Contoller short circuit

[alfio]

My name is Alfio and I´m from Brazil (sorry for the poor english)
I received my new kit last week (front 36V 750W, standart controller) and at weekwend I tried to test it.
I bought SLA batteries (3 x 12 A) and when I tried to connect the batteries in the controller the fuse (30A) melt. I changed the fuse, recheck the wires and it happens again. I tried to do the connection also whit the brake and meter wires disconnected from the controller... no way
I´m sure that the polarity is OK (i tested it whit a multimeter). Is it possible to be a short cirduit in the controller?
What can I do?
Thank you
Alfio

[e-lmer]

It is possible that the controller has the + and - reversed.

Mine came that way.

On my Std 36V controller with the power connector
closest to the controller, the red wire connector is a flat
(spade?) connection on the red wire perpendicular to the
widest side of the plug.

Unplug that connector, then connect your fuse and battery
and make sure that your +36 Volts goes to the pin that
will connect to the red wire on that plug.

Hard to say, easier to draw:

[biohazardman]

It is possible that the controller has the + and - reversed.

Mine came that way.

On my Std 36V controller with the power connector
closest to the controller, the red wire connector is a flat
(spade?) connection on the red wire perpendicular to the
widest side of the plug.

Unplug that connector, then connect your fuse and battery
and make sure that your +36 Volts goes to the pin that
will connect to the red wire on that plug.

Hard to say, easier to draw: One pic is worth a thousand words decent of you to take the time to do that.

[alfio]

e-Imer
Thank you for the reply, but I have already checked the wires and its Ok.
You think possible that the wires are inverted inside the controler (i.e. the red is negative and the black positive?)
How to check this?

[TOM]

Could you take a photo about your wires?

[alfio]

I found the problem!!!!
The charger came whith inverted wiring and the battery store guy mounted the plug inverted too!! The batteries charge OK, but the wiring to the controller short
Now I fixed the wires and the motor is running OK
Thank you all for help and stay in contact