temperature is 107F ( 42C)?

I'll be storing these batteries shaded, outdoors in a metal box. Thinking Peltier and solar panel for chilling if necessary.

Thanks
 
SOC and temp are critical for life.
http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries
 
Been storing and using lipo in my garage where the ambient temperature is a bit less than what you have probably 95-100 F without issue. I can get good cycle life on most lipos that I have otherwise taken care of properly. I think Dogman can confirm similar results, but he is a bit warmer in the Mesilla valley than the 4500 feet Tularosa Basin that my lipos call home. :p
 
The calendar life of the cell is cut in half for each ~10degC temp increase.

http://en.wikipedia.org/wiki/Arrhenius_equation
 
Get a post hole digger and go down as far as you can. Now stick a big pipe in the hole and fill up around it. Lower your lipo into the pipe to the bottom and seal the top in the shade. This should keep the temps within reason. At a depth of 4 feet temps should be fairly constant somewhere below 60F. Just don't drop the rope. Tie it through top cover. If you have ground water, you obviously want to seal the bottom of the pipe with an end cap.
 
They will last a few years anyway, stored in a warm garage. It will help that the box is shaded. An un shaded metal box would just solar cook them. It's quite clear though, that room temp would be best.

You might get an insulated box, and put it inside your shaded metal box. Like a thick ice chest. Or perhaps metal boxes inside a big ice chest. That will level out the hottest temp swings. If serious about keeping it cool, toss a small cool pack in there every day. Could be not so inconvenient, if you were putting them away in there daily. Just toss in the cold pack when you toss in the cells. Perhaps put a towel around the cold pack to wick up condensation.

I'm just using an old, unplugged refrigerator for my bulk lico storage summer or winter. What I use daily is kept inside, but that's the new packs. Lots of 3 years old, seldom used lico is stored out in that fridge. When those packs were young, they were all kept inside at room temp. I put them on my fireplace hearth, in metal boxes.

In general, it never gets much over 85F in my unplugged fridge all summer. In the house, 80f isn't unusual. One option I considered, was a timer to run the fridge for an hour a day. I never did it, because it's not near a convenient plug, and the stuff in there is old and crappy anyway.
 
I suspected >100F LiPo storage would not be a good idea. Science and anecdotal evidence confirm this.

I was knocking together a stand alone outdoor charging station with an integrated steel storage box. Now, I'll make the box portable and use Dogman's idea of storing the batteries in the fireplace during the summer. My garage goes to ambient temperatures so it would be too hot for storage. The house is kept at 82F.

Problem solved. Thanks for all your inputs.
 
why not put them in a hole in the ground. it should not get much above 60o i would expect. still do not understand why you need a steel box for storage when the risk is during charging. in fact i think the heat is less of a problem than leaving the pack charged at full voltage so if you just charged only before you need it then you could leave it stored at the higher temp imo. as long as it is not fully charged. i thought they are rated to 40o C.
 
To clarify, the steel boxes on my fireplace hearth are for making any fire go into the fireplace. The boxes have vents in them, and the vents point into the firebox of the fireplace. So that's why the steel, to try to contain the fire into the safest area if it should happen.

What chance is there of them flaming while I sleep? Pretty small. But I sleep better with them stored that way. Any damaged packs, those that stink, or those that show other signs of damage don't come inside anymore. I don't trust a pack that is really puffed, or really dented, or leaking.

If you have a yard, a hole in the ground could work well. But an ice chest or old fridge works well too. My old fridge is on the north west side of the house, so it gets pretty hot there for a few hours. It's shaded all morning, so it stays pretty cool there for most of the day, and by the time it's warming up inside the thing, it's sunset. Again, the severely damaged stuff is not allowed in there, since it is close to the garage. Trash is stored in a metal box in the sun away from all flamables till I get around to disposing of it.
 
The hole in the ground idea is good. It's just that we don't have soil here, it's caliche. A sedimentary rock bed. At my place it starts about a foot below the surface. From there it's caliche all the way down. It takes a strong back with a pick or jackhammer to break it up. Ugly work. Not for me. I watched a neighbor this summer dig for a new septic tank and leech field. He really tore up a rubber tired Case backhoe. The pros use a tracked hoe with a pneumatic hammer tip instead of a bucket.

http://en.wikipedia.org/wiki/Caliche

Since I don't ride much in the summer (too hot), the batteries would be stored at the recommeded storage voltage for weeks at a time. They would be fully charged when I want to use them. I understand that part. I also understand that the risk of fire is low when LiPos are properly stored.

dnmun said:
i thought they are rated to 40o C.
Click to expand...

True, but they don't speak to batterly life at that temp, which I'm sure is somewhat degraded. In the end, I can always leave them outside and expect a shorter life. Sounds like they are only good for a couple years anyway.
 
Or earlier in the morning. I don't get quite as hot as Tucson though, the hottest it gets at dawn here is 80F. Tucson is close to 2000' lower elevation.

But seriously, I find riding an ebike at 20 mph or more quite tolerable as long as it's under 100F. For a trip under 5 miles, you are hotter in a car, since the thing won't really cool off till mile 10. But I have to say, protective gear is limited to shoes and a minimal bike helmet. I even ditch the gloves when it's that hot.

But it's true, riding season in much of AZ is right now. Here we tend to ride less in January, but once valentines day is past, it's time to ride. Most of the town puts the bike away by June.

Metal box on the fireplace hearth should work fine for the summer. Not like you use the fireplace much in July. FWIW, I put a smoke detector right by my fireplace to get the quickest warning possible if something happens, and I have a door to outside right there to make getting wood into the house easy. The last touch is a flat shovel outside right by the door.

Repeating for the others reading. I NEVER store obviously damaged packs inside. None with big dings, or leaking and stinking come inside.
 
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