DC lighting periodical bright to dimmer

[Liza Powell]

Hello,
Have noticed for some time that our lights go from regular to bright, bright shorter intervals. We’re full time and we live in SE Florida. Thought it was AC compressor related but not sure. Topped off batteries with distilled water and ran generator to charge after cleaning connections. Starting to wonder about converter, any thoughts or advice?

[Canonman]

Are your lights LED or conventional?

[foszoe]

I am new to this scene but since the lights are pure resistive load, I would think that when they dim there is additional demand being placed on the DC circuit. It could have something to to with the inverter though. Do you hear the fan running at the power panel? Perhaps it is a cooling issue.

[JRTJH]

If you live in the RV and are connected to shore power (almost all the time) then I'd first check the battery. Chances are it's low on electrolyte and needs to be replaced. Many dealerships install "maintenance free" 12 volt "marine/RV deep cycle batteries" (which aren't really maintenance free) with the "sealed cap system". Use a screwdriver to pry open the "sealed caps" and check the water level. Chances are you'll find a dry cell. If so, the battery probably needs to be replaced.

What's happening when there is a large 12 VDC load is the battery is drawing too much power from the converter because of the faulty cell and you're seeing the "brownout condition" because there's not enough power remaining from the converter to power everything.

In a nutshell, I think you've got a bad battery.