How to make your own APU

8978

** Commie Express **
Supporter
I've heard so many people wanting to make their own setup. Believe me, I've been through all aspects of this. You need heat, AC, electricity and battery charging. Here is a list of the things you need.

Honda 3,000 watt generator. $2329.00
Xantrex Prosine 2.0 inverter/charger/shore power $1,200
Low voltage alarm $15.00
10,000 BTU AC unit $300
Axillary gas tank with wheels $200 or less
Remote start $200. Not needed if your handy

If you are handy you can take the wires off the key start and run them into the cab for remote start or you can pay $200 for the real deal.

The Xantrex inverter/charger/shore power is the big deal. This will provide REAL PURE 110 volts. Not like a Cobra inverter which is a modified sine wave. The generators 110 output is plugged into the inverter. The 110 output is also plugged into your AC. The thing about shore power is that when your home you can plug an extension cord from your house into the inverter and it makes the switch automatically. This inverter is also a 100 amp battery charger and it's SMART. It will not fry your batteries like a battery charger. Your cannot leave a battery charger on your batteries non stop. They don't give up and they are normally not big enough to put out the amps needed to keep up with the demand inside the cab.

This type of setup is what boats and RV users have. When the boat docks they plug it in or the RV parks and it makes the switch from internal battery power to external power. You can even be watching TV and make the switch and you won't even know it.

The battery alarm can be mounted anywhere in the cab. Usually next to your bed so it will wake you up. Most APU's start up automatically when the batteries need charging but this setup cannot. You can plug the alarm into a cigarette lighter plug also. ANY 12v source will work. This will wake you up so you can start the generator. Once the generator starts the inverter will kick in it's battery charger automatically and will back off amperage wise when the batteries are close to being charged and eventually shut off all together until needed again.

The Honda generator can also be used with an external fuel tank shown below. You really only need the hose fitting and you can use ANY tank you want. You can either buy one with wheels and a handle or use a luggage carrier. You can also mount an aluminum external fuel tank to the frame. Many options here.

The AC and heater will run directly off the generator. I have a 15,000 btu AC mounted on the back of my cab and it's way overkill so 10,000 would be perfect.

That Xantrex inverter/charger/shore power is the REAL KEY here. It's a smart battery charger. If you park your truck at home you just plug an extension cord into it and it's all automatic. Batteries are always charged 100%. Keep fridge running and heat and no worries. Your best bet for heat is still an Espar.









 

ironpony

Professional Pot-Stirrer
Supporter
Add one item that is critical... a carbon monoxide detector. Gasoline fired engines create a lot of CO, and under the right conditions it could fill your sleeper berth, killing you in your sleep. They pulled a driver out of his truck last winter who had died from CO poisoning over his break. He had a gasoline engine APU setup.

So... you're at about $3500. For comparison, a rebuilt APU is in the neighborhood of $4000. Diesel engines don't create a lot of CO.
 

8978

** Commie Express **
Supporter
Yup. I have no pity for someone who dies in their truck from fire or CO and doesn't have a detector. It's just plain stupid.

With the setup I mentioned above you can just buy the generator and AC as a start and add options as you can afford them.
 

mndriver

curmudgeon extraordinare
Supporter
Must be that new math thingy. I come up with $4200.

Plus you need to add in your labor.

And then look at a larger generator to handle the heating load for a block heater and such for winter running.

The time required for handling additional fuel.


Both directions are trade offs. Way the differences and see where they are for you.

Find a diesel fired genny and see what that would cost.
 

krelithous

Well-Known Member
Supporter
Interestingly, the Honda inverter generators are not that fuel efficient per unit of energy produced.. But, far better than non inverter units.

Compare that to a modern small diesel generator. Some of which consume 250g/kwh. Such as you might find on a sailboat. larger units are around 200g/kwh.

As I'm sure you know, the thing that makes those inverter generators so good is the fact that during no load and low load conditions, they idle. While still producing perfect 60HZ power.

Diesel engines under low load conditions, inject very little fuel, and have no "throttle" to cause pumping losses. So, they are quite a bit more efficient under low load conditions, even at rated speed. An 1800RPM diesel generator will easily outperform a Honda inverter generator with regard to overall fuel consumption.

With all that in mind, a properly designed, small diesel-inverter genset could be interesting.

A larger diesel genset can have excellent fuel specifics while, for example, powering a home. I'm not sure an inverter setup would help more than a few percent under such conditions. The advantage would be under no load conditions, where the generator could idle and consume little fuel, while being quiet.
 
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8978

** Commie Express **
Supporter
There are many better options but now your getting up their in price. This is the cheapest solution I can think of. The only thing you need in my list is the generator and an AC/Heater. The rest of my list would give you an ideal setup for the cheapest price.
 

krelithous

Well-Known Member
Supporter
Must be that new math thingy. I come up with $4200.

Plus you need to add in your labor.

And then look at a larger generator to handle the heating load for a block heater and such for winter running.

The time required for handling additional fuel.


Both directions are trade offs. Way the differences and see where they are for you.

Find a diesel fired genny and see what that would cost.
he also forgot to add in the steel box wich almost if costs as much as the genset itself
 

Blood

Driveler Emeritus
Everything above is pretty much crap if you're trying to get started on the cheap depending on your operation and needs. A $300 gasser will run everything you need.

$1,000 - $1200 will get you started if you can get along with reasonable temp swings and don't mind getting out to start the genny.

