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Dual battery Setup/Inverter/ Marine Batt

I am thinking about a Dual Battery setup in my Cherokee, but want to do it the correct way. I am looking also to add a decent power inverter in the trunk or under the hood if that is preferred.
I am just looking for write ups, suggestions, and pictures. Is it even necessary for a decent inverter to have Dual batteries?
Also, does anyone run a Marine Battery for a longer runtime if the chagrining system failed?
 
You will want to mount the inverter in the cab and as close to the battery as possible. Under the hood will have way too much heat and dust. You could mount it in back but you will want to use big cables to keep the resistance low. I suppose you could isolate a secondary battery in back dedicated to the inverter.

Inverters range in size from powering a laptop from the dash cigarette lighter to powering a small house connected to 250lbs of batteries with 0-guage wire. I've got both. . .

Dual batterys would be a good idea if you are expecting a high draw and extended run times. You need to figure out what you are trying to run on the inverter, how long, and then start designing. . .
 
I want to be able to do several things such as:
Power a laptop (Rarely, should not even list)
Run a small 3/8th Drill (Almost as Rare)
Fill my tires with a small compressor nothing over 1 gallon (Once a quarter)
Run a hot plate if need be to warm some food camping (A few times a year)
Possible run my Porter Cable 7424 XP Dual Action Orbital Polisher if I ever do on site detailing. (Not sure yet)
 
Power a laptop (Rarely, should not even list)
- 175 watt cig lighter inverter
Run a small 3/8th Drill (Almost as Rare)
- 500 watt
Fill my tires with a small compressor nothing over 1 gallon (Once a quarter)
- Impractical and inefficient - use a 12 volt pump
Run a hot plate if need be to warm some food camping (A few times a year)
1000 watts but in about 10 minutes it'll bring your batteries into serious discharge- just use a small fuel stove
Possible run my Porter Cable 7424 XP Dual Action Orbital Polisher if I ever do on site detailing.
- probably like the drill, 500 watt - which means in about 20 minutes your battery is low. . .

Obviously you can start the jeep and charge batteries to get a longer cycle but, 500+ watt loads put an incredible drain on a 12 volt system

Those are guesses without looking at the appliance tags for Amp load - Inverter should be higher than your appliance is rated - especially for motors. 1200 watt will do most anything needed. That's what we run at the cabin hooked up to 250lbs of deep cycle batteries and we mostly quit using the 850 watt microwave and save the power for a movie.
 
For the hot plate/hot pot, you might want to check around truck stops on the Interstates. They have all sorts of "domestic" 12V goodies for use on the road, and that would save you the inverter overhead. Ditto the air compressor - I've gotten consistently good reports from the field on the Viair units (they're spendy, but seem to be worth the money.)

Also bear in mind that many inverters do not like "pure inductive" loads (read: electric motors only,) and will want a small resistive load (like a small lamp) plugged in to stabilise the inverter's output - so factor that in with your calculations as well. And, "universal" laptop power supplies are available that will take 12VDC natively - if you're a member of Costco, you can find decent small inverters there for $10-20 that will pack in a laptop back, and be useful on the ground and in the air.

The battery setup is its own headache - I can help you design something if you like. The catch to "banking" batteries full-time is that all batteries in a bank must be of the same type and age - or connected using some variety of isolator that will allow simultaneous charging, while breaking the connexion with the charge current removed. Treat this point as important - failure to isolate the DC from the starting battery will result in one battery killing the other one (typically, the starting battery ends up killing the deep cycle - tho both often end up as scrap.)
 
If the inverter is ((((SELDOM))))) used a marine or deep cycle would not be of any benefit. If your currant battery is fresh I see replacing it as a waist
Dual battery even more so.
The inverter should be mounted as close to the battery as reasonably possible. You will lose 1 to 1 and a half volts to the inverter if mounted well to the rear of the XJ. This will be no mater how big of a lead you run to it. And inverters output amps/watts are tied to there input voltage or you GENERALY need a full 13.6 input volts to get the inverters full rated output wattage. Also with a low(ER) input voltage the inverter will draw more amps from it's load. This will shorten the useful run time between battery charges. The inverter will also tend to run hotter as input voltage drop under a heavy output load. But any GOOD inverter is well sinked and faned.

The inverter needs a good clean cool(ER) supply of air. Tucked up under the dash sucks. They don't even put the ECU under the dash any more because of the heat. Under the back seat isn't any better unless you willing to lift the rear cushion or somehow vent that space when operating the INV.
I'm sure I have muded thing up so luck.
 
Power a laptop (Rarely, should not even list)
- 175 watt cig lighter inverter
Run a small 3/8th Drill (Almost as Rare)
- 500 watt
Fill my tires with a small compressor nothing over 1 gallon (Once a quarter)
- Impractical and inefficient - use a 12 volt pump
Run a hot plate if need be to warm some food camping (A few times a year)
1000 watts but in about 10 minutes it'll bring your batteries into serious discharge- just use a small fuel stove
Possible run my Porter Cable 7424 XP Dual Action Orbital Polisher if I ever do on site detailing.
- probably like the drill, 500 watt - which means in about 20 minutes your battery is low. . .

Obviously you can start the jeep and charge batteries to get a longer cycle but, 500+ watt loads put an incredible drain on a 12 volt system

Those are guesses without looking at the appliance tags for Amp load - Inverter should be higher than your appliance is rated - especially for motors. 1200 watt will do most anything needed. That's what we run at the cabin hooked up to 250lbs of deep cycle batteries and we mostly quit using the 850 watt microwave and save the power for a movie.

out of curiosity....how do you recharge those batteries?
 
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