Hello, after spending a long time researching I recently decided to purchase and install a Bafang 750W BBS02 kit which I paired with a 48V 17AH battery and L200 Bluetooth display
Almost everything is working great except the unit seems to be very inaccurate when it comes to detecting how much capacity is left in the battery, and gets more inaccurate as voltage goes down.
Basically it thinks there is no power left when the battery has approx 40% capacity remaining - I believe this is the correct number b/c both the battery indicator on the battery pack itself (shows 2/4 bars), as well as manually measuring the voltage on the battery (45.3V), match up with this. I also tested with multiple voltmeters showing the same measurement.
Here's a short clip:
I'm using this 48V battery chart to map from voltage to battery capacity
https://docs.google.com/spreadsheets/d/1E1HCw-kZOfo8pdpjXWLjaK5VaTN5axZFjDMcuTpb_b8/edit?usp=sharing
I understand there is a low voltage cutoff setting on the controller (42V) but I am nowhere near it and afaik that shouldn't cause the battery % remaining reading to be offset so significantly if at all.
I also understand there is both a voltage sag that scales with load and that the voltage can be prematurely lowered and recover a bit after leaving the battery alone. I've experienced both with my setup and behavior is what I'd expect except occuring with this large offset. Ex. near 50% battery capacity (based on manually reading voltage in rested battery), if I try to use PAS at level 4 it feels like the unit's performance seems to downgrade to PAS level 3 after ~1 second, and if I do this around 45% the unit will cut power, saying there is no battery left. Anything lower than that I need to stick to PAS level 1 or 2 until around 40% where it doesn't have enough left to run at all even at lowest PAS.
I've begun tracking the manual battery measurement against what the Bafang unit thinks remains with the following results. For the Bafang % measurement I've used both the bluetooth on the display + manufacturer's app, as well as the Bafang programming cable + Speeed app, both show the exact same numbers so I don't think it's the display that is the issue:
You can see how the difference increases as the voltage decreases, and when the Bafang unit thinks there is around 10% remaining, it does not run anymore even at lowest PAS.
I was never expecting to get to use the whole battery capacity, only up to maybe 80-90%, but it feels like I'm currently only getting to use a little over half the full capacity which seems wrong
Is this normal and has anyone else experienced this? I really hope I don't need to get a new Bafang unit just for this
Almost everything is working great except the unit seems to be very inaccurate when it comes to detecting how much capacity is left in the battery, and gets more inaccurate as voltage goes down.
Basically it thinks there is no power left when the battery has approx 40% capacity remaining - I believe this is the correct number b/c both the battery indicator on the battery pack itself (shows 2/4 bars), as well as manually measuring the voltage on the battery (45.3V), match up with this. I also tested with multiple voltmeters showing the same measurement.
Here's a short clip:
I'm using this 48V battery chart to map from voltage to battery capacity
https://docs.google.com/spreadsheets/d/1E1HCw-kZOfo8pdpjXWLjaK5VaTN5axZFjDMcuTpb_b8/edit?usp=sharing
I understand there is a low voltage cutoff setting on the controller (42V) but I am nowhere near it and afaik that shouldn't cause the battery % remaining reading to be offset so significantly if at all.
I also understand there is both a voltage sag that scales with load and that the voltage can be prematurely lowered and recover a bit after leaving the battery alone. I've experienced both with my setup and behavior is what I'd expect except occuring with this large offset. Ex. near 50% battery capacity (based on manually reading voltage in rested battery), if I try to use PAS at level 4 it feels like the unit's performance seems to downgrade to PAS level 3 after ~1 second, and if I do this around 45% the unit will cut power, saying there is no battery left. Anything lower than that I need to stick to PAS level 1 or 2 until around 40% where it doesn't have enough left to run at all even at lowest PAS.
I've begun tracking the manual battery measurement against what the Bafang unit thinks remains with the following results. For the Bafang % measurement I've used both the bluetooth on the display + manufacturer's app, as well as the Bafang programming cable + Speeed app, both show the exact same numbers so I don't think it's the display that is the issue:
You can see how the difference increases as the voltage decreases, and when the Bafang unit thinks there is around 10% remaining, it does not run anymore even at lowest PAS.
I was never expecting to get to use the whole battery capacity, only up to maybe 80-90%, but it feels like I'm currently only getting to use a little over half the full capacity which seems wrong
Is this normal and has anyone else experienced this? I really hope I don't need to get a new Bafang unit just for this