Intermittent 12v current drop when on shore power

Your year model and Brand you should have a Converter. Now, for your specific, problem, the first thing I would check is the condition of the Coach Batteries. Water/test of all the coach batteries. When you have a defective cell or bad battery/s(just one of multiple will cause a problem), the converter will act just like you state. The Battery Charge portion of the Converter, may be trying to charge and the defective battery/s are causing a higher amp load causing the 12 volt system to spaz out. Usually a bad converter will just be BAD, and not go in and out every 30 minutes or so. The fact you hear the Genset surge for a demand points to this. IF the batteries check out, I would kill power to the Converter charger section, for a couple of hours and see if the lights continue to dim. If so, then I would probably replace the Converter. Especially if it is over 20 years old. Doug

rgatijnet1 wrote:
I would guess that this is when your Inverter/CHARGER cuts in to keep your batteries charged. The charger portion of your inverter can draw a lot of power and cause a momentary surge in amps needed. ON my inverter the charging rate is adjustible, or can even be turned off entirely.

You need to rethink how you think your INV/CHR operates. It does NOT operate like you posted. Yes, it goes to hi amp BULK charge when 120 volts is applied to it. BUT, it tests the battery state and depending on the charge of the batteries will go from bulk to mid charge to float charge, usually pretty quick. Now, when Camping, the Inv/Chr will NOT go to a bulk rate again. It will constantly supply a charge to the batteries (Float) and IF you have a hi draw appliance activated(M/W), then it may ramp up the charge rate a little but not to bulk. The Charge rate you can set is basically for that initial 120 volt connection to limit the 120 amps on BULK charge. There are other parameters, but you need to research the operation manual for your size and Brand Inv. Doug

I have been RVing for 20 years, for the last 10 I have been full-time. Currently I have Camping with full hookups For the past several months. My batteries are getting a little old, I have two 12 V batteries. Once or twice over the past month my 12 volt lights have flickered much as described by the original poster, Except the flickering only occurs for a few seconds every few weeks.

Since I'm connected to a stable shore power I am surprised if the battery is the problem but the 1st warm day that will be my Task to check out the batteries.

A 50 amp RV plugs in to a 240 volt outlet. That 240 volts is split in to TWO 120 volt circuits at the RV's main panel.
A 30 amp plug is 120 volts ONLY.

Is your rig a 30 or 50 amp shore power? If it is a 30 amp and you plugged into a 240 volt receptacle, your converter is toast!
Otherwise it could be a bad battery. Converter cutting in and out to charge or to try to charge it.

My guess would be the converter.

And just so you don't end up with a lot more problems down the road, you do not have a 240 volt system.

I would guess that this is when your Inverter/CHARGER cuts in to keep your batteries charged. The charger portion of your inverter can draw a lot of power and cause a momentary surge in amps needed. ON my inverter the charging rate is adjustible, or can even be turned off entirely.