Should the cold weather affect Battery or Controller?

Of late the power cuts out for no reason. Power is restored immediately upon turning the key off and on. The only thing i can think of is the weather, which is a bit nippy of late. Also there appears to be plenty of juice in the battery.

Would the controller cut out due to the weather? Is it possible the controller is registering any unusual load and cutting out to protect the battery? The only other time i experienced anything like this was when i was running very low on power after a long ride.

Any ideas how i solve this?

It can but make sure all your connections are good, from battery fuse, through battery contacts to controller to motor wires. Batteries are chemical devices, lowering the temperature affects their ability to deliver power...internal resistance rises, voltage drops more and the controller may hit its Low Voltage cutoff setting sooner. The bike will feel less powerful and you wont go as far on one charge the range will be reduced

My suggestion would be to keep the battery indoors, room temp, charge indoors and only leave it on the bike when you ride it.

Cold weather will also highlight an aging battery, maybe yours is getting on a bit?

Edited January 17, 201313 yr by NRG

As NRG says above.

The reason is that the battery internal resistance increases when it's cold. This causes the voltage to drop when current is drawn. If the voltage drops below the low voltage cut off then the ebike will shut down. This is then reset by turning it off and on again (or sometimes by just closing the throttle and opening it again).

Additionally, batteries don't accept charge as effectively when cold, again because the higher internal resistance will cause the battery voltage to rise higher during charge, which then causes the charger to detect full charge before the battery is really fully charged.

I'd not recommend charging indoors, but bringing the battery in to warm up before charging it, then wrapping it up to keep it warm when charging may help. When charged, bring the battery indoors so that it will be warm when you come to use it. You'll probably find that the performance will markedly improve when the battery is warm.

As NRG says above.

 

The reason is that the battery internal resistance increases when it's cold. This causes the voltage to drop when current is drawn.

When charged, bring the battery indoors so that it will be warm when you come to use it. You'll probably find that the performance will markedly improve when the battery is warm.

I am not a battery expert but over twenty years ago when Lithium batteries were becoming popular in cameras their biggest selling points were that they gave full performance in cold weather, even at -20 C, unlike the NiCads more often fitted to cheaper cameras. Also Lithium batteries prefer to be recharged often as they have no memory effect like NiCads but over charging or completely discharging shortens the life of Lithium batteries.

Well known?

Yeah right.......I get approx 20-30% more range in summer riding in Italy. Its well known that bike batteries suffer in cold conditions

Have you any info of independent tests to back your comments!

Electric cars and hybrid cars fitted with lithium batteries have very complex cooling systems

fitted to keep the batteries cool even when not in use.

Perhaps you could enlighten us by pointing us in the direction of published information on Lithium batteries re: ambient temperature differences as you say it is well known?

I have noticed my battery performs a bit better in warm weather but not by a massive amount. It is pifepo4. In warm weather the voltage doesnt seem to sag as much when you draw full power, which I guess correlates with the higher internal resistance in cold weather mentioned above

I think its probably far more noticeable with small capacity batteries...

Have you any info of independent tests to back your comments!

Electric cars and hybrid cars fitted with lithium batteries have very complex cooling systems

fitted to keep the batteries cool even when not in use.

Perhaps you could enlighten us by pointing us in the direction of published information on Lithium batteries re: ambient temperature differences as you say it is well known?

http://ma.ecsdl.org/content/MA2012-02/10/1057.full.pdf

Note the reference to the 2011 Nissan Leaf loosing 40% (only realizing 60%) of its range at -10deg C

I am not a battery expert but over twenty years ago when Lithium batteries were becoming popular in cameras their biggest selling points were that they gave full performance in cold weather, even at -20 C, unlike the NiCads more often fitted to cheaper cameras. Also Lithium batteries prefer to be recharged often as they have no memory effect like NiCads but over charging or completely discharging shortens the life of Lithium batteries.

Some lithium chemistries are certainly pretty good at low temperatures when compared to lead or nickel chemistries, but they do still suffer from a fairly hefty increase in internal resistance when they get cold. If you're only drawing a low current from them then this doesn't matter too much, but ebikes tend to draw fairly high peak currents at times that can cause a substantial momentary voltage drop. The low voltage cut off circuit can activate pretty quickly, so tends to sense these momentary voltage drops that occur whenever a high pulse of current is drawn.

I think its probably far more noticeable with small capacity batteries...

Quite possibly so ... but I had mine out in well sub-zero last night with the front dynamo lighting on and having started with about 40% charge. I definitely noticed a bit of a drop in 'perkiness' compared to when riding at similar time in temps not quite so low also with a pretty-much half-charged battery, on both occasions starting 'cold'.

Just back from a 7 mile trip taking the unpowered Trek with the knobbly tyres to Halfords through the falling snow to collect / fit its new rack. I can definitely sympathize with small capacity batteries - my increased internal resistance was initially responsible for a noticeable performance sag, until I warmed up at least... thankfully I didn't cut out completely. Perhaps starting warm (with a cup of tea ?) and being wrapped in a cozy towel would work for me too ...

