Over Charging Batteries

More likely an internal issue with the battery. After 6 years of successful use I guess the charger could also have gone belly up.

Hi
I would certainly get the CHARGER checked before fitting new batteries
It has possibly failed to regulate & cooked the batteries [heavily overcharged ,one thing that AGMs cannot take]
PeterQ

I would also check the specs of the battery to see what the maximum recommended charge current is. I have been surprised how low many of the cheaper AGMs are. I lost 2 AGMs prematurely due to my failure to check. One got too hot and failed after 2 years, one ballooned and only had about 1/3 capacity. I have only bought good quality since. Expensive but they last. I now use LiFeP04 batteries in the new truck which will happily charge at very high rates like 10C = ie 10 times capacity.

I would do as others have said, check the setting and if ok then check if it is correctly operating. Given that the charger has a rated max of 15A it would be surprising if it is the cause unless it has gone faulty.

Further to the issue of limited charge current the following is a link to the specs for a Fullriver 105AH AGM which is considered as a fair quality deep cycle battery. Note the suggested 21A or less charge current. I was considering using these until I saw this limit. I did confirm it with the battery supplier.

http://www.batteriesdirect.com.au/files/products/DC105-121332110312_1.pdf

The remco equivalent suggests 30A max which is better but easy to exceed in vehicle if the battery is significantly discharged.

http://www.batteriesdirect.com.au/shop/product/4386/rm12-100dc.html

By contrast a Lifeline 105AH can be charged at a much higher rate 500A+. This is a Mil-spec battery and more expensive, but gives much better life and performance. This was the AGM I planned to use until I swapped to LiFeP04.

http://www.batteriesdirect.com.au/shop/product/4265/lifeline-12v-105ah-agm-battery.html

I have several chargers. For charging from the mains I have a Projecta 35A unit and several small Projecta or Ctek units to keep batteries on float. For the Li batteries it is a whole new world and not relevant here.

Nice thing about the Projecta is that it supports different types of batteries and you can set the maximum charge currents.

http://www.batteriesdirect.com.au/shop/product/10146/ic3500.html

Yet another can of worms that is fun to explore.

It is my view that you can not overcharge a LA battery unless you offer excessive charge voltage. Offer excessive voltage and any amps will overcharge it.

I have used a Fullriver HGL AGM starter battery in the OKA for 6 years. It is offered 14.3V at up to 85A. It does not "overcharge".

Cheers,
Peter
OKA196 Motorhome