Nova Kool R4500 ACDC, DCissues - Maxum Boat Owners Club

geoffm70 · 08-12-2023, 06:16 PM

My fridge compressor will run for about 3 to 5 seconds every 2 minutes when on DC power? Checked and have over 12.5v? Did the by pass of the thermostat and still does this? On AC works perfect.

mmwjr · 08-12-2023, 06:37 PM

I’m not familiar with how it works but sounds like something is thermally kicking out. I believe the compressor only is powered by 12V and the 110VAC is converted to 12VDC. Therefore the issue would be on the unconverted side of the power supply.

geoffm70 · 08-12-2023, 06:40 PM

Thanks for the reply, I have no idea what I'm doing with electricity, going to call in help for this one.

shrew · 08-15-2023, 02:45 PM

Quote:

Originally Posted by geoffm70

My fridge compressor will run for about 3 to 5 seconds every 2 minutes when on DC power? Checked and have over 12.5v? Did the by pass of the thermostat and still does this? On AC works perfect.

12.5 seems low for a fully charged battery. min. recommended by Nova Kool is 12.4.

Voltage Cut-Out: 10.4
Voltage Cut-In: 11.7

You could have resistance in the line where the fridge is only getting 12.4 instead of 12.9. When the compressor cycles on it might cause a voltage drop where the fridge cuts out. Waits, senses 12.4, then kicks on and goes through this cycle over and over.

geoffm70 · 08-15-2023, 05:18 PM

Thanks Shrew, that is what the fridge is doing on DC over and over. Checked again and my house bats are 12.6 to 12.8. Plus, I have two deep cycle bats paired together and their both over 6v. Got a new control board coming.

geoffm70 · 08-15-2023, 05:35 PM

Shrew, one more thing, one of the dash volt gauges, when at idle, the needle flutters slightly. Is this a sign of something or just a bad gauge?

shrew · 08-17-2023, 05:24 PM

I'd put a volt meter on the connects and see what they are reading. Then turn it on and watch. The fridge usually waits 30-60 seconds before actually turning on the compressor.

geoffm70 · 08-17-2023, 07:25 PM

Got a new control board from Novakool, will test the incoming volts when I put it in today

geoffm70 · 08-21-2023, 09:49 PM

Tested the volts coming into the fridge before i changed the control board, getting now 13.5 on DC. New control board in and fridge works on DC now.

shrew · 08-23-2023, 06:32 PM

Quote:

Originally Posted by geoffm70

Tested the volts coming into the fridge before i changed the control board, getting now 13.5 on DC. New control board in and fridge works on DC now.

13.5 on DC?? On DC (fully charged batteries) I'd expect 12.9. On DC being pushed by a battery charger, I'd expect 14.0 - 14.4.

Was this with the Fridge AC breaker turned off?

Was this with the battery charger turned on? You usually have a wait a while for the voltage to stabilize when you shutoff the battery charger.

geoffm70 · 08-23-2023, 09:45 PM

I don't know what I am doing obviously. But that's what the battery leads say going into the fridge. I turned the breaker off to see if it works on DC. tested the batteries the day before and was over 12.6 to 12.8, but then the next day, the 13.5 at the fridge and it now works?

geoffm70 · 10-05-2023, 06:57 AM

Quote:

Originally Posted by shrew

12.5 seems low for a fully charged battery. min. recommended by Nova Kool is 12.4.

Voltage Cut-Out: 10.4
Voltage Cut-In: 11.7

You could have resistance in the line where the fridge is only getting 12.4 instead of 12.9. When the compressor cycles on it might cause a voltage drop where the fridge cuts out. Waits, senses 12.4, then kicks on and goes through this cycle over and over.

You were bang on Shrew, bad wire from the fuse panel to the battery and it was doing exactly what you describe above.

considering a whole boat rewire this winter. 29 year old wires.