Blackout during cranking

[Islandworks]

I have a setup with a PDM30, C1212 and a M150.

The cranking is setup via a 20A output from the PDM and the starter is initiated from a can-keypad.
When I’m cranking the display goes black and the canbus keypad also it seems.

So the starter runs strong for a second and then disengages to engage again once the keypad restarts.

I’m guessing my lithium Liteblox is on the low side for my Porsche 964!

Is there a workaround other than pulling a hardwire? I’ve tested that and it works, but all harnessing is already done…
Is it likely that the digital inputs on the PDM would work better?

Happy for any input!

[David Ferguson]

I would investigate the battery voltage drops when cranking. What is the lowest battery voltage when cranking?
Have you tested the battery with a load tester?

Using a digital storage oscilloscope, what is the voltage drop between the battery positive & starter, between the starter & starter ground, and finally between the starter ground and the battery negative. The wiring should be sufficient that the positive and negative (return path) drops should be .5v (certainly no more than 1v each).

That test can help you decide if the issue is the wiring, starter or battery.

[Islandworks]

It seems I made a real rookie mistake and had a hardcoded limit as to when the output powering the dash and the canbus keypad shut off. It works now...

Thanks!