Sealed Lead Acid Batteries

Charles in Aus.

Well-known Member
I have a number of these batteries in various uses at the farm , the small sealed brick types .
A few have been letting go lately , most of them were from the scrapyard originally anyway so I am not so concerned but it is a pain having to find replacements .

I pulled the stuck on plastic cover plate off the 'absorbed glass' [ whatever that means ] battery in the John Deere mower I just got , [it was flat and wouldn't hold a charge ] then the rubber caps off each of the cells , every one was bone dry . Filled them with water , charged for a few hours and all seems good !
Am I living in a fool's Paradise ? Surely this can't be more than a temporary fix ?
 
The absorbed glass mat batteries have a very limited amount of electrolyte, just what is soaked in the mat as I understand it.

That is what makes them work in any position and be able to be sealed.

It also makes them very sensitive to damage from overcharging.

Filling it with water "might" revive it, but will make it prone to leaking and making a corrosive mess. You might even can dump the excess out once the mat is wet.

If it works, go for it!

Those are available online, usually at better price than retail stores. Match up the amp hour rating and it should be the same dimensions.
 
Always run Yuasa batteries in our ATVs and Side x Sides.

They are shipped dry with the correct amount of acid. You add the acid and are suppose to wait X number of hours for the acid to soak into the glass mats before you charge them. If you fail to follow the directions, you will be luky to get six months use out of one. Normally we get 10+ years out of them.

They expand and contract with use. Filling one with water is not good. Doing so you will have a mess on your hands before long. I have saw people add an ounce or so of battery acid to each cell and letting it soak in over night to bring them back to life.
 
HELLO Charles in Aus,

If they are lead acid then 100% water will not give you the rated amp capacity of the battery. The mix is 35% acid to 65% water. better then dry, but the cells being that dry? not a good thing. At lest you will get some use out of them, although will be short lived,

Guido.
 
(quoted from post at 16:16:50 10/15/18) better then dry, but the cells being that dry? not a good thing.

Guido.

The lead plates are wrapped tightly with woven fiberglass type material. That material is what holds the acid. AGM type batteries are built to take a lot of shock and abuse thus making them idea for off road vehicles such as ATV's, SxS etc. With the glass mats holding all of the acid needed to make one work. They can be mounted any way you wish, even upside down and it does not effect them.

Not to fear.. Lithium ION car batteries will take over once the price of them gets down to be affordable for the average consumer.
 

Thanks for the information , especially about the absorbed glass .
Surely though any electrolyte that boils off leaves acid behind , only the water is lost . So by adding water you should in theory restore the acid to near to its previous strength ?

I did the same to the other ' normal ' SLABs that had lost capacity , all regained power , some to good if not very good , certainly enough to keep using them for lower amperage drains .

So I suppose I should drain some electrolyte out of the absorbed glass battery and see what happens next .
As far as the others go I will keep an eye on them and see if topping them up with water lasts more than a few weeks .
 
Am I living in a fool's Paradise ? Surely this can't be more than a temporary
fix ?

Some on YT say a carbon load tester is the way to tell if a battery is
healthy.

Midtronics makes a device that actually measure the output of a battery.

I've owned a midtronics conductivity tester for 6 years and find I'm no longer living in a fool's paradise
when it comes to monitoring the condition of my batteries.

I'm a fan of sealed batteries, especially on lawn mowers that bounce the acid
out the vents non AGM's.
midtrontics
 

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