A2B problem

alfgar

100 mW
Joined
Mar 18, 2017
Messages
41
Hey everyone.

Picked up an A2B gen 2 from a bike shop. It was their floor show model for 2 years since the owner purchased the shop. He doesn’t know how long the previous owner had it for. If anyone knows how to determine the year of the bike, I would appreciate it.

The bike is “new” but they couldn’t get it to work so they sold it as is for parts. Surprisingly the battery charges up. When I go to throttle, the back wheel jolts about 1/8th of a turn and then locks up as if the brakes are immediately applied as soon as I throttled up. At this point the back wheel is difficult to turn by hand or pedal.

When I unplug the motor connector the back wheel easily turns again by hand or pedal. I reconnect the motor, throttle it up and it jolts a little again and stops immediately with the same symptoms every time I connect and disconnect the motor. If I persist on the throttle, the motor hums lightly , the battery indicator on the odometer reduces to about ½ and the bike powers down by itself only to turn on again 1-2 seconds later. And the battery showing full power again.

Volt meter shows 41.5 volts on the battery from where I charge it.

Thanks in advance for any suggestions.
 
Could be blown FETs in the controller.

If your controller is external to the wheel, then disconnecting that from the motor would let the wheel roll normally.

At least some of the A2B bikes use the Ultramotor, which has a built-in controller. If yours is one of those, then disconnecting the motor connector from the bike doesn't disconnect the controller from the motor/wheel, so if the wheel rolls normally with it disconnected from the bike's cables, then the controller FETs are probably fine, but something else is probably commanding the controller to lock up.

If it has an anti-theft feature, that might be enabled. Or a brake switch might be engaged, and that might cause the wheel to lock.

If you need to open up the motor for any reason, there's a number of threads about taking the wheel apart to get the motor case open, and some have also removed the internal controller and wired up an external one.

Stromer bikes also used that motor, so threads about those also may have that info. I know there's some in a thread by GCinDC.
 
Sounds like a blown controller. It's buried inside the wheel.

There are a few topics around on A2B bikes.

Mine is only one of them, but shows replacing the controller with an external one.
https://endless-sphere.com/forums/viewtopic.php?f=6&t=50590
 
Sorry for the delay in responding, was away for a few days

Thanks for the suggestions, I will look into them as soon I get a chance. Hoping it’s a brake cut off switch, it’ll make my $350 (CDN) investment worthwhile.

I was under the impression that the controller was inside the main frame as well for the gen 2’s. Especially since the wheel turns freely after disconnected. Guess I'll find out easily enough once I remove the cap off the bottom of the main frame. Just need to find some spare time without risking sleeping on the sofa :D

As to the connector, it has 3 large pins along with 6 other smaller pins distributed around the 3.

Any suggestions as to how find out the age of the bike?

edit:
Almost forgot. Another symptom that seems to leads me towards the brake cut off is the brake lights. There always “on” , as if the brake levels were being pulled. And once or twice I did see them work normally...light up only when the brake lever is pulled....


tks again.
 
alfgar said:
As to the connector, it has 3 large pins along with 6 other smaller pins distributed around the 3.

Yes, that does sound like the external controller type.

The brake switch does sound like a likely suspect.
 
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