Help diagnosing battery issue

[JPS27]

I’d like to replay my recent experience to get your advice on what might be wrong with my batteries or charger. Starting my engine has never presented a problem.

Two weeks ago, I started the engine as always, went sailing, motored into the slip. Last week I went to fire up the engine and was not able to crank the engine on. The batteries seemed to give an effort but not enough juice to bring the engine to life. I always turn off the shore power before I start the engine. Used my voltmeter and essentially got nothing, as in the number 1 flickered on and off.

But, with the shore power on and the charger on, the engine cranked on with some effort. It took enough cranks that I closed my raw water until it fired up.

Two days later I went back to puzzle over it some more. This time the voltmeter read 19 volts before I tried anything! Each battery separately started the engine no problem with the charger and shore power off.

I checked water levels. My batteries always need a little water every 5-6 weeks. They were not low this time but below full. So, I added water. After about 30 minutes used the hydrometer. On both batteries I got essentially the same readings. First cell in each bank was fair and the 2nd and 3rd cells were high and sometimes off the charts high.

I always have a little water in the battery box, very little, but it’s reactive to a spritz of water with baking soda. I’ve always wondered about this.

Batteries are over 5 years old.

Any thoughts on what might be going on or how to further diagnose? Is it a charger issue?

Thanks for any advice.

 

[Frank Langer]

Hmmm... I have never heard of 12 volt DC batteries showing 19 volts on a voltmeter. I think normal charging from alternator or battery charger is about 14.2 volts, and when charged, about 12.8 to 13.2 volts. And the reading between cells should be very similar.
Many batteries don't last longer than about 5 years, depending on how deeply and often they have been discharged, though they can last twice as long if "babied".
I'm no expert on this, but I'm thinking you will need new batteries. It may be helpful to tell us what kind of battery charger you have, and whether it's a smart, marine charger or a cheap automotive one, as that could also be part of the problem.
I'll be interested in what others think on this.
Frank

 

[Loren Beach]

Our boat came with an OEM 1988 ferro resonant battery charger. It had boiled the old batteries dry, and was on the way to ruining the two new ones installed just so that the owner could sell the boat. I replaced it with a new solid state charger. Years later I had to replace that one with a more modern one.
If the boat in question has an older charger, it may be way overdue for replacement.

That said, I would first check all of the wiring connections for connectivity and excess resistance. Remove and clean up terminals, one by one, and reconnect. Ground wires, and also the hot wires (+ and - ). Sometimes this saves a lot of anguish & trouble shooting things that intermittently function.

 

[Stuart 28-2]

I’d like to replay my recent experience to get your advice on what might be wrong with my batteries or charger. Starting my engine has never presented a problem.

Two weeks ago, I started the engine as always, went sailing, motored into the slip. Last week I went to fire up the engine and was not able to crank the engine on. The batteries seemed to give an effort but not enough juice to bring the engine to life. I always turn off the shore power before I start the engine. Used my voltmeter and essentially got nothing, as in the number 1 flickered on and off.

But, with the shore power on and the charger on, the engine cranked on with some effort. It took enough cranks that I closed my raw water until it fired up.

Two days later I went back to puzzle over it some more. This time the voltmeter read 19 volts before I tried anything! Each battery separately started the engine no problem with the charger and shore power off.

I checked water levels. My batteries always need a little water every 5-6 weeks. They were not low this time but below full. So, I added water. After about 30 minutes used the hydrometer. On both batteries I got essentially the same readings. First cell in each bank was fair and the 2nd and 3rd cells were high and sometimes off the charts high.

I always have a little water in the battery box, very little, but it’s reactive to a spritz of water with baking soda. I’ve always wondered about this.

Batteries are over 5 years old.

Any thoughts on what might be going on or how to further diagnose? Is it a charger issue?

Thanks for any advice.

Like Frank, I've never heard of 19 volts on a 12volt DC system either. You also said it showed flickering between 0-1volts on a previous visit ( if I understood correctly). Equally strange, particularly given the engine fired up without issue the next time. Even if the battery is dead (in terms of discharge) it shouldn't show much below 12 volts. Could be multiple issues including an issue with the voltmeter.
I've never heard of a charger failing in such a way that it outputs a significant increase in voltage.

 

[Jerry VB]

I’d like to replay my recent experience to get your advice on what might be wrong with my batteries or charger. Starting my engine has never presented a problem.

