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BBS02 Voltage Issue

mpr48

1 µW
Joined
Aug 7, 2022
Messages
3
I have a BBS02 conversion with a 48V battery and 500C display. The voltage indicated on the display recently starting reading about 5 volts lower than actual. It appears to be controller related as different displays show the same voltage and I have confirmed that the reading is about 5 volts lower than the battery voltage. I really don't care as I use my own power meter and shunt BUT have an issue with the cut-off voltage which would occur at 46V rather than the former 41V greatly reducing range. I have reduced the cutoff to the minimum (38V) but it is still reducing available battery some. Any idea what is going on?
 
If you're still using the littlle bullet connectors that come on the battery wires, check those. Mine were getting hot for a while before I noticed.
 
I remember looking at pictures of a BBS02B controller, and it looked like a straight shot from the positive battery wire to the P+ wire on the wire harness. Try to see if you get the drop at the main connector where it attaches to the handlebar harness. If it's there. could be a frayed wire on the cable inside the motor or corrosion on the circuit board on either the P+ or ground. Either can be repaired.

FQzHpBv.jpg
 
You might try opening up the controller side of the motor and re-seat the small connectors, especially the one from the display. There is a direct connection from battery positive to the brown wire going to the display.
 
My voltage will be fine then it will dip and fluctuate wildly & motor cuts. Volts returns to normal after 5+ min (47v). Have you seen this? youtube.com/shorts/tH5gbwOy7Ig
 
My voltage will be fine then it will dip and fluctuate wildly & motor cuts. Volts returns to normal after 5+ min (47v). Have you seen this? youtube.com/shorts/tH5gbwOy7Ig
Looks like a bad connection somewhere between the battery and the controller. It could also be the BMS inside the battery or a connection to it. Use a voltmeter across the main battery wires going to the controller and see if it is steady there. If it is fluctuating, the problem is with the battery. Double check all the battery connections.
 
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