Winter battery storage?


So, it's getting cold here in New England -- 26 degrees when I woke up this morning. Yikes. A few battery questions:

I'll continue to ride my bike for a while longer. During this time, with the temps dropping, do I need to do anything special with the battery? Keep it inside? Charge less or more or?

And then, when I stop riding for the winter, what then? Do I bring it inside, into the warmth of the house or can I leave it outside or what?

Finally, I'm going to leave the cold for 3 to 4 months this winter and will not be around the bike to periodically charge the battery, if that's what's called for. Will this be a major problem?



Active Member
I am guessing the battery will hold its charge better if it is kept in warm temperature. But based on my experience there isn't such a big difference even in subzero temperatures. Three four months absence is probably not going to be a problem, at least according to what Specialized advices.


Well-Known Member
Well you shouldn't ever charge a very cold battery. Keep the battery and bike if you can, in a warm room overnight.
Precondition the battery by charging it before you go out and use it.. Capacity will still be less in cold weather but at least it will be warm to start.
Store it over winter in a warm room (50-80F).. As far as keeping it charged over the winter you should look at your manual. Some say fully charge it, others say store it at 50% charge.

My stromer manual says:
+If the battery is not used for an
extended period, it must be recharged
fully. Store at room temperature and
recharge every 2 to 3 months.
+ If the battery is not charged for an
extended period, a deep discharge may
occur. The warranty is thus invalid.
+ Charge your battery at room temperature
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Well-Known Member
I have a creative way to charge your battery every 24 days or so with just two inexpensive timers in series.


I was about to ask the same question as flipper...since I keep my bike with battery locked to the porch overnight. Is there a general temperature threshold at which I should start bringing the battery inside?


Well-Known Member
Don't leave it out in freezing temperatures, and if you do, don't charge it until it is returned to normal temperature of >50F. A cold battery pack could take hours to warm up

From Battery University:
Li ion batteries offer reasonably good charging performance at cooler temperatures and allow fast-charging in a temperature bandwidth of 5 to 45°C (41 to 113°F). Below 5°C, the charge current should be reduced, and no charging is permitted at freezing temperatures. During charge, the internal cell resistance causes a slight temperature rise that compensates for some of the cold. With all batteries, cold temperature raises the internal resistance.

Many battery users are unaware that consumer-grade lithium-ion batteries cannot be charged below 0°C (32°F). Although the pack appears to be charging normally, plating of metallic lithium can occur on the anode during a subfreezing charge. The plating is permanent and cannot be removed with cycling. Batteries with lithium plating are known to be more vulnerable to failure if exposed to vibration or other stressful conditions. Advanced chargers, such as those made by Cadex, prevent charging Li-ion below freezing.

Manufactures seek ways to charge Li-ion below freezing. Charging is indeed possible with most lithium-ion cells but at very low currents. According to research papers, the allowable charge rate at –30°C (–22°F) is 0.02C. At this low current, the charge time would stretch to over 50 hours. It is for this reason and the ability to control the current that manufacturers prohibit the charging below freezing.
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