Recharging an old battery...

Aug 7, 2011
496
MacGregor 26S Lakeland, FL
I have an old battery - old in age, not necessarily old from use. Was a house battery, was not old when pulled from the boat, and likely saw very little draw down in its former life.

It was on the shelf in the garage, and I had been okay about putting it on the charger periodically to keep it charged up. I tried to just keep it at a good state of charge so I wouldn't lose it. But I got busy and had forgotten about it for a while - a year or two? - and just pulled it back down. I don't have a ton of money to replace it right now - other priorities, so I decided to put it on the charger and see what happens. Charger is a typical 10/2/60A automatic charger with float.

Was showing 9.15V before I plugged it in. Set it on the 10A selection. It only took about 2 Amps for a long while, at about 13.4V from the charger, and then it slowly climbed up around 6 or 7 Amps. I left it overnight, and then I disconnected it from the charger for a while (rainstorm coming so I brought the charger inside). When I went to put the charger back on, the battery was holding 12.6V pretty steady.

So I put the charger back on and it has held pretty steady, taking between 4 and 5 Amps continuously, at about 13.8V across the terminals with the charger on. The battery is warm. Bubbles can be seen rising pretty frequently in the open water fill ports on top (yes, I left the caps off while charging). It has been on the charger now about 3 full days, and does not really show much sign of slowing down.

I'm not really worried about it, just want to know if anyone with real battery experience can tell me if I'm wasting my time or if this is normal, and the current draw will eventually drop down to the 2 Amps or less range where the low range of the charger will float it? (manual switch to the low Amp rating) It isn't in the way or anything, just sitting on the patio with the charger attached.
 
Jan 6, 2010
1,520
Vis,

I assume you are talking about a "flooded" battery & knot a sealed one.

House batteries are just that......a house battery.
Is it a deep draw or, more or less a starter battery?
Batteries like people, they get old & their capacity diminishes.

I, do not use flooded house batteries. I live in hot-n-sticky Florida & flooded batteries do not fare as well.
Vis, it's not always about price man, it's really mainly about what is sufficient for expenditure.

CR
 
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Apr 19, 2012
1,043
O'Day Daysailor 17 Nevis MN
I'm afraid Justin is probably right. To be sure you can take it to an auto-parts store and they'll check it for free.
 
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Jan 6, 2010
1,520
Really Guys?

It's a cheap old battery man, if cost outweighs logic,
I wish you all well however, each to his own.

Me, I want batteries that I can count on & why,
because my electrical power always gets me back to the dock.

I speak from years of experience & those with hearing problems,
you others should maybe get checked out, as you are now on your own.

I will also, now ignore this thread.............Amen,

CR
 
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Jan 1, 2006
7,040
Slickcraft 26 Sailfish
I don't know anything about batteries except what I've read from Maine Sail. Given his many detailed posts and tutorials on the subject of batteries, I would regard him as the "Battery Coroner." No need to take that one to any testing place. It has been pronounced dead. Have the funeral and move on.
 
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Sep 25, 2008
7,077
Alden 50 Sarasota, Florida
I've seen too many examples of mistreated batteries pronounced dead which were put back into useful service to make any declarative statement based on little information. It's useful life may likely have been shortened by carelessness but we can't know by how much. A load test after it is properly recharged which can reach acceptable electrolyte specific gravity is the only dependable way of actually knowing.
 
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Aug 7, 2011
496
MacGregor 26S Lakeland, FL
First, i'm extremely grateful that everyone was honest. As always, useful weight toward a decision. I realize that I didn't say, flooded battery, no starting required, 7-year warranty battery (not a cheap-o)...but that doesn't matter.

Let me say, I'm not a cheap-arse by any means. I just have a lot of "must-haves" looming ahead right now, and I'm having to weigh out what my limited resources will go toward. For example, I also live in FL with a lot of sun... I'd rather use those $$ on a solar panel setup than on the battery, if it means not having a solar arrangement at all.

And, I too fully respect Maine Sail's input, knowing he has a lot of experience. So I was going to ask if a "reconditioning" step might breathe enough life back into it to make it worth keeping. (I think I learned about that first on his site...) I just didn't expect to get such definitive death sentences for the battery! :)

I don't have a lot of electrical needs - pull start motor, LED lights, handheld GPS, handheld VHF (have an installed VHS, but don't really have to use it in our coastal waters). Mostly lighting needs, recharging the handheld stuff, fan for the cabin.

And...CaptnRon, you are forbidden from responding to this thread again. :p
(just kidding)
 

capta

.
Jun 4, 2009
4,766
Pearson 530 Admiralty Bay, Bequia SVG
Vis,I assume you are talking about a "flooded" battery & knot a sealed one.CR
Wouldn't "Bubbles can be seen rising pretty frequently in the open water fill ports on top (yes, I left the caps off while charging)." be a clue that it was a flooded battery?
 
