3 battery system ?

[Darije]

My car is EU model, it has OEM dual battery system. In parallel. 2 x 95 amh. My idea, because of a fridge, is to install 3rd battery in the back of the car, behind the fridge. And connect it with ONE of the oem battery with Victron DC DC 12/12 30 charger. In that case my fridge will run till 3rd battery last. 3rd battery will be charged while driving. Does anyone have something similar? Fridge is ARB Zero 60L single zone

 

[radman]

I unintentionally have a similar system.
I added a 2nd battery (group 27) using a slee tray and I’m using one of these to isolate/combine it:
Blue Sea Systems ML-ACR 12V DC... Amazon product ASIN B001VIXLRO
I also have 100ah of lithium batteries sitting behind my drawer system. The lithium bank is charged with a victron 12-12-18
Victron Energy Orion-Tr Smart... Amazon product ASIN B0851TPKV7
The lithium bank runs my 55L dometic, my inverter, and my aux 12v ports. The second SLA battery only has my winch on it, and it’s pretty much extra weight. It could jump my main if I ever need it, but I have a noco gb50 that could easily jump if needed.
I’m considering taking out the secondary SLA to shed weight….

 

[Fisher23]

My car is EU model, it has OEM dual battery system. In parallel. 2 x 95 amh. My idea, because of a fridge, is to install 3rd battery in the back of the car, behind the fridge. And connect it with ONE of the oem battery with Victron DC DC 12/12 30 charger. In that case my fridge will run till 3rd battery last. 3rd battery will be charged while driving. Does anyone have something similar? Fridge is ARB Zero 60L single zone

I have Dual batteries up in the engine bay, and have a 3rd battery (Lithium) for the fridge. I ran a large 2 AWG to the cargo area with a breaker at each end. It goes to a DC/DC charger to charge the battery for the fridge. I went with a 40 amp dc/dc charger, but many people use the 20 amp. I originally had a 20 amp charger but it took too long to charge the lithium back up. I ran the lithium to a fuse box and then the fridge and camping lights and radios.

I use a lithium as it charges up faster and has more Amp Hours.

Works Great.

 

[FrazzledHunter]

I have a dual battery system via a Redarc 1225D and an AGM battery both in the engine compartment on a SLEE mount. For my 3rd battery I got a Goal Zero Yeti 1500X. It's portable, has solar charging capability and eliminates the need for hard wiring to charge it. We take it when we need it and as its portable can be carried anywhere. This works better for me than a permanent 3rd battery.

Of course if you do want to hard wire its charging Goal Zero makes both a low and high wattage a car charger accessory.

Yeti 1500X - https://www.goalzero.com/products/goal-zero-yeti-1500x-portable-power-station

 

[TeCKis300]

I'd recommend looking into a LiFePO4 type lithium if you're going to permanently install a 3rd battery in the rear. They're more heat resistant, safer, and longer lasting.

I like @FrazzledHunter idea of using a portable solar generator as a 3rd battery. As you already have two, a flexible 3rd battery could be really handy for different use cases. Run a blender on the camping table, help charge buddies electronics, ready to go for solar charging, etc.

 

[NTV]

I'd recommend looking into a LiFePO4 type lithium if you're going to permanently install a 3rd battery in the rear. They're more heat resistant, safer, and longer lasting.

I like @FrazzledHunter idea of using a portable solar generator as a 3rd battery. As you already have two, a flexible 3rd battery could be really handy for different use cases. Run a blender on the camping table, help charge buddies electronics, ready to go for solar charging, etc.

Agree percent. I have dual installed permanent under hood with red arc 1250D and 75 amp hour Battleborn. I also have my jackery 1000 which I used to lower my fridge prior to the permanent dual install. Now the jackery and live in the rear attached on top of my drawers and get topped off if I need that amount of power. But for lost tips 75amp hour battleborn is more than enough to power my fridge and charge my basic devices. I barely ever use an inverter and the jackery works for that if needed but honestly inverters are overkill unless you just have to mix frozen margaritas in camp. I also have a VictronConnect smart shunt to monitor my usage and secondary battery as well as a Noco 10am charger to keep my main and second battery topped off via the red arc.

 

[Darije]

Thanks for info. In my country I can not get Jackery or Redarc... Not sure yet about Lithium battery. I am in Europe but not European union. And no one want to shipping me a sh*t because of it. But I managed to get few things here and there... I decided to go with Victron Orion TR smart DcDc 12/12/30 non isolated charger for 3rd battery, to hook it up on one of two oem batteries + Victron Smart Solar MPPT 75/15 paired with Bluetti SP200 (200w) foldable solar panel, when I am stationary. Also hooked up on 3rd battery. I know it sound like overkill but I would like to have peace of mind while I am off grid.

 

[NTV]

Thanks for info. In my country I can not get Jackery or Redarc... Not sure yet about Lithium battery. I am in Europe but not European union. And no one want to shipping me a sh*t because of it. But I managed to get few things here and there... I decided to go with Victron Orion TR smart DcDc 12/12/30 non isolated charger for 3rd battery, to hook it up on one of two oem batteries + Victron Smart Solar MPPT 75/15 paired with Bluetti SP200 (200w) foldable solar panel, when I am stationary. Also hooked up on 3rd battery. I know it sound like overkill but I would like to have peace of mind while I am off grid.

That works. Basically near same as my set up with different products. Your in good shape there!