10-27-2022, 06:23 AM
In my defense, you opened the post with “would I be crazy”.
It for the most part is technically possible as Jack has outlined. Before spending that kind of effort, what is your intended use and purpose?
Plans for extensive boondocking?
Plans for boondocking where you can’t run the generator?
Just don’t like the generator running at night?
Don’t like the generator while traveling?
Here are some fundamental points to consider.
What does one AC draw on your coach? Jack’s estimates are a bit low from what I remember the Dometic split units drawing. That number impacts your run time. Also calculate an 85 or 90 percent efficiency on the conversion from 12VDC to 120VAC.
I don’t think you can install enough solar on the roof to recharge the batteries in a day of boondocking to carry you through the next night. So either you will plug in to a pedestal, run the generator, or charge with the alternator while driving. If the plan is to use the alternator, there is a lot of thought and execution needed to make the alternator survive.
Seriously consider a higher voltage system than 12V, all the way up to 56V if you are really intent on this. The wire diameter and voltage loss is significant at 12V. The voltage drop with even 4/0 wire at the charging currents you will use is enough to cause inaccuracies in the charge cycle. I say this based on my own system of 1000 aHr, Magnum 2812, and NEW 4/0 cabling. When the charger is putting out it’s max of 125 amp, there is about a .3V drop at the batteries. So what you say. The Magnum reads the charge voltage at the inverter charger not the battery. Also, when using a heavy amp draw (over 300 amps) on the batteries such as the 120 water pump and oven at the same time, the voltage at the inverter will drop below the LBCO even though the voltage at the bank is well within the limits I am comfortable with. Again, this is due to voltage drop in the wiring. Yeah, I know, I have done the calculations and the actual is more than the calculations. I have new wiring, new lugs, and clean connections.
A higher voltage system with a dedicated alternator minimizes these challenges.
My .02
It for the most part is technically possible as Jack has outlined. Before spending that kind of effort, what is your intended use and purpose?
Plans for extensive boondocking?
Plans for boondocking where you can’t run the generator?
Just don’t like the generator running at night?
Don’t like the generator while traveling?
Here are some fundamental points to consider.
What does one AC draw on your coach? Jack’s estimates are a bit low from what I remember the Dometic split units drawing. That number impacts your run time. Also calculate an 85 or 90 percent efficiency on the conversion from 12VDC to 120VAC.
I don’t think you can install enough solar on the roof to recharge the batteries in a day of boondocking to carry you through the next night. So either you will plug in to a pedestal, run the generator, or charge with the alternator while driving. If the plan is to use the alternator, there is a lot of thought and execution needed to make the alternator survive.
Seriously consider a higher voltage system than 12V, all the way up to 56V if you are really intent on this. The wire diameter and voltage loss is significant at 12V. The voltage drop with even 4/0 wire at the charging currents you will use is enough to cause inaccuracies in the charge cycle. I say this based on my own system of 1000 aHr, Magnum 2812, and NEW 4/0 cabling. When the charger is putting out it’s max of 125 amp, there is about a .3V drop at the batteries. So what you say. The Magnum reads the charge voltage at the inverter charger not the battery. Also, when using a heavy amp draw (over 300 amps) on the batteries such as the 120 water pump and oven at the same time, the voltage at the inverter will drop below the LBCO even though the voltage at the bank is well within the limits I am comfortable with. Again, this is due to voltage drop in the wiring. Yeah, I know, I have done the calculations and the actual is more than the calculations. I have new wiring, new lugs, and clean connections.
A higher voltage system with a dedicated alternator minimizes these challenges.
My .02
Richard and Rhonda Entrekin
99 Newell, 512
Maverick Hybrid Toad
Inverness, FL (when we're home
)