Charging battery outside ideal 15-20c range

[confusedcyclist]

Bosch claim "The ideal charging temperature is 15 to 20 degrees Celsius. If the battery temperature is below 0 degrees Celsius, the intelligent battery management system from Bosch prevents charging – in order to protect the battery cells."

Does anyone know what the long term impact of charging at >5C - <15C might be? Is it simply charging efficiency or cell longevity at stake. Notice how they state the intelligent system prevents damage. Does this mean it's safe to charge above 0C?

This time of my year my garage tends to be 10C, I'd like to stop bringing my battery in to the heated house overnight as it's a pain unlocking it and putting it back the bike twice a day. Charging on the bike would be ideal.

 

[Pale Rider]

Does this mean it's safe to charge above 0C?

I'm sure I've charged mine a few times at close to freezing point.

No immediate sign of damage.

Not sure what damage is supposed to be done, but I might bring it indoors if I thought the temperature was minus an awful lot.

No point in worrying if it's zero and above.

Absolutely no point in worrying in March when it's a few degrees and above.

 

[Levo-Lon]

I'm pretty sure it's all down to charge capacity.
A warm battery will charge better than a very cold one.

I've charged mine on the bike outside in 3-10 deg but I usually do it indoors.

When I had a Bosch system I biked to work in cold weather and just took the battery off when I got to work, it just lasted longer.

 

[confusedcyclist]

My garage is integral, but not heated, but because the boiler is located in there it retains some waste heat, hence the slightly higher than outdoor temps. I wouldn't class it as indoors as it's not insulated, with a leaky garage door I'm sure the temps could fall lower overnight when the boiler isn't called for heat for up to 8 hours. Battery always comes indoors when the bike is stored in a rack outdoors at work, purely for security.

 

[raleighnut]

My garage is integral, but not heated, but because the boiler is located in there it retains some waste heat, hence the slightly higher than outdoor temps. I wouldn't class it as indoors as it's not insulated, with a leaky garage door I'm sure the temps could fall lower overnight when the boiler isn't called for heat for up to 8 hours. Battery always comes indoors when the bike is stored in a rack outdoors at work, purely for security.

charge it at work

 

[CXRAndy]

There must be something to charging at an optimal temperature. My Tesla will spend a while warming the battery pack before applying charge current if its cold. Similarly preconditioning before arriving at a 125kw supercharger raises the battery temp to accept that amount of current

 

[confusedcyclist]

charge it at work

The thought has crossed my mind since I would be brining it in anyway, and it's OK as a one off, but I'd be swapping the logistics of moving a battery around to moving a charger around instead, albeit the faff of locking is omitted. Leaving my charger at work isn't an option as the ride home depletes roughly 30% of my battery, any long evening riding outside commuting would become problematic. Bosch's chargers are silly expensive. I've set up an ebay search for second hand chargers, but these are not the kinds of things people sell frequently, so I'm not holding my breath for a bargain.

 

[sheddy]

I think we had this same question last month.

 

[Pale Rider]

Tempting to think Bosch, er, over charges for their chargers when others are available for thirty quid.

However, the electrical engineering of the Bosch system is the best on the market.

I'm not sure how much part the charger plays in that.

There seems to be a relay in mine because I can hear it clicking.

That might be because my bike has the dual battery system which the charger charges alternately a little at a time.

 

[confusedcyclist]

I think we had this same question last month.

Can you link to it, I didn't spot it?

 

[confusedcyclist]

There seems to be a relay in mine because I can hear it clicking.
That might be because my bike has the dual battery system which the charger charges alternately a little at a time.

Yes, mine clicks as the charging starts, but as mine only charges a single battery, it's only heard once when it kicks in, maybe again when it reaches 100%, but I've never been present for the switch off at full charge.

It makes sense that it alternates the charge, if it charged one to full before the other, if you make a habit of interrupting the charging and then riding off, it will put more stress on the battery that gets more full charging/depletion cycles than the other. Alternating the charge and depletion keeps things as level as possible.

It's definitely a complex bit of kit as the electronics spends a bit of time thinking about the voltage before it's applied to the cells before charging starts. I've used an energy meter and it doesn't go all guns blazing when the switch is flipped.

 

[Pale Rider]

I don't claim to fully understand it, but it seems to work well.

Owners of generic Chinese chargers and batteries speak of sparks when connecting and disconnecting.

Eventually, this burns away the battery or cradle terminals.

Bosch may be dear, but you don't get nonsense like that.

 

[confusedcyclist]

I ran a completed listing search on ebay, and it looks like a few standard charges sold around Jan roughly £20-30 plus delivery a pop, I could justify that expense for the sake of convenience. Clearly though the second hand market is not very big, at least for now, in-garage charging is a sensible option.

 

[raleighnut]

I don't claim to fully understand it, but it seems to work well.

Owners of generic Chinese chargers and batteries speak of sparks when connecting and disconnecting.

Eventually, this burns away the battery or cradle terminals.

Bosch may be dear, but you don't get nonsense like that.

Mine says in the destructions to connect before turning the power on, maybe that is to avoid the sparking

 

[Pale Rider]

Mine says in the destructions to connect before turning the power on, maybe that is to avoid the sparking

That's what I do, although I've read other opinion which says to power up the charger before plugging it into the battery.

Makes more sense to me to connect to the battery first, then connect the mains to the charger.