Second Battery in SH Forester

[geschy83]

Hi All,

Just fitted an 80Ah AGM battery in the boot of my 2010 Forester and thought I would post some picks of how it was done.

I mounted it within the spare wheel. A bit of a pain when you get a flat I know, but the mount will release from the wheel with two wing nuts.

I condensed the jack & tools that usually live inside the wheel into a bag which fits beside the spare wheel.

Pretty happy with the result. Should be able to run my 48L ARB fridge for a couple of days.

If anyone could provide some advice on 12V chargers/battery management that would be appreciated, as I like the idea of the Redarc 1220 but don't wish to give up the arm & leg to pay for it.

 

[geschy83]

More photos

more photos

 

[geschy83]

still more photos

more photos

 

[sjm]

Nice idea. I've got a battery in the spare wheel too, but mine is just padded with a blanket packed in around it

 

[Barry]

Geschy83, I TOTALLY recommend the 'Traxide' system, which I use to charge the 100AH AGM in the rear of my Outback AND the 100AH AGM in my camper trailer.
See the link here: https://offroadsubarus.com/showthread.php?t=1475 (Traxide circuit diagrams at post #3)
The wiring diagrams are suitable even for someone like me, who has never wired anything before.
The important thing is to use heavy duty wire (6 gauge / aka 6B&S) otherwise it just has huge voltage drop, gets way too hot, melts the insulation and shorts out, sets fire to your car.
Traxide's web link is on the circuit diagram, which will take you to their e-mail / phone contact details. Give TIM a ring, a great bloke and thoroughly helpful.
*No affiliation with Traxide, just a 'very happy camper'*
MOST IMPORTANT: When using your system to run fridge, etc, make sure you don't let the battery drop below 50% state of charge, or you will significantly reduce the life of the battery.

 

[Kevin]

I have on order a CTEK D250S dual 12V DC DC charger to replace my current Matson controller. The reasoning is that normal dual battery controllers can only charge aux AGM batteries to 75-80% of full charge whereas a DC DC charger can get them up to 100%. And - with a solar panel attached, the CTEK will auto switch and start charging the starter battery once the aux battery is full. More expensive of course (cheaper than Redarc) but more sophisticated. I think you can use lighter cable as well but as I've already run my cables it's not an issue.

https://www.ctek.nu/Archive/ProductManualPdf/D250S DUAL_EN.pdf

 

[geschy83]

Thanks for the reply's. I understand that the DC DC chargers are much better, but after talking to some "experts" around town I am getting a 100amp Redarc isolator installed on Friday.

Don't get me wrong, if I could afford the DC DC chargers I would go with one, but for the occasional camping I do the price didn't make sense.

Voltage at the battery terminals was 14.3 volts at idle so using heavy cable should put enough charge in the battery each day, as I normally do a bit of driving up the beach.

Thanks barry, I have a low voltage cutout on my fridge (ARB). Do you know what voltage is approximately 50% charge of a 12V deepcycle AGM battery?

 

[Barry]

Can't recall off hand.
Somewhere around 11.5 volts springs to mind.
I'm sure you will find the answer in the electrical forum on myswag.org.
Over the long weekend just gone my in-line digital volt meter on my fridge input was reading about 12.75 - 12.8 volts whenever I checked it. The magic button on my REPCO battery box also showed a full line of illuminated LEDs - i.e. fully charged.
I totally agree that heavy cable to the second battery is the key to adequate charging of the second battery.
With such a set-up dc:dc chargers are just unnecessary expence IMO. (I also have a solar panel to trickle charge when camped for a few days.