Was in Sears this evening and saw this really cool little 1 1/2 hp compressor that goes to 120 psi. Only thing is, it is 110 volts. This thing would be great for those along the road tire pressure adjustments and who knows what else. The thing was on sale for $99 and is oil lubricated and has a cast iron cylinder (COOL).

I saw it on here before but can't find it. Has anyone installed an inverter, where, where did you get it, and what size?

If I remember, it is about 750 watts per HP so I would need at least a 1200 watt to be safe by my primitive calculations.

ANy ideas?

 

I have seen them in the Northern catalog 15kw Vector for about $349.99 Item# 45691-1412
In Cabelas catalog 12kw Coleman for $199.99 Item# MD-52-1097
Mounting them in the truck will be tricky. It will have to be a very large cable to take about 160 amps. These inverters will surge double their rated kw. If you ever nicked the insulation on that cable you will have an arc welder, and not to mention the draw on the batteries. You would want to make sure the truck was running when it was on.
Proceed with caution.
Hope this helps.

 

I have permanently installed a 2000 watt, 4000 watt surge inverter in my truck. It works great for almost anything but unfortunately it will not start a 1.5 HP motor. Have tried it on both capacitor start and non capacitor start motors. Mine is a modified sine wave converter. It turns a 1.5 hp motor over but can't get it up to speed. I fed the inverter with 1/0 welding cable and installed a 200 amp fuse 4" from the battery. The entire length of this monster cable is encased in a heavy plastic shield. This shield is used in my area to be encased in concrete walls for electrical cable.

 

I have a Prosine 2KW mounted in the fiver. All battery cabling is 4/0 - - huge wire and a pain to work with. I was having low voltage drop out on higher rated draws, so I went to the recommended 4/0. Works like a champ now. I have a 300 amp catastrophe fuse in line on the positive side right after the DC disconnect switch. Huge thing, but necessary. The Prosine is far more than would normally be required for use on the truck - - it has pure sine wave output and has a three stage 100 amp battery smart charger. It will run my 1 1/2 HP air compressor with no problem.

Mexstan - - you may be getting too much voltage drop on your cables to run that high of a draw. It is amazing how much DC current these suckers draw.

Bob

 

FiverBob. I must admit that I have never done a voltage check under a heavy load. Must do that sometime. My DC feed cable is only around 9 feet long and at that length I seem to remember that it is good for about 250 amps. I don't think it is the voltage that is a problem in my case as I also tried it on a small 1/4 or 1/3 HP motor. Same problem. In your case with the pure sine wave you can do a lot more than my modified sine wave. My unit is supposed to drop off line with low voltage but it never has so far. Wish I had a high power pure sine wave but those suckers are really expensive.

 

the voltage is never a problem, it's always the amperage. Volts ain't squat without amps. You can grab 10 million volts, but pray to God there is no amperage behind it, that's what will fry your butt. Mexstan, check you amperage draw, make sure the motor is wired for what it can put out, also check what you motor is wired for and rated at, 50 vs 60 hz, a 50 hz motor will not run on 60 hz very long, but if it's 60 hz, check the voltage, lower voltage means higher amp draw

 

DD4x4, go ask one of the nukes at the powerstation about Ohms Law. Here's an excerpt from an old thread on how big an inverter is required to power an onboard tv and game:

Here's a way to take some of the guessing out of it. The formula to use is P = I*E (Ohms Law).

Power (Watts) = Current (Amps) x Voltage (Volts).

Look at the manufacturers tag on the back of the tv, it'll have its Current requirements printed on it. Lets say it says 2A, or 2 Amps. Voltage is 110V. 2*110 = 220W. The power requirement in Watts is 220W. Do the same for the Playstation. Add up the Wattage requirements. Thats what you'll need for normal operation.

You also want to factor in some reserve capability for surge when you turn things on so the circuit breakers won't trip. Not that a tv or game will have much surge, but motorized tools etc can have significant surge loads.

The typical cigarette lighter current load is about 20A, so you're probably good to go to for your intended use. If you need more power, most Inverter manufacturers require you to hardwire the higher capacity inverters directly to the battery using heavy guage wire cable. Basically, don't try and use a 3KW inverter with the cigerette lighter.

Now the second half of class (and homework):
Using that same formula (P=IE) for the 12V side.

300W = I * 12V

Q: Solving for I, how many Amps of current will be flowing through the cigerette lighter wiring when the inverter is operating at rated wattage?

<end of old thread>.

I'm happy with my 2KW Coleman Inverter. Haven't hooked it up to a decent compresser yet, but it will power 2 large wetvac's and a few drop lights simultaneously, or a refrigerator, elec impact wrench, etc....

I'd get the biggest one you can because its really frustrating to see it go into overload when you need it the most.

 

Mexstan, when doing wire length calculations for DC (or getting them from a table), you have to add the length of the POS and NEG cables.

Its very easy to get into the double 00 cable sizes real quick. And if you want to run them any distance, you'll need even heavier stuff.

Having said all that, I'm happy with my "temporary" 4ga setup.

 

Thanks for the input. One thing to remember is for calculations involving inverters is that they only run at the most about 90% efficiency. My ground wire is about 15" long and goes directly to the chassis. At the front it is about 12" long and goes to the same bolt on the engine the battery negative connects to. Don't remember what gauge my ground wires are but they are a little less than the feed wire. They are the ones that came with the inverter.

 

I wasn't really guessing, I was looking for the number of watts per HP and my local friendly electrical lady just told me 746 watts per hp. I would need 1120 watts just to run it not figuring in surge right?
Now I guess I need to figure out what the surge would be and buy a unit capable of handling that.
How long will the inverter run the equipment before the batteries go dead or do you have the truck running when using the inverter?
I'm thinking it would be cheaper to buy a 5kw generator and mount it on the GN trailer at this point.

Thanks
Joel

 

This is getting interesting.

Our batteries in the truck are not suited to long steady current drains. They are designed for quick, high current for starting the BIG CUMMINS. You need deep cycle batteries to allow draw down without damaging the battery.

So, let's assume you need 1200 watts. The current drawn from the battery would be about 100 amps (assuming no losses). You then need to determine the ampere hour rating of the batteries and do not draw them down below 70% or so before damaging them. Deep cycles can be drawn down much lower depending on the construction. Starting batteries are not normally rated by Amp Hours, so it is difficult to get a feel of how hard you can push them in discharge. I have 450 AH of battery in the fiver. I could draw 100 a for several hours before requiring a recharge. Just purely guessing, I would not want to draw 100a from my truck batteries for more than 1/2 to 1 hour before I would worry about damaging them.

The long and short of it, gasoline generators are really cheap now. You may be better off getting a 4 or 5 kw unit.

The inverter in the fiver is marvelous when we are camping in the boonies, stopping at Wally World overnight or having lunch on the road. We can microwave, run the TV and satellite all on the inverter and not have to fire up the generator to do this. Then, once a day, fire the genny and recharge the batteries. With the high current output of the inverter/charger (100 amps), the batteries can be recharged quite quickly.

We also carry a 350 w inverter in the truck. This allows charging small batteries, the GPS, the laptop, the FRS radios, etc. It is the CFO's responsibility to keep up the small batteries - - I keep up the big ones.

Bob

 

The more I read, the more I'm liking the generator idea. Pull the rope and plug it in. Simple just like me.