Jeep Wrangler JK Rubicon JL 2-Doors & Unlimited 2007-2018

How to power the rear outlet 12V (without turning the key)

Make your Jeep 12V Trunk Outlet always ON

 

Understand the fuse box. It’s just a 1-minute job when you know what to do. The fuse box is the same for any Wrangler Sport, Sahara, Willys Wheeler, JL and Rubicon.


Jeep Solo Off-Roading

 

Prepare your first expedition with your Jeep in the extreme remote wilderness. Using the rear outlet to power a 12V Defroster/Heater, or small electronics could make a difference on the trail.

 

Why they want you to have the key in BATT/ACC SELECT position to power the Jeep JK rear outlet
The problem

Sometimes, you just want to use your Jeep for charging small electronics like a satellite phone, a tablet, a GPS, a pocket radio, weather instruments, etc. while you are not around. And if you are not there, the last thing you want to do is to leave the key in the ignition.

Whatever your Wrangler model, it looks like the manufacturer absolutely wants to prevent total battery drain in case you forget to disconnect your 12V beer cooler, for example. But if you feel you are grown-up enough to mitigate the risks, I’m going to show you what to do.

Jeep JK 12V Rear Outlet

 

What to do

1. Remove the key from ignition and make sure you don't have wet hands

2. Locate the fuse box under the hood

Wrangler JK Fuse Box

3. Open the fuse box

Open Fuse Box

4. Locate the M7 fuse (Yellow 20)

M7 Fuse Jeep JK

5. Move the M7 to the next fuse cavity

M7 Fuse Rear Outlet Always Hot Jeep JK

Bingo! You now have an "always on" port and you can test it now (remember you don't need the key anymore).

 

What not to do

1. DO NOT replace the 20-amp fuse with a 30-amp fuse: If you are plugging in a device that keeps blowing your fuse, replace the device (not the fuse). If you put a 25-amp or 30-amp fuse in the 20-amp cavity, there is a strong possibility that it eventually leads to heat and melted insulation because the wiring is only rated to handle 20 amps. Melting your wire will not only require a lot of work for you (or the mechanic) and/or money to replace it but could even start an electrical fire. To make sure to never blow the rear outlet fuse, never plug in a device that exceeds 160 Watts.

2. Don’t underestimate vampire power: You must be careful. If you can afford it, a top-of-the-line AGM battery like the Odyssey 48-720 is specifically made to survive the punishment of extreme off-roading adventures and has a generous capacity of 69 Ah. It’s a lot (50%–60% more than a typical car battery), but it can drain completely in less than 48 hours if you forget to disconnect an already fully charged device. How come? The fact is that most electronics and their chargers continue to draw a little power in standby or charging mode. It’s called “vampire power.” A small laptop can easily “leak” 5 watt-hour of electricity, and a charger drains up to 0.5 watts every hour. That is especially true in cold weather, or if your plugged-in electronic keeps trying to connect to a satellite, a cell phone carrier, or a Wi-Fi network. You also have to remember that there’s always a slight loss of energy caused by normal resistance in the wires that carry the current from the battery to the rear outlet. So, you should be fine for an overnight recharge but never leave a device connected in the “always hot” rear outlet for long periods.

Be careful using the 12V rear outlet if you are alone
What if you drain the battery in the remote wilderness?

Using your 12V rear outlet when the engine is off to power electronics, a 12V cooler bag or a 12V heater (for intermittent usage) exposes your battery to drain below cranking voltage. It’s a risk you may be willing to take on the trail but still a silly way to get stranded for good. If it ever happens, you will have three options:

1. Borrow a battery: If you don’t have jumper cables at hand, yes, you can wait for a good Samaritan to show up and beg on your knees to “borrow” his battery. You’re just asking the battery to start your engine, after all. The problem will occur when disconnecting and giving the “borrowed battery” back while the engine and the alternator are still on. Driving your Jeep without a battery is a sure way to supply most of the car’s electrical components with powerful voltage spikes and pulses that could fry vital circuits, diodes, and possibly the alternator itself. That journey back to civilization could cost you thousands of dollars and put your safety at risk. Instead, maybe you should move your Jeep out of sight, ask for a ride to the nearest store, and hitchhike your way back with the new battery.

