Battery Water Level

[Stu Jackson]

I've been advised by fellow boaters that I should leave the shore power plugged in and battery charger on as a precaution in case I develop a leak and bilge pump does its job it will eventually draw down the batteries and the water will flow in and sink the boat.

What you really need to do is learn how things work, and stop listening to people. Why? The old "saw": ask three skippers for opinions and you'll get four answers.
For example, this question about a bilge pump and your boat sinking. Are you in a marina? Do you have a cell phone? How far away from your boat do you live? How long would it take for you to get to the boat if you got an emergency call?
And: How many reports of this occurrence, other than the idiots on your dock, have you ever heard? I've been boating for eons, and simply haven't heard of this. One boat in our marina started to get low in the water, skippers on the dock told the marina, the skippers rigged extra dock lines to keep it from sinking lower, the marina got a pump to the boat and saved it. Once in the 35 years I boated in the SF Bay Area. Once.
AGM batteries have their own "issues" which you should know about first before you spend unnecessary $$ on them. They are not a cure for your lack of knowledge or deferred routine maintenance.

I had my local shop ... replace two batteries and install an intelligent charger in August of 2016.

That was two years ago! Could have done a lot of reading and learning in that time. I believe that in this internet age there is absolutely no excuse for not learning.
Here's a place to start: (and includes a few AGM threads you MUST read)
Electrical Systems 101 http://c34.org/bbs/index.php/topic,5977.0.html

Finally, we'll ask again:
WHAT CHARGER?

Randall, good luck, but your repeated "I was told" is essentially a "tell" (pun intended). The information you seek is out there, without too much effort on your part.

None of us was born an electrician, we learned. Admittedly, some folks can't. I recognize that - some of my friends are artists and turning on a table lamp is actually hard for them!!!

But, you own a boat. You need to learn about its systems and how to take care of them. Think about it as analogous to mowing your lawn - something ya just gotta do. To avoid more of the "tells."

If you'd just bought your boat, I'd understand more, but two years?

Don't buy sealed wet cell batteries. Why? Cuz you can't add water.

Again, good luck, happy learning.

 

[Ward H]

What you really need to do is learn how things work, and stop listening to people.

Kind of negates the purpose of the forum, doesn't it?

I can't add anything of value to the advice already given but I can give you a benchmark.
My O'day 25 had a single Grp 24 wet cell battery. It was charged each spring before launching the boat. I would day sail 2-4 hours at a time using my Garmin GPS, standalone depth sounder and tiller autopilot.
The only charging was from the outboard motor which at full throttle might produce 6 amps. It would run at half throttle for 30 to 45 minutes each time I went out.
I'd go for 25 to 30 day sails before I would put a charger on the battery to top it off.

With your amp draw and day sailing, with two batteries I doubt if there is a need to keep the charger plugged in all the time unless you don't get to the boat for weeks and there is no one around to notice your bilge pump running a lot.

 

[Davidasailor26]

I don't think AGMs are a terrible idea in this case. Yes they have their own challenges and you still need to pay attention to your charging system, but they do solve some of the OP's problems. In particular it means not needing to empty and undo the quarter berth every month to check fluid levels. Yes you need to check charge voltages but that can be done with a remote volt meter combined with a check of the connections every 6 months or so.

 

[Don S/V ILLusion]

I blame this on questionable design. Batteries, regardless of type, should never be inaccessible. It is an invitation to problems.

My car is similarly designed in that the battery (AGM) is in the trunk under the spare tire. It's a weekend project to inspect even the connections.

At least with a boat, there is greater flexibility for locating batteries using common sense.

 

[Gunni]

1. Have I done damage to the batteries by not paying attention to the water level for so long?
2. with a properly functioning and well maintained battery how often do I need to check the water levels?
3. Could my intelligent charger be defective and causing the battery water levels to decline so rapidly?
4. Do I replace the batteries with sealed units or upgraded lithium batteries?

1) yes.
2) in use, every month. Winter layup, every other.
3) unlikely, but Zimmerman can answer that question.
4) If you don’ want to clear the debris from the battery bay, yes. I haven’t checked my Lifeline AGM battery fluid in 3 years. No need to. I paid extra for that feature.

 

[Stu Jackson]

I don't think AGMs are a terrible idea in this case.

He still hasn't told us what charger he has. Soooo, if it's too small for his house bank, he'll kill AGMs right away. You know, after all that expense.

it means not needing to empty and undo the quarter berth every month to check fluid levels

Would it not be prudent to find different locations for gear? It's not a 22 foot boat where you have to keep moving stuff. I have cushions I need to move to gain access to some stuff, but I prioritize where stuff goes to minimize moving stuff for regular access. I think we all do that. They're boats...

 

[dlochner]

If your batteries are in a place without proper ventilation, like many boats built in the '70s and '80s, I would agree with the above recommendation and replace with AGMs, just for safety. Vented batteries release hydrogen, same gas as the Hindenburg.

The amount of hydrogen that can be released from a battery is pretty low. About the only condition that a battery can explode because of hydrogen is one in a tightly sealed container that is being over charged. Hydrogen is the lightest element, it will rise and escape from any area that has some ventilation. A bigger problem is the off gassing of sulfuric acid which will corrode stuff, cause over heating and then a fire.

When batteries "explode" I suspect the real culprit is a poor charger that is over heating the batteries and then there is a short.

A while back we had this discussion about hydrogen gas. If I recall correctly, @thinwater did the calculations about how much hydrogen could be generated from the acid in the battery. It wasn't much.

 

[FastOlson]

Perhaps I missed it, but the type of battery charger may not be appropriate for this usage. When the OP's boat was built it was common for boats to have a ferro resonant charger installed. That type of charger technology will boil off water from standard flooded batteries. Ours came with one installed new in '88. I replaced it with a solid state multi stage charger. The boat had dead (cooked) batteries in it when we bought it in '94.
Since then I only need to add a little water a couple times a year.
Those 'old technology' chargers are only useful if you check the battery water level really really often (IMHO).

Anyway, good luck in solving the mystery.

 

[MikeHoncho]

Hydrogen has a lower explosive limit of 4.1 percent in atmosphere which is almost twice as much as gasoline vapor as a reference. This means you need 4.1% hydrogen in a given atmosphere for that atmosphere to become flammable/explosive. It has a interestingly very high upper explosive limit of 75% but that is irrelevant to the discussion.
I have experienced the main culprit with battery boil over from chargers (smart) in battery banks is a single bad battery and the charger senses the lack and kicks up the amps, heating up the others, causing your symptons.