Have I shortened my batteries life?

[westwinds]

Originally Posted by sailinglegend

I've had some of my AGM batteries disconnected after load tests and they are still at 13.2 volts. It's called surface charge, which puts a higher charge on the outside of the plates than on the inside. This is one of the reasons that charging takes so long when the battery is nearly full. The surface charge has to migrate to the inside to "fully" charge a battery.

After seven hours resting for an AGM?

[sailinglegend]

Originally Posted by westwinds

After seven hours resting for an AGM?

I've added on my post: EDIT: After 4 days they were still at 13.2 volts, and these are 10 years old.

That was after recharging them.

After a 10 hours discharge they recovered from 12.09v to 12.3v in 30 minutes and to 12.36 after 6 hours.

[cburger]

I would like to make sure I do not let my fluid levels get this low again. I am by no means an expert with DC systems and have relied on CF for much of my learning curve. As a full time liveaboard by refrigerator is in use full time and as it has been my understanding that keeping the batts fully charged is beneficial to maximizing their life and with that thought in mind when in the slip the 40 amp Charles (No equalization) three stage charger runs full time to charge the Exide 6volt golf cart batteries. Both batteries when checked for the first time in a year each required about 1/3 of a gallon of distilled water to top off and some here have mentioned that this appears to be a lot of fluid all things considered. So am I missing or doing something wrong?

[nigel1]

I check fluid levels every 3 months. At same time I check and record each cells specific gravity, correct for temp, and record. Gives a good early indication if a cell is going bad.

[rw58ph]

If you check once a year being down below the plates is to be expected with a full time charge. For long periods best to have no charger. The windless bateries are hard to check, so the charger is turned off and they can go for 6 months. I check the main batteries ever month.

[foggysail]

Originally Posted by rw58ph

If you check once a year being down below the plates is to be expected with a full time charge. For long periods best to have no charger. The windless bateries are hard to check, so the charger is turned off and they can go for 6 months. I check the main batteries ever month.

That depends on the charger! Sure, one of the older ferroresonant chargers will boil out the electrolyte due mostly to a voltage spike in the transformer waveform. Unregulated chargers will do the same. I have gone two seasons with modern 3 stage charger plus solar without even checking the batteries.

The last time I checked my 27 cells, I did add distilled water but less than an ounce/cell.

[cburger]

So after the issues with the low fluid levels in the house batteries I finally got to looking at the starting batt today. So to my surprise it is an Exide zero maintenance battery with no caps and no way to inspect the fluid level. Battery is a lead acid and it has a little circle window about the size of a dime with a green indicator, model is called the "Classic". So what do I do with this just run it till it dies. Came from Sams club a year ago for about $80.00, was told they are installed in BMW's and other high end cars for around $300.00

[forsailbyowner]

People get so technical here. My last set of batteries lasted 6 yrs and would be around 12.4 cold after a full charge, but I never had issues with them, My current set, 8 , 6v were showing 12,5 two years old and hold that charge today. It doesnt drop below 12.5 overnite with the fridge running and watching movies for 3 or 4 hours before bed. I went on a 3 week sail recently running autopilot radar running lights fridge the whole night and still had no issues and never saw below 12.3. Im a believer in the epsom salt thing. 'When I top the batteries off I always do it with concentrated epsom salt/distilled water combo. Dont sweat it, the lead acid batts can take a lot of abuse. I dont have any regulation except turning things on or off and or turning off the solar or windgen.