Hooking up an inverter

[AMink]

I have a 1500 watt inverter that I want to install in the back of my truck (under the cap). I know that the wire from the battery to the inverter should be short as possible. My questions are:



1. Can the wire from the alternator to the battery be long? As long as I use heavy wire?

2. Where's a good spot to put 1 or 2 additional batteries near the back of the truck? The bed is obvious, but is there a good spot underneath?

3. Should I get a heavy duty alternator or is the stock one good enough for occasional use? I intend to run a small freezer (mostly while driving) and a blender (mostly when not driving):-laf .



Thanks!

 

[ToolManTimTaylor]

I intend to run a blender (mostly when not driving):-laf .



Thanks!

Man after my own heart!!



There are a few that have relocated batteries with no ill effects under the rig. Maybee a couple will chime in or a search may net some great info.

 

[DennyDay]

Inverter

The 1500 watt inverter will take some serious power! My experience is with a 1000 watt unit mounted in the rear or the bed. I used 2 ea. 4 ga. welding leads, 1-positive and 1 negative, from the battery to the inverter with a 75 amp relay and fuse at the battery. The reason for the relay was I didn't want that size cable going that distance to be hot all the time but I still didn't power the iverter with a load on it. I always started the inverter and then applied the load after it started. The inverter was used to operate a 1000 watt flood light and I do NOT operate the inverter with the engine off.



I have a 400 watt inverter under the back seat to run a computer and battery chargers for the camera and drill, and this one also only operates with the engine running.



I think you may have a problem with battery drain unless you add several batteries to the system.



Be careful about overloading the system and using too small wiring, as the 1500 watt unit will get warm.



Have fun - -



Denny

 

[JFaughn]

I've done this a few times, I would avoid putting any of that under, you'll need to protect the inverter from dust and let it have ventaltion , the batteries you'll need access to keep conections clean and add distilled water to the cells , also do'nt forget that the batteries will gass and thats carosive. the place I've ended up was infront of wheel well in bed build a box to hold and protect , then you'll only need about a 10ga. wire to Alt. . Do'nt forget a battery isolater.

 

[DKlimas]

1. Can the wire from the alternator to the battery be long? As long as I use heavy wire?

Short answer, Yes.

2. Where's a good spot to put 1 or 2 additional batteries near the back of the truck? The bed is obvious, but is there a good spot underneath?

Can't be of much help on this one -- someone else been there done that?

3. Should I get a heavy duty alternator or is the stock one good enough for occasional use? I intend to run a small freezer (mostly while driving) and a blender (mostly when not driving)

If you use a minimum of about 150-200 amp/hour batteries and limit the current from the alternator you should be fine. I do not know the rating of your alternator, but I believe the 3g is rated at 135 amps and works fine on my rig.

Visit my project page here to see how I set mine up. For your setup you can just ignore the camper stuff. One other item you should include in your setup is an Isolator/Combiner to keep from running down the truck batteries. Check the links on my project page for additional information.



Cheers,

Dave

 

[AMink]

Thanks for the tips. DKlimas, that's a cool page about your upgrades! One of these days I'm gonna learn how to do that!

 

[pwerwagn]

A batterey will fit under the bed, in front of the wheel-well's. Another fellow member (JWolf) has done it on his 2nd gen. You cant even see the batterey. Im fixin to do it to mine for a 3rd batterey for the Lance.

--Jeff

 

[ndurbin]

I relocated the passenger side battery to under the front passenger side of the bed on the frame (which was easier since the E-brake cable was in the way on the DS). Theres alotta room on the inside of the passenger side frame if you goto stacks and if you relocate the spare tire.



Nathan

 

[thejeepdude]

4g wire is way to small for that long of a run. I had a 1000W mounted under the seat in my '99 with 4g wire and after running a microwave for about 20 minutes (love those frozen pot pies!) the lugs and wires got so hot it started smoking! I now have a 1500W under the passenger seat of my '05 and wired it with 1/0 gauge this time. So far no overheating problems. Personally, I wouldn't mount the inverter in the bed. It's much easier to pipe the 110V than it is the 12V at those power levels... 1/10 the amperage to worry about, and a lot cheaper wire, plus I know it's 100% protected from the elements. I put the fridge, microwave, and blender on the FFF behind the passenger seat. When I need the space and want to run it in the bed, I use a $2 extension cord and run it out the slider window, which still closes fine over the cord. If I wanted it more permanent, I'd run romex under the truck to the bed and install an outlet back there. It would only be active when the inverter was on, and the inverter will fail if there's a short. It'd be a lot safer fire-wise to short out a protected 110v line than the 1/0 carrying ~200 amps!

