Converter

salem wrote:
Is it just recharging the batteries?

Everyone who owns an RV needs a multi-meter.
Nobody else can answer this question for you.

IF....you have been in the habit of letting it sit for months without throwing a disconnect switch or manually disconnecting the batteries or connecting a charger/tender......your batteries are probably toast.

There are about a million posts on here about the care and feeding of batteries. Have you read any of them ??

salem wrote:
I always disconnect the batteries when parked at home. My question is, does the converter normally run for a while when first plugged in?

Yes.

There are 3 sources of noise in converters
1: Most all of them have a fan, IF the trailer has been sitting for "Some time" (months) the batteries have self discharged (not to mention parasitic loads that never get shut off) and they are very hungry, in fact they are likely damaged, The converter will work hard to bring 'em back up and thus it will need to fan itself.. NOTE in some installs just sunlight is enough to fire up the fan.

2: Some older converters have big, heavy, iron core, power transformers.. These cores are made up of many many leaves of thing pressed iron, varnished together, well over time the varnish dries and flakes away and when you plug in the leaves vibrate,, and thus hummmmmmmmmm


3: This one is more likely a "HISS" than a HUMM.. it's TROUBLE.

I always disconnect the batteries when parked at home. My question is, does the converter normally run for a while when first plugged in?

If you didn't disconnect the batteries for that storage time, they are starting at flat dead. You may wish to put a meter on the battery posts to see if there is a charge voltage going into them.

We often hear it when we're just sitting in the rig watching television, etc. But, I guess I've just never noticed it when I first hook up to electricity. I always plug in a few days at home to get the frig/freezer ready. I do not know if the batteries were charged.

It's likely quite normal. It does depend some on the model of the converter; the older ferroresonant converter designs are almost notorious for humming, due to the big honking transformer in them operating at 60 Hz. Many newer converters are based around switching power supplies and are much less likely to hum as they have much smaller transformers operating at a much higher frequency.

It may also be fan noise, particularly if the fan is a variable speed fan (which is common), it might be noisier at particular speeds.

In short, so long as you're getting expected operation from of the converter, I would not worry about the noise.

It's common to hear the fan on and sometimes a bit of noise from the switching coils. Was your battery charged when you put it in?