I frequently go hunting and camping where I do not have access to electricity. I do not like using my Jeep to charge all of my devices as I run the risk of killing my battery and being stranded. I came up with two possible ideas and wanted to see if anyone has any experience with them.

1. Simply switching my current battery with a marine cycle battery. I know Marine Cycle is better for prolonged use; however, I do not know how this will perform with starting the engine.
2. Wiring a separate Marine Cycle Battery to my alternator to charge the battery while my engine is running (Keeping my original starter battery). I could run the Marine Cycle somewhere in my trunk and attach a power inverter so I can charge my devices. I like this idea a lot more because I could plug anything into the inverter rather than being limited to the cigarette outlets, plus it seems like a fun project. I just have not seen a write-up for this kind of wiring.

Please let me know which you think is the better route. Thank you all!

 

I would wire the marine battery in secondary and put a disconnect on it so you don't drain your main battery, when your camping.

 

Okay so are you saying I would have two batteries wired in? Do you know of any write-ups for this? or are you saying to literally just bring both batteries with me and swap them out as needed?

 

Put the marine battery wherever you want to mount it, ground the negative side to the body, run a 12 gauge wire with an inline 20 amp fuse from your main battery to an on/off switch then to the positive on the marine battery. Keep the switch on when the vehicle is running to charge the battery and when you are camping turn the switch off so it doesn't drain your cranking battery, and use the marine battery to power whatever you need to.

 

I assume you are talking about a Deep Cycle battery. A good quality AGM will give you everything you need. I run Odyssey AGM batteries exclusively. You can run two batteries in parallel and by installing a cutout switch in the positive cable you can isolate one battery and so you can use one battery to power stuff but keep the second battery available to start the engine.

 

You can also get a Dual battery kit, I know Painless wiring makes them. They have the 40102 and 40103, (40103 is weatherproof). I have had one of them in my pickup truck for the past 10 years or so, and zero problems. It is a little expensive, but I would rather have something I can rely on and not have problems. The kit also allows you to use the second battery to jumpstart if needed.

You could run the wiring back to the cargo area with some 2 gauge or 0 gauge cable, and have that battery hooked up to an inverter. and you would be all set.

 

Bear with me, some of this may be relevant... On my old man's boat, he runs 2 starting batteries wired in parallel. I asked him why he doesn't use a deep cycle for one. Answer "they suck". Ok Pop... He's got a switch for Bat 1, both, Bat 2, or off. At the dock we switch it to either 1 or 2 just to isolate the drain from the bilge pump to one battery. Before heading out, we switch to both so they both get charged. This would be a decent setup for a camping xj. Just a simple on/off switch from the parallel cable would accomplish the same thing. Keep it on both most of the time. Turn it to off while camping to isolate the main battery it from the aux battery drain. You could have the inverter wired direct (yes fused) to the aux battery.

https://www.westmarine.com/buy/marin...6?recordNum=28

 

Probably more reading that you can shake a stick at:
https://www.expeditionportal.com/for...-solar-gen.48/

 

Is this a year round camping thing....most marine batteries are not rated well for cold temps..how about you just buy a good quality jump pack and either use that for your electronics or just use it to restart the jeep if you do accidentally kill the batt.

 

I have an extra Group 34 battery (need an Optima Blue Top) where the winch is suppose to go for aux and my chuckwagon box electrical needs. I use an electronic combiner box (quite pricy) to charge by solar panel (SolarFilm and need a bigger one) and truck's alternator (use a 130 amp) for charging the additional battery. It runs my refrigerator, lights, USB ports, 12DC port, and, water pump. I might hookup a solenoid for a boost but I have swapped them a couple of times to get my Jeep started. It's not the best setup but I wanted the same size battery as what the truck uses so I could use as a backup.

 

RVs and boats do this sort of thing routinely. RVs usually use a start/run relay to separate the batteries when the engine is not running. Boats are more likely to use a mechanical switch.

In either case, you will want fat wires to handle charging amps especially if the auxiliary battery is some distance from the alternator.

Deep cycle batteries are better at handling deep discharges than starting batteries but are not well suited for starting an engine. They can in a pinch, most RVs have a switch to tie the batteries together for starting in an emergency.

 

Why do you say that? Pull behind Travel trailers and 5th wheels charge the battery off of the vehicles 7 way plug circuit which is usually no more than 30 amps. Even most plug in battery chargers only charge at 15 amps or less. If you aren't using the accessories that are connected to the battery while the engine is running you don't need high amp rated wire just to charge the battery.

 

I think if you are only going to use the connection to charge the battery while the vehicle is running, you can get away with a thinner wire. However, some of the dual battery systems (like the painless one) require you to use the larger cables since the switch will allow you to "self jumpstart" using the aux battery.

At that point, why bother running all the wires? Just carry a spare battery in the trunk with the inverter when you go out in the woods. Use it as needed and then charge it when you get home, that way you don't run the risk of wearing down the vehicle battery. If all you are doing is charging batteries in devices, a large deep cycle battery should handle it fine.

 

Buy or build a solar generator. I built my own. I charge everything off of it when camping . It has the advantage of being able to be moved around camp instead of being permanently attached to the Jeep.

 

There are two reasons that I recommend fat wires.

1.) On my RV, I monitor amperage with a shunt ammeter. After some discharge of my coach batteries, I routinely charge them over 60 amps. This is simply a function of the alternator cranking out serious amps. It's not like I get a vote.

2.) The real problem is voltage drop. The longer the wires, the more the voltage drop. This affects how well batteries charge. Fat wires will have a lesser voltage drop than skinny wires. Have a look at the AWG wiring charts.

Charging through the 7 way connector is more like a trickle charge, it will do some good.