Anyone know a lot about 12V to 120V inverters?

[Mark W.]

I have a question about mounting and inverter in my 48 Willys Jeep. Does anyone know of a reason that I could not mount an inverter upside down on a 1/8" thick aluminum plate spaced 1/2" from a second aluminum plate that makes up the bottom of my Battery tray? The space would prevent heat transfer and the Inverter would be out of the way.

As you can imagine space in a tiny Willys Jeep is at a premium and since I have to scratch build a battery tray anyway. I was thinking I could raise it up a couple inches and have a place for the inverter under it. The inverter is going to be pretty much hard wired into the vehicle. Looking into about 4000 watt unit.

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[WAYNO]

Some inverters produce quite a bit of heat. The cooling fins and vents were designed to draft heat from the electronics to the vents and out. An upside down inverter could cause heat to be trapped in the circuitry. I guess depending on the inverter, a feller could run it for a while under some load, and see where the heat sinks to. Some inverters have a built in fan, depending on the size of the inverter. Being upside down may or may not impeed the cooling flow. Again, just try it and see what happens.

 

[RVTECH]

What are you planning on running off this inverter?

 

[Joe13]

What size inverter?

You may need a second battery depending on the size.

 

[Mark W.]

4000 watt as I said. As to what I want to run off it think csmping and emergancy short term power outage. I would be running the engine for anything past making coffee. 100 watt alternator. Series 31 battery 1000CCA

 

[orygun]

Why not a small PTO driven generator? Couldn't be that hard to make.

Unless there's a specific reason to not mount the inverter upside down, I like the original idea.

 

[mkwerx]

I run a 1000W in my truck, granted much smaller than the one you want BUT, it has its vents and fans on the sides, so cooling should not be too tough a task. The bottom of mine is totally flat, its the mounting surface. I bet you can find one in the size you want with the correct design for cooling.

Sounds like you are on the right track with battery size and alternator output too. I am getting kind of anxoius to see pix of this infamous jeep when shes all done.

 

[Kruel J]

Get a dedicated deep cycle battery and install a cut off switch so you can isolate the start battery from the inverter's battery. Stick with a quality pure sine-wave inverter to make sure it will run anything you want it to. Electronics tend to dislike modified sine wave inverters. Running a high watt inverter on a start battery is asking for trouble. Plus, you can leave yourself stranded. A battery isolator is an easy install, and it's automatic. You shut off the ignition, and the isolator switches to the deep cycle cell.

Typical inverters, especially cheaper ones tend to run on about a 1/10 ratio of output power.

Example:

4000 watts of AC power will require around 400 DC Amps to produce it. In short spurts. That would require at least 4 6 volt batteries wired in series to make a 4000 watt inverter reliable. And at that amperage, you would need to feed the inverter with 4/0 welding cable no longer than 6 feet from the battery bank.

Inverter technology is really cool, but just hooking a 4k inverter to your start battery on your Jeep doesn't mean you're cooking with Crisco.

And mount it any way you want, it's a solid state unit and doesn't care at all about how it's mounted. As long as you have airflow across the heatsink (the fins).

 

[Kruel J]

And just to be clear here, you'll not get 4000 watts from your group 31 for any amount of time to make it usable. Engine running or not.

 

[IronMonster]

Get a dedicated deep cycle battery and install a cut off switch so you can isolate the start battery from the inverter's battery. Stick with a quality pure sine-wave inverter to make sure it will run anything you want it to. Electronics tend to dislike modified sine wave inverters. Running a high watt inverter on a start battery is asking for trouble. Plus, you can leave yourself stranded. A battery isolator is an easy install, and it's automatic. You shut off the ignition, and the isolator switches to the deep cycle cell.

Typical inverters, especially cheaper ones tend to run on about a 1/10 ratio of output power.

