Originally Posted by dusty b
most likely a silly question but i have a 85 a/s 25 and when you plug in for shore power you can hear a audible hum. not bothersome but is there. also if i have the battery turned off my lights aren't as brite as when i have the battery switched on with the shore power. is this as it should be or is my converter getting old? so what's the opinion about this? inquiring minds want to know! thanks all for any help-----------------dusty
Any device that is powered by AC has the potential to hum and probably does at some noise level. It is because the current and voltage are varying. The hum can be exacerbated by anything that can vibrate. Examples are loose screws, sheet metal objects touching each other but nor secured, bad design in the first place. Generally the more power that is being utilized, the worse (louder) the hum. Some solid state devices whine in addition to or instead of humming.
The hum could indicate a electrical problem or a mechanical mounting problem or nothing at all.
Anytime a charger is charging a battery, the voltage output of the charger must be higher than the voltage of the battery. So any time you turn off the charger, the DC voltage will drop and the lights will dim somewhat. The question is how much, and is it enough to notice.
There is no answer to whether or not anything is wrong with your converter or batteries, without testing the whole system piece by piece. An owner who is familiar with electrical equipment and batteries can most likely figure it out with a multimeter. An owner who is not is best off finding someone local who knows how or taking it to a repair technician.
If I were to make a wild guess based just on what you have said, I would say your battery/batteries need to be replaced. If you have a 2 stage charger, that may be a good time to upgrade to a more modern charger.