Cooked my #1 battery, why?

[Pat T]

Had my boat (used) for 4 years prior and no battery (flooded) or charger (Newmar Phase 3 model PT-25) problems. I normally leave charger on and shore pwr. on when I depart boat. I disconnected batteries over the winter and once per month put a charger on them and in less than 1 or 2 minutes each battery was fully charged.
A week ago I connected everything and launched the boat and parked in the usual slip. Noticed a sulfer smell upon entering boat lately and found my #1 battery cooking, it was warm. This had been going on for maybe 5 -7 days. Checked voltage today and #1 was 10.2v and #2 was 12.5v. This was with the charger on.

Many questions for you guys. Why #1? Do batteries just decide to quit? Seems voltage is a little low for charging. Shouldn't I be seeing at least 14 volts charging. Is my charger toast also? I am resigned to the fact that I will purchase two new batteries. Since I bought the boat 2nd hand I don't know how old they really are. Could be time anyway? Before installing the new batteries what should I check besides charging voltage and making sure that the charger cycles off? Thanks for your inputs.

 

[Stu Jackson]

A good battery resource is at www.amplepower.com, click on the Tech tab and download & read their Ample Power Primer. It answers many of your questions. Batteries are like cars, they crap out at different times.

 

[Steve Dion]

I doubt that your batteries charged in 1-2 minutes. I think your batteries sulfated. If your charger supports an equalization phase, it may be time to try it now.

Be sure to keep an eye on the batteries and keep the water topped off.

Depending on the battery quality you may have outlived their service life.

 

[Ed Schenck]

I think your winter charging experience tells the story. Sounds like your charger was the problem. If you were seeing the batteries topped off in one or two minutes that is a signal I think. I would guess that the charger was starting and remaining in a full-charge state and never going to float state. Then when you left it on full time it cooked the battery it was connected to. You did not say what the battery voltages were when you started your monthly charge. But one or two minutes? I don't think so.

 

[kloudie1]

Older batteries may short across the plates and create the mess you are seeing. It may be only that and not the charger.. When sulfation or internal mechanical damage shorts some plates, the battery will take more current and that can draw down the charger voltage. The higher current generates a good bit of heat .. Sounds like a set of new batts and a check of the charger is in order..

 

[Pat T]

Thanks for the notes guys. Apparently it was a battery that had gone bad. I purchased 2 new Interstate batteries and installed them yesterday. The charger voltage went up to 14 volts plus and the amps gradually went down until the charger cycled off. All is well !
Interesting info on the amplepower site Stu. I wonder how many people actually break in their new batteries? Or maybe that's a question in a new thread.

 

[Stu Jackson]

Ample Power Primer

Interesting info on the amplepower site Stu. I wonder how many people actually break in their new batteries? Or maybe that's a question in a new thread.

Glad it worked for you.

I've been suggesting the Ample Power Primer here on this MB and others for years. Batteries do not come with Instructions for Use, so I figured since I found this material, I'd share it.

I do break in my new batteries and they last a long time. Others don't and they also last a long time.

What I can say, based on personal experience, is that the two worst things one can do to a bank is to constantly undercharge or over charge them. Due to my ski accident and subsequent second unexpected surgery, my batteries were horribly neglected between January 2009 and early this year when I finally got back to regular sailing and boat maintenance. The house bank is toast because I hadn't had my solar panel connected and I rarely leave my boat plugged in when I'm not there. And those who leave their boats plugged in all the time are doing damage as well, even with a "newer" 3 stage charger because keeping batteries on float all the time sulfates the plates, too. The newer Xantrex chargers, you will note, have "time out" functions, which is a very good thing.

I like the Ample Power Primer, but I can't make skippers read it, less do anything with it.

 

[jibes138]

Why leave it plugged in when not there?

When I leave my boat I always disconnect the shore power at the pedestal, to me this breaks the circuit to the ground wire on the dock reducing the galvanic problem with eating up zincs (I think). It also reduces the chance of fire since no current ging to the boat. I leave my car for weeks at a time and it starts right up when I return, so why all the concern with constantly keeping a charger on with a maintenance charge level?
I can understand if you are worried about the boat sinking and want to run bilge pump all the time when you aren't there but it seems like that is a risk worth taking. Not many boats sink at the dock as a percentage of all the boats and those that do were probably neglected.
It might be just as useful to run a submersible sump pump you can get at a hardware store and run that directly to the dock power if that is the concern.
To the OP did you keep the water level in the battery topped off? If allowed to expose the plates you may have really damaged the battery.

 

[Pat T]

Why leave it plugged in when not there?

Hey Jibes,
I can understand your reasoning and no doubt this works for you but my situation may be a little different. I run my 12 volt refrigeration while away. Like to have my beer, and other drinks, cold upon arrival! And these Catalina 36's are know for their poor insulation in this area. Consequently the refer runs a lot. I don't think anything has a bigger draw on the battery than the refer. I made the mistake of leaving my self unpluged on my previous boat and ran the battery down pretty good. I have never had a problem with galvanic corrosion. I'm lucky to change them every few years or so. I just check my engine anode a couple of days ago and put it right back in. Is this a fresh water benefit? Always keep my batteries topped off (distilled of course). If anything I had too much water as some boiled over into the tray.
Good discussions by all. Thanks again.

 

[jibes138]

I met a guy once who was checking a battery on the dock. He was taking a voltmeter and inserting the probes into each cell to make contact with the plates and checking from cell to cell that way looking for low voltage in each cell. Other than the acid eating up the probes it didn't seem like a good practice but does anyone know if this make sense as a check of a battery?

 

[Johnb]

If you have access to the cells even the most basic hydrometer will give a wealth of data. If all the cells are down evenly charge it up and see what happens. If just one is down then that cell most likely got an internal discharge and the battery is probably toast.

One bad cell will become a high resistance in series with the other cells. On charge the impressed voltage will be high without much charge being absorbed. On discharge it will prevent the battery from delivering much current.

I don't see poking around in the cells with probes being a good idea. Also proper safety precautions should be observed all the time, especially eye protection.

 

[Stu Jackson]

I run my 12 volt refrigeration while away. Like to have my beer, and other drinks, cold upon arrival!

Everybody's got their own way of doing things. I figure if I leave my fridge off when I'm not there it'll last longer.

Cold beer? That's why they invented 7-11!

There have been stories of folks leaving their fridges on and having the power interrupted or lost. If there's anything other than beer, like mayo or other "goodies" there's a heck of a smell and mess to clean up.

Your boat, your choice, and this has been discussed for years.

Have a cold one for me!

 

[Geoff K]

Ample Power also has a book called "Living on 12 Volts with Ample Power." It's an excellent source of knowledge about batteries and their relation to chargers, use and abuse, etc. It's better than anything I've seen in the sailing literature. I purchased the book about 7-8 years ago. At that time David Smead, the author, said little about AGM because they were so new. Perhaps he's updated since?

Geoff