Battery Maintenance question

[Tim R.]

We live aboard and use a combination of 12v battery and 110v shore power. We have 2 Kyocera 130w solar panels under our clear(translucent) shrink wrap. Our house bank consists of two Lifeline 8D AGM Batteries (Installed 2008, Current Capacity 520 Amp Hours)

When we cruise, the solar is usually enough to handle all of our 12v power needs including refrigeration. Every couple of weeks I would discharge the batteries to about 50% and recharge.

Now that the solar panels are doing very little and we are at dockside, is it better to let the batteries discharge to 50% and then recharge or keep the chrager running full time?

 

[Maine Sail]

Tim,

AGM's don't like to sit discharged and it will shorten the life. Ideally they like to be recharged to 100% after each discharge. If the Truecharge is properly set, and you're using 12V power on-board, then I would just leave it on, provided it is set correctly.

The links below are a good read on AGM's, specifically Lifelines, by John Harries. He has 8D's like you. It documents his experiences & troubles with Lifelines, while off cruising. With your solar you should be in much better shape than John is.

AGM Part 1 (LINK)

AGM Part 2 (LINK)

Read all John's experiences with chargers, equalizing and, in general, Lifeline batteries. It is full of good information as is the rest of his site and he's a super nice guy to boot!

Next time I come over we can measure the condition of the batts with my tester and see if you are due for an equalization. After an equalization we can test them again..

 

[Roger Long]

The links below are a good read on AGM's, specifically Lifelines, by John Harries.

Wow. This is very interesting stuff. I can see that it's quite the challenge having cold drinks and all the comforts of home while cruising.

My AMG's seem quite happy after 5 seasons of living primarily off a regular alternator with built in regulator but I do a lot of motoring and have almost no electrical loads other than lighting and my small lap top computer. I live simply and buy ice. I didn't plug the shore power in once this season but I probably never draw my batteries below about 80%. I think I'll try to stick to that.

 

[kenn]

Tim, I don't think your solar panels will generate at their peak if they're under shrinkwrap. It would be an easy test to confirm this. You might get more of a contribution from the solar panels by setting them outside and angled for the winter sun.

 

[Witzend]

Question:
I fully charged my wet cell bat. bank (3, 4Ds) and then topped off the water, added maybe 1oz of distilled water/cell. By adding water after you charge will the bat. accept more charge if you tried to charge again ?

 

[rpwillia]

Probably minimal

Question:
I fully charged my wet cell bat. bank (3, 4Ds) and then topped off the water, added maybe 1oz of distilled water/cell. By adding water after you charge will the bat. accept more charge if you tried to charge again ?

Witz, I am thinking the amount of water you added was probably minimal, and the new water would get dissipated into the existing electrolyte. Don't think you will see much change.

Stu, I applaud that you did not plug into shore power at all this season. I did once in the Spring when we spent the night in the marina so I could run our portable heater. I have minimal loads running when I am not on the boat (usually only the bilge pump is turned on auto) and have a 15watt solar panel to maintain the batteries.

 

[Witzend]

I think your probably right, just wanted to see what kind of response I would get.

 

[Stu Jackson]

Stu, I applaud that you did not plug into shore power at all this season. I did once in the Spring when we spent the night in the marina so I could run our portable heater.

I've somewhat modified my battery behavior. I do plug in now at the end of the day to assure that when I do leave, and do unplug, that the batteries are fully charged. That's because I learned from my Link 2000 that battery acceptance is very important and those last few amp hours take a loooong time to put back in, and that one of the worst things to do is to leave batteries without fully charging them. We do have an 11 watt solar panel, too, so even if there are a few amps left to go before I leave, they're always fully back up to 100% SOC by the tiem I return, cloudy or not.