12v always hot options

[Halston Hunt]

So I'm wanting to make a constant hot in the rear of my 5th gen 4runner (for my dometic fridge) I'm on the fence if I'd rather just upgrade my battery, dual battery setup, or possibly have a battery in the back with a solar charger, completely separate system.

 

[ZRex]

For an always hot connection the dual battery set up is really attractive to me. If the fridge stays plugged in constantly then the dual battery setup (isolated) will save you from being stranded due to a dead battery. Protecting the starting battery has been a major priority to me since I ended up with dead starting batteries a handful of times. I'm lining up a National Luna set up for my current rig, although I DIY'ed my last setup with a continuous duty Cole Hersee 12VDC solenoid, you do have to be careful about duty cycle and amperage ratings.

Food for thought.

Mike

 

[mep1811]

If you plan on using an ARB fridge it is recommended to use the ARB fridge wiring kit.

 

[Luinil Explorations]

We have a single battery setup, with portable solar from Overland Solar and carry a jump pack for emergencies. We went this way partly based on cost but mainly ease of installation. Most trips we drive every day so the power drain from the fridge, lights, phones, etc is not enough do prevent starting in the morning. If we are staying for a few days then we put out the solar panels. We also added a battery voltage meter. This helps us keep track of power usage and battery health.

 

[geekyadam]

We have a single battery setup, with portable solar from Overland Solar and carry a jump pack for emergencies. We went this way partly based on cost but mainly ease of installation. Most trips we drive every day so the power drain from the fridge, lights, phones, etc is not enough do prevent starting in the morning. If we are staying for a few days then we put out the solar panels. We also added a battery voltage meter. This helps us keep track of power usage and battery health.

What kind of battery do you use as your single battery though? I would be surprised to hear you run a fridge and other accessories overnight on a starter/crank battery and it continues to work fine.
From what research I've done so far, it seems single battery setups can be perfectly sufficient, but only if you switch to a hybrid battery. Deep cycle is best for consistent drains/recharges, but they usually lack the cranking amps to replace a starter battery, hence the need for a hybrid; best of both worlds. I intend to replace my stock battery with a hybrid, then add solar later, and eventually go to a dual battery setup. At least that's my current intended timeline...mostly based on $$$. ;)

 

[Plasmajab]

What my freind did in his gmc was he mounted a deep cycle battery and a relay with 4ga to an anderson power pole in the back.

Not fancy, but the relay was tied into the 0 guage wire and also the bridge between the standard battery and the deep cycle. So when we were on route to the site and on the highway he could flip the switch and charge up the deep cycle.

The other switch was wired in to isolate the deep cycle from the starting battery. So even if the fridge sucked the deep cycle dry, he could still start the engine on the gmc using the regular battery with no issues, then flip the switch and recharge the deep cycle.

 

[Wanderlost]

We're in the process of putting together a state-of-the-art system to do the same as what you need. It's an under-the-hood dual battery, a dc-dc charger with built in solar controller, and circuit breakers to protect everything. In the rear cargo area there'll be a panel with 12v and high output usb outlets, all fuse protected.
It's not going to be cheap but it will be super reliable and capable. With it we'll be powering our Dometic 75 fridge/freezer, charging camera batteries, and powering work lights.

 

[Luinil Explorations]

We have a standard sizeTrojan starter battery that is sized for the 4Runner. Like I said, no problems with starting wehen sitting for one night and driving every day.

 

[justjames]

Here's a well written commentary on this subject from a SME on another forum. Read post #5.

https://americanadventurist.com/forum/threads/anyone-use-a-small-12v-marine-battery-as-a-house-battery.6204/

 

[Steve_Midlands_UK]

From several years using 12v compressor fridges they are not so heavy on current but are very voltage sensitive .

Use the (physically not ampage) largest fuse you can, with the best quality heaviest cables and connectors you feel you can get away with .

Minimise voltage drop from battery to fridge .

It’s hard to explain but as the voltage in the battery starts to get close to the fridge cut off voltage ( 11.5 volts or so) it has the tendency to cut in and out rapidly which can reduce battery and fridge lifespan.

This gets even worse of an overcast day when charging with a solar panel.

Voltage goes up as panel starts charging so fridge kicks in, this drops the voltage and fridge shuts off ... solar panel starts charging ... sets up a cycling situation ... hood I explained ok !