Two weeks ago, I started the engine as always, went sailing, motored into the slip. Last week I went to fire up the engine and was not able to crank the engine on. The batteries seemed to give an effort but not enough juice to bring the engine to life. I always turn off the shore power before I start the engine. Used my voltmeter and essentially got nothing, as in the number 1 flickered on and off.

I don't believe 1v is able to even click in the starter solenoid. If I understand the above, it cranked but not fast enough to start the engine? I believe you have battery and charger problems, but the 1v reading is not really believable either.

But, with the shore power on and the charger on, the engine cranked on with some effort. It took enough cranks that I closed my raw water until it fired up.

OK, sounds like battery (and probably charger) problems.

Two days later I went back to puzzle over it some more. This time the voltmeter read 19 volts before I tried anything! Each battery separately started the engine no problem with the charger and shore power off.

19v indicates the batteries are being severely abused by the charger. Or your voltage measurement is wrong. Likely both are a problem.

I checked water levels. My batteries always need a little water every 5-6 weeks. They were not low this time but below full. So, I added water. After about 30 minutes used the hydrometer. On both batteries I got essentially the same readings. First cell in each bank was fair and the 2nd and 3rd cells were high and sometimes off the charts high.

I always have a little water in the battery box, very little, but it’s reactive to a spritz of water with baking soda. I’ve always wondered about this.

You should not have water (acid, actually) in the battery box. This is indicating your charger is boiling your batteries either because the charger is bad or because the batteries are bad. Likely both.

Loren is probably correct:

Our boat came with an OEM 1988 ferro resonant battery charger. It had boiled the old batteries dry, and was on the way to ruining the two new ones installed just so that the owner could sell the boat. I replaced it with a new solid state charger. Years later I had to replace that one with a more modern one.
If the boat in question has an older charger, it may be way overdue for replacement.

Ferro resonant chargers are pretty crude and are pretty hard on batteries. If your charger is big, extremely heavy, warm, and hums when plugged in, it is ferro resonant. They don't regulate the charge current and voltage very well so they like to boil batteries which can kill the batteries pretty quickly. We had a trailer with a ferro resonant charger and it ate batteries for breakfast, lunch, and dinner. Partially my fault because I wasn't good about topping off the water in the batteries, but ferro resonant chargers should be replaced - a modern charger will pay for itself quickly in (avoiding) battery replacement costs.

Batteries are over 5 years old.

Due to be replaced, especially since they apparently have been abused by your charger.

Any thoughts on what might be going on or how to further diagnose? Is it a charger issue?

Thanks for any advice.

What is the charger manufacturer and model?

 

[JPS27]

Thanks for all the responses. They are very helpful. It may be all of the above including the meter. I replaced the battery on that and go readings of 12.60 and 12.68. That was with the charger unplugged for the prior 24 hours. I didn't try to start the engine as I was on my way to work.

I plan on cleaning the terminals although they look fine. I'm inclined to replace the batteries and the charger. See pics. The batts were purchased in 12/15 and the charger came with the boat, which I purchased in early 2014, so I have no idea how old charger is. But something's not right.

 

[Loren Beach]

Promariner is a good brand, altho I am not familiar with the ProSport 12. I recall reading that a 12 volt battery is considered fully charged at 12.6 volts or more. When our batteries are 'floating' on shore power charging, they read 13. 2, give or take.

 

[Frank Langer]

If you are thinking to replace batteries and charger, you won't lose anything by delaying those purchases while you problem solve a bit more, if you're so inclined.
If it were me, and I had the time and patience, I would clean all the connections as you mentioned even though they look ok, as resistance is sometimes hard to see. Then I would try to recharge the batteries (top up water levels first) for at least 24 hours. The charger should charge them at 13 to 14.5 volts, as measured by your voltmeter. If it doesn't show that when you start charging, or if the charge level is outside of that range, I'm guessing it's faulty. If it charges at an acceptable level, disconnect the charger after 24 hours and measure battery voltage. If it's above 12.6 (better would be about 13.0) I would try to start the engine. If the engine starts as it normally would, I would take the batteries to a reputable battery shop and have them load tested. They will likely want you to charge them fully again, disconnect from the charger and let them rest for 24 hours before they do the load test, but you can ask them about that.
If the batteries test ok, you could keep them and monitor the whole setup before spending lots of money on new battery and charger. If money is no issue, then clean connections, new charger and batteries may be worth the peace of mind and time saved.
Let us know what you decide.
Frank

 

[Jerry VB]

Thanks for all the responses. They are very helpful. It may be all of the above including the meter. I replaced the battery on that and go readings of 12.60 and 12.68. That was with the charger unplugged for the prior 24 hours. I didn't try to start the engine as I was on my way to work.

