Generator voltage and 12V system fluctuations

The flickering is rapid and consistent. Not intermittent like just when a load kicks on. The lights are all incandescent and florescent and not LED. It does not occur at all when plugged into shore power, only when the generator is running.

Is this a random flicker or a regular flicker?

Do they flicker on shore power?

Are these LED lights?

Willie,

Unless you have a house electrical system that is very different than anything I have seen either in boats or RVs, the AC power (be it from the genset (APU) or shore power has almost nothing to do with the things like lights and pumps that are run on the DC power.

Yes, problems with the batteries and converter could possibly be it, but you did the right thing there.

You say flickering, but you don't say if that flicker is connected to anything else that might be happening. If it continues after you have checked/cleaned/tightened all the connections you can find, then go looking to a load that has activity that is sort of connected to the flicker. I had to solve a problem for an owner once that though he had a random flicker, but when I sat there long enough, I realized that it happened every time his reefer kicked in. I was electric, but it was have a bad time starting and drew down the power when it did.

Matt

I'd guess that you have an unknown load on the 12V system that is causing the flickering. Your new converter and a good battery should smooth DC voltage to no ripple whatsoever.
Suspects high on my list would be the fridge, the thermostat for the furnace, and the circuit board for the water heater. I would suggest you try disconnecting them one at a time to narrow the cause.

do you have a spare 12v battery you can use for testing the generator

disconnect the genset 12v+ main cable
use jumper cables connect the generator to the spare battery
start and run the generator
now check for the flickering lights

if the problem goes away you know for sure its interference from the generator
possibly the field control circuit which is used to control generator output

this could be dirty field brushes or a bad control board

Before changing out the converter and batteries I tried minimal 120v loading to running both AC units and the microwave to see if the light flickering would calm down. It did not. After the converter and batteries were changed the lights did not flicker as much and the only real load was a drip coffee maker.
I need to try another test tomorrow afternoon and try it with large and small 120V loading. Will also check hertz and make an attempt at checking all ground connections.

A three volt fluctuation is well within the usual tolerance or specs for 120V utility power. Absent any other problems, I wouldn't worry about it. That should not be causing your 12V lights to noticeably flicker. (119V to 122V also sounds reasonable for a 120V nominal output, though I don't know what the voltage vs. load specs are for this particular generator.)

Lights flickering may be due to a poor or slightly undersized connection in the 12V system, coupled with varying other 12V loads. Making sure all the connections (ground and power) are clean and tight in the 12V system would be a reasonable first step to take.

119 to 122 volts from genset is lower then I would be looking at. I would be looking for 125 to 128.
If you have a meter with HZ setting, the genset may not be putting out a good 60 cycles.
What kind of load was on with when measured?