DIAGNOSIS????

[steelefist]

I've just finished modifying a new scooter, but having a major problem getting the thing going!!! it's so frustrating to because everything is ready to go.......

The system I am using is a 750 Watt 36 Volt MY1020 motor run at 48 Volts using forty 1.2V 14Ah F-size NiMh Cells.

The power pack seems to be fine and fully charged. The motor runs fine when tested at 36V with the original 36V controller.

I then bought an LB-37 48V controller from TNC Scooters. Wired it all in correctly and immediately when i completed the circuit by attaching the final wire..... the batteries were shorted for a couple of seconds before i detached the wires. I checked all the wiring and kept the system to the minimum of the motor, the throttle and the speed controller.....

....Again the batteries were shorted, this time blowing a fuse I put in the circuit.
So, after inspecting it I thought it must be the controller! I ordered a new one, a better, bigger and more sturdy (Model YK42-4) Yi-Yun, which also runs on 48V with a greater current handling capability.

Again, popped the fuse straight away. The sparks are clearly from a short circuit current. So far I have blown two 10A, one 15A, one 20A and a 35Amp fuse. I cannot see anything wrong at all. The throttle seems fine, the motor, the cables, there is no frame contact from any terminals.

Everything seems absolutly fine, yet the batteries keep shorting out...

Any help or advice, theories or possible causes would be appreciated...

 

[Deepkimchi]

Before you hook up another battery use an ohmmeter/multimeter to check the terminals that would be connected to the battery.

Sure you are using the right type controller for the motor (brushless or brushed?)

Bryan

 

[lawsonuw]

I hate to ask this but are you SURE the battery polarity is correct? Controllers act like a dead short when wired up backwards. If you have a multi-meter it's easy to check this. In "diode check" mode the controller will read about 1.2v when the multi-meter probes are hooked up backwards. Hooked up correctly, "diode check" mode will read a slowly increasing voltage that either won't stop rising, or will eventually settle at some high voltage.

Marty

 

[steelefist]

Yeh the batteries are all connected in series and the correct polarity to the speed controller. I've checked every cell with the multimeter and the combined cells, giving a total voltage of just under 50V. Positive to red, negative to black. The multimeter reads negative voltages the other way around.

This controller has been used on My1020 1000Watt motors before, so definately the correct type. Mr Exon uses this controller on his little 40mph bike.

 

[fechter]

It sounds like the controller is shorted. Disconnect the battery and measure resistance with a meter across the battery leads going to the controller. Measure both polarities. A good controller should read low at first, then steadily climb up as the capacitors charge. A shorted one will just read zero no matter what.

 

[steelefist]

Wrong polarity. Im an idiot! thanx for ur help every1