Hi everyone,
I'm fairly new to the world of ebikes. Bought a Woosh Big Bear last year and have had minimal problems with it, have since done almost 5000 miles!
My only niggle is the battery life. The bike came with a 15ah battery, and I can get about 35 miles out of it. I've been looking around online for a supplemental battery and eventually went down the whole rabbit hole of figuring out how to build your own. Copious notebook page filling and a lot of cash later, I got all the parts I need, and I've built a 36v 10s7p battery with a 30A BMS over the weekend, which should have approx. 24ah of capacity. But... I can't get it to work!
I cut the connecting cables between the bike's controller (20A max draw) and the primary battery and soldered on a couple of XT60 connectors so I could test out my new battery. I was very careful when building it, making sure all the connections were right, all the BMS wires in the right places, properly insulated, all the rest of it. Even left it on to charge overnight before I tried it. Multimeter probes connected to the newly charged battery's terminals read 42v.
However, I can't get my bike's display to turn on, and therefore can't use the new battery at all.
I had a few spare female charger barrel connectors and quickly fashioned together one of those with some 12awg wires and another XT60 and connected that to the charger and my controller, and *that* works just fine, even though the charger is only putting out 2A. Display turned on and with the front (motor) wheel lifted off the ground I could turn the throttle all the way on and the wheel would spin at maximum speed, just like it would with my original battery.
I'm at the point now where I'm completely stumped. My only thoughts were that I may have connected the BMS incorrectly somehow or that the sensor wire/s had come loose. I took off the shrink wrap tonight to check everything out and I'm still none the wiser. Everything looks to be in the right place. I measured the voltage directly on the battery pack with the negative end of cell 1 and the positive end of cell 10 and it's now showing 41.5v, which doesn't seem to be a concern, but also doesn't help me troubleshoot the issue either.
The only thing I can think of is that the BMS I got from AliExpress is faulty. But if it was faulty would it allow charging to the maximum voltage and/or put out the 42v at all? Am I fundamentally missing something here?
Happy to provide any photos or follow-up info if it's needed. And my eternal gratitude for anyone who can help me fix this!
Thanks,
-Mark
I'm fairly new to the world of ebikes. Bought a Woosh Big Bear last year and have had minimal problems with it, have since done almost 5000 miles!
My only niggle is the battery life. The bike came with a 15ah battery, and I can get about 35 miles out of it. I've been looking around online for a supplemental battery and eventually went down the whole rabbit hole of figuring out how to build your own. Copious notebook page filling and a lot of cash later, I got all the parts I need, and I've built a 36v 10s7p battery with a 30A BMS over the weekend, which should have approx. 24ah of capacity. But... I can't get it to work!
I cut the connecting cables between the bike's controller (20A max draw) and the primary battery and soldered on a couple of XT60 connectors so I could test out my new battery. I was very careful when building it, making sure all the connections were right, all the BMS wires in the right places, properly insulated, all the rest of it. Even left it on to charge overnight before I tried it. Multimeter probes connected to the newly charged battery's terminals read 42v.
However, I can't get my bike's display to turn on, and therefore can't use the new battery at all.
I had a few spare female charger barrel connectors and quickly fashioned together one of those with some 12awg wires and another XT60 and connected that to the charger and my controller, and *that* works just fine, even though the charger is only putting out 2A. Display turned on and with the front (motor) wheel lifted off the ground I could turn the throttle all the way on and the wheel would spin at maximum speed, just like it would with my original battery.
I'm at the point now where I'm completely stumped. My only thoughts were that I may have connected the BMS incorrectly somehow or that the sensor wire/s had come loose. I took off the shrink wrap tonight to check everything out and I'm still none the wiser. Everything looks to be in the right place. I measured the voltage directly on the battery pack with the negative end of cell 1 and the positive end of cell 10 and it's now showing 41.5v, which doesn't seem to be a concern, but also doesn't help me troubleshoot the issue either.
The only thing I can think of is that the BMS I got from AliExpress is faulty. But if it was faulty would it allow charging to the maximum voltage and/or put out the 42v at all? Am I fundamentally missing something here?
Happy to provide any photos or follow-up info if it's needed. And my eternal gratitude for anyone who can help me fix this!
Thanks,
-Mark
