Dual Battery Help

[Yeti's Beast]

Thanks for all the advice guys, really appreciated.

I think my plan for now is:
I have a sparky mate willing to help out this weekend, and we will run the 8 gauge wire to the rear of the vehicle (and set up all the anderson plugs, fuses, etc). This will give me a chance to test the battery with the Engel fridge for 12-24 hours. If it holds its charge roughly as expected, then great. I'll probably go to battery world after this as well to see about that health check just to confirm. If it does not hold charge, then its an obvious replace.

Either way, Cuppa and Yetti's Beast make great points that it is probably not enough should a literal rainy day occur (and I do not want to leave yet). And while 50-75% of the trip will be at least somewhat near civilization, a minimum of 25% of it will be completely out in the bush (eg. Plan to do at least 7 days across the Gibb River Road, and would love to just sit in Cape Range national park, or Karijini for a few days without moving)

So this leaves me with 2 options in my mind. Either get a new 120-140AH battery to replace the current one (the obvious choice should the current battery turn out to not hold charge). or I could get a 100-140AH AGM to throw in the back that is completely detached and only charges via solar.

For the first option, does anyone have any recommendations on deep cycle batteries (AGM or wet) that can live in the engine bay half decently. Was busy today, so did not have time to measure what the current tray can hold.

For the second option, I would likely have a setup where I could swap anderson plugs to power the fridge via the front aux batter, then switch to the rear aux battery. Does that seem sane?

I think both these options take Yeti's KISS advice to heart, and involve the least amount of electrical work. It also lets me get some work done this weekend that will not go to waste. As much as I would love a dc to dc charger setup, I cannot find one for less than 250 that looks even halfway decent. And the good ones seem to be at least 500.

Once again, thanks for all the feedback so far. It's been really good, and helped me start to make a better plan going forward.

Most battery trays can only take a battery that’s 305 mm long which will limit you to 105-110 ah
Anything over that capacity goes up to the next size case that’s 330mm long and also taller.

My old Patrol had a VSR connecting my batteries with leads strong enough to start off either battery and had a link switch on the dash.
My second battery was a 110 ah Ultimate Extreme AGM and would run my 60 litre Waeco for 4 days easy.
I had an Anderson plug on the tow bar connected to the AgM battery so I could hook a solar panel up and if needed although it never was, I could link the batteries and charge both.

It was a basic set up that worked


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[Yeti's Beast]

An Anderson plug for the fridge is a must also




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[GQtdauto]

Have killed plenty of batteries from doing the wrong thing but current setup has lasted ,one agm under the bonnet and one in the back both are 110 amp Chinese specials about $220 each from memory.
When we're touring they run a freezer full time plus camp lights from four to six months each trip , I have about 140watt of solar on the roof and a Victron charger with the ability to add my 200watt solar if cloudy .
Start with a good battery so follow advice and get it tested .

[Brass]

Most battery trays can only take a battery that’s 305 mm long which will limit you to 105-110 ah
Anything over that capacity goes up to the next size case that’s 330mm long and also taller.

My old Patrol had a VSR connecting my batteries with leads strong enough to start off either battery and had a link switch on the dash.
My second battery was a 110 ah Ultimate Extreme AGM and would run my 60 litre Waeco for 4 days easy.
I had an Anderson plug on the tow bar connected to the AgM battery so I could hook a solar panel up and if needed although it never was, I could link the batteries and charge both.

It was a basic set up that worked


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Figured the tray might be a bit small. Looks like my current one is 305, so will look to get a new 105AH Battery for the front if the current one ends up being a dud.

I'm going to go forward with the 2nd Aux battery in the back though. Aiming for a 130-140AH AGM deep cycle. Obviously trying to keep costs down, but not sure what to look for to make sure I am not getting a dud. 2 options that looked reasonable were the 140AH Giant for $267, and the 130AH Eclipse for $269. Happy to pay that if they are half decent, and would love any feedback on them as well. These would be sitting in the back of the Patrol, and would only be hooked up to the fridge, and be charged by solar panels.

As for the tray, looks like I can pick one up at Jaycar for about $14 for the tray and another $10 for the holder. Seems like a good enough price, and they are close to my work. Again, this would just be bolted down to the drawer system I am building for the back of the Patrol, so as long as it can hold the battery then I think it will do the trick.

[Cuppa]

All I know is there are good & bad out there among the cheapies. If you score a bad one it is more expensive in the longer term. I have only ever had Fullriver, Ritar & Optima, all of which cost more than those you are looking at. I expect to get at least 10 years lifespan, certainly got that with the Fullrivers, they were still in use at 12 years old & going strong. The Optimas had 8 years on them & still ok when I sold our bus. Current Ritars in the Patrol are now over 8 years old & still hold a rested voltage of 12.8v. All have been well use, full time for long periods as well as laid up for lengthy periods.

In regard to Giant & Eclipse - an old friend used to sell batteries, originally Fullriver, then Ritar & before he retired changed to exactly those two brands. He is someone who knew his way around RV electrics better than most & is a man of integrity, choosing his stock to be able to give his customers what he considered to be the best value for money. When Fullriver prices rose as they became popular he moved to Ritar, & when they too became more expensive he moved to Giant & Eclipse. In my book that is a pretty good recommendation for them.

This is his web site https://www.fridge-and-solar.net/batteries.htm - some useful info on batteries & other stuff on there.
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