The battery on my Electric Xtracycle is 36 volts (V) and 12 amp hours (Ah). The trouble I was having with the battery was that it had degraded to a point where even on a full charge, I was only able to use 5Ah out of the theoretical 12Ah, meaning I could only travel 8 miles per charge instead of 20. Something had to be done. BMS Replacement
It turned out the culprit was the battery management system (BMS), which acts to balance the 12 cells that make up the battery. Justin at eBikes.ca, the source of my bike's electrical components, discovered the problem nearly a year ago and presented the BMS manufacturer with a solution to resolve the issue.
In what can only be described as involving one of the worst, successful soldering jobs on the planet, I swapped the old BMS for the replacement provided by Justin. In two days I managed to take off the heat-shrink and tape that encased the battery, desolder the old BMS using a worthless, $7 soldering iron from RadioShack (I plan to use this iron
or maybe this one
for subsequent work), connect the new BMS, tape it all back up, wrap it in bicycle tube, and seal everything up with a little duct tape.
***************RAW NOTES KEPT DURING PROCESS***************
PRIOR TO BMS REPLACEMENT :
5.544Ah / cycle
Cell voltages following 24+ hour rest:
3.27 | 3.50 | 3.43 | 3.40 | 3.34 | 3.29 | 3.35 | 3.38 | 3.36 | 3.35 | 3.34 | 3.33
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FIRST DISCHARGE WITH NEW BMS
I started worrying when 1 cell dropped below 2.5V and the BMS didn't shut things off, so
I cut things short with 7.32Ah consumed at pretty constant rate of 2A
Conditions at the end of the first discharge(before any charging):
With 2A load:
Cycle Analyst: 37.8V
most cells: 3.15-3.2V
1 cell: 2.49V
No load:
Cycle Analyst: 38.3V
most cells: 3.2 - 3.25V
1 cell: 2.65V
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FIRST COMPLETE CHARGE WITH NEW BMS
20:20 charge begins using 2.5A charger
22:31 green light comes on
23:10 just noticed red light turn back on - possibly balancing cells?
01:00 removed from charger
11:10 (cold for about 10hrs):
3.29 | 3.30 | 3.31 | 3.31 | 3.31 | 3.31 | 3.31 | 3.32 | 3.32 | 3.33 | 3.32 | 3.33
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FOLLOWING FIRST REAL WORLD TEST RIDE
CA: 38.9V this was a nice surprise, I'd been used to seeing 38.3V at the end of a ride
Ah: 8.046
This is before the battery cut out too, I just didn't want risk dropping that first cell below 2.5V.
Charge time until green: 2hr 50min
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DATA LOST :(
I would guess another cycle of around 8Ah and one of about 5 or 6Ah.
Battery had lots of time on charger (at least one overnight session).
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12AH RIDE (4TH CYCLE?)
Occurred immediately following overnight charge (I have noticed that it helps to charge the battery immediately before a ride since apparently the new BMS discharges the battery to a small extent)
According to the CA:
Ah: 12.00
Wh/km: 11.4
Time: 1hr 42min
Following ride, the charge time until green was apprx. 4 hours
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