Adding on board AC power to a 923

[shohnson]

So here's the general idea folks. I would like to have at least 3kw of power available on my truck. (buying it very soon but not here yet). I would like to heat and cool the cargo bed as well as a few other accessories that will require AC. I have kicked around a few different options.
1) Adding another alternator to the truck.

2) Adding a pto driven generator.

3) Installing a gen set

4) installing a high output alternator (hmmwv?) in place of the existing alternator.

Each option has pros and cons. But I wanted to see if any other members have already installed on board ac systems on their trucks or had any advice to offer to help me decide which route to go. I am still pretty new to the MV world and I am not an electrician so I here to learn. Feel free to ask further questions, tell me I'm crazy or offer your personal experience.

Relevant Items to consider:
Tight budget
Basic electrical understanding
Fabrication work for brackets and such won't be a problem I own a fab shop
Reliability is a big concern

I look forward to your sugestions.
Thanks,
Shohn

 

[patracy]

I don't see an inverter listed here.

 

[Suprman]

Put a 3k diesel gen in the back of the bed. A 3kw continuous duty inverter will be quite expensive and put a large drain on your electrical system, probably enough to eventually overwhelm the alternator/generator. What are you planning on running that you need that much power?

 

[emmado22]

HMMWV 12/24 gennys only put out a small amount of amps on the 12V side.....

 

[Suprman]

If the inverter was 100 percent efficient (which none are) it would draw 125 amps at 24 volts to provide 120vac at 3000 watts. It would be a lot cheaper to run a generator when you needed that power compared with modifying or upgrading the trucks onboard capabilities. If you got a mep002a you could bolt it down in the back of the bed and set up the aux fuel feed to draw from the trucks tank for longer run time.

 

[wreckerman893]

Do you really want to run a 6 cylinder diesel engine to produce 3K watts? Many over-the-road trucks are now running Auxillery Power Units to keep from running the truck engine. In many states they have "anti-idling" laws and will ticket you for excessive idling. Get a small diesel genny (no hauling gas around) and you will be set.

 

[shohnson]

Sorry for the confusion guys the inverter was assumed on all of the alternator options. I was just listing the way to make the power before it was converted. I'm am certain the truck's original electrical system can't power a 3kw inverter. The gen set is a very valid option I just think I would prefer to have one engine and electrical system to maintain and not a big fan of it taking up bed space. I do think however it would be the easiest/ cheapest way to make this all happen.

 

[quickfarms]

The PTO generator would be more efficient than a alternator inverter setup.

 

[tim292stro]

3kW (3000Watts) = 210Amps @ 14.4VDC or 105Amps at 28.8VDC. That's going to be a big alternator if 12V, and still a pretty large one if 24VDC.

Interesting to note, 3kW = ~4.5HP (no loss assumed), so you should be able to get that out of a 5HP diesel (finding a quiet 5HP diesel is going to be tough though).

If you do go the stand-alone generator route, some things to think about:

• Air cooled is louder than liquid cooled - the air cooling fins radiate vibration noise
• Liquid cooled is more expensive than air cooled, and more complicated to maintain.
• 60Hz (I presume is the AC output you want) can be had with multiples of 60
  • For small generators, 3600RPM is more common - but higher revs equals more fuel consumption and higher noise output
  • For larger and liquid cooled, 1800RPM is common
  • For very large generators (1MW +) 900RPM is possible and very common over 2MW (but think locomotive sized engines)
• Brushless generator heads are more reliable than brushed, but weigh more, and are less common in lower power output.
• Diesel engines can sit for longer than gasoline, and the fuel is common to military vehicles, diesel engines are also more "torque-y" so they accept load better than gasoline engines.
• If you plan to run at elevation, expect to lose about 3-5% of your power per 1000-feet of elevation for a naturally aspirated engine, not an issue for turbo charged (again turbos are less common for smaller engines). Also cooling systems for liquid cooled engines are more challenged at altitude - for every 1000-feet you can assume water will boil 1-degree F sooner (due to vapor pressure reduction), and very importantly the air density affects how much heat can be carried away from the cooling surfaces (either air or radiator cooled), so you may need to have an over-built cooling system to compensate for the reduced cooling capacity of the air.

 

[tim292stro]

...In many states they have "anti-idling" laws and will ticket you for excessive idling...

I wonder if you get around that if you have a PTO generator and you are not sitting at "idle" but rather 900RPM or 1800RPM and obviously have power cables running from the truck to another location...

 

[buggyman]

All right my recommendation.
If you need/want the power all the time, then the least cost, best option is a generator. If you have a small budget then the best gen for the money is an old generator out a motorhome. I see 5-7.5k motorhome generators sell on craiglist for less than $500. These would be gas and low RPM “quiet” generators; five gallons of gas would normally run these at light load for 24 –36 hours.
Other options are LOTS more money and really all have drawbacks too. Good luck, Paul

 

[wreckerman893]

I wonder if you get around that if you have a PTO generator and you are not sitting at "idle" but rather 900RPM or 1800RPM and obviously have power cables running from the truck to another location...

Let me know how fighting city hall works for ya. The idiots that created these laws never had to sleep in a little metal box after driving for ten hours. Don't get me started.

 

[KsM715]

I wonder if you get around that if you have a PTO generator and you are not sitting at "idle" but rather 900RPM or 1800RPM and obviously have power cables running from the truck to another location...

The OP is not running ac to another location, he wants to use it in the back of the truck. As far as those laws are concerned "idle" does not mean rpm idle speed but idle as in sitting still with the motor running.

 

[joesco]

I would go standalone, had a PTO generator on my Kubota tractor years ago, 8kw or 10k (??) and it sure drank fuel. Two years ago messed with the a MEP unit, but ended up scrapping it and bought a real nice Yanmar 6.5kw from Central Maine Diesel, modified it with a 12 gallon external fuel tank and Spin-off filter setup. The unit runs forever on a tank of fuel. In fact last year, I had to shut it down to check the oil after running for 50 hours straight!