Winter battery storage

[taoist]

I store my sailboat in Rhode Island and getting too old to be hauling the batteries off each winter. I have a solar panel that keeps the batteries fully charged during the season. If I leave panel uncovered and connected can I leave batteries in the boat for the winter?

[Dsanduril]

For the most part, yes, as long as they stay reasonably charged. As they discharge the electrolyte freeze point goes up, and if the electrolyte freezes then the batteries are gone (and you likely have a mess). We leave ours on the boat with a solar charger, but temperatures usually stay above 0F.

This is from Trojan:
Battery Storage Temo.PNG Views: 115 Size: 71.6 KB ID: 203412" style="margin: 2px" />

You might want to review their whole white paper, pretty useful. Note that self-discharge could lose 20% over a winter, but the cold really helps to reduce self-discharge.

[DDouglasone]

Originally Posted by taoist

I store my sailboat in Rhode Island and getting too old to be hauling the batteries off each winter. I have a solar panel that keeps the batteries fully charged during the season. If I leave panel uncovered and connected can I leave batteries in the boat for the winter?

Personally, I wouldn't but contact the mfr to see what they say. I have left batteries on boats without even having a trickle charger set up(2yrs with one) and just went about reviving it. It is still working and has a full charge as we speak.
Lucky? You bet. It's just a regular deep cycle and I had simply forgotten it because it was an extra and stowed in a place I don't normally use.
So, you could leave them and hope for the best but plan to replace them. If you don't, cool.

[kenbo]

You didn't say what type of battery, what type of solar controller you have and how often you'll be checking on things during the winter layup. But yes it can be done. This advice is for flooded lead acid batteries.

I would fully charge the battery first and then change the settings on the solar controller to max 14.3 VDC for absorption and then set the absorption time to 60 minutes. The setting will keep gassing and water loss to a minimum and prevent over charging.

Also if your controller is temperature corrected you should check with the battery manufacturer to see if there is a high limit on temperature correction. Many batteries do have high limits for cold weather charging.

[kenbo]

Originally Posted by DDouglasone

Personally, I wouldn't but contact the mfr to see what they say. I have left batteries on boats without even having a trickle charger set up(2yrs with one) and just went about reviving it. It is still working and has a full charge as we speak.
Lucky? You bet. It's just a regular deep cycle and I had simply forgotten it because it was an extra and stowed in a place I don't normally use.
So, you could leave them and hope for the best but plan to replace them. If you don't, cool.

How do you know that?

[NYSail]

I never take the batteries off my boat and don’t have solar. I full charge them prior to haul then disconnect them from the boat wiring so no “parasite” puts any demand on them. I’ll check the soc a couple of times during the winter and if needed I will plug my boat in for a couple of hours to bring them back up..... otherwise they are fine on boat. If you have solar panel attached you will be more than fine. Go to marine how to by Maine sail..... he has a nice article on this.
Many opinions....... this has always worked for me

Good luck

[kenbo]

That's why I said "how often will you be checking up on things". If you go there every 30-45 days and get there early in the morning and put the charger on for 6-8 hrs you may be fine. But sitting in any state of partial charge, even 90% SOC will result in a non recoverable loss of capacity. Even disconnected, a lead acid battery will self discharge at a rate dependent on the type. A flooded battery will self discharge at about 4-5% a week. So after 28 days your down to 80-84% SOC. It takes HOURS to bring that back to 100% and the charger better be temp corrected as well.

[Mike OReilly]

NYSail beat me to it. I've (almost) always simply fully charged my batteries, then completely disconnected them, and left that alone. I leave my boat for six months, or more, at a time. With nearly two decades of experience doing this, I've never yet had a problem.

Batteries are deep cycle, wet cell. I've always been further north than the OP; most years significantly so. But a few years I left my boat on the north shore of Lake Ontario (Belleville), which is still further north, but not dramatically so.

I do know of people who do as the OP suggests, and it also usually works fine. I actually tried this one year, and managed to kill my batteries (the "almost" reference), but I probably did something wrong .

[Dsanduril]

For cold weather storage (as is likely with the OP in RI) self-discharge is much less of a concern than in warmer climates. Self-discharge is a chemical reaction and is very temperature dependent - Trojan says a factor of 5 between 86F and 42F, and more like a factor of 10 if you get down to freezing.

From their stand test, at 86F a battery goes to zero SoC by self-discharge in 19 weeks, the same battery is still at 78% SoC after 19 weeks at 42F.

[kenbo]

This is from Rolls on battery sulfation. The emphasis added is mine.

Causes of battery sulfation:

Batteries sit too long between charges. As little as 24 hours in hot weather and several days in cooler weather.

Battery is stored without some type of energy input.

Undercharging of a battery to only 90% of capacity will allow sulfation of the battery using the 10% of battery chemistry not reactivated by not completing the charging cycle.

Low electrolyte level - battery plates exposed to air will immediately sulfate.
Incorrect charging levels and settings. Rolls recommends a 3-phase charge cycle (Bulk, Absorption & Float) and a charge rate equal to 10% of the C20 (20 hr AH rating) of the battery bank. See State of Charge & charging information.

A battery sitting for extended periods in a partial or discharged state is more likely to retain a build up of sulfation, which hardens and is more difficult to remove through equalizations.

Will the battery work come spring, yes most likely. Will there be a permanent loss off capacity, yes most likely.

[Maine Sail]

This may help:

https://marinehowto.com/winter-batte...aracteristics/













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[kenbo]

MS

Don't disagree with your article at all.

But I'm willing to bet that the great majority of sailors who lay their boats up for the winter don't completely isolate each battery, fully charge each battery with a regulated power supply to a tail current of less than 0.5%C, and then equalize each battery hoping to get to as low a level of sulfation as possible.

A solar panel with the controller adjusted for long term storage, will in my opinion, yield a very good result. And I bet a better result than can be achieved by most on on board chargers and the time it would take to fully charge each isolated battery.

[rslifkin]

I never remove my batteries for winter. For the times the boat has wintered in the water, it's plugged in, so the batteries stay topped off. On land, refrigeration and just about everything else is shut down, all breakers except cabin lights and the stereo are turned off (I don't isolate the batteries completely, as some of those items are useful to me when I'm at the boat), so there's basically no power draw. Any time I'm at the boat doing work, it's plugged in, so the batteries get a top-off. If I'm not doing work on anything for a bit, I'll go down and plug in for a couple hours every couple of weeks to make sure things stay charged.

[Mike OReilly]

Thanks MS. As always, your advice and recommendations, based on actual research, is incredibly helpful.

I can't say I'm as diligent (or anal ) as you recommend, but I'm pleased to see that my general approach seems acceptable. As I say, I fully charge my batteries using a proper 3-stage charger. This happens over hours or days. I then completely disconnect all leads from the batteries. This removes them from the boat systems, and completely isolates each one from the other.

When I come back to my boat, often six months later, I do a simple voltage test on each isolated battery before reconnecting. So far they have always showed healthy voltages.

I suspect this has a lot to do with my relatively cold haul-out locations, but as I said, even in southern Ontario (which can be fairly warm at times in the winter), I had no problems.

[thomm225]

I've always leave my batteries on the boat with the solar still hooked up.

Same with the car batteries but no solar there.

The boat is usually in the water so I like the bilge pump to have power mainly due to rain water accumulation

I usually will just use one panel in Winter normally a 65 watt panel, but when in the yard due to all the dust last year I used a single 20 watt panel with the controller's float set at around 13.6 volts

Temperature can get down into the single digits at times here