The title says it all. I have a gazelle Innergy 36V e-bike with a geared front hub motor.
I only have to commute 3km to work, but there is a rather steep slope of a few hundred meters.
That's where I get the impression that the motor pulls much harder with a full battery compared to when the battery voltage is lower.
A full battery can give up to 41.5V bringing cable losses and internal battery resistance into the equation, let's assume we have 40V arriving at the motor under load.
A nearly empty battery might only still give 30V to the motor. That's like 25% less.
However, the theory says that voltage is important for maximum speed and current for torque.
On the other hand, if I feed the motor with 40V and 8A it will get 320W. If I feed only 30V and 8A, it's 240W
I searched the internet but couldn't find if this behavour is normal.
Maybe some controllers increase motor current when the voltage get's lower, maintaining the legal allowed mean power going to the motor?
Mid drive motors likely will have a different behavour, as you will switch to a lower gear when climbing.
The gazelle Innergy has the motor controller build in the motor. It uses a TI DSP microcontroller, so there isn't much room for experimentation. I was playing with the idea of using a boost converter or maybe adding 2S in serie with the battery and using a step down on them to keep the battery always full. (as a matter of speech)
I only have to commute 3km to work, but there is a rather steep slope of a few hundred meters.
That's where I get the impression that the motor pulls much harder with a full battery compared to when the battery voltage is lower.
A full battery can give up to 41.5V bringing cable losses and internal battery resistance into the equation, let's assume we have 40V arriving at the motor under load.
A nearly empty battery might only still give 30V to the motor. That's like 25% less.
However, the theory says that voltage is important for maximum speed and current for torque.
On the other hand, if I feed the motor with 40V and 8A it will get 320W. If I feed only 30V and 8A, it's 240W
I searched the internet but couldn't find if this behavour is normal.
Maybe some controllers increase motor current when the voltage get's lower, maintaining the legal allowed mean power going to the motor?
Mid drive motors likely will have a different behavour, as you will switch to a lower gear when climbing.
The gazelle Innergy has the motor controller build in the motor. It uses a TI DSP microcontroller, so there isn't much room for experimentation. I was playing with the idea of using a boost converter or maybe adding 2S in serie with the battery and using a step down on them to keep the battery always full. (as a matter of speech)