Making use of the onboard 400 Amp generator

[Gamble]

Since the 400 amp generator was installed to supply power to several power hungry on-board systems. It would make sense to make safe use of that power since that massive thing is installed on the truck.

I'm not an electrician but I know just a LITTLE about currents and circuits. It would seem to be that if we allow 200 amps for truck function and just play with 80% of the remaining 200 amps (160 amps) we should have significant electrical capacity in the truck to power all sorts of devices.

Things like starlink devices, wireless routers, small on board servers, cameras, radios, computers, tablets, chargers for phones/drones etc. It seems as though this could easily be installed to support these needs and wired appropriately would provide significant advantages over standard passenger vehicles.

Needed would be a 24->12v converter.
DC-AC Inverter.
Fuse Block(s)
Maybe a deep cycle aux battery
Appropriate Guage wiring
Run isolated and fused circuits?

Is there anything I am missing?

 

[155mm]

You can use 50 amps of 12v straight from the voltage regulator but you can use all 400amps if you use 24v

if dc-ac inverter is a new purchase anyway just buy 24v to 120/240,

When i start on electrical for my SECM, truck will have 2 batteries and the box will have 2 batteries, the SECM had its own 24v to 120/240 inverter built in already

 

[Coug]

Short answer is it isn't cost effective to try to utilize all the available power from a 400 amp alternator. Even trying to fully use the output of a 200 amp is challenging when you consider just how much power it really is.


Longer answer, not complete but should give a basic idea
(side note for context: I'm a standby generator repair tech and some of my customers live off grid and we've discussed power utilization and other subjects related to stand alone power)


The 200 amp is massive overkill for your standard HMMWV. The 400 is double that massive overkill.

In an average truck, you're really only using around 5-25 amps of 24V power when in operation. Might be more if you have accessories added like radios or aircon. That in reality gives you over 300 amps to play with

200 amp 24V is 5kw of power.
400 amp is 10kw.


I can run my house off of a 5kw generator (only one major appliance at a time, like water heater or dryer)


You would need to have many batteries in the auxiliary battery bank to make use of the amount of power available from the 400 amp alternator. I'm talking like 16 deep cycle 100 amp hour 12V batteries wired to make a 400 amp hour 24V system. That's 1000 lbs worth of batteries. Or you'd need a 200 amp hour 24V lithium battery to safely absorb that much amperage, and decent ones of those aren't cheap.

A 24V 100 amp lithium battery can safely be charged up to 200 amps, though reality is you'd want to do less than that

like starlink devices, wireless routers, small on board servers, radios, computers, tablets, chargers for phones/drones etc. It seems as though this could easily be installed to support these needs and wired appropriately would provide significant advantages over standard passenger vehicles.

You can easily run all of that off of a 200 amp alternator unless you are trying to run an entire mobile operations center that is going to be operating days on end with no other power source.

Auxiliary battery isn't a bad idea if you plan on running a lot of electronics with the engine off.


The most cost effective thing you can do is rather than try to utilize all of that 400 amp generator, is remove it and install the 200 amp. It takes a lot less engine power, less weight hanging on the engine, less space in the engine compartment so you can actually reach around it to access the engine and fuel filter, and just generally less stress on the engine.

Even idling the diesel engine is pretty loud, and uses a lot of fuel compared to something like a Honda of Harbor Fright inverter generator. It also frees up the truck to go do other missions while all the electronics are being used.

 

[Mogman]

If you have the 400A alt. you need to carefully check the wiring harness passing behind and below the alt, they are very bad about shorting out because it was never intended to pass around such a large alternator.

 

[Gamble]

If you have the 400A alt. you need to carefully check the wiring harness passing behind and below the alt, they are very bad about shorting out because it was never intended to pass around such a large alternator.

Yes, @Retiredwarhorses already sorted that out on my truck but that's a good call out in general for anyone else looking to do this.

 

[Gamble]

Short answer is it isn't cost effective to try to utilize all the available power from a 400 amp alternator. Even trying to fully use the output of a 200 amp is challenging when you consider just how much power it really is.