Feb 6, 1998
11,667
Canadian Sailcraft 36T Casco Bay, ME
Wouldn't "Bubbles can be seen rising pretty frequently in the open water fill ports on top (yes, I left the caps off while charging)." be a clue that it was a flooded battery?

There were and are a lot of clues in the original post.



I got busy and had forgotten about it for a while - a year or two?
A "year or two" means a very sulfated and self discharged battery especially in a warm climate like Florida... If temps were in the 30's to mid sixties you'd be in much better shape but if temps approach 80F for more than a few months damage has been done. If temps exceed 90F at those voltages & duration it is the final nail in the coffin.

Charger is a typical 10/2/60A automatic charger with float.
The 10A or 2A settings would be been fine for a healthy battery.

Was showing 9.15V before I plugged it in.
At resting voltage (sitting for a year or two is certainly a resting voltage reading) a 100% dead battery occurs at about 11.4V. To take a battery to 9.15V is simply a death sentence unless you noticed this within a few days, such as a stuck bilge switch. Even then severe capacity loss damage will have been done to the capacity, I get to physically test for this many times per month.

I recently had a 3 month old battery bank delivering just 28% of its capacity rating after sitting for approx four days at a less than 0% capacity, 8.1V when the owner discovered the stuck bilge switch. The only thing attempting to keep the bank above 0V was the small 30W solar panel, which was really not much of a match for a stuck bilge switch. This capacity test was after very carefully attempting to recharge and equalize the expensive AGM battery bank. Nothing could save it and this was only four days and the bank still accepted current in a marginal fashion, much better than your battery is. Once you take it below 0% SOC / 11.4V, even for a short period, all bets are off...


Set it on the 10A selection. It only took about 2 Amps for a long while, at about 13.4V from the charger, and then it slowly climbed up around 6 or 7 Amps.
This is a prime example of severe sulfation. A battery at 9.15V should take everything that charger can throw at it on the 10A setting, for many, many hours before the battery hits absorption voltage. A severely sulfated battery can not accept the current into the plates at the rate it needs to..

I left it overnight, and then I disconnected it from the charger for a while (rainstorm coming so I brought the charger inside). When I went to put the charger back on, the battery was holding 12.6V pretty steady.
A full flooded battery should be resting at 12.70V to 12.74V after 24 hours. Still even a very damaged battery, lacking any real usable capacity, can still be charged to 100% so this number is pretty meaningless unless you know how much capacity the battery is actually storing.

So I put the charger back on and it has held pretty steady, taking between 4 and 5 Amps continuously, at about 13.8V across the terminals with the charger on.
By now the battery should have been full. A healthy full battery will get down to tenths or hundredths of an amp of current flowing into it at 13.8V.


The battery is warm.
At that voltage and current this is not a good sign at all and could prove to be dangerous. If you were at the tail end of an absorption charge with a high current charger you could experience a 10F to 15F rise in battery case temp but this should not be the case at your charge rate or voltage.

Bubbles can be seen rising pretty frequently in the open water fill ports on top (yes, I left the caps off while charging).
Your flooded battery should not be gassing at 13.8V and this is yet one more sign that the battery is well beyond useful life.

It has been on the charger now about 3 full days, and does not really show much sign of slowing down.
At 3 days of 4A (using your low end amperage number) you have thrown 288Ah's or more of charge at a battery likely rated at well under 100Ah's. It is simply converting that energy to heat, a dangerous situation. A healthy battery would be taking 0.02A or so to maintain 13.8V (on a smart good quality charger) your should have turned off by now... Your battery is not healthy and is bordering upon dangerous.

I'm not really worried about it
You should be because this battery could become dangerous when being charged...

just want to know if anyone with real battery experience can tell me if I'm wasting my time or if this is normal, and the current draw will eventually drop down to the 2 Amps or less range where the low range of the charger will float it? (manual switch to the low Amp rating) It isn't in the way or anything, just sitting on the patio with the charger attached.
This is not normal and yes you are wasting your time.

So I was going to ask if a "reconditioning" step might breathe enough life back into it to make it worth keeping.
Please, please, please do not attempt to equalize this battery. In that condition you will run a very high risk of grid fracture and creating a shorted cell..
 
Aug 7, 2011
496
MacGregor 26S Lakeland, FL
Wow! Thank you for taking the time to address this in such detail, Maine Sail! I hope this is also useful to others who may be in a similar situation! I definitely understand the risk you are describing, MS, and will cease attempting to revive it.

I just ran the battery up to AdvanceAuto for a quick load test, and they have confirmed that the battery is an ex-battery. I will put "New Battery" on the list of must-haves, and move other things around. Thanks again to everyone who participated!