Cornfield

Winter is coming to Illinois soon. Some folks ride their bikes year round but not us. Our E-Bikes will sit in the garage all Winter. It’s not a heated garage so it’s been known to spend 1-2 months in sub freezing weather. Are the batteries OK or do they need to be brought in the house?

Dewey101

Maybe a car battery heater, or some sort of insulated bag or fire-safe with the pack wrapped in some attic insulation and add some dessicant sachets to absorb moisture, and bring the battery pack inside to warm to room temperature for at least an hour before you plug in to charge.

skookum

Good question. Definitely do not charge the battery when the temperature is below about 5 C. Room temperature is better. From what I have read, Lithium batteries are less affected by cold than most other battery chemistries, and they wont freeze until about -40C. So you should be okay storing the battery in the garage as long as you warm it up before you charge it or use it. I still wouldn't do it, and I bring my battery inside the house for the winter. Batteries should be stored partially charged.

sloppy12

I bring mine in. Its not gonna help the battery thats for sure.

2old

Nothing I've read states that cold temperatures (below 40 - 50 F) are benign to batteries. Not a problem in socal. Insulate well or store inside.

chas58

NOOO! Not OK!
I've done this with a couple of batteries (at your latitude). They lasted 2-3 years. So, ya know - if you are OK with that. This year I'm keeping them inside in the winter.

(insulating something for a couple of months below freezing isn't gonna keep it warm guys).

Pop N Wood

Thought I read something about never storing in the cold, but these guys say just make sure it is a certain level of charge (and to check it once a month)

https://electricbike.com/forum/forum...li-ion-battery
https://electricbike.com/forum/forum...-ion-batteries

An insulated bag will do nothing since the batteries don't develop internal heat when sitting still. A bag does help when riding.

skookum

Good info in those links, thanks.

DangerousDanR

Li polymer batteries may not all use the same polymer electrolyte secret sauce, so contact the manufacturer! All batteries loose capacity when they get cold, but the point of damage depends on the chemistry of the battery.

My electric mower manufacturer is OK down to -40C. I contacted Campagnolo and was told that for my version EPS battery, storage below -20C can cause damage. That may not be the limit for other generations of EPS. Same thing for your E-Assist device. Read the manual or contact the manufacturer.

Charging some Li polymer batteries when they are below a temperature point may damage them. Same thing for prolonged storage at cold temperatures. Similarly, exposure to temperatures above some limit (often 70 to 90C so very hot) will damage them.

https://www.electronicdesign.com/pow...iion-batteries

pdlamb

Years ago when I started my own tomato plants from seed, the garden places had a plug-in cord that kept seedlings warm even facing a cold window. About 10W worth of heating, IIRC. I wonder if you could wrap your batteries with something like that and leave it plugged in over the winter.

Pop N Wood

I tried turning an old refrigerator into a paint locker. Something I could put in the back yard full of half full paint cans than heat with a couple of incandescent bulbs hooked to a house thermostat. Condensation turned that into a mold pit. Got the idea of installing an old window AC unit in there, both to heat and dehumidify, before deciding I just wasn't that much of a redneck.

But shouldn't be hard to build some type of insulated box/cooler and heat that with something equally simple. Don't have to keep it warm, just keep it from freezing. One could download a controller from an Arduino site or repurpose an aftermarket radiator fan controller from a car catalog.

Whatever you do I wouldn't wrap heat tape on a battery and would definitely include some sort of over temp cut off.

My $600 Luna battery is coming in the house with me. Let the wife sleep in the paint locker.

Pop N Wood

This should be required reading for anyone with an ebike

https://electricbike.com/forum/forum...ter-repository

chas58

Great link, but a lot to read all at once. More of a reference library.

Or for this thread:
Someone should just sell a cheap 50% charger.

sloppy12

any charger is a 50% charger. Just use a cheap volt meter. Just keep a eye on charge.

chas58

How do you put a volt meter on a battery that is charging?

sloppy12

You can make a plug up pretty easy that goes in line.

skookum

Another good source is Battery University

alloo

Bring your battery indoors. The bikes can stay in the garage.

ARider2

Bosch has a battery guide with good tips that can be found here:

https://www.bosch-ebike.com/fileadmi...f?_=1597732627


Here are Bosch tips for optimum service life:

unterhausen

It would be nice to have a storage charge option for batteries. RC chargers have that

Cornfield

Yes, I put my R/C airplane and car batteries at “Storage level” if I won’t be using them for a few weeks. My lipos last a long time that way. I wish chargers for electric devices like bikes and snow blowers had a discharge feature like this.

01 CAt Man Do

Just an idea. If you are going to store the ebikes in a cold garage for long periods and not use the bikes this will help preserve the battery. ( best to store at less than a full charge ). Now if you plan on riding the bikes every day I would recommend bringing the battery inside the house. You do not want to charge the Li-ion cells at freezing temps . Now if it's too much trouble to remove the battery from the bike you can go out to CVS and buy a cheap heat pad , wrap it around the battery and set it on low. This should be enough to keep the battery at ambient room temp and allow for charging while in the garage if that is the way you want to go. Personally my ebike battery is very easy to remove so I'd just take it in the house every night. That said I store all my bikes inside the house where it is warm so condensation doesn't form on the metal parts and speed up any oxidation processes. Anyway, if you ride in freezing temps and want to recharge the battery, it would be best to let the battery acclimate to ambient room temp before recharging. ( give it at least 2hrs to warm up before charging. )

sloppy12

Heating pad is exactly what I have done for years with all power tool batteries. I got a curb side igloo cooler, toss batteries and chargers inside set a 110v wall stat up in a metal box with a outlet and set stat to 65. the heating pad goes on and off as needed. the igloo is always a nice temp...

Heck you good find a old steel igloo and use it as a fire box and add the heating pad.

chas58

I know, right? ebikes.ca has one, but it costs about 2 times what my batteries cost. I've used a trickle charge on my old cars for years.