# Temperature and battery ?



## Wolfe (26 Oct 2019)

What's the lowest temperature to ride, without causing damage to your battery? Is it also safe to use insulation??


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## sheddy (26 Oct 2019)

Why should there be damage when riding ? When I was a boy, battery power output fell with temp so range will reduce. 

There may be issues with charging at low temps, if so charge indoors ?


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## IanSmithCSE (27 Oct 2019)

Good morning,



sheddy said:


> Why should there be damage when riding ? When I was a boy, battery power output fell with temp so range will reduce.
> ....



If we are talking properly cold -5 to -20 degrees centigrade then there is a real issue of damage.

As the battery capacity reduces dramatically at these temperatures (90% to 65% of capacity) as well as just shortening the range you can get permanent damage from cell reversal as you are more likely to run some cells within the battery flat.

Whenever you get close to fully discharging a multi cell battery there is a risk/certainty that various cells within the battery will have various levels of charge, when a cell has a significantly lower charge it risks a current flow from the surrounding cells in the wrong direction to recharge it, this will cause cell reversal which is permanent damage.

The same is of course true whenever you get close to fully discharging a battery pack in the warm, but protective electronics may say "no more power" when there is still some power left to avoid this. 

As the temperature reduces cells with significantly lower capacity will discharge faster proportionally than their surrounding cells thus may be enough to kill a few cells but not enough of an overall power drop to trigger the protection circuitry.

Bye

Ian


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## Yellow Saddle (27 Oct 2019)

Wolfe said:


> What's the lowest temperature to ride, without causing damage to your battery? Is it also safe to use insulation??


Batteries have a temperature range specified and usually printed somewhere on the battery. Look in the manual. You'll be surprised what's in there.
Your question needs some clarification however.

If you have the bike at room temperature and then go out and ride in the freezing cold, the battery will keep itself warm. Insulation may or may not help, I doubt it, the thing will look after itself.
If you plan to store the bike outdoors in the cold but "protect" the battery with insulation, you're wasting your time. No matter how well you insulate it, it will reach ambient temperature if there is no heat source. In other words, in the morning when you break your two bikes out of the ice, the one with the battery in a blanket and the one with the naked battery will be at exactly the same temperature.


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## Wolfe (27 Oct 2019)

Yellow Saddle said:


> Batteries have a temperature range specified and usually printed somewhere on the battery. Look in the manual. You'll be surprised what's in there.
> Your question needs some clarification however.
> 
> If you have the bike at room temperature and then go out and ride in the freezing cold, the battery will keep itself warm. Insulation may or may not help, I doubt it, the thing will look after itself.
> If you plan to store the bike outdoors in the cold but "protect" the battery with insulation, you're wasting your time. No matter how well you insulate it, it will reach ambient temperature if there is no heat source. In other words, in the morning when you break your two bikes out of the ice, the one with the battery in a blanket and the one with the naked battery will be at exactly the same temperature.


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## Wolfe (27 Oct 2019)

Thank you for the info, problem is I have seemed to have misslayed my manual. I remember reading in it somewhere, the temperature below which it is not recommended to ride. The charging is not the problem, as I always charge in the garage, which is nearly the same temperature as outside.


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## CXRAndy (28 Oct 2019)

Pulled from Google search- should cover general guidance of operating range

The use of a *lithium*-*ion battery* is possible in a *temperature range* of 10°C to +55°C. However, the charging should take place only at a *battery temperature* of +5°C to +45°C. The ideal *temperature range* of the *batteries* is room *temperature*.


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## Milkfloat (28 Oct 2019)

Lithium -ion batteries don't work at below +10°C? That is nonsense.


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## ebikeerwidnes (28 Oct 2019)

CXRAndy said:


> Pulled from Google search- should cover general guidance of operating range
> 
> The use of a *lithium*-*ion battery* is possible in a *temperature range* of 10°C to +55°C. However, the charging should take place only at a *battery temperature* of +5°C to +45°C. The ideal *temperature range* of the *batteries* is room *temperature*.


As commented elsewhere - the 10C figure seems like rubbish. However, I have found a proper reference to it - so your comment is not daft - you just used data that cannot be correct. The source I found indicated that the battery would not function below 10C - and I know I have cycled perfectly well below that - even when my bike+battery had been in the shed all night at below that (that was before I knew better!)

I have looked around and found other sources that suggest that below -20C is a better figure and the performance drops off quite quickly before that - I think that maybe the figure you used was a misprint and should have been -10C not +10C!
This is one source I saw
https://www.electronicdesign.com/power/operating-conditions-get-tougher-li-ion-batteries
There is also some proper chemistry stuff on there that I should read and try to understand - when I am in the right mood - it all looks complicated!


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## CXRAndy (28 Oct 2019)

ebikeerwidnes said:


> think that maybe the figure you used was a misprint and should have been -10C not +10C!



