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Discussion Starter #1 (Edited)
With all of the electronics on the FJ, and with the addition of probably six lights (fogs, auxiliary driving lamps, rear lamps) and a winch next week, it occurs to me that it would be very bad if I were to drain my main battery while out in the woods. And the chance of me doing that with all these new switches has to increase.

Dual-battery setups, while appealing, look expensive, complex, and not something that would make the warranty police happy.

Always looking for a simple solution, it occurred to me that I might just carry a spare battery in a box in the back of the car. With that, I could give my main battery a jump start, or if things got really ugly I could swap in the new battery.

This looks too easy. Can somebody tell me the obvious flaw in this plan, because I don't see it yet.

Thanks,
Chris
 

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You'd be much better off carrying one of the small car jump start devices rather than a spare battery.

How do you plan on securing a 50-60lbs projectile in the case of an accident or rollover? I hope someway extremely strong. Also, unless you op for the more expensive AGM batteries, battery acid can be an issue.

If i was you, i'd buy a Diehard platinum marine battery (Odyssey batteries rebadged as diehards), run this as my primary, and then keep one of the smaller lightweight stand alone jumper units in the truck if you are wanting to avoid a dual battery. The stock battery is not designed to be drained and recharged which you will do using a winch. Drain and recharge the stock battery a couple times and you will kill it.

Make sure when you are using your winch you do not turn off the engine during use, or anytime shortly after as the alternator is recharging the battery. I had a buddy in highschool get his jeep stuck. He turned off his jeep, winched it to dry ground (completely unstuck) and then was stuck because he couldn't start the engine. He dumb.
 

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Layonnn made some great points! I run a huge deep cycle battery as my primary and I invested in a Black & Decker 3 in one power pack 400 amp...what I found interesting is it comes with a cig lighter cord that can be used from the pack to the 12v receptacle and charge your battery or charge the pack if the engine is running. I just saw the new power pack by B&D it has 600amp cranking and 3 110 plugs with 600Watt inverter for $139
 

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Discussion Starter #4 (Edited)
Thank you both for the advice and solutions. I WILL get a Portable Power source to carry (the perfect answer to my problem), and I will look into replacing the main battery with the one that you mentioned (Die Hard also).

That's exactly the advice I needed, the forum comes through again!

Thanks again, folks.

Chris
 

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Good question, I'm looking to add a mini fridge for those camping/road trips. I don't have aux lights or winch or anything at all. I don't have the rear power outlet either and can't afford the ARB fridge. Would a mini fridge drain my battery if I added a 12v to the rear? I thought bout carrying a spare battery too. Would it be wise to just invest in a jumper kit or a power strip inverter?
 

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Good question, I'm looking to add a mini fridge for those camping/road trips. I don't have aux lights or winch or anything at all. I don't have the rear power outlet either and can't afford the ARB fridge. Would a mini fridge drain my battery if I added a 12v to the rear? I thought bout carrying a spare battery too. Would it be wise to just invest in a jumper kit or a power strip inverter?
X2 for this exact question.
 

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Good question, I'm looking to add a mini fridge for those camping/road trips. I don't have aux lights or winch or anything at all. I don't have the rear power outlet either and can't afford the ARB fridge. Would a mini fridge drain my battery if I added a 12v to the rear? I thought bout carrying a spare battery too. Would it be wise to just invest in a jumper kit or a power strip inverter?
Anything attached to the battery that runs when the engine is not on will drain the battery, it's just a question of how long it will take. You can get a rough idea by dividing the amperage draw of the device(s), the fridge in this case, into the amp-hours of the battery. That would tell you how many hours it would take to drain a new battery at continuous use (the fridge running all the time, which will not happen on a good one).

If the fridge is fairly efficient and you're only going to use it a night or two at a time without starting the engine and re-charging the battery, you will probably be fine - but if you're going to camp in the same spot for a week, or be out in the back country alone, far from a jump start, then you are asking for trouble.

The other thing to consider is that most starting batteries are not made to be deeply discharged and re-charged repeatedly, and doing so will shorten their useful life much more quickly. Hence Layton's advice to use a deep-cycle or at least an AGM battery.
 

