Help! “Our Other Car” (a cheap but flash tandem cruiser with a GM BCK motor and 12AH, 36volt, Li battery) just died. The chrome-and-scarlet hussy is heavy - nearly 100# with motor, batt, racks, and four grocery panniers, but she has hauled a bunch and turned a few heads to boot.
We installed the motor about two years ago and the battery about two weeks ago (after giving up on SLA and after GM replaced a battery with a bum
BMS. With the new batt, I also added a Watts-Up power monitor.
After a couple of serious climbs (300 ft elevation gain on a 6% grade) with rest and recharge in between, she was treated to two much shorter but equally steep grades with plenty of time to cool between them. At the end of the second, she quit. Symptoms that might guide the autopsy:
Abrupt onset of continuous strong vibration and almost total loss of power.
With the throttle set for full power, a current draw (on my Watts Up meter) of only about six amps
Dead spots; even with the motor wheel off the ground, it may not start without being first turned by hand.
When the motor is turning at just a few MPH, its now very low power comes in discrete pulses as it passes the many dead spots during each rotation.
My electrical knowledge is largely limited to rewiring houses, not motors. Can more savvy souls tell me where and how to begin?
