Which inverter voltage input?

[Sharecropper]

I plan on installing a 3000 watt Pure Sine power inverter in my M1028 to provide 120 volt AC to power electronic equipment during emergency situations. AIMS offers these with DC imputs of both 12 and 24 volt. http://www.theinverterstore.com/3000-watt-24-volt-pure-sine-wave-inverter.html

Question - would there be an advantage to installing the 24-volt model in lieu of the 12 volt model?

 

[Keith_J]

Advantage of 24 volt? Half the draw on each alternator and battery. Half the copper required to connect the inverter. You still need at least 4 gauge wire. 3000 watts at 24 volts is 125 amperes. 3000 watts at 12 volts is 250 amperes.

i have one, in 24 volt setup. When running a 1500 watt load, it draws 70 amps. But this is a motor load so power factor and inverter inefficiency is probably the reason for the additional 7.5 amperes.

 

[Sharecropper]

Keith, thanks for the info. I will buy the 24 volt model.

My next question, where is the ideal connection location under the hood?

 

[Skinny]

I wouldn't think twice...24 volts if the CUCV or any other MV is your primary usage. Probably not ideal if you wanted to swap it and use it in a boat/car/civvy truck, etc.

How do you plan on using it? Personally if I wasn't going to establish a permanent mount, I would wire it up to a spare slave cable to that I could just stick it on the hood and plug it into the grille area.

 

[Sharecropper]

Skinny - I intend to permanently mount it. And I plan to mount it inside the cab so it is accessible while in transit to power one or more computers and a ham radio. The unit is only 3-1/2" tall so it may fit under the seat, or mounted on edge behind the seat.
I still need to determine where to tap into the 24 volt feed to provide sufficient amp capacity and how to "plumb" the feed wiring to the unit inside the cab in a safe and protected way. Any ideas?

 

[Shark Bait]

I install inverters for industrial clients often. Run directly to the battery, fuse it within 18 inches of the power source. I use an ANL fuse and holder. Go through the firewall using a grommet. You do not want it to rub through the insulation of the wire. I use 1/0 ga wire and fuse it for 300 amp for a 3k inverter. Depending on the inverter you use, you'll want to leave clearance for cooling fans. If its 3000 continuos / 5000 peak at 24 volts the peak would put it around 208 amps. Continuous would be about 125 amps on the 3k. The ground is as important as the power connection. Remove the paint to bare metal for the grounding point. Just my 2€ worth with experience on the inverters.

Dave

 

[MarcusOReallyus]

Sharecropper, you might want to check my thread on the muddy resistor bypass to see some pics of how I did a new power run to the GP relay. You'll need bigger cable, as Shark Bait pointed out, but the concept is the same.

I suppose you could go to the 24v bus bar and the ground bus bar on the firewall, but I agree with Shark - to the battery is better. For that kind of current, I'd run a ground all the way to the battery. You run as much current through the ground as through the hot lead - don't go small on the ground.

 

[Skinny]

Agreed, both power and ground need to be same size. I always get a kick out of the stereo guys that spend big $$$ on the power line but then ground the amp to a seat bolt. So where did the electrons go exactly???

I have no idea what type of inverter you have or what you use the truck for but you may be able to get away with mounting it in the engine bay closer to the 24v source. Then use cheaper 120v braided 3 wire line to go into the cab. Mount a small outlet box down near the tcase shifter. Most higher end inverters have optional remote panels for turning the unit on/off or can easily be wired to do so.

Of course if your unit isn't well sealed or you take the truck into the deep mud all the time...probably not the best idea.

 

[Sharecropper]

Agreed, both power and ground need to be same size. I always get a kick out of the stereo guys that spend big $$$ on the power line but then ground the amp to a seat bolt. So where did the electrons go exactly???

I have no idea what type of inverter you have or what you use the truck for but you may be able to get away with mounting it in the engine bay closer to the 24v source. Then use cheaper 120v braided 3 wire line to go into the cab. Mount a small outlet box down near the tcase shifter. Most higher end inverters have optional remote panels for turning the unit on/off or can easily be wired to do so.

