question about acid.

[manikyath]

so, now that the clickbaity title is out the way, let me explain my issue.

recently i've got my hands on a 12 volt power supply with built in UPS, running off of two 6 volt lead acid batteries.

 

now, the batteries in case have probably been unplugged sitting idle for 15 years, and they're pretty dead.

the batteries are labeled "DM6-4.5" 6 volt, 4.5AH / 20HR.

http://www.diamec.com/dbimages/8_l.jpg

now, i know they say "sealed" and that you're not supposed to do maintenance to them, but i've spent my fair share of time in the world of private yachts, and the maintenance of them, and its more so a "the batteries arent made to be repaired" than a "they cant be repaired"

 

i've set to find out, and in fact the "sealed" top pops off quite easily with access to the cells. which brings us to my problem.

my batteries cap out at 3.8 volts, but they do seem to have at least some life in them, and i know in the world of yachts people often do something with the acid in the cells to get the batteries to last a bit longer. but i cant for the life of me remember what they did to it.

 

does anyone here happen to be an "expert" on lead acid batteries, and know which treatments exist, and which are the better/worse, expensive/cheap ones.

 

i have a charger made for 6 volt lead acid batteries, as do i have vareous loads to hook up to them for discharging in case necessary.

i'm not looking to get them "as good as new" because i know thats not realistic, but i kinda want to experiment with them before i ship them off to recycling.

[thekeemo]

http://batteryuniversity.com/learn/article/how_to_restore_and_prolong_lead_acid_batteries

is this helpful?

[kittywantsbacon]

Honestly, from my very limited experience though, don't try anything unless you're confident you know what you're doing.

[manikyath]

http://batteryuniversity.com/learn/article/how_to_restore_and_prolong_lead_acid_batteries

is this helpful?

my brain is a dud and pressed "mark solved" instead of quote, maybe i need sleep <.<

 

i've read trough that article, but it mostly seems common practisces to make batteries last longer, instead of actually bringing back worn out batteries.

[W-L]

-SNIP-

 

If your trying to revive dead batteries that are not recognized by the UPS you can try hooking them up to a variable power supply and charge them at around 6.5V at a fairly low current (<0.5A) to see if they hold a charge still. If they are still good and can be saved you should be able to keep a decent charge. 

 

As for topping them off some have those plastic caps they seal shut, while I don't recommend it you could theoretically pop the caps off and re-hydrate the battery with distilled water if they are low that tends to help if they are dry. You will want to glue those caps back shut to ensure it's water tight though since you wouldn't want acid to leak out of them in operation. 

[thekeemo]

my brain is a dud and pressed "mark solved" instead of quote, maybe i need sleep <.<

 

i've read trough that article, but it mostly seems common practisces to make batteries last longer, instead of actually bringing back worn out batteries.

adding water does something I think

[manikyath]

If your trying to revive dead batteries that are not recognized by the UPS you can try hooking them up to a variable power supply and charge them at around 6.5V at a fairly low current (<0.5A) to see if they hold a charge still. If they are still good and can be saved you should be able to keep a decent charge. 

 

As for topping them off some have those plastic caps they seal shut, while I don't recommend it you could theoretically pop the caps off and re-hydrate the battery with distilled water if they are low that tends to help if they are dry. You will want to glue those caps back shut to ensure it's water tight though since you wouldn't want acid to leak out of them in operation. 

i've put a charge on them for a good 5-6 days and they cap out around 3.8 volts, my specific batteries have the combination of a pressure fit plastic cap, and rubber seals per individual cells, so i'm quite secure leak wise.

 

if the battery acid has dried up, distilled water should at least help a little bit then? i'll see if i can check how much acid is inside them.

EDIT: yeah, they're dry as a rock inside from what i can see, i'm surprised they have voltage at all...

[Naeaes]

My uncle services cars and I followed him when I was younger. Can't remember much and don't know the correct phrases but what I can tell you, you're supposed to somehow know how acidic the acid needs to be and make a right mixture of sulphuric acid and distilled water. The thing he used to measure the acidity was a long glass tube and he looked how deep it sunk in the acid and there was a scale on it.

[manikyath]

My uncle services cars and I followed him when I was younger. Can't remember much and don't know the correct phrases but what I can tell you, you're supposed to somehow know how acidic the acid needs to be and make a right mixture of sulphuric acid and distilled water. The thing he used to measure the acidity was a long glass tube and he looked how deep it sunk in the acid and there was a scale on it.

well, since we're not quite doing fine science here, and i live in a place where even isopropyl alcohol is a problem... i might just poor some distilled water in to see what gives.

[iamdarkbowser]

I  remember something about epsom salt but I don't remember what to do with it exactly, @iamdarkyoshi used it before.

[W-L]

i've put a charge on them for a good 5-6 days and they cap out around 3.8 volts, my specific batteries have the combination of a pressure fit plastic cap, and rubber seals per individual cells, so i'm quite secure leak wise.

if the battery acid has dried up, distilled water should at least help a little bit then? i'll see if i can check how much acid is inside them.

 

One other thing you could try is adding a small amount of Epsom salts by dissolving it first in warm distilled water and adding small amounts to see if it boosts it's charge. There are also ways like desulfating to remove any build up of sulfates on the plates making it have more usable surface area.

[manikyath]

so, a quick status update - i started with the lowest voltage battery of the two, and added a few drops of distilled water to each cell, and it seems to  be doing better already.

 

while messing with it i've come to realise i know a "lead acid enthousiast" that has probably around 50kWh worth of lead acid batteries in his basement, i'll see if i can get a hold of him, he tends to be a tad hard to contact tho