St4000 - wiring and voltage drop

[Bikerbob]

Hello,

I think I know my answer, but i thought I would post and that way someone else might avoid having to ask.

I have just installed a pedestal in an old sailboat. Along with that I installed an ST4000 system that I had. It all works fine, except...

The system wiring comes off a 8 awg 30amp fused line from the battery switch, that also hosts the engine systems, gauges. I then run 14 awg less than 8ft to a junction that connects the positive for the St4000(fused@15amp as 12amp agc could not find), Garmin GPS(fused inline as well) compass and cockpit lighting(LED). As you can see the only item that would draw significant power at times would be the drive motor.

When the system is put into Auto - In 30sec to a min I will get a brown out that will turn off the power to the GPS and reset the ST4000.

If I am under power and the alternator is charging - no brown out - I have run for hours in this mode.

So it would seem obvious I am getting voltage drop because of the potential draw of up to 10amps from the drive motor. I am going to assume because of the systems age - it could be spiking higher.. though it has not blown the agc 15amp fuse. 14 awg should be enough to handle 10amp draw on that short of run. My batteries pass load testing, but they are deep cycle not starters.

Is my answer to simply run a single line to the drive motor from one of the batteries? I would prefer to draw after the battery switch so that if I am on 1 battery or the other or both and can use that.

Thanks

James