Of course if your unit isn't well sealed or you take the truck into the deep mud all the time...probably not the best idea.

Skinny - Thanks for your comments. Here's a link to the inverter - http://www.theinverterstore.com/3000-watt-24-volt-pure-sine-wave-inverter.html#

My truck has never been muddy and will never be muddy. It sat on a National Guard base in Arizona for 25 years. When I bought it in 2010 it had 12,338 miles. It now has 13,012 miles and hasn't been rained on since I got it. It stays inside my heated and cooled warehouse under tight security. I am up-fitting this truck for emergency situations.

 

[Skinny]

I would avoid the WTSHTF commentary because it is a frowned upon subject in this forum, plus you will face public humiliation and rude treatment rather than a simple or polite "hey can you change that" note. So I will carry on "hypothetically" discussing inverter usage in a survival scenario

I like that you treat your rig like a prized possession, mine used to spend its life in a storage facility too! I'm almost to the point of buying another one just to beat on because this M1031 is in such great shape.

That inverter is a big boy, I think the only place you could mount it with enough clearance would be on the back of the cab as far down as possible behind the seat. The good news is that the unit does have remote panel capability so you could mount it anywhere and still be able to switch it on or off. Not sure if it comes with that panel or you need to buy one. I do know my Xantrex has one that connects using an old style phone cable (RJ11 or 45?) and it gives you a ton of info like battery voltages, current draw, etc.

Now having said that, for the near $700 that will cost you...would it be better just to buy a Honda EU2000i or similarly sized Yamaha equivalent? You can even get a slightly lower quality inverter genset for $500-700. Much more portable and you don't have to keep your truck running. The little guy would consume .5 to .75 gallons of gas for 8 hours run time, the 6.2 diesel is a lot more and much noisier. Just throwing it out there. Then you could just get a little inverter for charging phones and computers in the truck while on the go. Not to derail the thread, just throwing out discussion topics.

 

[Sharecropper]

Skinny - Thanks for your comments. You have stimulated me into additional thought regarding the inverter size. I had already planned on purchasing a small Honda generator for emergency situations and keeping it in my truck tool chest. Maybe I should downsize the inverter capacity and rely on the Honda for larger power requirements. The main reason I want an inverter in the cab is to power a computer and ham radio, along with keeping batteries charged for portable tools such as my Milwaukee 600 foot-pound cordless impact wrench (everybody should have one of these).

 

[Skinny]

I have a small guy mounted right under the foot heater vent up on the trans tunnel. I use it to power my laptop and charge my phone in the truck since I have no other 12v lighter receptacle or radio to do so. It's just a little 400 watt unit. Just as a side note, I've noticed that my phone gets cranky trying to charge off a cheap square wave inverter yet the laptop could care less as long as the power is close enough. Weird...

For backup power, I've got the honkin' M1031 along with the Honda EU2000i which is a ton quieter and more fuel efficient. I have debated getting a portable solar charger. You can find a decent suitcase one on Amazon for under $250 for 200 watts of power. You also can wire it to do 12 or 24 volts. I want to make a setup so I can plug the solar into the slave receptacle and charge my truck along with run 24v accessories like my portable fridge freezer. In an emergency, I could also rewire it quickly to run my Subaru if I'm on the road with the car instead. Just an alternative to having to run the CUCV all the time to keep things charging.

I think either way you could come up with some good back up power scenarios well within budget but I'd certainly stay away from having to run the truck in order to have power. My truck is wired with a shore power plug so that running the little Honda generator right into shore power, I recharge my batteries, run block/oil heaters, and additional outlets in the truck all with one cord going into shore power. I also have a gigantic aluminum box on my truck so space is easy to come by

I'm just throwing this stuff out there, do not want to de-rail your thread at all. Topics of conversation only...

 

[cranetruck]

You may want to consider the truck's power generating capacity before installing a 3KW inverter.
The generator must be able to keep up with your inverter current demand or you will run down the batteries.
Lead acid starter batteries do not like to be discharged beyond normal starting loads and should be charged up right away after a start to maintain the original amp-hour capacity.
Deep cycling LA's will reduce the capacity dramatically and after not so many (cycles), render them permanently useless.
I would recommend that you install separate "house batteries" for inverter and other non-vehicle related uses. That way you don't risk running down the starting system and you can use deep-cycle batteries.

