Battery "power" drops at about 20%

[CanNik]

I did a 32 mile round trip to Aberystwyth from home yesterday (LOVED every second)

But I have a question, being Wales there are hills, not massive but some along the B4340.

I believe I have the 36v battery on the 250w B001 Bafang. (works perfect)

Question is, I do believe I could have done the whole 34 mile trip, but last hill I swapped over, didn't know how little I had left to do.

I noted that even with supposed (I know they are not accurate) battery still just in the yellow, no near the red, there appeared to be a lack (not great but enough) of power on the hill.

I thought they maintained maximum power until they hit the red.

Thanks

Fortunately I have 2 bikes so always take the spare battery

 

[rcdanner]

Most BMS start limiting battery output as it nears 0%, maybe around 15-20%.

 

[harryS]

The motor wattage is proportional to the voltage. Your 36V pack is 42V at full charge and will drop to around 30V. That's like a 30% swing, It can't go much lower than 30V, because there are safety cricuits in both the ebike and in the battery that will shut it down,

With experience, you'll be determining your range by the trip odometer. You'll know how far you can go on a full charge, and know that wind, cold weather, and hills will knock your range down.

 

[CanNik]

Thank you

 

[Slaphappygamer]

I have a voltage read out on my display. When going uphill, I may see up to 4 volts drop. Voltage drop is normal. To account for this drop, I usually charge my battery when it gets to about 50%, roughly 47-48 volts. For reference, I have a 48v battery.