Will depend greatly on alternator temperature and speed (note pulley ratios). Combined output from hot alternators at idle (700 rpm?) might be “only” 200 A.

HTH,
Jim / crewzer

It alternates between the two alternators, the 230 amp upper, the 147 amp lower. Depends on how hot each one is, it alternates between each of them, doesn’t run both at the same time. Output is dependant on temperature and rpm like above. A charge cable of that size means your equally charging the truck and the camper batteries, and would be better a relayed charge circuit that can be turned off. A 30 or 40amp circuit from your upfitter would easily suffice. They are fused and relayed. A 1/0 cable is risky, expensive and would need to be fused at both ends because it can carry so much juice. If you have a camper that is full of lights, and a 5th wheel plug in the box, there is a charge circuit you can access there. I believe for it to provide power, you need brake lights to activate the built in 30amp charge circuit. If you search this forum, there is some good info on it.

Ford OEM alts are generally known to produce about 50 to 60% of their rated maximum output. My 06 powerstroke had dual alts. My 2016 has a single extra HD alt which I replaced with a DC Power XP 270 amp alt. It will put out 200 amps at hot idle. I have a 100 amp charge circuit going to my Lance slide-in. I have a single group 27 battery in the camper and with the refer on DC mode I have seen the truck pushing 70 amps to the camper battery (and up to 14.4 volts). I ran #2 copper welding cable and used 100 amp marine circuit breakers on both ends.

Lots of speculation here — I’ll share my actual experience.
If you run a 1/0 you can pull 200A+ all day. I have a 1/0 run to my bed, with a quick disconnect and 1/0 jumper to my slide in camper batteries. I have a 500a solenoid (triggered from an upfitter) to control the line (which also has plugs for remote jumper cables) and a 2500w (5000 surge) inverter running off two house batteries (supplies and supplemented by the truck alternator and batteries when the supply solenoid is shut). The inverter is wired to power the entire AC load of the camper.
When I start the truck, I have a 10 second timer wired to the 500A solenoid, so if I leave the upfitter in the “on” position, 10 seconds after starting the truck, I have full alternator power to the camper. This works with remote start as well.
I leave the inverter “on” in the camper all the time when traveling. I wired it with a 30A automatic transfer switch with shore power so when I plug in at night (if we have hookups) it auto switches over. If we are boondocking, I turn the inverter off once we are setup.
I run the fridge in AC mode all the time off the inverter (truck alternator) unless boondocking. In the winter months I have a plug in heater I run while going down the road to keep the dogs (and tanks) warm. (No propane use too). In the summer I run the roof A/C until at full blast going down the road. In the morning if boondocking, I remote start the truck and can run the microwave (or A/C) from the alternator. We had one ridiculously hot night boondocking where I let the truck idle for about 4 hours with A/C blasting in the camper until it cooled off enough outside to shut it down and open windows. The truck is so quiet at idle (17 F450 6.7) that I’m not worried about idle noise and you can’t really hear it past 30 ft away.
When running the A/C and fridge, the 2500w inverter is near maxed out, supplying about 20A AC at 120V, which pulls about 220-240A DC (assuming 10% inverter losses). I have started the truck in the early morning at a campsite and turned the truck off 14 hours and three fuel stops later with the A/C running the entire time keeping the dogs cool. It does this all day every day when we are out and never blinks. My truck reads 14.4-14.7 volts with both the A/C and fridge running. I don’t carry a generator (or have one in my camper) because I simply don’t need it. The truck alternator can supply as much power as a 3kw generator (and still run the truck)
Many next camper (or electrical rebuild) will get a 4000w inverter and even heavier cables, which should allow A/C, microwave (which is a short duration high current load), and fridge all at the same time.
So, in short, YES, my dual alts run over 200A load (plus actual truck draw) all day every day even in 100+ deg heat.

This particular Ford Bulletin discusses 6.8 V10 + single 240 A alternator performance in a possible high-load ambulance application. The general discussion about engine idle speed, high under-hood temperature, and high load might be applicable to other engine and alternator combinations.

https://madocumentupload.marketingas...968ae&v5=False

HTH,
Jim / crewzer

happy to share my setup, pictures, etc!

Here is the heavy duty solenoid, battery connection, and feeds to front and rear quick disconnects/remote jumper cables. Front QD pictured. Rear is same type plug, mounted in the bed high on the sidewall above and forward of the 5th wheel plug.
Yes, I should have a fuse or ckt breaker close to the battery. It’s on my mod list.

i see the benefit while going down the road and tavelling to and from a destination. AC power is much more efficient than DC in terms of sending significant amperage over distance - like back to a slide in camper or trailer.

The part I struggle with is running a 6.7 powerstroke engine to feed an inverter which then powers something that a portable generator could run? I would much rather drag my 2400w Yamaha genny along and run that when I am boondocking and need AC power, than run my 6.7 powerstroke to serve the same purpose. Essentially, when the truck is parked, put the wear and tear on the genny versus burning diesel in the 6.7 and loading up the DPF will lots of idling.

Exactly ScanJ10, my Honda EU3000i burns less gas in a whole weekend, than the 6.7 l diesel would burn in two hours on high idle. But, I don’t run a whole bunch of stuff in my camper like DC fridge, tank warmers, etc while driving.

i like this setup of the quick connects to the box of the truck and to the front for winches, battery packs. I think the key being how well it is wired and wire loom protected with braided material protecting against any chaffing. A hot wire of that capacity would be a dangerous thing if ever damaged and grounded to something. In line fuses, relays all very well done.

the dual alternators set up again, do not run continuously, or at the same time, they alternate based on load and heat. For the above wired setup, a monster 270XP would be a necessary investment. I ran a Leece Neville(Prestolite) 230 amp on my 2005 diesel. It produced nominal 170-180 amps on start up cold at idle, 200 at high idle of 1250 rpm. Never put the meter on it at higher rpm, but sure had good batteries all the time after upgrading from a 140 amp unit. I started this truck cold for 8 winters, short trips, always 13.2 volts fully charged, -20 to -40 C every winter.