Edited January 17, 201313 yr by 103Alex1

Well , my take is not scientific

30 mile route summer 3 lights left

30 mile route winter 0c 1 light left .

I could give you the watt hours left but cannot be arsed looking .

Ok maybe slower and colder in winter

It can but make sure all your connections are good, from battery fuse, through battery contacts to controller to motor wires. Batteries are chemical devices, lowering the temperature affects their ability to deliver power...internal resistance rises, voltage drops more and the controller may hit its Low Voltage cutoff setting sooner. The bike will feel less powerful and you wont go as far on one charge the range will be reduced

 

My suggestion would be to keep the battery indoors, room temp, charge indoors and only leave it on the bike when you ride it.

 

Cold weather will also highlight an aging battery, maybe yours is getting on a bit?

Thanks for your advice. I'll certainly go over the main wires. As for the battery, its one of those bottle types in a metallic casing. I'm now seriously considering some kind of insulation of its internal batteries, with a possible reversal for summer conditions.

I wonder what this means for e-transport in colder countries? Its one of those questions which one wont see asked?

As NRG says above.

 

The reason is that the battery internal resistance increases when it's cold. This causes the voltage to drop when current is drawn. If the voltage drops below the low voltage cut off then the ebike will shut down. This is then reset by turning it off and on again (or sometimes by just closing the throttle and opening it again).

 

Additionally, batteries don't accept charge as effectively when cold, again because the higher internal resistance will cause the battery voltage to rise higher during charge, which then causes the charger to detect full charge before the battery is really fully charged.

 

I'd not recommend charging indoors, but bringing the battery in to warm up before charging it, then wrapping it up to keep it warm when charging may help. When charged, bring the battery indoors so that it will be warm when you come to use it. You'll probably find that the performance will markedly improve when the battery is warm.

Does anyone know of a way to affect the low voltage cut off without compromising the battery too much?

Does anyone know of a way to affect the low voltage cut off without compromising the battery too much?

Not really, unfortunately. Lithium cells are easily damaged by low cell voltage, so the LVC is set to ensure that cells don't get damaged by being taken to too low a voltage.

The bottle battery you have is probably the worst in terms of this problem, as the small cells inside already have a pretty high internal resistance, even at normal temperatures. When they get cold the resistance increases a lot, causing the voltage drop to increase, almost certainly creating the problem you're seeing.

Warming the battery before use will make a difference, and is well worth trying.

Not really, unfortunately. Lithium cells are easily damaged by low cell voltage, so the LVC is set to ensure that cells don't get damaged by being taken to too low a voltage.

 

The bottle battery you have is probably the worst in terms of this problem, as the small cells inside already have a pretty high internal resistance, even at normal temperatures. When they get cold the resistance increases a lot, causing the voltage drop to increase, almost certainly creating the problem you're seeing.

 

Warming the battery before use will make a difference, and is well worth trying.

As a follow up:

The bottle battery is very probably suffering with the colder temperature, but i've found a stop gap

which appears to work.

This is simply not to use the throttle max'd out. I find the bike responds if i have it on half throttle

and then peddle against that. There is some peddle effort involved in this mode, more than when the throttle is fully open, but its certainly better than peddling with no power assist, eg no power at all.

When i get the chance i'll see what i can do to insulate the battery. A foam lining ought to work

if there's any kind of space inside the battery for this.

fully open, but at least there is

 

When i get the chance i'll see what i can do to insulate the battery. A foam lining ought to work

if there's any kind of space inside the battery for this.

fully open, but at least there is

Sorry if this is stating the obvious but insulating it won't warm it up (apart from retaining a little of the heat generated from internal resistance during use) ...as others have advised it would be better to just keep it inside until you use it. If you can supervise it then charging inside in my opinion is not particularly risky, I just wouldn't leave it alone on charge.

Insulating will only really be worth it if your journeys are long enough for it to really get cold in that time.

Sorry if this is stating the obvious but insulating it won't warm it up (apart from retaining a little of the heat generated from internal resistance during use) ...as others have advised it would be better to just keep it inside until you use it. If you can supervise it then charging inside in my opinion is not particularly risky, I just wouldn't leave it alone on charge.

 

Insulating will only really be worth it if your journeys are long enough for it to really get cold in that time.

On this last point, this is really about riding conditions and as i say the effects of the weather on the battery's performance. Charging is always done indoor in ok conditions. The metalic casing isn't helped in conditions where there is snow fall etc..

If you start off with a battery pack at room temperature, then it'll probably not cool down a great deal internally over a ride. Drawing current from the battery warms it up internally, probably by enough to keep the overall temperature from dropping much over the course of an hour or so.

The amount of heat the battery pack gains from use depends on the cell internal resistance, so the high internal resistance packs, like the bottle packs, will generate significantly more internal heat in use than the very low internal resistance cells in something like a home made pack that uses RC type cells.