If you're staying out for weeks at a time and fueling at the bigs a gasser will be a pain in the asser.
;)
 

Duck

Nose-Man
Supporter
Everything above is pretty much crap if you're trying to get started on the cheap depending on your operation and needs. A $300 gasser will run everything you need.

$1,000 - $1200 will get you started if you can get along with reasonable temp swings and don't mind getting out to start the genny.

If you're staying out for weeks at a time and fueling at the bigs a gasser will be a pain in the asser.
;)
Hey you Mr Propane expert,..

How long would you expect a gasser,... Let's say,... 10 hp OHV Briggs engine at half load, to run off a BBQ size propane tank. I think those are 20# tanks.

If I was going with a gasser I'd convert it to propane. Engine will last longer with no crap getting past the rings into the oil, and it'll be easier to start in cold weather. And it's exhaust won't be quite as stinky.

You can swap them out at most Flying J's I think.
 

Blood

Driveler Emeritus
Hey you Mr Propane expert,..

How long would you expect a gasser,... Let's say,... 10 hp OHV Briggs engine at half load, to run off a BBQ size propane tank. I think those are 20# tanks.

If I was going with a gasser I'd convert it to propane. Engine will last longer with no crap getting past the rings into the oil, and it'll be easier to start in cold weather. And it's exhaust won't be quite as stinky.

You can swap them out at most Flying J's I think.
I dunno.
I'm on the same grill bottle I started with on my little zero turn (13 hp Briggs) and I've probably got around 4-5 hours on it.
It feels like I've used about half of the gas. If you were going to buy a new gasser for the purpose you'd be better off buying a propane genny to start with.
Home depot had one for about $350 last time I looked.

I've been meaning to convert one of mine for permanent placement at the house.
I could hook it up to my gas line and not have to worry about fuel for weeks.

It would be a PIA on the truck though if you were staying out.
Pricey too.
20 lbs is less than 5 gallons and the swap scams charge around $20 which is over $4 per gallon.
Residential retail delivery right now is $1.39 here (250 gallon minimum).
I had a tank filled at Tractor Supply the other day and it cost less than $8.
 

Flemming Andersen

Well-Known Member
Supporter
I'm one big question mark here, why would you need all this stuff ? What size batteries do you have on your trucks - Volts/amps ?

As some of you know, I'm driving in pretty wintery conditions for 6 - 8 months a year, and I run my computer, various chargers for cell and headset, and my microwave oven on the 220V inverter, and my Cabinheater, TV/DVD, Fridge/Freezer, Coffeemaker are coupled directly to the trucks 24V system.
Depending on the outside temp, I leave the truck idling while I use the coffeemaker and my Microwave oven, but other than that after a days driving, I let it idle for half an hour before going t bed, and I'm in the clear.
If standing for a 24 hour period, I let it idle for about 45 mins in the morning, and again before going to bed.
If the temp comes down to -4 and below, I don't switch of the engine at all.
My batteries are 2 x 12V 220 amps each, coupled to give 24 Volts
 

Duck

Nose-Man
Supporter
I'm one big question mark here, why would you need all this stuff ? What size batteries do you have on your trucks - Volts/amps ?
We have 12 volt systems.

We run four 12 volt batteries wired in parallel to give 12 volts but quadruple the amps.

Our thin plate batteries are rated in "cold cranking amps" which is how many amps can be delivered for 30 seconds at zero degrees Fahrenheit.

There really is no good formula for converting CCA to amp hours, as the characteristics of thin plate (automotive/starting) vs thick plate (deep cycle/marine/industrial) batteries are too different to compare them.

Typically about 900 to 1000 CCA per battery.
 

krelithous

Well-Known Member
Supporter
Hey you Mr Propane expert,..

How long would you expect a gasser,... Let's say,... 10 hp OHV Briggs engine at half load, to run off a BBQ size propane tank. I think those are 20# tanks.

If I was going with a gasser I'd convert it to propane. Engine will last longer with no crap getting past the rings into the oil, and it'll be easier to start in cold weather. And it's exhaust won't be quite as stinky.

You can swap them out at most Flying J's I think.
I thought grill tanks were #30 same as on rv's
 

Hammer166

Instigateur №166™
Hey you Mr Propane expert,..

How long would you expect a gasser,... Let's say,... 10 hp OHV Briggs engine at half load, to run off a BBQ size propane tank. I think those are 20# tanks.

If I was going with a gasser I'd convert it to propane. Engine will last longer with no crap getting past the rings into the oil, and it'll be easier to start in cold weather. And it's exhaust won't be quite as stinky.

You can swap them out at most Flying J's I think.
Plus you have the fuel part of an FE bomb handy, in case the zombie apocalypse happens while you're away from home!
 

Blood

Driveler Emeritus
If I was going with a gasser I'd convert it to propane. Engine will last longer with no crap getting past the rings into the oil, and it'll be easier to start in cold weather. And it's exhaust won't be quite as stinky.
:cool:

 

true blue

New Member
I'm looking at getting some kind of setup, if only to spare my engine the idle time for heat and air when I need it. But, I also need the power inverter to run a laptop, cell phone charger and eventually a coffee maker and microwave (and maybe some power tools, at times). The idle laws are part of the problem in the northeast and once in a while a customer has me go up there, so I gotta go. I'm leaning toward the diesel - probably a Kubota. I've heard the Perkins are pretty noisy and I don't want to be the bad neighbor. I'll have to go used, since I just sunk lots of money into my pre-EGR truck in rebuilding it. Any thoughts?
 
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