AGM batteries

[R Baker]

I am entering the 6th year for my 6 AGM batteries. How long have others had acceptable service from their AGM's ? I know that responses may wax how well you have done this or that, but... the boats electrical systems are not designed to properly look after AGM batteries.

AGM (Deka / Penn) require a charge voltage of 14.4 V and are very sensitive to this voltage to ensure long life. The Promariner can be adjusted to provide 14.4; my solar panel provides normally about 13.9, but varies depending on the solar intensity; the alternator is set at 13.9 or 14.1 (mine seems to vary). There are means to equalize the batteries either with the Promariner or by the Solar panel which goes thru an equalizing cycle every 28 days. The Deka / Penn battery site has considerable info on these batteries.

All in all, the life of these expensive batteries is compromised by the installed charging systems, primarily the alternator output. It seems to me that since Ranger offers AGM's as an upgrade, they should include an upgrade to the voltage regulator to provide the required AGM voltage.

So, how many seasons have you run AGM's ?

 

[NewMoon]

New Moon's first AGM house bank (2 x Deka g31's) lasted 11 seasons. I replaced the stock alternator with a Balmar 912-75, and a Balmar MC-612 external regulator, set to proper AGM voltages. On shore power, the Freedom 10 inverter/charger was controlled by a Link 2000, also set to AGM voltages. New Moon has no generator, and anchors out ~3/4 of the time during summer cruises. The boat was plugged into shore power continuously while on the hard through the winters.

The AGM starting bank (2 x Optima 34M's) lasted 7 seasons.

 

[Cutwater28GG]

were the 11 seasons after you replaced the alternator?

 

[Levitation]

Flooded Battery
http://support.rollsbattery.com/support ... -batteries

AGM Battery
http://support.rollsbattery.com/support ... m-charging

This web site is a veritable treasure trove for battery afficianos :

In summary at 77 degrees
Flooded Bulk Charge at 15.0V and float at 13.5V
AGM Bulk Charge at 14.7V and float at 13.8V

(note in the graphs how the optimum voltage changes a surprising amount for a given temperature change)

I have cheap auto store "on sale" flooded batteries that are in their 6th season. ~$59 a pop at the time and I thought that was dear - HEY! I'm not cheap, just frugal
The charger is set for AGM to which I ascribe the longevity.
I do NOT let the water go down.
It takes me all of fifteen minutes to to pop off the cables blocking the caps on the battery and top off the water (real distilled H20, not faux) and get back to hammering down a couple of 6 packs of Yingling before cocktail hour arrives.

I would prefer a charger that bulk charges my flooded batteries at 14.5 and floats at 13.2 - but the world seems to ignore my obvious intellectual brilliance and superb physical handsomeness :mrgreen:

 

[NewMoon]

were the 11 seasons after you replaced the alternator?

Yes, did them at the same time.