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Blew pack fuses on ignition. Curtis 1238se controller and AC-50 motor help

1585 Views 11 Replies 7 Participants Last post by  Russco
Sort of a huge disappointment, but after wiring up my whole conversion verifying the wiring and turning the ignition I blew the pack fuses and my worry is that I fried the controller.

I wired up my system matching the attached EV West schematic, I've got the AC-50 motor with the 1238SE-7971 controller.

I've got 5 Tesla Modules wired in series, they're divided into three battery boxes, two boxes each with two modules wired in series with those two boxes each containing one 150 V 600 amp fuse on the negative lead coming out of the box. Then the final battery has its own 150 V 600 amp fuse on the negative line, which is the pack most negative lead.

When I turned the ignition for the first time I heard a big click. I thought this was the contactor, but discovered the controller didn't light up, or turn on. I discovered that the fuse between the negative most battery terminal and the shunt had blown. I wasn't sure if it was perhaps a bad fuse, or what, so I thought I could perhaps test to see if it was by bypassing that last fuse and try again without touching the throttle or anything. I did that, and ended up blowing the two other fuses apparently?

Definitely a bit unsettling, as I checked all my HV wiring against the schematic. I measured resistance of the main contactor after the event (with batteries disconnected) and it looks like the contactor is still open so I'd imagine that wasn't the issue? I also checked resistance across B+ and B- on the Curtis controller and there was no resistance, but I'm not sure there is supposed to be. I checked to make sure that my KSI was still functioning correctly and it seems to be.

Where/what would you start to diagnose next? My fear is that I not only fried three $100 fuses but also a $2k+ controller.

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if KSI is working, then controller will run its diagnostics and blink out whatever problem may be, including blown MOSFETs.
FWIW the EV West schematic for the 1239 controller(revision1.7, 9/22) shows a dedicated precharge circuit, something lacking in the 1238 schematic:

You might try to put a precharge resistor across the HV terminals of your main contactor(with the main battery disconnected, of course!). Someone here could size it for you. If you wait for the controller capacitors to charge-up through this resistor after the main disconnect switch is turned on and before the main contactor is activated, the controller may still work.

Before you do this, it looks like the 1238 has an ignition switch/HV relay controlled tap to pin 1 of the controller. This may be a HV feed to an internal controller precharge system. You can test this, if you can do it safely and carefully, by measuring for HV between the lead to pin 1 on the controller and B-, with the ignition switch/HV relay cycled on and off. Do this initially with the batteries and other parts of the system connected EXCEPT for the main contactor. Again, only do this if you can do it safely and carefully.

It's interesting that Curtis would switch to an external precharge system(if this is the case) in a presumably later model controller, the 1239.
Indeed 1238 is supposed to precharge via KSI, from Curtis docs:

The KSI input provides power for all low power control circuits. This includes the microprocessors,
power supply outputs, power for the digital and PWM driver outputs, the power-capacitor
precharge (before main contactor closure). Battery voltage is sensed on the input for the VCL battery
discharge function.
It has a dedicated parameter to enable / disable precharge.
If you use AC induction/asynchronous motor, you can consider using our controller.
View attachment 134283
Where to buy ?
We will ship controllers from China. You can add my contact information.
That's great, but where are the prices / ordering information ?
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