 

[monkfarm]

Something no one has talked about is: you really need to put a fuse (125 amp fuse (1500 watts divided by 12 volts (right by the battery) (In case something happened to the wires).

(I have installed a 2500 watt , and a 1500 w inverters, in our (big trucks) I also put a

circuit breaker right next to where I installed the inverter (S). )

 

[thejeepdude]

Good point. And yes, I put a fuse in too... I didn't mention it because I thought that was common sense. 1/0 wire with no fuse is just ASKING for a fire! :-laf

 

[AMink]

The install directions for the inverter specifically call for a fuse. I put a fuse on everything!

 

[surfbeetle]

You might try the sealed optima batteries. supposedly you can mount them sideways without any ill effects.

 

[BK]

Fuse, a relay discount (engine off = open), and the optima batteries are all the right things todo. While a real deep discharge will harm the optima batteries, they will not gase terrible on their way down there as wet cells do. Constant deep discharge and quick recharge of the wet cells will cause lots of gassing and not be great for being either in the bed or under the bed. The optima's will work in either area. There are only so many recharge and discharge cycles in a SLB battery.



When your truck is NOT running, you do not want to be drawing current from the batteries under the hood, nor can you be drawing current from the alternator. So the wire guage can be used to limit the current to charge the two batteries you'll be putting at the back and not size to supply 100% of the current.



Don't know the size of your fridge, but I'll assume a few things.

Depedning on the duty cycle of the fridge depends on how often you'll be pulling 1. 5kVA or so from the batteries and how much recharge time you need vs how much current you have to supply over that time.

Figure if the fridge is pulling 10A @ 120Va, thats 1. 2kVA from the inverter.

The inverter is probably ~70% eff (being conservative)

, so the input power will be ~ 1. 6kVA.

The current into the inverter is 1. 6kVA / 12V = 133A. !!

So if you want to supply the current all the time from the alternator while the truck is running... . no the alternator is not big enough and you'll need some massive wires to the back of the truck to not to have too much voltage drop on the way to the back.



Probably 00 welding cables, I'd have to dig out my wire resistance charts.



So back to duty cycle and wires being big enough to charge the batteries and not supply 100% of the current.

That's the trick you'll have to balance with remote batteries and see how it works.

With out the engine running, you'll quickly discharge both batteries.



In RVs there are tri-power fridges. 115Vac/12vdc/propane.

When dry camping we use propane. I can get a whole summer of a lot of camping from one RV propane bottle. Heating the trailer depleats my propane much much quicker.

The 12Vdc is used ( for those luckly enough to have it , I don't) when the trailer is under tow so has not to have to keep the propane on.



So why not go propane... use it for an RV fridge, and use it for a propane injector kit as well.

For the mixer go with the tailgator. would be nice if they made on diesel powered.



just some things to think about.

 

[Forrest]

I just checked wifies blender ... 350 watts. :{ I've got a 75 watter laying around ... gonna need a hefty invertor. Time to do some browsing. Fishing will never be the same. Oo.

 

[OTRPU]

