I built to a friend of mine an electric skateboard with 10S3P battery pack using genuine Samsung 25R cells. The BMS is a Bestech HCX-D131 model. My friend told me he noticed a really odd behavior recently.
He uses the eSkate VESC iOS app to see what is the voltage of the battery. Usually, the app shows about 42V when battery is fully charged. However, in the last couple of days, it shows around 37V. When the battery is being charged, it reachs back to 42V, but when you disconnect the charger, guess what? It goes back to 37V!
Here is a video to see this “phenomena” -
I measured the voltage of the battery directly, without the BMS, and it shows 40V. It’s still not 42V, but I can live with that. I’m assuming the BMS is not letting it reach its max capacity. Something is wrong here.
This board is up and running for the last 5 months with no any battery issues. Does anyone have any idea what the hell is going on?