Thread: Second battery question....

I have a Sonnenschein 50AH battery in an arb battery tray in my V8, it runs a fridge overnight no problems, never had to use for longer without driving car. I have noticed that battery sizes vary between brands even if AH rating is the same.
Cheers Matt

Originally Posted by AussieAub

Looking to use it for, at worst, a few weekend trips away a year where I can hire a fridge to use (Engel or similar), and run the rear worklight off it.
What do you recommend, and what kind of price am I looking at?

Cheers in advance.....

Hi Kieren

If all the other required gear is under the bonnet, and it's only for occaisional use, I'd reccomend the Optima Yellow Top D34 (55A/Hr). Check that it will fit first. They do in the Td5 engine bay with some slight shoe-horning ... search the forum. There's a few write-ups on how.

rrTurboD on the forum does excellent prices on Optima batteries delivered. I think my D34 yellow was $255 delivered.

I'm saying the Optima yellow (or Blue D34) as they have excellent shelf life (12-18 months of no use will not kill them), and can recharged faster than any other type of battery ... very important when you only have a limited capacity to start with.

Allowing an average 40-50L fridge size, leaving friday afternoon/night, and travelling (engine going) with the fridge turned down to say -2 to -5 deg C, means you arrive with everything really chilled, then you turn the fridge back up to 2-3degC when you arrive. With the fridge chilled low, and a fully charged yellow top, allowing and average fridge draw of 24A/Hrs/day (1A/Hr), you should get up to 1.5 days run time for the fridge ... a little less if you use alot of worklight .... so late sat' night/sunday morning before the fridge battery needs a charge ... go for a 30min+ drive sat/sunday and you won't have any battery charge issues.

I'm using a Traxide USI-160 controller, so I also get 1/2 of my starting battery (Optima Yellow D31 75A/Hr) to use along with my D34 ... so I can go 2-2.5days before having to recharge.

Other types of non-AGM batteries suffer from taking 4-6hrs of driving time to get fully charged.

Originally Posted by alpick

There is a thread on here somewhere that gives all the good guts on what AH really means.

My recollection of it was that a 100 AH battery will only give you 50 hours at 1 amp of drain and then it would be considered a flat battery. Again from memory a batt is flat at 10.5 v?

I run an ARB 49ltr from a 100AH and with the fridge set to shut off when batt v is 11.3
I get at least 48 hours from the fridge set at 2 deg, they are super efficient. Love it.

Al, I concur ... I also have a 47L ARB, run at 10,5v shutdown (but my crappy wiring, that has yet to be upgraded, has about 1.2v voltage drop so when fridge shuts down, the battery reads about 11.7v - I need to upgrade the wiring to get a better run time). I've been very happy with the ARB, and it seems to average about 1A/Hr, so 24A/Hr per day ... with the 2x yellows and the usi160 theoretically, I should be able to go 3 days (About 70A/Hrs available/useable from the 2x yellows and the USI-160).