I know there have been a million posts on this topic but I'm not finding that many involving an isolator and power talk just makes my eyes glaze over, but I'm trying to understand this.

We were told that we needed a battery isolator (2004, Duramax, 2500HD, Chevy) so that if the DR DC drained the marine battery, I wouldn't drain the truck battery.

The isolator was installed and I believe the set up is that it goes between the truck battery and the marine battery and allows the truck to charge the marine battery while it's running but won't let the marine battery draw from the truck.  We installed a separate plug into the truck bed that only works the marine battery so I have two plugs from my trailer into the truck.  The original one still runs the trailer lights and brakes when it's plugged in.  When the original is not plugged in, the marine battery takes over for the internal DC lights.  I have a third shore power recepticle under the nose for the 110 power if available. 

While on a recent trip, the isolator appeared to overheat and I believe turned itself off.  I wasn't in the truck so I don't know exactly what happened but I'm under the impression that this shouldn't happen. 

Questions:

Are isolators really necessary?  I get the reasoning behind them but I don't see that many others talking about them so wonder what I am missing.

If an isolator is used, how is the truck to trailer wiring done?  Are two plugs normally installed?

There are not a lot of places to mount it so has anyone else had a problem with their isolator overheating?  It was hot this weekend and it only did it on the return trip in the hotest part of the day in OH.

Thanks...Erin who is learning more about power than I ever wanted to know...watts, amps, volts, DC, AC, 9V, 110V.

An isolator consists of two diodes which are simply electrical one way valves so to speak. The output of the alternator goes TO the diodes, each battery recieves it's charge FROM one of the diodes. Since the power from the alternator can go only "out" the batteries are isolated one from the other. The correct wiring scheme would be wiring the pin of your trailer plug that goes to the house battery to one output of the isolator, this will charge the trailer battery, and the origional wire from the alternator to the other isolator output, this will charge the truck battery. Hope this helps.

Whinneyman