Paul & Sabrina's cheap DIY 144v motor controller

[Crossdan]

I have another question about the pre-charge connection. After the pre-set time I get the 12volts between the +12v and middle terminal of J1. However when I attach a relay it won't pull down. I eliminated all wiring thinking the resistance was too high and jumpered directly to a small pcb mountable relay. Still no luck. Anybody have any ideas?
Thank,
Dan

[MPaulHolmes]

Well that's weird... Was it a 12v relay? I've tested it with an EV200 and a schrack pcb relay. What's the voltage from the middle of J1 to the bottom of J1 when the relay is attached?

[Crossdan]

Weird is right. The relay is 5volt rated up to 28v. Works fine when i attach it directly to a 12v battery. When I hook it up the middle and bottom of J1 the voltage drops from 12.8 to 1.5 volt and the relay doesn't latch.
I'm stumped!

[Crossdan]

Some more data. I measured the amps the relay draws when connected to the battery. Comes out to 180ma. Did the same thing when connected to the controller. I got a reading of 30 ma. So it seems the controller isn't putting out enough amps to latch a relay. Does anyone know what amperage should be coming out of the controller?

[zsnemeth]

Somebody, who knows the hex fault bit values could tell me what is 02?
Couldn't find any cross reference, just fault code names and a few binary values, none of them are hex 02...

Cheers

[MPaulHolmes]

02 is the vref fault. That means that either the current sensor is unplugged, or maybe the wires are soldered in the wrong holes, or it's a bad current sensor, or some weird 4th option I can't think of.

crossdan, are you sure about the orientation of the Q1? Could you take a picture of that part of the board?

[Crossdan]

Here are the pics of the board.

[jedsmd]

Originally Posted by Crossdan

Weird is right. The relay is 5volt rated up to 28v. Works fine when i attach it directly to a 12v battery. When I hook it up the middle and bottom of J1 the voltage drops from 12.8 to 1.5 volt and the relay doesn't latch.
I'm stumped!

Hi CrossDan
Have you fixed it yet?

If not,
Looking at the schematic I think the relay should connect between pins 2 and 3 of J1 (Contactor and ground) rather than middle and bottom as you state above (contactor and throttle pot)?

Jerald

[Crossdan]

Hi Jerald,
No, I haven't fixed it yet. Connecting to pins 2 & 3 doesn't give any voltage.
I can think of a few workarounds so I'll mull it over while I install the controller in the car and do some tests.
Dan

[MPaulHolmes]

It sounds like the P channel mosfet isn't working right, or it's got a really high resistance while on for some reason. I'm going to build the circuit and see what's going on. I'm sorry about this!