Originally Posted by Pogo397
What would be wrong with leaving the house batteries hooked up to the generator.
Reason against hooking the two together. Electricity doesn't care which direction it flows through the cable. Leaving the house batteries hooked up will draw down the additional generator battery.
Reason for connecting both together. If the house batteries would have enough power to start the generator with a proper cable, then they wouldn't draw the generator battery down enough to cause a problem. This would simply put the generator battery into the house battery bank.
The image shows a 12v 'car' battery. Those aren't designed to be deep cycled like the house batteries. If there were room for another pair of 6v golf cart batteries, then hooking them together might make sense, but there might be other reasons to not do that.