Thermal insulation for batteries?

Username1

100 W
Joined
Nov 26, 2013
Messages
168
I'm going to buy a long range ewheel, and want to be able to ride it in winter for many hours at a time. It gets well below freezing here in the winter, so I'm looking for the best insulation to wrap the batteries with. I believe the best stuff you can buy is aerogel insulation, but it would cost hundreds to do the job. What is the next best material to use? I'm willing to spend some money, just not hundreds.
 
A half inch of XPS foam board on the outside, then polyiso board for the rest of your thickness available.

Great Stuff foam to fill in any gaps, a well sealed envelope is more important than high R-value

Silicone heating pads if needed, can be custom ordered cheap with embedded thermostat, might need a buck converter or maybe available to work off your pack voltage.

If you store your pack in your heated living space the active heating may not be needed.

Always bring your pack up to warm temps before charging, especially if high current, over 0.4C

I'd start pre-warming below 10° if going over 0.1C

Actually hot over 30°C is best if charging over 1C

Below 15°C my limit reco is maybe 0.2C

 
Note that LTO chemistry, although low energy density, lasts forever, can be charged at 6C, discharged all the way down to 0% SoC, and has a much lower operating temps range than any other LI type.
 
What I'm talking about specifically is insulating the battery inside an ewheel (electric unicycle), so I'm trying to find the best insulator per thickness. There's usually not much room between the batteries and the case, maybe a quarter inch on each side if I'm guessing. Here's a picture of an ewheel battery to give you an idea. Not the one I'm buying but probably similar.

I have considered using heating pads, but I think if i can insulate it really well it may not be needed. But I don't know how I'd power the heaters considering they would need their own battery which there may not be room for.

electric-unicycle-Battery-Size.jpg
 
Cooling issues in summer, heating in winter. Any solution you go for best be temporary.

I've run years without heating my batteries in minus centigrade temperature winters, only charging as soon as i came home from a ride when the battery was warm, then later i added one of those silicon mats and used standby heating from my wall supply for some time.
 
How good of an insulator is neoprene? I think it's fairly affordable and easy to work with.
 
Aerogel insulation should be under $100 for such a small enclosure. The stuff has been available for several years. As for battery enclosure heating most off the shelf stuff would either be 12 or 24v so you'd need a DC to DC converter and a thermostat.

http://www.buyaerogel.com/product/spaceloft-10-mm-cut-to-size/

https://www.ebay.com/itm/264923483196

https://www.ebay.com/itm/182649600403

Or you could get lucky and find one that works at your main battery voltage but you'd still need a thermostat:

http://www.etl-trade.com/productdetail/CH0103
 
The silicone heating pads are not expensive to custom order, not just size an desired temperature range, built in thermostat

but I be voltage range too.

Check in with the Chine-direct sellers on eBay.
 
The main thing is a warmer place to store it overnight. Or while you work. It can be cold, but just not as cold as outside. You just don't want to charge a frozen battery, or try to use it when frozen. Ideally closer to room temp, but above freezing will do. The battery will warm itself as you use it. Once that starts, you don't need a lot to keep enough of that warmth inside.

Thin, cheap insulation will do just fine, whatever will fit. Yoga mats are a cheap form of foam similar to neoprene, or sheets of polyethylene foam that come in the box with something you bought. Whatever is handy, and will fit. If you have a half inch, you can go to foam sheets used as building materials, or a tea cozy you make from an old blanket or jacket.

For overnight warmth that is not too hot, reptile cage heaters can be a good solution.
 
The key is slowing down the charge rate the closer you get to freezing.

0.1C is fine for parka weather

0.2C for sweater weather

0.3C for flannel

0.4C for t-shirt

These are for optimal longevity, coddling other care factors too.

Many people go faster rates, and long as it's warm you're just sacrificing some cycles off the back end.

But as it gets colder you can really do immediate damage

and in extreme cases it's possible to destroy the pack, dendrites shorting the cells out internally.
 
Thats true! But bear in mind, it can be frozen as hell, yet a battery with some insulation on it that just ran can be at room temp. But your charging takes awhile, and that battery can easily freeze solid while its on charge.

You may need to do something special, like an insulated box you put the warm battery into, to charge with the snake heater inside with it. This would have to be a box the whole vehicle fits into in this case I think.
 
I really like the idea of easily swapped out packs.

You live in the Arctic NP, batt comes in with you.

Some have the ability to bring the whole rig in, great. But a big old cargo bike maybe not
 
Hi Mister One.
Consider the 35,000 foot view, the zeroeth, first, second. . . Laws of Thermodynamics. OK
And, your $$$ is like HEAT , Energy.
Put $$$ into heating your battery pack to affect it's heat retention within a subzero thermodynamic system ( Out the house ) I'm ....."willing to spend some money," buy heat, pay as you go, don't need it now.
Good Luck
 
It will be stored inside that's not the issue. It gets around -10 to -20c in the winter here, and I plan on going on long 5+ hour rides (3600wh battery), so the residual heat from the house will absolutely not cut it. The idea was to surround the individual battery packs themselves. When pricing aerogel it's going to cost around $50+ per battery pack, and there's typically 4 in an ehweel, so $200+ total. If it worked amazingly well I could consider spending that much.

The typical peak voltage of ewheels is 100v, so I don't know if there's heating packs that run that high. And would it cause any issues with the electronics to hook it up to the main battery? I'm still trying to work out if heating or insulation would be a better idea.
 
I am very interested in this thread.
I have 2 ebikes, winter one exclusively for riding on snow and ice in sometimes -20C.
I do not use any thermal isolation on winter ebike battery,
it is 11S made of Nissan Leaf cells.
I always charge just before ride when pack is still warm.
I can imagine any isolation would make battery 1/4 bigger if not 1/3 bigger.
and cold would penetrate anyway.
below zero when I need to stop I always try to find some heated area , like between entrance doors .
will never park my winter bike outside in even - 5C , would stop but not park like for 15 minutes.
 
I use a basic camping mat (~7mm thickness) to protect my 1 kWh battery.
https://www.decathlon.fr/p/matelas-mousse-de-trekking-arpenaz-m100-gris/_/R-p-13259?mc=5591048&gclid=CjwKCAjw_L6LBhBbEiwA4c46uhmPewR0bq7oVYvKodPDflwY-3ik32Gi6osVrD4sKUd60LRl6jTlhBoCPg8QAvD_BwE
And a thin adhesive foam (~3mm) for my second battery. In both case with heat shrink tube as final layer. This protection is more against shocks than cold.
What you can try is permanent thin (self-adhesive) foam around your batteries + heat shrink tube above it, for shocks protections and limited temperature protection. Then add during the winter only a removable thick isolating protection (made in camping mat for example). I’ve almost never ridden in sub-freezing temperature though. So consider my advice with care ;)

EDIT :
Username1 said:
I'm going to buy a long range ewheel, and want to be able to ride it in winter
I just see that this will be ewheel batteries. Not sure if you can properly insulate, the empty space must be very tight. And make sure there is no risk of overheating in summer with this insulation.
 
Back
Top