Looking for something to do on this long holiday weekend, I decided to put my L16 24V house battery upgrade ideas on paper. This was the next project for the '91 U300 before we sold it. A couple of key points:
- No change to coach house and chassis 12V systems. Upgrade to 24V alternator, headlights, ECM, etc not required.
- Implements a 24V-240V split phase inverter/charger ahead of the main coach 240V power panel - entire coach will be inverter powered with 120/240V similar to a residential off-grid inverter setup. Inverter will power 240V appliances, i.e. a 240V induction cook top I had planned.
- No longer can connect to 30 amp shore power.
- Requires 240V generator or one that can be converted to 240V.
- Need a high capacity alternator to handle charging the 24V battery bank while driving.
- I'm pretty sure this will void your warranty.
** Updated block diagram 5/28/2017
Couldn't you eliminate the 12v house batteries?
Yes, good point, I thought about that. You could run on just one 12V bank (and some do this), but there will still be some 12V house requirements when dry camping, such as below. This would be a personal decision based on how bullet-proof you want to be.
- generator start
- water pump
- furnaces, water heater
- kitchen vent, bathroom fan
- interior, outside 12V lighting
- tank level display monitor
- etc.
I used a 24v to 12v converter to do that in my '81
I think these two would be a concern for resale, particularly the first. Anytime you modify a coach so that the "average" shopper would need to understand the limitations, how to correctly service the coach or communicate to the service tech how it has been changed, you limit your buyer audience.
The user of a smart coach like an original Foretravel often is the type perfectly comfortable with being on 30 amp. If they required 50 amp (and were especially dependent upon the campground being wired correctly), this seems like it would limit (at least in a buyer's mind) options for commercial campgrounds and some state park-type ones. True, you could add solar to the equation, but tree cover (and weather) would still present challenges.
Now service. Most RV techs are going to expect a 12V DC system and a 120V generator. Taking a coach with these modifications in for electrical service/repair would also prove challenging. True, you could find a buyer who is a DIYer where this wouldn't pose as much of an issue, but that is also a limit on the pool of potential buyers.
All this thought is moot if you intend to keep it forever and drive the coach into the ground ;) I tend to view coaches like houses - you do buy/build for yourself, but it's wise to always keep resale in the back of your mind. You never know what life is going to throw at you. :)