How long can a starting battery sit?

[Sailmonkey]

Originally Posted by Chotu

OK. Sounds reasonable. What about just letting the engine charge it as you motor though? That’s a trickle charge, yes?

The engines are not meant to charge a battery, more to maintain one.

Either way, if these batteries have been sitting three years unattended and they’re dead now (what is the resting voltage if any) they’re toast. Like other posters have said, sulphation has done its work.

[Mike OReilly]

Originally Posted by deblen

My FLA's(house-deep cycle,start-common auto/truck)sit for 6 mos Nov thru Apr,aboard the boat,Neg wires disconnected,about same climate as NFLD. Have done this for 14yrs.
In Apr,they read 12.5. I hook up the Neg cables,start the engine & go.
They do get "grunty" at 5yrs old.
I replace them with like bats.
Works for me.
I also find that my road vehicle batteries work about the same way-except they get used year round.
Cheers/Len

Yup, same experience. Normal pattern is to leave them fully-charged and disconnected for six months. I've always come back to perfectly fine batteries. Recent Covid experience forced me to leave them for 33 months -- same outcome.

I really thing the so-called common wisdom about batteries and discharge rates is either wrong, or there's a lot more nuance to the equation.

[Chotu]

Ok, thanks for the input. I guess the answer here, combining all the posts, seems to be:

“Maybe they’ll work, maybe they won’t. Test the resting voltage, then try to charge them up.”

Ok. I’ll do that and see what happens. If anything, it’ll add a data point to the disagreement.


Thanks!

[rslifkin]

Originally Posted by Mike OReilly

Yup, same experience. Normal pattern is to leave them fully-charged and disconnected for six months. I've always come back to perfectly fine batteries. Recent Covid experience forced me to leave them for 33 months -- same outcome.

I really thing the so-called common wisdom about batteries and discharge rates is either wrong, or there's a lot more nuance to the equation.

It's probably a combination of things. Cooler temperatures mean slower self discharge and slower sulfation. Not all batteries self discharge at the same rate as well. And it's possible you got lucky and your batteries are performing better than spec in that respect. All of which could add up to only minor damage in the long run.

[deblen]

Originally Posted by Mike OReilly

Yup, same experience. Normal pattern is to leave them fully-charged and disconnected for six months. I've always come back to perfectly fine batteries. Recent Covid experience forced me to leave them for 33 months -- same outcome.

I really thing the so-called common wisdom about batteries and discharge rates is either wrong, or there's a lot more nuance to the equation.

Years ago,the local wisdom was putting a bat. charger on FLA's in off season.These chargers varied from 2Amp Can.Tire cheapies to quite sophisticated "float" chargers. The results were always the same--boiled bats. after a few months--down on electrolyte.Topping them up would buy you some additional months usage,but basically they were trash within the year.
Just my experience.Probably we were all doing something wrong. / Len

[mvweebles]

We keep a car at a mountain home in Colorado. If I don't keep a trickle charger (a modern float charge, not the old school constant 2-amp) on it, battery is dead (as in junk) by the following spring, even if the battery was new the previous year. After 3-years, my guess is there is a 1 in 100 chance you can recover your battery.

Maybe some sort of small solar panel for upkeep?

[Mike OReilly]

Originally Posted by rslifkin

It's probably a combination of things. Cooler temperatures mean slower self discharge and slower sulfation. Not all batteries self discharge at the same rate as well. And it's possible you got lucky and your batteries are performing better than spec in that respect. All of which could add up to only minor damage in the long run.

Agreed... which is why I've come to believe the common wisdom about batteries and self-discharge rates is inaccurate, or at least widely over-simplified.

When I was heading back to my boat after the 33 month forced hiatus, I was absolutely convinced my batteries would be toast -- there's no way they should still be alive based on the standard understanding. Even in NF, they sat through years of warm to hot months. And winter's aren't that cold here. And yet, when I tested them first-off, I got 12.5v on all batteries, and that included the cheaper starter battery.

These were not new batteries either ... at least five years old, and used as cruising batteries normally are; IOW, somewhat abused. I've now used them for the season and while they are definitely not in peak condition, they seem to operate like five/six year old batteries would.

So I don't understand it... Either I've got the best batteries made, or I got incredibly lucky, or (more likely) there's a lot more going on than our simple adages capture.


Chotu, I would do as you say: test the resting voltage when you get back to them. If they measure anything above ~12.2, I'd charge them and use them.

[MicHughV]

I'm certainly intrigued by this topic.

My history with batteries inside a boat has been a wild ride...make that a wild...and expensive ride.

I've come to the conclusion that something inside my body dischargers batteries as soon as I get near them is the reasonable conclusion I can arrive at.

I've often been asked by other boaters to come and look at their battery or charging system, but I always decline. People take this as being rude, whereas, I'm doing them a big favor.

[Sailmonkey]

Originally Posted by rslifkin

It's probably a combination of things. Cooler temperatures mean slower self discharge and slower sulfation. Not all batteries self discharge at the same rate as well. And it's possible you got lucky and your batteries are performing better than spec in that respect. All of which could add up to only minor damage in the long run.

That’s the other thing, the OP is in the heat of central Florida. And, if I read this correctly the batteries were left attached to the engines. Who knows what parasitic draws those have.

[Chotu]

4 volts and 8 volts open circuit.

But does that really mean I can’t charge them?

I am probably inclined to just get some new ones. They are just starting batteries after all. Shouldn’t be too expensive oh yeah. Inflation

[Chotu]

Originally Posted by Sailmonkey

That’s the other thing, the OP is in the heat of central Florida. And, if I read this correctly the batteries were left attached to the engines. Who knows what parasitic draws those have.

This is all correct.

It actually surprises me that they are not completely flat. I figured electronics would have some parasitic draw. They don’t seem to have any really.

[rslifkin]

Originally Posted by Chotu

4 volts and 8 volts open circuit.

But does that really mean I can’t charge them?

I am probably inclined to just get some new ones. They are just starting batteries after all. Shouldn’t be too expensive oh yeah. Inflation

You can try to charge them, but they may or may not ever come up to full charge. And even if they do, they'll almost certainly show severe capacity loss. I'd say you're best off replacing them.

[Wotname]

Originally Posted by Chotu

4 volts and 8 volts open circuit.

But does that really mean I can’t charge them?

I am probably inclined to just get some new ones. They are just starting batteries after all. Shouldn’t be too expensive oh yeah. Inflation

Originally Posted by Chotu

This is all correct.

It actually surprises me that they are not completely flat. I figured electronics would have some parasitic draw. They don’t seem to have any really.

4 & 8 V is completely flat!
They are toast, maybe good if you need a heavy weight somewhere.

[Chotu]

Originally Posted by Wotname

4 & 8 V is completely flat!
They are toast, maybe good if you need a heavy weight somewhere.

Well, not completely flat. That’s what surprises me. If there was a parasitic load (which there probably wasn’t since they are still putting out power), they would read 0v.

So they still have a little bit of stored energy. After all these years hooked up to very electronic outboards. Amazing

[Wotname]

^^ That is true!

Mind you, a single lemon cell will give you about 1V

https://en.wikipedia.org/wiki/Lemon_battery

So there might not be much capacity left in your batteries