Storing boat with solar?

[svlamorocha]

Originally Posted by Empty Pockets

6 x 6v GC2 flooded golf cart batteries (645 amp hours)
3 x 100w panels in series
I could easily take 2 panels offline and have only i panel charging if any advantage?

How long are you going to be away from the boat?

[Empty Pockets]

6 months-ish. As long as it takes us to hike the Appalachian Trail...

[svlamorocha]

Originally Posted by Empty Pockets

6 months-ish. As long as it takes us to hike the Appalachian Trail...

Originally Posted by Empty Pockets

6 months-ish. As long as it takes us to hike the Appalachian Trail...

6 months is too long for lead-acid batteries to stay disconnected.

5 watts of rated solar panel capacity is about enough to maintain for 100Ah of lead-acid battery capacity.

I would disconnect all loads (for this purpoise I prefer a physicall disconnect of a terminal, to kill any drains such as pilot lights, etc) and leave the the smallest panel connected. I am picky about that to avoid a heavy daily absorption cycle at 14.6V or so (which may "burn" some water) if the controller does not have a "storage" mode, and to minimize the risk from a bad connection getting hot (seen that!).

I believe that your charger does not have a "storage" mode and that you cannot program the absorption voltage down to a float sort of level , which is what I would do with a charger that does not have "storage" mode. You can make this up by configuring the cahrger for gel batteries, which should give you lower voltages (14.2V absorption instead of 14.6V, while keeping gfloat at 13.8V).

[Crew of Turning]

Yesterday Mar 19 2017 I reboarded our boat for the first time since late October of 2016. I had previously stated that I had disconnected my house bank and start battery from the solar panel and charger. All negative cables were pulled then, and reconnected yesterday. The start battery showed a charge of 12.5v with my cheap voltmeter and the house bank was a little better at 12.55 (which I got from the Link10). So leaving them on board during an Ontario winter had no adverse effect to their health. When I reconnected the charge controller and it was a sunny day, voltage started rising right away. Within 2 hours the voltage was 14.3v and 4 AH. I am only using a Flexcharge controller however the batteries were at float. Storing fully charged batteries without trickle charging does not destroy your batteries. In my opinion of course.

[a64pilot]

No it doesn't destroy them, however if you could have done a capacity check before and after storage you would note some capacity loss.
Stored in float, you will have some capacity loss too, just less loss.
Most of the time we replace batteries when the capacity loss is so great as to render them unusable, not when they can't be charged, and quickly coming back to what appears to be a full charge may not be a good thing, depending on the SOC you were at.
I don't know your battery bank, but look up the resting voltage SOC chart. If for sake of argument you have a 400 AH bank and resting voltage indicated a 80% SOC, yet your bank charged in a couple of hours by Solar, well you may have lost a lot of capacity.
Of course I hope not.

[ramblinrod]

Originally Posted by a64pilot

No it doesn't destroy them, however if you could have done a capacity check before and after storage you would note some capacity loss.
Stored in float, you will have some capacity loss too, just less loss.
Most of the time we replace batteries when the capacity loss is so great as to render them unusable, not when they can't be charged, and quickly coming back to what appears to be a full charge may not be a good thing, depending on the SOC you were at.
I don't know your battery bank, but look up the resting voltage SOC chart. If for sake of argument you have a 400 AH bank and resting voltage indicated a 80% SOC, yet your bank charged in a couple of hours by Solar, well you may have lost a lot of capacity.
Of course I hope not.

To many assumptions here mate. The panels may have only been putting out 2A. In which case, 2 hours to gain 4 a-hrs is fantastic.

Storage temp makes a big difference.

For Ontario winters, (avg. 0C - 32F) leaving the batteries without float has little impact.

Bahama winters, different story.