What voltage?

[luvrbus]

Wait a minute - are we talking about setting up a house system or just tapping 12v off the chassis system?

Sounded like the question was whether to set up a 12v or 24v house system, not how to tap the chassis system to get 12v. For many reasons, it seems that having a totally independent house system is the ideal setup. Whether to go with a 12v or 24v house system depends on various issues

, such as what appliances/devices one plans to power from it as mentioned earlier.

If the desire is an independent house system, then where/how to tap the chassis system for 12v is a moot point.

Its not a big deal on the DL to use the  factory 12v and tie it into the house batteries you can even charge a 12 v system from the 24 v engine alternator on a DL when he gets to that point he will figure it out quick even the disconnect battery switch is 12/24v to kill both 

[richard5933]

I'm a fan of having the house battery bank be able to run independently of the chassis batteries and be fully functional when the chassis batteries are disconnected.

Tapping into the chassis batteries to charge the house system is one thing - tapping into it in order to power house systems is another. Doing that starts to busy things up and makes it much too easy to inadvertently discharge the chassis batteries, as they must be left 'on' to power those systems tapped to the chassis system.

To me it's better to have separate systems, with possibly one point of connection enabling charging from the chassis to the house system when the chassis engine is running.

[dtcerrato]

Our house battery bank is connected to the start batteries/chassis alternator while OTR running 110 VAC A/C roof top from inverter power... That is when our house & chassis batteries are connected as one huge bank (two 8Ds - engine starts & five group 31s - house bank) while genny is resting.

[Jim Blackwood]

I am also a fan of separate battery systems but like the idea of bridging them too. I haven't selected my house batteries yet, that won't happen for probably at least a couple more years and likely more. Not much point in buying them until I'm ready to use them, but I expect I will swap in a 12v of some type once I start doing the wiring just as a substitute. It might be the generator battery for instance, as it's just sitting there growing old.

I'll have to look at the main disconnect to see how it is configured. Probably it isolates the 12v from the 24v system when shut off so it could make sense to power up the 12v side from the house batteries, just depending on what in the coach uses 12v already. If there are no significant passive loads I don't really see much of an issue with it. Use the main disconnect  to shut down the 24v side and leave the 12v side powered by the house?

Seems like my biggest challenge here may be the fans for the HVAC but that's a long ways off and will probably involve PWM controllers. But I haven't even worked out the schedule sequencing for that stuff yet or the genset work. It comes later. By then there could be some new developments.

Jim