Extreme pedaling resistance with power off.

[davevelo]

Hi All,
I have a dual battery setup controlled by two 80a relays. I can run on either pack or combine the packs in series for more power.

The problem is that when both packs are disconnected from the controller, I get extreme resistance from the HS3540 hub motor. Enough that pedaling is very difficult if not impossible.

When testing the system, with system on and controller engaged, the resistance felt when eBrake is applied is "less" than if everything is turned off! Anyone have a clue about what is going on? Thanks!

 

[bowlofsalad]

Does this problem persist with everything between the controller and the motor disconnected?

 

[John in CR]

It sounds like a security lock setting in the controller where when parked and off someone can't take off with your ebike and pedal away. This is accomplished by the mosfets on the phase side to be left in the on position to make the phase wires shorted together. If it's a programmable controller then you need to turn off the parking brake, security lock, or whatever it is called with that controller.

 

[Chalo]

One of the first e-bikes I built used a direct drive brushed hub motor and a Curtis DC controller, which engages automatic braking when it's not propelling the motor.

I circumvented that feature by putting a high amp plunger switch in one of the motor leads, and mounting it up near the handlebar. When the motor wasn't required, the circuit could be opened for minimal drag.

 

[dogman dan]

Sounds more like a lock circuit, than a blown controller causing the shorted phases, which makes the motor cog like hell.

 

[davevelo]

Does this problem persist with everything between the controller and the motor disconnected?

Haven't actually tried this since the wires are a bitch to get to but I can say that it's a lot tougher to turn now then when I had it on the truing stand.

 

[davevelo]

It sounds like a security lock setting in the controller where when parked and off someone can't take off with your ebike and pedal away. This is accomplished by the mosfets on the phase side to be left in the on position to make the phase wires shorted together. If it's a programmable controller then you need to turn off the parking brake, security lock, or whatever it is called with that controller.

Don't think the Grinfineon C7240-NC is directly programmable. Please let me know if I'm wrong. I have a CA3 but don't see this setting in the software. What boggles my mind is that merely connecting the battery to the controller leads frees the motor. A security lock of some sort makes the most sense... thanks.

 

[davevelo]

Sounds more like a lock circuit, than a blown controller causing the shorted phases, which makes the motor cog like hell.

Hmm, another poster also mentioned this. I'll have to check. I can tell you that the controller functions perfectly normal when powered up. What's confounding is that the controller switch is "off" when the extreme cogging occurs.

 

[dogman dan]

If it works, it's definitely not a blown controller, or short in the phase wiring, or short inside the motor.

 

[davevelo]

The mystery has been solved. My relay circuit shorts the controller power leads when the system is turned off. This also shorts the motor phase wires causing the resistance.