 

[cranetruck]

Agreed, both power and ground need to be same size. I always get a kick out of the stereo guys that spend big $$$ on the power line but then ground the amp to a seat bolt. So where did the electrons go exactly???
...

Actually, grounding to the frame is not a bad thing, just make sure the battery (negative terminal) is firmly grounded to the frame also, heavy strap with star washers.

 

[MarcusOReallyus]

It's adequate, if it's done right. It's not ideal, especially on older vehicles.

 

[Sharecropper]

Thanks everyone for your comments, which have enlightened me greatly. I will heed your advice and install a smaller inverter in the truck and opt for a small Honda portable unit in the tool chest.

Another Question - Would a 1000 watt inverter be within the truck's regenerative capability? If my calculations are correct, a 1000 watt inverter will provide 8.3 amps of continuous 120 volt clean electrical power (amps = watts divided by voltage). Does anybody know what is the total output of both alternators at idle speed and at 1000 RPM? (I have a HMMWV throttle control)

 

[Skinny]

I would think that if you are using a 24v inverter that the truck would supply in theory 2400 watts (24v x 100amps) if spun at a high enough speed. Of course this is max current and occurs in a perfect world. In reality they may only produce say 90amps due to efficiency loss and age. Then you have a slight drop going to the inverter, then the inverter has it's own draw. The inverter also loses some in the conversion to 120v. So take that number with a grain of salt.

Plus you are running a 6.2 Liter diesel engine to spin them so if you compare fuel consumption to 2400 watts of power generation, I think you will not like the outcome. This would be even worse if only utilizing a 1000 watts.

Clear as mud

 

[cranetruck]

I have a 100 amp generator/regulator on my truck and it has no problem putting out 100 plus amps, it self-limits itself to about 110 amps or so charging a bank of nicads. Yeah, it's old technology ca 1970...

 

[Shark Bait]

Grounding to a good solid clean part of the frame or body is adequately fine. Majority of the electronic components in new vehicles are attached this way. I personal would go with the larger inverter. Just because it CAN make 3000 watts does not mean it does it all the time. It is capable, but if you only need part of it it's only going to make part of it. It will require more amperage at the start up of an item but that fraction of time will not be harmful to your alternator and will draw the extra capacity from your battery for that fraction of time. I would not mount it under the hood. The heat and worst of all the moisture and humidity will have severe negative results to it. I use gold plated terminals for my connections most of the time but copper, tin plated or nickel plated copper is used some times as well. A twelve volt alternator spins out about 14.4 volts and the 24 volt alternators 26-28 volts so the 3k inverter will take about 107 amps at that. I would fuse it on 24 volts at 150 amps to give it the "surge" draw it would want for a larger load. As earlier stated in another post the location on the rear cab wall ( I'm not familiar with the cabs of these trucks) would be a better ideal spot than under the seat. It will cool better and stay cleaner versus under the seat. This is all only my 2 cents worth. Others may have other ideas. I've installed a few hundred of the larger inverters, 1500, 3000 and 5k/10k models. I've never had an installation issue.


Thanks,
Dave

 

[Skinny]

My quick math says that a 3000 watt inverter operating at 24v DC is going to draw about 125 amps. Mind you that particular inverter surges to 6000 watts so you are reaching 250 amps. I would think you'd size the wire according to that current amount and distance from batts to inverter. I would probably go up one size in wire and fuse it at 300 amps to play it safe. I'm going off the specs in the listing link at the beginning of the thread.

I think it was stated earlier but chassis grounding is OK the majority of the time. When you add something like this, now the factory ground has to accommodate the stock ground demands on top of this one. You would want to run an additional ground to chassis from the battery sized to handle 300 amps with the same size ground from the chassis to the inverter. Now if you mounted the inverter far away this may save you money but for me, I would just run a dedicated ground from the inverter to the battery. Eliminates voltage drop issues, connection corrosion possibilities, and may prevent any kind of electrical noise if using radios or electronics. Just my two cents.