Have you let it sit on the charger for an entire 24 hours yet?
It shouldn't drop back to that low immediately..
I was told the BMS for mine is supposedly set for 3.9 per cell, but I know it don't go that high...
Charger only gets to 45.6 which is 3.8 per, however, the BMS is definitely cutting off before that.
At 45.0v the charger turns green, and then does the on/off thing every minute or so (the BMS is balancing the cells).
It's possible your BMS IS set to 3.9 per cell group (or 62.4v) and if that's the case, then your charger is not going to be powerful enough to start the full BMS balancing..
I would say to do this....
Charge to full, then pull the charger off, disconnect the battery from the controller, pull the balance leads from the BMS and check every cell group with a multimeter and record the results..
(To test the cell groups, you start at the positive side of the charge plug on the battery with the positive lead from the multimeter and the negative lead from the meter to the first pin on the balance leads(if it shows high voltage you started on the wrong end of the balance leads, just start with the other end of the balance leads with the negative of your meter), then carefully go down the line of the balance leads and check each group, one by one. And at the last balance lead use the positive end of your meter to last pin on BMS and negative side of meter to the negative side of the charge port on the battery).
Report back what each group shows..
I have a feeling , you'll have some cells that are 3.9v each and some that are 3.2v-3.3v each. (Not balanced)
22 miles from a 48v 20ah is way to low..
I get 21 miles from a 36v 15ah battery. (And my bike is probably TWICE as heavy as yours, if not more.)
Comparing the WHs of each, you supposedly have 960wh and I have 540wh, which is almost half of yours..
That works out to 43.6wh/mile for yours while mine is 25.7wh/mile.
Something is just not right.
Last edited by Sangesf; 05-09-11 at 09:44 AM.