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winter battery killer


Chrisxr2
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Well the temperature is steadliy dropping in the UK and it really has dented my ditance on a battery charge, day yesterday i gor about half of what i am used too, not really much can be done to combat it unfortunately.

There is a way with an electronic thermostat & resistor wire (something like this: http://kanthal.com/en/products/materials-in-wire-and-strip-form/wire/resistance-heating-wire-and-resistance-wire/ ) wrapped around the packs, but of course care must be taken that it won't overheat the batteries (keeping them around 20-30 Celsius should be good for example) or cause shorts or such, and of course the resistance and the length of the wire itself must be calculated to get "correct" heating wattage without too high current. Vee has done this on his wheels. Probably the thermostat and heating will need a separate battery pack or step-down transformer, as the ones I've seen (such as http://www.aliexpress.com/item/Lowest-Price-for-DC-9V-15V-Intelligent-Digital-LED-Thermostat-Temperature-Controller-55266/32307535170.html?spm=2114.01020208.3.40.xlrsgG&ws_ab_test=searchweb201556_9_71_72_73_74_75,searchweb201527_4,searchweb201560_9 ) need an input voltage between 9 and 15V DC, and the packs in most wheels give out 40-67.8V.

Additionally I feel the difference between ride early in the morning when going to work (~0C) and coming back home when it is ~10C. My wheel "tells" me very early that I am going too fast while the same speed is ok afternoon. 

 

That's because the alarms are probably done by monitoring the voltage of the battery pack, which drops further & faster with lower temperature.

Edited by esaj
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Does riding in cold weather shorten the total lifecycle of the battery?

Batteries perform better above 10c, below that they will have a much shorter life. This is only whilst using them in these conditions however, when the weather warms up the battery life will return to normal.

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  • 2 years later...
On 28.10.2015 at 5:48 PM, Paddylaz said:

is there an......'unsafe' temperature to ride at? I mean if you're not too bothered about reduced distance..........is there a temperature below which cut-out probability increases exponentially?

This would interest me, too.

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14 minutes ago, LZmiljoona said:

This would interest me, too.

You can find some information here: http://batteryuniversity.com/learn/article/discharging_at_high_and_low_temperatures or search battery university for effects of temperature on Lithium Ion specific information.

From personal experience my 340Wh comfortably gets me the 7-8 mile round trip to a friends house once a week in the summer. In the winter I don’t dare do it, the range might be enough to get me home but the power is dangerously down on the way back. Obviously a bigger battery would fare better, but by around -20 degrees C (-4 degrees F) I would think power would be dangerously low unless the battery is heated.

I have more experience with Lithium Polymer batteries in model aircraft but the technology is very similar so the problems ought to also be. The big difference is they are much more “abused” than our EUC batteries being regularly used at 10-20C I.e. a 2Ah cell being discharged at up to 40 Amps and also regularly discharged down to 3V/cell. What I have found is that these often fail in the second or sometimes third winter - but they always fail in winter. This has improved as I have understood them better (and quality has improved) but in particular I now never leave them fully charged in freezing temperatures, that seems to age them very quickly, and I now take them to the flying field in a thermal bag with a couple of pocket warmers in it to keep them warm.

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Up to 20% range loss going from >25°C to <5°C on my 1300Wh ACM. Shocking:efee96588e:. And not even below 0°C yet. Might be even worse with smaller batteries?

On 28.10.2015 at 12:59 PM, Tom said:

Batteries perform better above 10c, below that they will have a much shorter life. This is only whilst using them in these conditions however, when the weather warms up the battery life will return to normal.

Also, ambient temperature =/= battery temperature.

On 28.10.2015 at 5:48 PM, Paddylaz said:

is there an......'unsafe' temperature to ride at? I mean if you're not too bothered about reduced distance..........is there a temperature below which cut-out probability increases exponentially?

The batteries themselves going below 0 while in use might not be soo good. Unqualified guess:efee8319ab:

Also, someone recently warned about the gyro sensor failung due to cold after storing the wheel in a garage. Might have been @LanghamP?

I guess the answer is, always store the wheel at room temp and make sure it can't cool down when riding in low temps (on breaks etc).

edit: oh wow holy thread necromancy:efee612b4b:

Edited by meepmeepmayer
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54 minutes ago, meepmeepmayer said:

 

Also, someone recently warned about the gyro sensor failung due to cold after storing the wheel in a garage. Might have been @LanghamP?

Possibly. Earlier this month I had left my MSuper 1600 in my car at below freezing because I didn't want to carry it up flights of steps, and the wheel had nothing to it when I rode it the next morning. The pedals were soggy and the wheel kept doing this weird aborted tiltback, and going up and down hills it'd suddenly level in a way I'd never experienced. 85% battery.

At work the wheel was like a block of ice, and I think it took like 4-6 hours to warm up.

Don't leave your wheel outside. Can't be good.

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