DC to DC Charger vs Battery Isolator

[Peterng]

I agree that it would be best to try an basic"isolator"setup first and see how that goes in charging your aux AGM battery and there are plenty in the 4wd market place. I have a basic system and it has worked well for over 6 years..but when I go lithium batteries...well, my set up will have to change. It is best to buy a reputable brand as they have back up quality service and guarantees.
If the isolator does not seem to work properly, then you will have to buy a DC -DC charger...cost about $300.00+ for a good quality product...again there are heaps of manufacturers sprucing their wares. This again will depend on your budget...but it is best if you can stretch for DC-DC charger with MPPT solar input and a lithium profile. These are costly...$400+...but you will be saving for a MPPT solar controller and a charger with a lithium profile...if you intend in the future to head towards getting lithium batteries. The best manufacturers with the "runs on the board" for quality product, customer service, product knowledge, good back up and most importantly... known reliability are Redarc, Projecta, Enerdrive, Braintech & Ctek, ..others on the next level below are Kickass, Kings, 4wdsupacentre, Supacheap..
Good luck

[pajflareo]

I bought a SuperCheap DC-DC 20a charger.

Was on sale for a fraction under $100 and works perfectly. Keeps my 115ah AGM in the rear at 13.8v

Compared to the smart isolators available at Supercheap there wasn't any price difference.

Unfortunately no solar input but I don't use a solar panel anyway.

[Ozzyal]

I have a cheap one off eBay . Works great with my 120Ah battery , but just be careful with it . Mine seems to be pulling from the main battery even with ignition off .

Sent from my SM-G965F using Tapatalk

[Mike DiD]

I have a cheap one off eBay . Works great with my 120Ah battery , but just be careful with it . Mine seems to be pulling from the main battery even with ignition off .

Sent from my SM-G965F using Tapatalk

In other words, it is doing exactly the same as a hard-wired cable between the two batteries

[Anky]

When you need Battery Isolator

I have a 2013 NW Pajero and I am in the process of wiring up an auxillary battery for my Waeco 40L fridge in the rear of the wagon.
I read somewhere that most 4WD's built after 2010 have cut back on the output from their alternators and that a DC to DC charger was needed to bring the second battery up to full charge. Is this the case?
I was about to hand over some coin for a Projecta 25A DC to DC charger but if the alternator pumps out enough for both batteries to fully charge, then I can purchase a Projector 150 dual battery isolator for less than half the cost of the DC to DC charger. Will the isolator do the job?
Thoughts?

In most cases, you do not want to connect the batteries using a battery isolator. The only time you use a battery isolator is in motor homes or boats. When you sit for long times with your motor off and you want to be sure your vehicle starts in the morning, this is when you would use a battery isolator.

[nj swb]

When you sit for long times with your motor off and you want to be sure your vehicle starts in the morning, this is when you would use a battery isolator.

Which is why most 4wders use battery isolators.