Longer answer, not complete but should give a basic idea
(side note for context: I'm a standby generator repair tech and some of my customers live off grid and we've discussed power utilization and other subjects related to stand alone power)


The 200 amp is massive overkill for your standard HMMWV. The 400 is double that massive overkill.

In an average truck, you're really only using around 5-25 amps of 24V power when in operation. Might be more if you have accessories added like radios or aircon. That in reality gives you over 300 amps to play with

200 amp 24V is 5kw of power.
400 amp is 10kw.


I can run my house off of a 5kw generator (only one major appliance at a time, like water heater or dryer)


You would need to have many batteries in the auxiliary battery bank to make use of the amount of power available from the 400 amp alternator. I'm talking like 16 deep cycle 100 amp hour 12V batteries wired to make a 400 amp hour 24V system. That's 1000 lbs worth of batteries. Or you'd need a 200 amp hour 24V lithium battery to safely absorb that much amperage, and decent ones of those aren't cheap.

A 24V 100 amp lithium battery can safely be charged up to 200 amps, though reality is you'd want to do less than that






You can easily run all of that off of a 200 amp alternator unless you are trying to run an entire mobile operations center that is going to be operating days on end with no other power source.

Auxiliary battery isn't a bad idea if you plan on running a lot of electronics with the engine off.


The most cost effective thing you can do is rather than try to utilize all of that 400 amp generator, is remove it and install the 200 amp. It takes a lot less engine power, less weight hanging on the engine, less space in the engine compartment so you can actually reach around it to access the engine and fuel filter, and just generally less stress on the engine.

Even idling the diesel engine is pretty loud, and uses a lot of fuel compared to something like a Honda of Harbor Fright inverter generator. It also frees up the truck to go do other missions while all the electronics are being used.

Thanks for this feedback. I also like @155mm idea of 24v to 120/240.

Thoughts on isolated fused circuits? Probably run 4 or so. What's optimal?

 

[Coug]

Run as many circuits as you need or want; it really depends on what you want to plug in and how much power it draws to figure out what is ideal for your situation.
Once you figure it out, add one or two more just for future expansion if necessary; it's easier to set up for extra now than try to add more later.

 

[thoner7]

Could one realistically use the humvee as a whole house generator? Through the slave port!?

 

[Coug]

Could one realistically use the humvee as a whole house generator? Through the slave port!?

Is it possible? Well, anything is possible if you throw enough time and money at it.

If it efficient? Nope.

You could theoretically run the slave port to an inverter.
You would need to have a very big inverter, and one designed to operate 120/240 split

By the time you buy the inverter and get it properly hooked up, you could easily have gone to costco and bought the Firman tri-fuel generator. 7500 continuous, 9400 peak (on gasoline, LPG and NG are derated) Even NG is still 5500 continuous rated, which is more than you'd get from a 200 amp alternator, and not too far under what you can realistically draw continuously from the 400
$900 normal, and goes on sale sometimes for around $760
There are cheaper gasoline only generators in that output range, but as a house standby I always recommend propane or natural gas if possible because it doesn't matter how long they sit the fuel won't go bad and the fuel system will still work when needed. Gasoline has a short shelf like (as little as 1 month) and diesel will last a lot longer than gasoline, it won't last forever.


You are looking at $1200+ for a cheap 24V 120/240V inverter in the 5kw+ range. Inverter would be dedicated to the truck (or to a battery pack that would be hooked to the truck to charge) and would require the truck to be present to operate. You would also still have to do all the wiring and plugs, as well as permanently mount it somewhere, either in the truck or the house, as it takes up a lot of space and weighs a fair amount.
A good quality inverter system is several thousand dollars on up.


If anything goes wrong, a portable generator is also a lot easier to get repaired or replaced when needed, as they can be found locally. The only places you're likely to find that size and type inverter short notice is going to be a solar store, and between the markups and short notice, you'll have to pay them whatever they want to get up and running again.


So while it is possible, personally I'd recommend against it as you lose use of the truck while using it for power, and there are cheaper, more efficient ways to accomplish the same thing

The only thing I'd say it's good for is if you already have a 24V inverter system then you could potentially wire it up to use the truck as a backup charging system. Definitely not a primary as it's way too inefficient on fuel (plus it's kind of loud) but in a pinch it would work.