2. Jumper cables: If you have jumper cables at hand, yes, wait for someone to show up. If your battery is dead and doesn’t recharge at all, there is 99% chance that it still regulates the voltage properly in the electrical circuit. So, you won’t fry anything. Just keep driving with the dead battery without disconnecting it. Of course, the jumper cables option sounds great, but you will still have to rely on a fortuitous encounter. Wandering alone on abandoned and god-forsaken trails is not the best strategy to meet a lot of new people. You could wait for days. Or even until next summer.

3. Push start: If your Jeep JK has manual transmission, you only need to put it into neutral gear and get some speed (10 mph or 16 km/h). Press the clutch, engage the second gear, and release the clutch. The 3.6l Pentastar engine will rotate, fire noisily, and probably start. But here’s the catch: you are alone and don’t have any pusher. You can use your Hi-Lift jack as a come-along with two straps and move your Jeep, foot by foot, until you reach the closest slope. That method is awfully dangerous because you will have to put your Jeep into neutral, push it until the very last moment, and finally jump into it when it starts to get momentum at the top of the slope. If you fail to jump into your Jeep at the last moment, the vehicle will just go down the slope and probably rollover or worse. And if you succeed to jump into your Jeep at the last moment, as we hope, remember that you are jumping into a moving Jeep with no power brakes and no power steering. It’s a dangerous gamble.



How to stop worrying about using the rear outlet

Here are two strategies to feel safer using the 12V rear outlet without the engine on (and without wasting your gas).

Strategy #1 : Dual Battery Tray ($500-$1000)

Many guys on the off-road scene simply carry a second battery on a dual battery tray.

Optima Dual Battery Tray Wrangler JK

But three problems come with that option:

1. Brutal weight gain: Since I strongly believe that a lone Jeeper should keep the available payload capacity as high as possible, adding 80 lbs means wasting a lot of usable payload for better things (like extra recovery gear, extra gas, and extra tools).

2. Expensive $$$: Even if you feel comfortable installing it by yourself in order to save money (it requires more disassembly/cutting/wiring than you may think), the battery trays have prices ranging from 120$ to 500$ (depending on the quality). You may also have to buy a separate “battery hold down” to make sure everything is perfectly safe ($50 to $200). And the price of a second good AGM battery ranges from $220 to $500.

3. Stuck with the Optima brand: Many dual battery trays work only with Optima batteries. Since the new owner now manufactures those in Mexico instead of the USA, they have decreased in quality and reliability. Of course, they offer a 36-month warranty, but it won’t be much help if you are stuck in the remote wilderness with a dead Optima battery. I’m not saying you should never buy an Optima battery, but many dual battery trays are specifically designed to fit Optima batteries. And, like many other Jeepers used to extreme off-roading, I prefer NorthStar and Odyssey batteries.

Strategy #2 : Jump Starter ($250)

So, you don’t want to spend $500 to $1,000 on a dual battery tray but still want to use the rear outlet when the engine is off without worrying. You need a jump starter that can still turn the starter without the battery connected. The average car driver doesn’t know that, but since you probably already want to scout the wilderness alone with your Jeep, you must know that all cheap jump starters only help your battery to turn the starter. It’s only a boost. For that reason, if the battery is completely drained or has a failure, most cheap and popular jump starters WILL NOT WORK.

Jumpit Cheap Jump Starter 300 Amp

What you need is a jump starter rated (at least) 800 cranking amperes / 2000 peak amperes, something like the ones used by tow truck drivers.

Schumacher DSR115-DSR Jump Starter

It’s unfortunate because those are too heavy and too big for the purpose of being carried on the trail by a Jeeper. For example, this Pro Schumacher DSR115-DSR weighs over 40 lbs.

...

But!

...

There is one option: the very compact model called the NOCO GB70. It’s powerful as hell and weighs only 5.5 lbs (including the little storage bag and cables). This little jump starter will work even if your battery is 100% dead.

Noco GB70 Case Jump Start Jeep JK

 

Noco GB70

Many YouTube videos show how good it is, especially with an old pickup truck’s engine. It’s actually designed to start 6l diesel engines and 8l gas engines.

You can also use it to recharge small electronics quickly.

Noco GB70 Power Supply

On my side, I prefer to jumpstart guys with my NOCO rather than using jumper cables. I do not put my Jeep battery at risk, whatever the circumstances are. It’s a precious thing in my life.

 

Canadian Tire
(Canada)
Walmart.com
(USA)
Rakuten
(Worldwide)

 

 




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