Cold Weather: Effect on battery range

Warwick

Esteemed Pedelecer
Jun 24, 2015
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Warwick
Is there a formula for calculating the effect cold temperatures have on battery capacity?

My Oxygen's battery definitely empties quicker on colder mornings like today's and I'd like to know how much.
 

Nealh

Esteemed Pedelecer
Aug 7, 2014
20,277
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West Sx RH
No formula I know of but have noticed on colder rides up to 20% less range.
 
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Danidl

Esteemed Pedelecer
Sep 29, 2016
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Temperature has an effect on battery performance, but not very much. I take it the temperature was above 0 Celsius the 10 degree drop between say 15 and 5 degrees Celsius would not have much effect. There are other contributing factors..
1. Were you wearing more clothes? A bulky coat perhaps would easily contribute 10% to your frontal area.
2. Slightly more windy
3. Cold weather might reduce your desire to breathe deeply and cold muscles are not great at excercise., so that the bike is contributing more of the power.
 
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Danidl

Esteemed Pedelecer
Sep 29, 2016
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Reading around the topic there is a concensus that a battery which gives 100% at say 20 degrees will have a capacity of 50% at minus 20. So for a 40 degree swing it loses 50%, or 1% per degree Celsius. I suspect that it is not linear and the majority of the decline will be at the lower temperature...
If you leave you battery in the house and just put in on the bike on leaving, its temperature will be 20 , it will not have any opportunity to cool down .
 

flecc

Member
Oct 25, 2006
52,897
30,427
Regarding the core subject of what capacity a battery loses due to temperature reduction, a formula isn't really practical due to the varabilities.

Being chemical devices which produce heat when they work, there's a balance between the heat the battery is generating and the rate of heat loss to the atmoshere, both variable.

The amount of heat generated during work depends on the current draw rate, in turn varied by the power settings chosen and used.

The rate of heat loss to the atmosphere varies according to the extent of wrapping around the cells, the thickness of the material used for the battery casing, what that case material is and the temperature differential between inside and outside the case.

And of course the initial temperature of the battery and length of the journey also have an effect.

Any formula taking all those into effect would be too complex for practical use, especially since there are so many factors that to the user are unknowns.
.
 
D

Deleted member 4366

Guest
In theory and in practice, the battery gives less when its temperature is lower, but it's much more complicated than that because as soon as you start using the battery, it heats itself up. The more power you draw from it, the warmer it gets. Some become quite hot, so I can't believe that cold weather would bother them. On the other hand, if you ride everywhere on eco setting, drawing minimum power, then in the battery will have less central heating. Like the penguins, only the cells on the outside are exposed to the cold. If one cell-group were positioned along the surface and were therefore cold, that would still affect the whole battery.

It wouldn't surprise me if the lack of range is more due to the rider working at a lower power when it's cold than the battery. Don't forget that you carry heavier clothing in the winter as well. On my own bikes, I can't say I noticed any significant difference
 

Warwick

Esteemed Pedelecer
Jun 24, 2015
731
225
Warwick
The bike is usually in the (integral) garage which doesn't drop down too low & is stored inside at work. My ride is about 30-45 minutes and there is definitely a drop in battery capacity in the colder weather. Earlier this year, I rode in -5C and I was lucky to get home, such was the drop in battery performance. I should add that the battery is over two years old and I've probably charged it a couple of hundred times, if not more.

When I get it sorted, I'll be able to compare it with the BGA battery on my (more efficient) Orbit.

Today I was actually wearing a smaller coat; my Foska jacket and a close-fitting, windproof Montaine shell jacket. I also had my winter tights on & those always add speed :)
 
D

Deleted member 4366

Guest
2 years is about the time that you start to notice a drop in battery performance. The only question is whether it will be better in the Spring. I doubt it though.
 

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