Sane DMM readings are good.

I plan on cleaning the terminals although they look fine. I'm inclined to replace the batteries and the charger. See pics. The batts were purchased in 12/15 and the charger came with the boat, which I purchased in early 2014, so I have no idea how old charger is. But something's not right.

The Prosport12 battery charger should be good - it's a "smart" charger with multistage charging that should not boil good batteries. FWIW, I installed the same model on my previous boat and it worked well.

Another diagnostic you can do: pop the battery vent covers off when the charger is on and the battery is nominally fully charged (DMM should read around 13.4v). If you see bubbles forming in all the cells, the battery is suspect. If you see bubbles forming in only some of the cells, that is a definite indication that the battery is bad.

Bubbles form when the charge current is high (excessive) - at 13.4v, the charging current should be low. If bubbles are forming in only some cells, those cells are sucking down excessive current because they are failing.

 

[JPS27]

An update, but no ah ha moments yet. This weekend I checked the batteries again as suggested by Jerry, Frank and others. I get 13.48 give or take .02 on each battery. when charging. With charger off, I got readings of 12.38 and 12.46. I started the engine fine with battery switch on batt 1 and then again on batt 2. I sailed for 4 hours on Saturday (chilly!). I don't run many instruments. Chart plotter, my signet knotmeter and depth sounder. Auto pilot was on and used it minimally. The engine started fine out on the water near the end of the sail.

What I still haven't figured out is why I have the acid cocktail in the bottom of my battery box. I'd guess I always have an 1/8 cup down there. I can see a little dried residue down the side of the batteries. Not so much on top. But there seems to be a little "sweat" sometimes on top. The batteries are never hot, or even warm for that matter. And every month when I check them I need to add water with my "turkey baster." Isn't that out of the norm? Would that indicate a bad charger?

 

[Frank Langer]

I don't know why you're still getting battery acid in your battery case. The battery level at 13.4 while charging is a bit lower than mine (14.2) and off the charger at 12.3 or so is definitely low in my opinion. After a complete charge mine are at 13.0 off the charger, after a day at dock (running my clock and LED volt meter) it is 12.9. After a night at anchor it will be down to 12.5 (refrigerator, lights, cd player, anchor light) but at 12.4 I'm wanting to start the engine to recharge.
I'm thinking your batteries may be a bit weak, so my next step would be to get them tested, after a full charge and a day at rest.
That's just my opinion, and others may have different views.
Thanks for the update!
Frank

 

[Loren Beach]

Another simple test: remove (ouch) and place each battery on some paper towels in a plastic tray. Observe closely for a day or three, for a crack and a leak from the case. That might explain why the liquid level goes down slowly. If that's the situation you will soon be replacing them anyway.

 

[Kenneth K]

My old charger never put more than about 13.5 volts into the batteries. When checking the voltage at the charger output terminal, however, it was more like 14.5 V. The difference was the voltage drop over the long (nearly 20 ft) and small (10ga) charging cables.

Even with my new charger installed, and new 8 gauge cables, I rarely have to add water to the batteries after charging. At the low charging volts you're getting, it's unlikely you'd be boiling out battery fluid. Sounds to me like you have a crack in a battery case.

 

[Leander]

Just a late reader picking up on an old thread. The burning question for me, reading through all the posts, is; Why hasn't OP ever said "I borrowed a voltmeter from my neighbor and with that 2nd voltmeter I also got sky high readings of 19 volts". There has been commentary on trying a different voltmeter by OP and others, but no mention of follow-through. A new voltmeter is much cheaper than a replacement battery or charger.

The reason I ask is because I don't think it is chemically possible to generate 19 volts from a standard 6 cell flooded battery. I believe the maximum possible potential between the lead plates and the lead dioxide plates is 2.10 volts per cell under perfect conditions, or 2.10 x 6= 12.6 volts per battery. (The charger generates slightly higher voltages, but the charge was reported disconnected.) Am I wrong? Did I misunderstand something? The only ways I can imagine a 19 volt reading are: having more than 6 cells hooked up in series, operator error, or a broken voltmeter.

Thanks for a great thread!

 

[Mr. Scarlett]

Promariner is a good brand, altho I am not familiar with the ProSport 12. I recall reading that a 12 volt battery is considered fully charged at 12.6 volts or more. When our batteries are 'floating' on shore power charging, they read 13. 2, give or take.

I seem to recall that those Prosport chargers are only good up to a certain size of bank.... And it's not very big.