What are the symptoms of serviceable batteries with low water

[Capt Robbie]

Three years ago I changed out my house and starting batteries with what I was told were not serviceable sealed batteries. As I found out today that the batteries are serviceable. Concealed under the manufacturer label are filling lids to add water.
Needless to say not happy with the company that did the work!
Lied to.
Now I noticed last fall that the batteries didn't seem to hold the charge as when they were new. They tend loose about 15% of charge when not being used for about three weeks. They also Appear to discharged slightly quicker now under normal use. They all charge up quickly and read 12.4 volts. They all read 12.4 volts after charging and appear to be good.

I have never had serviceable batteries on my boat before, I always had sealed batteries for a few reasons.
1st was for convenience one less thing to maintain and
2nd was I was concerned about possibly of leaking when the boat is under sail.

My questions and concerns are:

1) I have never inspected the water levels for the past three years, is it safe to open the fill lids with out knowing what the water levels are, if any? I don't want to get burned by acid.

2) What are the symptoms of low water in your batteries.

3) Could the batteries have been damaged.

4) If they are extremely low, can I just refill with distilled water and bring them back to 100% again?

5) Should they be inspected like my lawnmower battery every 6 months?

6). How can I test my batteries to see if they are damaged other then a volt meter?

I have asked automotive techs and have yet to get a consistent answer.
I am sure that others have forgotten to inspect batteries before.
Maybe not as neglected as mine are.
What should I do?

 

[Davidasailor26]

Sounds like there are a few things going on here. First, non-serviceable flooded batteries are a bit of a compromise, since they can still lose water the same way a serviceable one can, and there's no way to restore the water. In the future if you like the convenience and leak-proofness of sealed batteries you could consider AGM's, which don't lose water at all. Of course AGMs have their own considerations and you can check Maine Sail's posts in the archives for plenty more comparison between flooded, sealed floooded, and AGM.

If your batteries are only charging to 12.4 volts something may not be right. Full charge for lead acid 12V batteries should be over 12.6.

It should be as safe to open the batteries now as ever - maybe actually a bit safer if there's less water to splash. Just wear gloves and goggles in case anything does splash (and old clothes).

If the water level is low (below the tops of the plates) you will have reduced capacity. You can try to refil with distilled water and see if any of the lost capacity comes back. Exposing the tops of the plates may have caused corrosion that can't be reversed. In the future definitely check them routinely (6 months sounds too long) and add water as required. How much water they use will depend on charge rate and duration.

You can try to refill them, perform an equalization charge, then check the specific gravity and do a 20 hour drain down test to see how healthy they still are. Maine Sail has described the 20 hour test in the archives. And obviously if he chimes in with any other guidance I defer to him.

 

[Maine Sail]

#1 "maintenance free" batteries, unless deep cycle AGM or GEL, are a very poor choice for a cycling house bank.

#2 "Maintenance free" batteries are designed to be filled to a very precise level by the factory and over filling them, even slightly, can be dangerous. This is why manufacturers often hide the valves under stickers. Any tech crazy enough to fill "maintence free" batteries deserves the liability that comes with that. If indeed the batteries were labeled "maintence free" the tech was simply doing his job correctly and safely.

#3 Charging fast, meaning quickly rising voltage when you turn the charger on from a low SOC, is a sure sign the batteries are shot.

#4 A resting voltage of 12.4V, when not charging, means a ballpark SOC of about 70%. A fully charged flooded lead acid battery will rest at 12.70 - 12.74V.

#5 Any portion of the plates that become exposed are now dead and the capacity is gone.

#6 Serviceable batteries should be checked for electrolyte level at least every 3-6 months.

#7 For the type of battery you describe 3 years is not a horrible service life. A real deep cycle designed for true cycling service can easily go 6-10 years if well cared for.

#8 Your charger likely a contributing factor to the poor health of the batteries. There are far too many bad chargers out there that claim "smart" that are not. If your charger does not have an on battery temp sensor it is not smart. If it can not be properly set to match the manufacturers charge voltages for absorption and float to within +/- 0.1V it is only adding to the poor service life.

#9 Your use practices are also likely negatively contributing to the demise. Your batteries should not be discharged regularly below 12.2V, even under your average house loads. They should then be charged to the point where a resting voltage, after 12+ hours at 70-80F yields a resting voltage of 12.70 - 12.74V.

#10 If you've been accepting 12.4V or so as "charged" the batteries are sulfated and likely done for. All lead acid batteries need to get back to 100% SOC as often as is humanly possible to minimize the murderous effects of sulfation.

 

[Ralph Johnstone]

Three years ago I changed out my house and starting batteries with what I was told were not serviceable sealed batteries. As I found out today that the batteries are serviceable. Concealed under the manufacturer label are filling lids to add water.

What leads you to believe that they ARE serviceable ?

#2 "Maintenance free" batteries are designed to be filled to a very precise level by the factory and over filling them, even slightly, can be dangerous. This is why manufacturers often hide the valves under stickers.

From this, I would assume that they ARE "Maintenance Free". If you can find a model number on the batteries, it might be worth Googling (hate that word) to see if you can get the manufacturer's information on them.

 

[Capt Robbie]

Contacted Deka the manufacturer of all of my batteries today and they assured me that if I open the lids nothing bad would happen provided the isolator switch and battery charger is off.

They told me that my batteries have a normal life expectancy of 5-7 years which depends upon use of course. They said normal care of batteries is cleaning terminals checking connections which is what I have done on regular basis. They said that checking water level should be done yearly and absolutely at the thee year mark. They said that it is rare that the fluid levels would drop even after three years and even during the expected life of the batteries.
Over charging is normally the cause of a batteries going bad. Fortunately I have a charging system that was properly size for my system everything is fine.

They recommended I have a load test done to put my mind at ease.
Tech test all batteries load and they all tested good.
The tech told me that Deka batteries rarely ever need to be serviced, and he personally has only had to add water to this brand a total of five times out of about four hundred units. He also added that the ones he had serviced were being over changed and not properly sized. Nevertheless he said to check the water levels once a season not a bad idea.

This is a load of my mind, I really thought I killed my batteries.
Guess I dodged a bullet this time.

Thanks for everyone's comments.