AGM Battery Life Expentancy?

How long is a piece of string?

You partially answered your question, the less you use it and the less deeply discharged
it is then the longer it will last.

If you drive on rough roads a lot of the time, then mechanical damage will also come into it.

6 years is pretty good, you might get 10 but that's probably pushing it, bottom line though if you you were intending to do a 6 month trip to remote areas and relying on the battery to keep your freezer going etc I would replace every 4 years or so. If your only using it now and again around town I would keep it there till it dies.

Cheers
Leigh

Thanks for the useful information.

I have never charged the battery as it's wired up via a Redarc isolator and I thought that's all you needed to worry about when it came to recharging the battery???

I drive the car daily, does the second battery need recharging in that case??

Thanks again.

If it is indeed a good brand that publishes a full spec sheet, there should be some service life graphs, that take into account temperature,and other factors.

A while ago I read a paper written and researched by on aof the caomanies that makes AGM for stationary use.

They proved by actual testing that you could reduce the best reasonable life expectancy of 10 years to less than a month by poor treatment.

Then there is actual measured performance.

Most batteries are replaced when they fail......but truth to tell they have been well below spec for a long time before that.

What do you consider is acceptable performance?

These days I own a couple of testers that will quantify battery performance....most people don't have this luxury.

So.....it realy is an open question.

If you have got 5 good years out of any battery you are doing well.

cheers

Your setup - where your alternator is charging the AGM with no restriction on the amps, you may have shortened its life already. Common AGMs such as FullRiver and Remco (and pretty much all others apart from Optima and Lifeline) will have a maximum current on their spec sheets or written on the battery case. For 100Ah battery, this is usually around 25amps. If your alternator is allowed to pour more than 25 amps into the AGM the battery can vent - reducing its capacity eventually to the point where the battery becomes pretty useless. I measured 45 amps going into a brand new Remco after a couple of days camping - because I had good wire and a decent alternator.

If I were you I'd do a battery capacity check. Simple way to do this at home is to firstly fully charge the battery on a multistage charger, then run a fixed load (I use a 13W fluoro that draws 1.1 amps) for a long time while you're monitoring the voltage. See how long it takes for the voltage to drop to 12.0V - should take 30-40 hours for a good battery.

The Remco AGM mentioned above only got a few hours when I did this this test - it was only 2.5 years old, never been mistreated apart from the fact that it was subject to high alternator currents.

I had to replace one prior to doing the CSR last year.....I was so lucky that it collapsed on me in Kalgoorlie so was able to slip in and get a new one on the very morning we departed for Wiluna.

It hadn't missed a beat for 3 years BUT we had done a fair bit of rough road travel, and maybe 120-150 nights of remote camping in that time.

It was just used to run a Waeco 50 litre (as a fridge / freezer) and some LED lights, nothing else.

Started to lose power on the few days we were in Kalgoorlie, and that was even after doing a bit of running around in the Prado (well and truly enough running around to charge it up).

Ten years sounds incredible, even six would be great....mine lasted three!!