You're probably right. I noted another mis spelling in the text which I corrected. Quickly pasted so missed '-' symbol


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## gbb (28 Oct 2019)

I suspect, as always, the 10C figure mentioned is simply a manufacturer giving themselves a healthy safety margin against failure in cold conditions. Of course they will work in lower temps, its the manufacturer putting up the umbrella so's to speak. (IMHO)


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## Smudge (28 Oct 2019)

I dont overthink things with my ebike batts. They are left in different states of charge, sometimes charged from low, sometimes when 3/4 full. I've stored them indoors and often in a cold shed in winter. They get used in all sorts of temps from heatwaves to cold snaps. My last ebike batt lasted 6 years before the range started getting not so good, but it was still usable.
I just cant be bothered to have set rules for them.


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## Yellow Saddle (28 Oct 2019)

I'm sure the Teslas in Sweden and Finland have a coping strategy of sorts.

Here's an article that sheds some light on LiIon batteries in the cold.

https://www.wired.com/story/electric-cars-cold-weather-tips/


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## Wolfe (28 Oct 2019)

IanSmithCSE said:


> Good morning,
> 
> 
> 
> ...


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## Wolfe (28 Oct 2019)

Thank you all, very informative lot you all are.


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## Phaeton (30 Oct 2019)

On a similar note I'm currently keeping my e-bike undercover outside, would it be best to remove the battery & bring it inside, or will it happily stay out there along with charging it outside?


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## ebikeerwidnes (30 Oct 2019)

Yes - they work best if kept in the warm
I have been keeping mine inside but in an unheated room - I have noticed that the range has dropped to 2/3 -1/2 of the normal (it is difficult to tell as it has been windy lately)
So - I'm planning on bringing them into a warmer room - which should be better for them


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## Wobblers (30 Oct 2019)

Wolfe said:


> What's the lowest temperature to ride, without causing damage to your battery? Is it also safe to use insulation??



Assuming it's a lithium ion battery, using it in low temperatures will not cause damage. Capacity will be reduced though. The battery management system will (or should) detect if there are any weak cells, and disconnect the battery pack before the cell voltage gets too low. A typical symptom of that is one minute the battery will show a healthy charge status, the next a low battery warning or even it cutting out. This is most likely to happen to an old battery or low quality battery in the cold. Going up a hill when it is cold is when the battery is under the most stress, and this the most likely time for an old or weak battery to fail on you. Insulation is likely to be of marginal benefit, unless it is for a short journey.

Recharging it is another matter though. Do not recharge a li-ion battery when it is below 0C. This may cause metallic lithium to plate out, which significantly destabilises the chemistry (as in: fire!). Wait until it has warmed up - and remember that though the casing may feel warm, the cells inside may still be cold.


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## Wolfe (31 Oct 2019)




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## Zanelad (3 Nov 2019)

I've noticed a shorter range now the weathers turned colder. I could squeeze 5 commutes (110 miles), but now 4 trips is the limit. The bike's kept indoors both at home and at the office.

When it gets really cold I'll be in the car.


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## ebikeerwidnes (3 Nov 2019)

Zanelad said:


> I've noticed a shorter range now the weathers turned colder. I could squeeze 5 commutes (110 miles), but now 4 trips is the limit. The bike's kept indoors both at home and at the office.
> 
> When it gets really cold I'll be in the car.


I've noticed that as well - my normal ride can be done about 3 times on a full battery - but now it looks like 2 rides at most - if it is windy I'm getting low on charge after one trip!
I do keep the battery in the house - but the room has been quite cold until recently so I'm putting it down to temperature - but I'm not sure if it is cold when off the bike - of the cold air when I'm riding it


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## Smudge (3 Nov 2019)

Zanelad said:


> I've noticed a shorter range now the weathers turned colder. I could squeeze 5 commutes (110 miles), but now 4 trips is the limit. The bike's kept indoors both at home and at the office.
> 
> When it gets really cold I'll be in the car.



I can only dream of getting that sort of range from my 11 amp/hr batt....
Always using either medium or high assistance, plus being slow so i'm almost always under the 15.5mph cut off, doesn't give me the best range. Although, i've not noticed temps making much difference to my range.


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## confusedcyclist (4 Nov 2019)

When discharging, the chemical reaction will heat the battery to an extent. If you plan ahead and take the battery directly from a warm room, fully charged, to the bike and get going quickly, you'll limit the extent that the battery can cool, and the electrolyte impedes the lithium ions, thus increasing your range. The faster you discharge your battery, the warmer it will remain, so there somewhat is a disincentive to use eco mode and/or pedal under your own steam! The good news is, if your battery gets too cold to operate, you'll stay warm keeping your 20kg bike moving up hills.


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