What is that motor/fan sound?

[Coleman 6]

There is a sound, coming from underneath the fuse box-it sounds like a motor or a fan. It turns on and off every little while.

I don't know if it's normal. (This is a Sprinter 303BHS) in the past couple of camping trips, we've noticed a definite battery power decrease. We charge the battery with the Generator, but now, even when the battery is plugged into the house, the lights (even the gauge lights) are really dim.

Anyone have a clue what is going on?

Also, we use an inverter to charge our phones, and run fans at night, would that have something to do with it?

[az bound]

This is just an educated guess, The fan you are hearing is probably the one on the inverter and this is normal.
If the batteries are original they may be about at the end of their life.

[RustyJC]

It could be the fan in the power converter (120 VAC to 12 VDC) as well. If you're having problems keeping your batteries charged, first check the water level in the batteries - use only distilled water to refill them. If that doesn't do it and your batteries test OK, chances are your power converter may be going out (not unusual). You'll need to check the converter output voltage to tell.

If you do have to change the converter out, take this opportunity to go to a "smart" power converter with multiple modes (e.g., boost, normal, float and desulfation/equalizing). Chances are you have a single mode power converter that was designed to output only one voltage level - these are notorious for overcharging and boiling the water out of your batteries. I'd recommend the Progressive Dynamics 92XX series - XX is the amperage output, but there are others out there as well.

Rusty

[wa8yxm]

Is there a make and model on that fuse box? And is the same door also the breaker box?

Parallex, Magnetek and several others make a combination box that includes the 120 volt breakers, 12 volt fuses and converter all in one assembly.. The converter has a thermostatically controlled cooling fan that does, in fact come on and off as needed.