Can modern 3-stage chargers actually boil a battery?

[tkanzler]

I've had large, expensive chargers on larger boats, and small, cheap chargers on small boats, and I've never actually boiled a lead-acid battery down by leaving it charging in 'float' mode (as indicated by the LED light code). I also don't normally leave the chargers on for long unattended periods - mostly when I'm staying on the boat and am using power, or to freshen the batteries up before a trip.

I just bought a $133 (on sale for $100) two-channel Guest ChargePro 5/5A charger to top up the two batteries once in a while on the small boat I'm using now. It has a float mode that the manufacturer says won't overcharge the batteries. I only wanted it for the odd time I overnight on the boat - the Honda BF50 always kept the single battery I used fresh enough to start strongly, all summer long last year.

My FIL, with 50 years boating experience, swears up and down that any such charger will overcharge the batteries and 'boil them dry', no matter how good it is.

As a test, I combined both channels on that charger to one battery (WM branded Group 24 start/deep cycle combo that came with the boat) and left it on for two weeks, and the electrolite level didn't seem to move at all. Since it's old and I'll be buying new batteries this year, I didn't care about damage and just wanted to see what would happen, which was 'nothing'. Maybe I didn't leave it on long enough.

So which is it? Float mode will boil them down, or just the cheap ones will, or modern (3-stage) chargers won't boil them down at all, cheap or expensive. Is this just old-school experience (from my 80 YO FIL) that's no longer relevant, or is there something to it even today?

 

[Maine Sail]

Ignore your FIL.... He's from the days of ferroresonant chargers that did ruin batteries...

That said any charger even in float can boil a "contaminated" battery dry. It is very easy to contaminate and cause an early demise of a battery. IMHO some folks open up flooded batteries far too often thinking checking the SG often is a good thing.

Ever time you open the battery you run the risk of allowing contamination into the cells. Contamination can lower the gassing point of the batteries. I just swapped out a set of batteries two weeks ago that were gassing at 13.4V. Owner was insisting on how well he cares for his batteries by checking SG and checking water levels every few weeks. His batteries were very DIRTY on top. When I asked him to show me his hydrometer he opened a drawer full of rusty tools and pulled out a very dirty and contaminated hydrometer. Bingo... This owner very likely destroyed his own batteries by "thinking" he was doing the right thing.

*Check SG once per year, of if you have an "event"

*Keep your hydrometer 100% clean and rinse it/clean it only using distilled water.

*Before opening the batteries be 100% sure the tops of the batteries have been wiped perfectly clean using distilled water and a rag (microfiber rags work great here). If you pull the caps and there is still dirt near the hole pull the rag away from the hole NOT across it.

*Always keep your hydrometer in its own cleanTupperware or similar container with nothing else in there.Avoind sticking it in a drawer with other tools or in a tool bag or tool box....

That said leaving a battery on constant charge has risk. Many chargers are not nearly as "smart" as the marketing people make them out to be. Even small loads can send some chargers like the Guest units back into absorption mode and they can then stay there until they reach target absorption voltage for the set period of time.. I have seen one small charger that with the ships load could only reach 14.4V not the 14.6V that would trigger it into "absorption" thus the charger never got to 14.6V and it thought it was in bulk the whole time. The 14.4V over time boiled off the electrolyte before the owner checked it.

Truly smart chargers will remain in float, or will have an option to do a custom program, but they are expensive.

With healthy batteries a true "float voltage" will not "boil the batteries dry" unless there are other circumstances such as contamination. Your batteries should not be boiling at levels less than 14.2V (ideally, when in good health, 14.4V). If they are, they need to be replaced...

I've had large, expensive chargers on larger boats, and small, cheap chargers on small boats, and I've never actually boiled a lead-acid battery down by leaving it charging in 'float' mode (as indicated by the LED light code). I also don't normally leave the chargers on for long unattended periods - mostly when I'm staying on the boat and am using power, or to freshen the batteries up before a trip.

I just bought a $133 (on sale for $100) two-channel Guest ChargePro 5/5A charger to top up the two batteries once in a while on the small boat I'm using now. It has a float mode that the manufacturer says won't overcharge the batteries. I only wanted it for the odd time I overnight on the boat - the Honda BF50 always kept the single battery I used fresh enough to start strongly, all summer long last year.

My FIL, with 50 years boating experience, swears up and down that any such charger will overcharge the batteries and 'boil them dry', no matter how good it is.

As a test, I combined both channels on that charger to one battery (WM branded Group 24 start/deep cycle combo that came with the boat) and left it on for two weeks, and the electrolite level didn't seem to move at all. Since it's old and I'll be buying new batteries this year, I didn't care about damage and just wanted to see what would happen, which was 'nothing'. Maybe I didn't leave it on long enough.

So which is it? Float mode will boil them down, or just the cheap ones will, or modern (3-stage) chargers won't boil them down at all, cheap or expensive. Is this just old-school experience (from my 80 YO FIL) that's no longer relevant, or is there something to it even today?

 

[tkanzler]

Ignore your FIL.... He's from the days of ferroresonant chargers that did ruin batteries...

Thanks. I thought it might be something like that. I'm not going to argue the point with him, and given his age and hard-earned wisdom in most things powerboating (some of which is apparantly out-dated), and given that he's my most common sailing companion since MAIB is what he lives for, there's just no point. I'm not trying to win an argument - I'm just trying to learn something.

I only need this charger to maintain the batts now and again, especially when overnighting and using battery power, and I didn't even use a charger at all last year. I won't be leaving it on continuously.