Example:

4000 watts of AC power will require around 400 DC Amps to produce it. In short spurts. That would require at least 4 6 volt batteries wired in series to make a 4000 watt inverter reliable. And at that amperage, you would need to feed the inverter with 4/0 welding cable no longer than 6 feet from the battery bank.

Inverter technology is really cool, but just hooking a 4k inverter to your start battery on your Jeep doesn't mean you're cooking with Crisco.

And mount it any way you want, it's a solid state unit and doesn't care at all about how it's mounted. As long as you have airflow across the heatsink (the fins).

↑ This guy knows stuff.

 

[orygun]

↑ This guy knows stuff.

Sounds like it to me!

I guess I assumed it would be an isolated battery, but then forgot that even our Willys only has one!
Mark's not kidding when he says space is at a premium.

 

[mkwerx]

For what he says hes doing I cannot imagine needing 4000 watts unless running AC or an oven or power tools.

 

[RVTECH]

Inverter technology is really cool, but just hooking a 4k inverter to your start battery on your Jeep doesn't mean you're cooking with Crisco.

Yep - good advice! I need to 'do the math' regularly for people who are sold solar and inverter systems for their RVs thinking it will 'run them' - and they are sorely disappointed when the system falls WAY short!

 

[Kruel J]

I'd try to find a space for two 6 volt batteries and a 2000 watt pure sine wave inverter. Not a harbor frieght job either. Wire the cells in series (jump the positive from one cell to the negative on the other). Then use the remaining two open posts as your power. Use AT LEAST 3/0 welding cable to feed the inverter. Don't mess this up, MOST inverters (cheap ones especially) aren't polarity protected.

Install a battery isolator to an ignition-hot source to keep it all separated. That way you can "leave the lights on" all night and not kill your start battery.

Running a heating element or another appliance of high draw isn't really physically possible from a Willy's. Larger Buses that run all AC appliances have at LEAST 8 6 volt batteries, sometimes even more. And then typically have solar panels and/or auto genset starters to keep things on the up and up.

Yep - good advice! I need to 'do the math' regularly for people who are sold solar and inverter systems for their RVs thinking it will 'run them' - and they are sorely disappointed when the system falls WAY short!

Exactly.

 

[Squidly]

4 large 6 volt deep cycle batteries are not going to be practical in your jeep. Even if you could fit 300Ah batteries, at the 8 hr discharge rate, you would only be able to pull about 60 amps. I would suggest you get 2 of the largest automotive batteries you can fit under the hood. They would handle the surge current and a little storage. Replace your alternator with the biggest one that you can rig on you engine. You will also have to beef up your belt drive.

I would just buy a generator. It would cost less and work better.

 

[mkwerx]

Heres a thought, instead of mounting the inverter under the battery tray, could it be mounted under the dash on the passenger side? Or even in the cargo area? Is there room to build a battery / electronics box to have a deep cycle (or pair of them) plus inverter? Would require running cables to the back so they could be replenished by the alternator or an onboard charger like you find in a lot of boats.

 

[Kruel J]

The shorter the cable, the better. I know, this generally isn't the case.

 

[Ramjet12]

And just to be clear here, you'll not get 4000 watts from your group 31 for any amount of time to make it usable. Engine running or not.

That's what it comes down to. A 4000 watt inverter is designed for a solar power battery array. 16 Trojan L16H batteries to run that inverter for longer than 30 seconds at any high load. I did a google search for a few 3000-4000 watt inverters and I found that most of them use 4-5 amps just running at idle. 4000 watts is enough to run 3 toaster ovens. I've never needed more that 500-600 watts for anything camping.

In all seriousness if you need that much power buy a generator. 2000 Watt Super Quiet Inverter Generator

 

[IronMonster]

The shorter the cable, the better. I know, this generally isn't the case.

What you talkin bout Willis? We all know the best electron hose is a short, fat one.

 

[Kruel J]

What you talkin bout Willis? We all know the best electron hose is a short, fat one.

It will for sure deliver the biggest load.