monkfarm, your punctuation is a delight, you're obviously well schooled. I'm a has been typesetter. BK, changed my mind, seems there is something good in NY. I'm particularly interested in this thread due to virtually living in my Ram. To this point I don't invert much, rather stay DC with DC devices. Not a great solution but a good start, 2 6v Trojan T-145's in the bed, wired to the starter batts through a breaker. Should probably go direct to the alternator, but I don't know enough. Guy that rigged this truck used larger leads, maybe size of my little finger, running under the stretched truck to the bed with one of those forklift battery power connectors. Sorry, I'm older now, forgot the name for the connector. When I installed the Deep Cycle Batts I used the same size wiring and the female connector to his run. I know I need to visit Hellroaring for a combiner. For now I unplug the D/C system and trailer pigtail when not underway. I run a lotta lectrics more than the designer had in mind. Just running everything all the time is more than they had in mind. To that I added an Engel 15 cooler fulltime but thermostat controlled, while running Garmin StreetPilot GPS, Cobra CB, and periodically a Dell Laptop, (two batteries w/charger), and a CPAP machine while sleeping. Am I correct in my assumption that staying 12vdc is better, read more efficient, than inverting? My heat is supplied by ESPAR D4 Hydronic diesel burner, distributes cab heat through OEM heater blower defroster vents. Soon A/C will be 12vdc also. May have to go to 4 D/C batts to keep from drawing below half. Already charging 5 batteries while underway. I've got NO room in the bed to speak of, with a 105gal fuel tank, V-notch rear tool box, and an EasyRider Air Ride Hitch in the bed. Great hitch, but a realestate hog. The wheelwells are a problem, I can mount the batts higher in the bed and still clear anything. You can't believe how I gotta jack this rig sometimes, and a stretched pu turning radius sucks.



#ad




Cheers,

Steve J

 

[BK]

Steve, well thanks, but I want the heck off of this Island of long and out of NY, just can't get the wife to leave it.



"Should probably go direct to the alternator,"

It's probably fine, since the alternator probably isn't delivering all the required current anyway.

If it was, yes the closer to the alternator , the better as not to induce additional drops on the + lead from the alternator to the primary vehicle batteries.

What size is the breaker that feeds the rear batteries?





"Am I correct in my assumption that staying 12vdc is better, read more efficient,"



Any time there's a conversion it costs. So yes, staying with the original power is best and most efficient. Running a laptop from it's OEM 12Vdc power supply brick is more efficient that running the laptop off of it's 115Vac power supply brick that's plugged into an inverter that's plugged into your vehicle 12v power system.



But handling the current gets tough and not all our toys can be had in 12v.

If the low voltage / high current connections can become lossy, lots of drop the benefit can be lost... to keep the benefit, the connections need have low resistance.

That's why there is so much talk and already some action of raising the primary vehicle bus to 48Vdc or so. As we throw more electronics on board, handling and distributing the current has become more of a problem. The higher the voltage, the lower the current for the same given power requirement, the lower current is easier to bus around, smaller wires. UL condsiders a potential less than 72V to be safe (been a few good years since I've done UL work, so this may have changed).



Thats some long rig ! Seems you should start putting some gel cells under the body of the truck.

 

[tazzen]

Hey guys,



I have a 350 watt inverter that plugs into the cigarete lighter . and want to run my laptop of it will i be alright to do that? and if so should i only run it with the truck running?



ed

 

[BK]

from what I've seen the 350w inverter should be more than enough.

Most laptops draw from 75 - 100 watts when running, and a bit higher when spinning up the hd and or cd and things like that. You will be fine with the 350w inverter.

Most small inverters designed just for laptops are rated at 75watts or so.

I would tend to think they are a bit close in ratings.



Due to efficiency losses in the conversion, draw from the battery is a bit more, about 90 - 120watts.

It's about the same has your average 4 speaker car stero at slightly higher volume.

So you can run it for some time without the truck running, how long? depends on how healthy your batteries are and the outside temp. I would guess about two hours would deplete the batteries to a point of not starting the truck. Most inverters have a low battery shut off, but with as much energy as is needed to start our cummins, I think by the time the inverter shuts itself off, there wont be enough battery to start the truck.

If you want no worry about restarting the truck, either put a third battery in for aux power that's not connected to the starting batteries when the truck is off. Wire an outlet for your inverter and wire your stereo and such to the aux battery... or run the truck if your going for extended periods of time.

 

[thejeepdude]

from what I've seen the 350w inverter should be more than enough.

Keep in mind that even though the inverter is rated at 350W, you don't want to pull more than ~200 watts while plugged in through the cig lighter. You want to use direct leads to the battery if you want to use the whole 350W. You are correct, though, in that a laptop won't draw more than 50-75 watts or so and it totally safe through the cig lighter. I got a 400W inverter with a digital display from Costco for $25 bucks! It says my laptop pulls 40W when it's already charged, and 50W when it's charging and playing a DVD. I only use that in my boat tho since I have 1500W in my truck now. I run the fridge and play XBOX all night on that inverter while parked and still have enough juice to start the truck fine the next day!