But the subject of boiling out the electrolyte is something I keep hearing, and I've always questioned the veracity of such cautions given the state of the art and the claims by charger manufacturers that theirs won't boil them, so I thought I'd take advantage of an independent resource with nothing to gain one way or the other.

So, thank you.

 

[dlandersson]

FIL likely is thinking of 20+ years ago when it was an issue.

 

[DAVA390]

"MAIB" is ..what?

 

[tkanzler]

Oh, sorry. It's from The Wind In The Willows, by Kenneth Grahame.

`Nice? It's the ONLY thing,' said the Water Rat solemnly, as he leant forward for his stroke. `Believe me, my young friend, there is NOTHING--absolute nothing--half so much worth doing as simply messing about in boats. Simply messing,' he went on dreamily: `messing--about--in--boats; messing----'

MAIB = Messing About In Boats. :dance:

 

[Sailvayu]

Mainsail could you provide a source for information on battery electrolyte contamination?

 

[Maine Sail]

Mainsail could you provide a source for information on battery electrolyte contamination?

I learned this from Fred Wehmeyer (sp) at US Battery a number of years ago when dealing with a warranty issue that seemed odd. The relatively new batteries had cells gassing as low 13.2V and were chewing through water....

I spoke with Fred and asked my distributor to ship the battery back. I was told the electrolyte had been contaminated, which is what was causing the low gassing point. Despite this not being a "covered" warranty issue US Battery gave the customer two new US2200 batteries. Great company! The customer had used "distilled water" and even had it on-board. He had also been using a dirty hydrometer which is likely what caused the contamination. Could have also been contaminates on-top of the battery that fell into it when the cells were opened.

After all this transpired I had a long talk with Fred about how easy it is to contaminate batteries and what results from contamination, lower gassing voltages, cell imbalances etc.... I later had a similar conversation with Kalyan Jana at Enersys and he confirmed exactly what Fred told me. It is fairly easy to contaminate cells if you are not careful.

Since that event I have been able to see multiple instances of low gassing voltages with customers who open the batteries frequently and check electrolyte SG on a frequent basis. It seems the more you go in there the more potential for contamination you create.

Now that I know what to look for it is easy to help customer minimize these issues. Just keep the batteries and your hydrometer clean and always used distilled water and they will be in good shape. You can also contaminate the batteries by using the incorrect water but most people I know use distilled water.

If you want more detail Fred W. at US Battery is a wealth of information...

 

[Sailvayu]

Interesting I have not heard this before and have even used batteries that had oil in them with no issues. On one hand it sort of makes sense a contaminate could cause a chemical reaction but on the other it seems it would take a lot more than you are talking about. Honestly I have never heard anyone say this before but I am curious I think I will call US batteries on Monday and see if I can learn more. Thats why I love working on boats always learning something new. I will let you know what I find out.

 

[Maine Sail]

Interesting I have not heard this before and have even used batteries that had oil in them with no issues. On one hand it sort of makes sense a contaminate could cause a chemical reaction but on the other it seems it would take a lot more than you are talking about. Honestly I have never heard anyone say this before but I am curious I think I will call US batteries on Monday and see if I can learn more. Thats why I love working on boats always learning something new. I will let you know what I find out.

I never knew this either before Fred alerted me to it. What I tend to see is perhaps one or two cells gassing before the others. I suspect this type of behavior is more indicative of a dirty battery case with debris falling into a cell when it is opened or a dirty hydrometer with the pollution coming off in the first few cells tested.. It does not necessarily mean a dead battery. I have been able to adjust the float voltage down to a level below gassing and get another year+.. Some of the hydrometers I have seen have been so dirty the black tube is covered in tool rust. Once can only hope an owner would attempt to clean it before inserting it into a cell.

When I see all cells gassing at below about 14.4V then I have to suspect a a non pure water has been used.

Only in extreme cases will you see gassing into the low 13's but I have seen it. I do see quite a few batteries though that are gassing at 13.9V - 14.2V..

The easiest way I have to check for it is to use my bench top power supply and gradually bring the voltage up through the 13's and into the 14's and monitor when the cells start gassing..

 

[Chief RA]

solar panels

I am a Electronic & Industrial engineer (FCC lic.#1890) and was most pleased to read such a fine explanation on batteries and chargers! I learned some things!
This reminds me of how to double check that you do not necessarily need a solar panel regulator if you are max feeding no more than 2% of battery bank AH's. If your batteries do not need refill often then you know the panels are not causing problems.
Just got back from 3 months RVing in Arizona. Wife and I use inflatable kayaks on the Colorado and caught about 36 fish. One 18" largemouth and a 26" channel cat. Wife caught both of them! ha
Later, Chief

 

[Maine Sail]

I am a Electronic & Industrial engineer (FCC lic.#1890) and was most pleased to read such a fine explanation on batteries and chargers! I learned some things!
This reminds me of how to double check that you do not necessarily need a solar panel regulator if you are max feeding no more than 2% of battery bank AH's. If your batteries do not need refill often then you know the panels are not causing problems.
Just got back from 3 months RVing in Arizona. Wife and I use inflatable kayaks on the Colorado and caught about 36 fish. One 26" largemouth and a 26" channel cat. Wife caught both of them! ha
Later, Chief

May want to read and watch this: Do I Need A solar Controller

 

[dparilla]

For my nickel, I am surprised how often I see people using bottled water (spring water) to top up their batteries. Their thinking is that it is only a little bit here and there, but a seriously bad idea (even worse than tap water with the amount of solutes in spring water). It is especially stupid when distilled water is actually cheaper. I find that I am referring most of my fellow boat owners to your Musings and this topic is near the top of the list.