Add a Second Battery???

[Mountain Goat]

I currently run an ARB fridge in my Volkswagen on family camping trips, including multi-day, and have a voltage cut set at 11.8 volts if I remember correctly. The current draw on that fridge - even when I have it set in freezer mode - is so low that I've never once had it cut out or had any issue with the engine starting quickly when needed.

On the BMW I run an 850 CCA battery (AGM type) and can leave the car sitting for months at a time between starts, again, no issues with discharge.

It's a little different in an overlanding rig, and depending on how many accessories you are trying to run, then sure a second battery can make sense. But for basic fridge-and-phone-charger sort of usage, I would have no worries being off grid with a high quality AGM battery. Maybe that's a risk tolerance others don't have.

(I do carry jumper cables, and if I were going to be parked for a REALLY long time in a remote area, I'd park on a slight hill where the vehicle can be easily push started via the manual transmission. Or just remember to start it every few days to spin the alternator).

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[BroncoKong Jr.]

Genesis Offroad will almost certainly have a dual battery kit for the Bronco

 

[JesseS]

Very easy to install a battery isolator to prevent drain down of the second battery, with a aux switch wired thru a 100amp relay to use it as an emergency start in case you left your lights on As for lithium I installed 4X100 amp hour in my RV as house batteries, $500 each, max draw is 180AH each so plenty of power to crank. As for size the standard 100 AH LiFePo4 are GC2 so a little taller than normal start batteries. But they have a MUCH deeper DOD down to 10% vs Lead Acid @ 50%, and charge much faster.

 

[guernsej]

I have a dual battery setup that's great and I use it all the time. Next vehicle I'm just throwing a portable Li-Ion "solar generator" battery in the trunk and calling it a day.

 

[Aman]

The Pajero has an isolator between the two batteries. It may also be a relay that allows the 2nd battery to jump the primary starting battery. I should probably know that ... Anyway it's a factory setup.

Very easy to install a battery isolator to prevent drain down of the second battery, with a aux switch wired thru a 100amp relay to use it as an emergency start in case you left your lights on As for lithium I installed 4X100 amp hour in my RV as house batteries, $500 each, max draw is 180AH each so plenty of power to crank. As for size the standard 100 AH LiFePo4 are GC2 so a little taller than normal start batteries. But they have a MUCH deeper DOD down to 10% vs Lead Acid @ 50%, and charge much faster.

Isolators don't work well with a lot modern vehicles. They tend not to give a full charge to the second battery. A DC to DC charger is the way to go!

 

[guernsej]

Isolators don't work well with a lot modern vehicles. They tend not to give a full charge to the second battery. A DC to DC charger is the way to go!

Yea Ford BMS can make it tricky to integrate a second battery to the charging system without causing issues. I have mine installed through a Victron Intelligent Combiner connected to the BMS current sensor on the negative terminal, but there's no official guidance and recommendations are mixed on doing it this way vs bypassing BMS and connecting directly to the negative terminal. Anecdotally I've had no issues.

I also have a solar panel hooked to the house battery that charges the starter through the combiner, so I'm actually amazed BMS has handled it without tripping to failsafe charging mode.

 

[JesseS]

I have never had issue with one, the alternator charges both batteries and the HP Diodes in the isloator prevent any drain unless the relay is closed. Been using them on my Jeeps and boats for years, simple and effective. A DC>DC charger is a more elegant way to go, but this works fine

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