Hi Folks! I have been working on a few electric scooters for a local bike shop that are having a few issues.
There is a large variation in the range between brand new identical scooters. Also there have been cell failures.
The scooters use 20 X 40AHr ThunderSky cells, there is no BMS which doesn’t help! The cells are arranged in batteries of 4 cells.
I have measured the DC resistance of about 60 cells and found the lowest are about 3 milliohms with the highest at 13 milliohms.
I fitted one of the scooters with an ammeter (0-100A) which showed peak current of 75A which equates to 4kW, the motor rating, and between 30 and 40A while cruising at 45mph which seems in order.
It looks to me like the internal resistance of the cells is a real problem, these are supposed to be brand new!
Does anyone have any experience of these cells?
Thanks in advance, Martin