Lazy battery maintenance.

[TomY]

Last season, my ancient hardware store 6amp dumb charger, died. I picked up the current hardware store 6amp charger, which is supposedly a smarter version. It turns itself off at a certain voltage.

Fair enough. But I was used to the dumb one, and used that -sort of- manually, watching the voltage. It would overcharge the batteries if left on too long(I never leave a charger or anything, plugged in when off the boat).

The only time I'd charge the batteries outside of the alternator, is at haul out time to top off the batteries for winter storage - and spring, before launch.

In season (sailing), they average nearly fully charged(90-95%?), with some deep discharges after days little engine use, followed by a near full recharge via the alternator.

Except for peering into the cells in the fall to check the electrolyte levels, that's been my complete battery maintenance program for 3 deep cycle grp 27's - the cheapest lead acid I can find - for twenty or more seasons.

I'm a little perplexed by my spring readings. I'm used to all three batteries (2 house, 1 start), reading 12.6V+ after sitting over the winter.

This past haul out, I charged all three with the new charger (turning OFF and ON, OFF and ON,...), at the beginning of November. I'm a little late this spring, getting the charger on them: May 1. That's 6 months of storage over winter, on the boat, no charging.

But before I connect the charger or take any load off the 3 batteries, I do a spring voltage check. The voltage tells me the condition of the batteries and when they need to be replaced.

I got 12.6V on both of the house(which I expect from experience), which are the newest(2 seasons old).

Then I checked the starting battery, which is a combination start/deep cycle( I've read that doesn't mean anything), which is 3 or 4 seasons old, and got this reading.

I'm wondering if my meter, which is 20-25 years old, is suspect? Or does the combination battery have a slower self discharge rate(I've noticed it reads higher, generally).

Or, is my new charger the blame? I usually charge the house batteries in tandem with my switch set at BOTH and all circuits off. Maybe I should charge them individually with the new charger?

My lazy battery maintenance program yields an average life of 5 to 6 seasons for cheap deep cycle lead acid batteries.

 

[Maine Sail]

Self discharge in, Maine, in the winter, is pretty close to nil. If you charged to 100% in Nov, the temps have been cold enough that your batteries have likely not been above 50F since. A fully charged battery, such as the deep cycle versions you have, should have a full charge resting voltage of about 12.71V to 12.74V, when healthy, and the dual purpose can be slightly higher often 12.74V to 12.78V.

Your house batts are most likely suffering, which is not surprising since they are not really a deep-cycling battery, more so a "light cycling" battery, and your start battery is probably doing quite well. The fact that the start battery is doing so well is not surprising since it really does not do much.

For most healthy flooded batteries, when I charge them in the fall, then 100% disconnect & isolate them, the spring voltages are normally still above 12.70V. When I find voltages lower I begin to suspect sufficient capacity loss. For example I had a healthy Crown G-31 in my shed all winter. In the fall, mid November, it had been equalized and stored. When I retrieved it the last week, to re-install on the customers boat, the resting voltage was still 12.83V or a "surface charge." At 80F this battery will hit about 12.73V after 30 +/- hours rest. When it's cold it can rest for months and not dissipate all of the surface charge.

Rx - Time to EQ the house batts.

If they can't maintain 12.71V or close to it, for more than 2 days at 80F (actual battery temp not air temp) they are suffering. Alternatively, you got two years, try pushing a third and replace at 4. Based on years of testing these batteries, here in Maine for mooring sailed boats, they are usually technically dead (by industry standards) by year two or three when put into a cycling situation. You can sometimes push them to 4 or 5 but this is where I begin to see a significantly higher incidence of failures such as internal shorts & crumbling plates.

 

[TomY]

Thanks, Maine.

And still many will tell you that leaving the batteries charged and disconnected over the winter, will harm them.

I'll charge the 2 house independently to see if I can bring them up. I fear you can't get a high enough voltage from my 'smart' charger. I only put them in and take them out of the boat, once.

It's been the relationship of the open voltage readings of my 3 batteries, that's told me the most about each. Set on 100ths, you can age the batteries easily, in relation to each other. Once one begins to vary a 10th or 2, I know it's gone.

I usually don't know how old they are until I pull them out, and see the date label. Maybe I'll find the 2 house are older than I suspect, when I replace them(probably next season).

I run them the same way-simple: On the boat, the house switch is set to BOTH, discharging or charging, no isolation between the two. Then OFF when we leave the boat. Next time on the boat (days later, week), I check the open voltage of each.

I do run the windlass off the starting battery, usually before starting the engine(rope/chain-not much). Still, that starting battery is always fully charged.

The charging is via a 70 amp balmar 2 output.

 

[Gene S]

You should borrow a newer meter to compare. I have a cheap one on the boat just for quantitative readings and thought the new solar setup was not charging enough. I got my newer Fluke and found that the cheap meter was reading about .3 volts or so low.