Auxillary battery on cigarette lighter?

[robmobile73]

I know there are many ways to skin this cat, but I'm looking at something simple. I'm considering hooking my deep cycle marine battery onto a auxiliary "cigarette lighter" power plug in my tundra for camping trips. The idea is that my electric cooler refrigerator plugged into the cigarette lighter, and any devices I need to charge will run off the cigarette lighter circuit from the marine battery when the truck is turned off. When the truck is running the circuit will also charge back up the Marine deep cycle battery.
My questions are: 1. will the recharge current draw be too great for the fuse on the cigarette lighter outlet circuit. 2. On the 2019 tundra or the cigarette lighter and all of the auxiliary power outlets on the same circuit? 3. Are these outlets on their own circuit or is there a variety of other items in the truck on the same circuit that would be drawing down the marine battery with the truck turned off?
Information which helps answer my questions or greatly appreciated. I do realize there's a variety of ways of doing what I want that involve purchase of charge controllers and switchboards and more expensive equipment. I'm trying to go simply and use what's on hand. I'd like to be able to recharge phones and stuff without cranking the truck up. I also like to recharge the deep cycle battery without having to pull it out of the truck and get out jumper cables.

 

[Dindu Nuffin]

So wait... you want to send power from the battery into the lighter outlet so that it can then go to the fridge when the truck is off? And when the truck is on, you want said battery to be charged from the lighter outlet while the fridge is then powered by the truck?

Lighter outlets are limited to something like 5A and usually have a fusible link in the outlet that will blow at less than 5A if used for long enough (it's a temp thing). Additionally, they're wired in with 18- 20 gauge wires. They're only good for phones or tablets. That's it.

Why not just figure out how much power your fridge draws over the course of however long you need it to stay on for, buy a battery accordingly, run the fridge off the battery isolated from the rest of the truck and throw it on a charger when you get home? We run a fridge on our day boat off a 100Ah deep cycle battery and it'd run for about a week straight if we needed it to. We go out almost every weekend and only charge the fridge battery overnight once a month. Cheap, simple, no bull****, no reinventing the wheel.

 

[bj70bc]

So wait... you want to send power from the battery into the lighter outlet so that it can then go to the fridge when the truck is off? And when the truck is on, you want said battery to be charged from the lighter outlet while the fridge is then powered by the truck?

Lighter outlets are limited to something like 5A and usually have a fusible link in the outlet that will blow at less than 5A if used for long enough (it's a temp thing). Additionally, they're wired in with 18- 20 gauge wires. They're only good for phones or tablets. That's it.

Why not just figure out how much power your fridge draws over the course of however long you need it to stay on for, buy a battery accordingly, run the fridge off the battery isolated from the rest of the truck and throw it on a charger when you get home? We run a fridge on our day boat off a 100Ah deep cycle battery and it'd run for about a week straight if we needed it to. We go out almost every weekend and only charge the fridge battery overnight once a month. Cheap, simple, no bull****, no reinventing the wheel.

run it off the truck plug when driving
run off the isolated battery when not driving
and if you have an inverter plug on the tundra you could plug in an off-the-shelf battery charger onto that lonesome battery when driving around if you really wanted

 

[Dindu Nuffin]

run it off the truck plug when driving
run off the isolated battery when not driving
and if you have an inverter plug on the tundra you could plug in an off-the-shelf battery charger onto that lonesome battery when driving around if you really wanted

Ah, I get it now.

I kind of feel like this is being made more complicated than it has to be because if he's buying a battery to run the fridge from, just get one that'll run it the whole time. Like I said above, our 100Ah battery could run our fridge for about a week straight. I'm pretty sure this dude doesn't need that much run time, so why bother with the added complexity (albeit, very little) of making it also run off the truck? I dunno. If he's dead set on that, I guess just use an off-1-all-2 battery switch where 1 is on the battery and 2 is on the truck.

