What would be the maximum current I can feed my 36v 250w Bafang BPM motor running at 48v?

[WheezyRider]

I'm not sure of those details unfortunately. All I know is that it is listed as 48V. This is the battery: https://www.dhgate.com/product/ebike-lithium-battery-48v-20ah-lithium-ion/384948639.html
I bought it four years ago, and its still running fine and doesn't seem to have lost any range yet (at least, not that I've noticed).

Ok, looks from the webpage a charger voltage of 54.6, so at a max of 4.2V/cell, that means 13s ie, 13 cells in series, which gives a nominal voltage of 46.8V.

I asked as "48V" is a bit of a messy voltage for Li-ion batteries. you either go under 48 nominal with 13s, or go over it with 14s. Legally speaking anything with a rated voltage of more than 48V is against the rules (although no one takes any notice).

For me I was wondering if you were getting 16 to 18 at around the 46V or the 50V mark.

Anyway, good to hear that you've had good results with it. I have ordered one on your recommendation

 

[John_S]

Ok, looks from the webpage a charger voltage of 54.6, so at a max of 4.2V/cell, that means 13s ie, 13 cells in series, which gives a nominal voltage of 46.8V.

I asked as "48V" is a bit of a messy voltage for Li-ion batteries. you either go under 48 nominal with 13s, or go over it with 14s. Legally speaking anything with a rated voltage of more than 48V is against the rules (although no one takes any notice).

For me I was wondering if you were getting 16 to 18 at around the 46V or the 50V mark.

Anyway, good to hear that you've had good results with it. I have ordered one on your recommendation

I see. So in my case, the nominal voltage is actually just under 47V. If I were to get a 14s battery in the future, I figure that my bike would go very slightly faster (perhaps 1mph faster) than it does currently, although as I'm keeping my bike legal, the result would just be that the bike would keep cutting power more frequently.

I'm glad that you've found my advice useful in your decision to order a BPM yourself. Its a great motor.

 

[StuartsProjects]

I see. So in my case, the nominal voltage is actually just under 47V.

The 'nominal' voltage is only an invented value.

In use a Lithium Ion battery might start at 4.1V fully charged (per cell) and be considered as discharged at 3.0V or matbe a bit higher. So the 'nominal' volage is ?

 

[WheezyRider]

The 'nominal' voltage is only an invented value.

In use a Lithium Ion battery might start at 4.1V fully charged (per cell) and be considered as discharged at 3.0V or matbe a bit higher. So the 'nominal' volage is ?

For a typical Li - ion cells, nominal voltage is usually around 3.6 to 3.65 V. For Lipos around 3.7 and for LiFePO4 cells around 3.2 V.

The definition of what "nominal voltage" is can be somewhat woolly. However, it depends on the chemistry of the cell and is specified by the manufacturer.