Lights going dim then bright

[Dom Ferris]

OK, so do I have a problem? http://www.rvforum.net/SMF_forum/Smileys/default/huh.gif

My 12V interior lights dim, slightly, for a while. (I suppose I could say that they brighten, slightly, for a while, now and then.) They stay dimmer for a few minutes to an hour or so, and then brighten back up. The dimming is not severe - in fact, sometimes I only notice that they are a bit dimmer, without having noticed when they did that. All of the lights do this in unison. I am not aware of any other symptoms.

I have 50 amp park service, and I am using it almost to the hilt. I have 2 heaters running. I have no 120v lights, no TV working. The fridge is on Auto, which means it is using 120 for heating the refrigerant. I am using my laptop, plugged into 120. I am not using 120, internally, for anything else.

I have an AC Line Meter plugged in, in the bathroom. It reads anywhere from 114v to 116v, and does not vary with the dimming of the 12v lights. I do have a microwave, but I use it for a few minutes a day and it does not seem to affect the lights.

I am using 12v lighting, as needed. I'm not using 12v for anything else that is voluntary. Of course, the fridge has a circuit board that is using 12v, but I wouldn't think a lot of it - and I don't get into the fridge, often. I suppose there are other circuit boards being powered by 12v. I suppose the furnace is controlled by a 12v board, but the lights do not react in time with the furnace. (It's not running, very often.)

So should I worry, or quit worrying?

[folivier]

Your inverter/charger may be switching or pulsing the charge rates which could be causing the lights to dim.

[The Newell]

about the only thing that you haven't mentioned that could be happening (barring something malfunctioning) is the battery charger maybe shifting from float to absorb mode or absorb or bulk charge mode. Either shift could result in a little more umph available to your dc lights.

[1993Newell]

Like Forest said check your inverter. I bet that's whats causing it.

[77newell]

Dom: If all your 12V lights are doing this at the same time the problem must be something they all have in common. Assuming you change nothing (like having some 12V usage switching on and off randomly) then either the supply of 12 volts (your charger or inverter/charger) is raising and lowering voltage for some reason or the ground to the charger has got a bit of variable resistence in it (when this happened to me it was the lug where the ground cable connected on the charger)