 

[robmobile73]

Did some more research since I posted the question. What I'm seeing is that my auxillary outlets are limited to 120w/10amp. If the voltage on the auxillary battery is too low it can pull more than 10Amps trying to recharge it and pop the fuse for the auxillary outlet. I will attempt a workaround this weekend involving a small inverter to the cigarette outlet and a 6 amp 12V charger. If the voltage differential is not to great it should work. It seems there's no good way to make it work in all battery discharge conditions from the auxillary outlet without buying a DC to DC charger.........................One thing I do appreciate about my BJ73 is that the cigarrete lighter outlet is still hot when the truck is off so I can charge my phone.

 

[Dindu Nuffin]

Have you figured out what your power requirement will be? What fridge do you have? How long will you need it to run on pure battery? How long will you need it to run total per trip- a day, a weekend, a week, ect?

I had a thought after posting the last reply. What about a dual battery setup with the house side being a deep cycle that the fridge and chargers connect to? You could set up a simple relay to disconnect the house battery from the starting battery when you turn the key off so your house load doesn't drain your starting battery, and then reconnect it when you start the truck back up so the alternator charges the house battery and runs your house load? A bonus is that you'd then have an onboard jump pack if the starting battery goes tits up.

 

[robmobile73]

Have you figured out what your power requirement will be? What fridge do you have? How long will you need it to run on pure battery? How long will you need it to run total per trip- a day, a weekend, a week, ect?

I had a thought after posting the last reply. What about a dual battery setup with the house side being a deep cycle that the fridge and chargers connect to? You could set up a simple relay to disconnect the house battery from the starting battery when you turn the key off so your house load doesn't drain your starting battery, and then reconnect it when you start the truck back up so the alternator charges the house battery and runs your house load? A bonus is that you'd then have an onboard jump pack if the starting battery goes tits up.

That's what I'm leaning toward now. Simple 30amp key switched relay to send power from truck battery/charging system to Auxillary battery.............the choice seems to be spend money and effort on switches and wiring or spend money on a 12V DC to DC charging setup...........I'm fairly sure I can buy a $70 small lightweight 20AH LIPO rechargeable to power the fridge when the trucks not running. Just have to run key/relay switched power on a 10 guage(or dual 12guage) wire to run it. Lot of ways to skin this cat.

 

[robmobile73]

On power requirement: the marine deep cycle battery will run the fridge for a couple of days no problem. I'm leaning toward getting a 20AH lightweight LIPO battery to run the fridge when the truck is shut off and then that bat will charge when the truck is running.

 

[LandCruisinMy93]

So, when I bought my ARB Zero I mounted the ARB power outlet in the truck bed. Basically I designed a base to fit the plastic oval plugs at the back of the bed. The base has nuts fit into it that allow the ARB outlet to screw on and the whole assembly sandwiches the sheet metal. No drilling or invasive stuff to the truck.

I then purchased a cheap smart switching relay that allows you to set a voltage at which the circuit shuts off. So, the relay would sense it was getting only 11 volts and it would shut off the fridge circuit, protecting the start battery. The only issue I ran into is that the ARB is already equipped with said circuit and wouldn't run, Lol. I just had to remove the relay and it was good to go. Anyway, the point is you could run your fridge like that and install an inverter to charge a battery bank.

There are also battery banks made for keeping your fridge going when it's not plugged into the vehicle, jackery, goal zero, ARB and dometic all have battery packs and some even have standard 110v outlets on them. I know a lot of RV places carry them too.

If you're handy and own some milwaukee power tools milwaukee makes the "top up" inverter that runs off their batteries. I learned during the ice storm that caused a 9 day power outage, that the top up can fast charge your phone, run an ARB fridge, run a TV and wifi router. I was able to run my ARB down low and then unplug it. Then I would watch some TV while fast charging my phone. Luckily I was able to recharge my batteries at my shop which somehow had power.

Lots of options.