winter battery care

[Steve W]

The years I "winter" in the water (at a marina with an excellent bubbling system!) I've been plugging the boat into shorepower and leaving the inverter/charger on and once the batteries are brought up to "full" (it's a 3-stage Freedom) it reverts back to "float" and there it stays for 5-1/2 months until I sail back to her summer home.

Am I damaging the batteries by leaving them plugged in all winter?

And the answer to question everyone will ask is they're 6-V wet-cell batteries.

And yes, I usually try to remember to do a equalization every fall before putting the boat to bed for the winter...

Thanks in advance for any information or education on this.....


Steve

 

[Don S/V ILLusion]

In theory, batteries should not be charged, even on float, constantly. My experience with our 6V battery bank, which some may disagree with but it is my experience, is that fully charging them in the Fall is sufficient IF they are good to start with. It won't hurt to periodically plug in during the winter if you can.
If you want to go through the academic exercise of calculating loss during the winter, most battery mfgs publish self-discharge rates which you can use to calculate loss over time. The Ample Power Primer also contains that info.

 

[Barnacle Bill]

What is important is to make sure the batteries are fully charged over the course of the winter, If they are, they will not freeze. If they are not fully charged, they will freeze and then crack the batteries (in most cases, but you might luck out) and then you throw them away.

 

[moehorenfeldt]

My boat is hauled at the end of October and stay on the hard until the end of April, in Toronto. I used to take the batteries home and store them in my basement. I use 3 wet cells, marine deep cycle from Walmart.
I now leave them in the boat, making sure they are topped up, and dry. I "visit" th boat periodically during the winter, and "plug" it in so that I can use the space heater while I'm in the boat. My inexpensive batteries last 5-6 years, but I replace all three together every 5 years. Works for me, anyway.

 

[Maine Sail]

In theory, batteries should not be charged, even on float, constantly. My experience with our 6V battery bank, which some may disagree with but it is my experience, is that fully charging them in the Fall is sufficient IF they are good to start with. It won't hurt to periodically plug in during the winter if you can.
If you want to go through the academic exercise of calculating loss during the winter, most battery mfgs publish self-discharge rates which you can use to calculate loss over time. The Ample Power Primer also contains that info.

Bingo! The only thing I will add is that if in the water, with bilge pumps connected, you'll probably want to top them up once every four weeks or so. If on the hard the colder the climate the slower the self discharge and they can be, and ideally should be, disconnected.

Perhaps the best option is to add solar and disconnect from dock power altogether to limit corrosion potential.

Lifeline is one of the few manufacturers that has studied this at length and their advice is to NOT trickle charge but that advice is for their AGM's...

 

[navigator97]

If they are Wet Cell batteries, you should top them off with distilled water (just don't over fill the cells). Then put them on a 3 stage charger for a day or so to top off the charge. When I do that I find that the batteries voltage level doesn't drop more than 0.1 Volt over the winter. Last spring they were down by by 0.04 Volt. I have used 12 Volt Wet Cell batteries, the last ones (5-1/2 years ago) were Die-Hard Marine Deep Cycle batteries. I will probably replace them next spring. I use them as both house and engine starting on a Yanmar 2GM20F. I alternate betwee Batt 1 and Batt 2 on consecutive uses.

 

[Steve W]

Thanks to all for the responses. It seems to me that the take-away on this is 1) top off the distilled water, 2) run the charger 'till the output changes to 'float', 3) unplug, and 4) go skiing for the winter .

Steve

 

[FourPoints]

Perhaps the best option is to add solar and disconnect from dock power altogether to limit corrosion potential.

Maine, Would you suggest I leave my batteries in the boat with my panel installed and maintenance charging via the genasun, leave them in the boat but disconnect them, or take them home?

 

[Maine Sail]

Maine, Would you suggest I leave my batteries in the boat with my panel installed and maintenance charging via the genasun, leave them in the boat but disconnect them, or take them home?

Disconnected.. That goes for the bank too.

You can install a switch in the OUTPUT + feed between the battery and controller and you can flip it on for a couple days at a time if you want...

The controllers do use power in stand-by and with the low sun angles you may actually use more current than you put back unless your panel is strategically angled towards the winter sun. Our boat will be next to the house and the panel will still not be left on and the batteries will still not be left on a shore charger...... YMMV..