I just connected the key switch wire to B+
But I have a pre charge problem now..
Sevcon had its own pre charge and contactor control, so I didnt have to worry about it.
I tried to keep the electrical system simple, and didnt have a 12v system at all.
I had an idea for a simple pre charge system with a resistor and a 12v converter in parallel.
Here is the converter I am using.
And pre charge resistor.
I have a built in relay in the batteries that i control on the negative side with a switch, because I dont want hi voltage at the switches.
When that relay turns on both the resistor and converter gets power at the same time. It takes about 0.7-0.8 seconds for the converter to power up and switch on the contactors, and during that time the controller gets pre charged.
With the contactors disconnected from the controller it looks like this:
The yellow line is the voltage on the controller, the green is output from the contactors.
That the voltage is climbing a little on the contactors before they close is probably just some interference, as there is nothing pulling the voltage down.
As you can see, there is about a 20v difference when the contactors close. I dont know if that is good or bad.
The problem now is that my small relay in the battery dont seem to handle the pre charge current very well
I am thinking that it might work if I use a second relay or something, that turns on a little after the one in the battery.
It would still have to take the load, but it wouldnt have to switch under load.
That could be controlled by the 12v converter, but then I would loose my "ghetto pre charge timer"
Doug, how have you solved the pre charge?