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I've considered the DP daul battery setup also but can't justify spending that much money on a kit.
My solution is to get a battery isolator and fab my own tray for 2nd battery. This is the same setup a police car uses and it's very simple and self maintained. This will allow only 1 battery to die and always leave you with reserve power.

My main batt. is an odyssey pc2150 and when I get the 2nd batt. I will get the smallest odyssey with enough cranking amps to start the car. I don't need 2 huge batteries in my car.

Doing a setup like I plan should run $175-200
YES no need to carry an extra batt. Get a jump box!
 

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Thanks, so in a nut shell: here's basically my situation, I camp 1-3 per year for usually a weekend tops 3-4 days. My rig is stock w no added power usage (lights, winch). I doubt I'll get a dual batt set up. I mainly need the fridge to get from point A to point B, then hope the pals have a cooler to stock my stuff, I would prefer a fridge over a cooler ( to transport) for various reasons, which are? Idk just want a fridge in my rig lol. So I'm surely gonna add a 12v to the rear. I'll most likely carry a jumper kit. Is a inverter needed to supply power to the fridge? Or would the jumper supply that power? Any tips on what inverter/jumper/fridge are recommended. And last the whole drainage thing ur saying I should start the car every so often to recharge the battery? If I decide to use the fridge all weekend long? Thanks guys all advise helps. I'm a dummy when it comes to this stuff.
 

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I made this a few days ago



Basically a 12Ah 12v SLA with a 400w inverter inside a Pelican 1200. Granted I wouldn't try to start the engine with this battery if I could help it. I can connect this power pack to the main battery and let the main battery charge enough to start. I also have a "Priority Start!" which is a device that goes inline with the main battery. It prevents the anything attached to it from draining the battery below it's starting voltage.

 

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wow, that pelican case mod is awesome! Are you using one of those odyssey pc680's? Great little battery and the size of a book with plenty of power to crank over a v8 race engine.
 

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I made this a few days ago



Basically a 12Ah 12v SLA with a 400w inverter inside a Pelican 1200. Granted I wouldn't try to start the engine with this battery if I could help it. I can connect this power pack to the main battery and let the main battery charge enough to start. I also have a "Priority Start!" which is a device that goes inline with the main battery. It prevents the anything attached to it from draining the battery below it's starting voltage.

I like the design a concept you have there! how long on just the Battery will it power the inverter with out hooking it up to the Vehicles battery? I would like to see the lay out of the interior..
You should do a build thread on that!
 

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I wish I understand all thus lingo lol
 

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wow, that pelican case mod is awesome! Are you using one of those odyssey pc680's? Great little battery and the size of a book with plenty of power to crank over a v8 race engine.
Nope, I am just using a common sealed lead acid battery that I got from Fry's. I guess they are common with house home alarm systems, solar power systems, and computer UCP's. Is that pc680 AGM or flooded btw, I couldn't see anything on my quick search. The main reason I went with the battery I did was the cost and the safety of it being fine turned on its side/upside down.

I like the design a concept you have there! how long on just the Battery will it power the inverter with out hooking it up to the Vehicles battery? I would like to see the lay out of the interior..
You should do a build thread on that!
Thanks. The battery is 12Amp hours or 144 watt hours. So whatever you wanna run with it just divide the amps or watts to get your hours of use. It should keep my macbook topped off drawing ~2A for about 5 hours. It's a little less than 6 hours because these batteries aren't meant to be drained all the way down. I would need a sealed deep cycle battery for that, but the $$$ started adding up quickly so I had to keep the costs down.


I'll do a full writeup when I finish everything. I still am waiting on a few parts coming from the slow boat from China.
 

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You can always use a battery from a cordless drill with a couple spare wires.
Yeah... that can be done, but it's probably not safe. You notice how thick the wires are that run from the battery cable. I am not sure of the exact number of amps our engine takes to start but I am pretty sure the drill battery nor the wires are rated for that kind of power.

Though you probably can charge your battery with the drill battery, using small gauge wire to trickle charge the main battery to get the voltage high enough to start it, but I would highly advise against using the drill battery to jump start a vehicle.
 
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