AGM Group 31 starting batteries-gctid821815

[talman]

We had a battery failure yesterday. What smelled like a stinky head turned out to be an overheating, off-gassing AGM. The symptoms were not new: Port engine was slower to turn than SB, but not to the point of having to parallel to start.

It took us a couple of hours to pin point. We were in our home harbor (not at my slip, though). I had to yank the battery. Disconnecting did not help too much. Now, on a Sunday, I am down and engine and a thruster. I don't feel like I need the excitement of backing into my slip on one engine and a stern thruster.

So, I have been asking myself: Do I replace wit AGM again? or flooded cell? I religiously check my house bats, so not too hard, maintenance wise. Money wise, I did budget for new batts this year. the way Meridian wires these boats, it seems to me that you cannot have house and start on the same charger (like it is) especially if they are half AGM and half flooded. Craig (Tozz) and I had this discussion over beers at Friday Harbor. He has two chargers now.

I believe I have gotten good life out of the way things are, but both of my failures this year are over-heats. (Replaced the house bank over winter)

What have you done?

[kev_rm]

I am overly opinionated on this particular topic.. I don't think the cost per amp nor cost per lifetime amp hour of an AGM battery makes any sense in most boats. Tacking for days on end? Sure. Running 40mph off shore? Sure. Just not sure anything outside of that justifies AGM or other types of battery beyond classic flooded.

[Chart-table]

After discussions with my boat yard, we changed to all AGM's. separate chargers for house, start and thrusters. This was done more for convienience and ease of maintenance.

[Papa_Charlie]

Tally,

I am of the opinion that unless the batteries are inside where out gassing is of concern or the batteries are located where maintenance is almost impossible, I don't see the value in spending the extra money on AGM batteries. I have one under the master berth for the bow thruster but everything else is lead acid. Service is easy, I add water once a year, my charger/inverter maintains them just fine and replacement won't brake the bank.

[Norton_Rider]

"talman" post=821815 wrote:
.... it seems to me that you cannot have house and start on the same charger (like it is) especially if they are half AGM and half flooded.

AGM batteries are more sensitive to over charging than flooded cell batteries. The charger for either type should have charging curves that are optimized for the type of battery. Most modern boat chargers have selectable charging curves, but usually they do not have different curves for different banks. The solution is to use the same type of batteries throughout the boat or have multiple chargers, each set to the specific battery type that it is charging.

I agree with the rest here: replace the AGMs with flooded batteries.

[talman]

Thanks, all. Napa on Sunday. 10 percent off online, pick up in store. Wickus now has 4 new starting batteries and it didn't break the bank (AGM would have been a tough pill to swallow)

I regularly check my house batteries. This won't be hard at all.