How much water should I add to old AGM battery?

[Sunking]

Quit kicking a dead horse and wasting our time. The batteries are Boat Anchors. Geez you do not even know VRLA = AGM. Northstar batteries are made for Telecom and completely useless for cycle service. So stop wasting our time and get rid of them at your local recycle center.

[davethedrummer]

Ideally a Valve Regulated Lead Acid (VRLA) battery will be charged at a low enough rate that no water will be "boiled off" to a pressure greater than the operating pressure of the valve. Once you have removed (or damaged the integrity of) the valve cap or caps you no longer have VRLA. The pressure is necessary to cause catalytic re-conversion of the elemental oxygen and hydrogen back to water inside each cell.

I guess you can't really see from the pictures but the caps are made of very soft and elastic rubber that is less than 1mm thick. I seriously doubt those caps would withstand any kind of pressure. There are no valves that I can see, unless they are calling those flimsy little caps valves? Seems like a bit of a stretch of the term.

Maybe this is an older design? Would be interesting to see if the "valves" on the new Northstar batteries are also just thin rubber caps.

[inetdog]

That's why I decided to only add 30ml, thought that might be a similar amount that might have gassed off over the years...?

Ideally a Valve Regulated Lead Acid (VRLA) battery will be charged at a low enough rate that no water will be "boiled off" to a pressure greater than the operating pressure of the valve. Once you have removed (or damaged the integrity of) the valve cap or caps you no longer have VRLA. The pressure is necessary to cause catalytic re-conversion of the elemental oxygen and hydrogen back to water inside each cell.

[davethedrummer]

Bear in mind that AGM batteries are 99% saturated with electrolyte. They are designed to be non spill able, in the event that a case gets cracked the electrolyte is supposed to stay suspended in the matting. Adding water seems like it would dilute the electrolyte to a lower specific gravity than a fully charged battery would like to see.

That's why I decided to only add 30ml, thought that might be a similar amount that might have gassed off over the years...?

[littleharbor]

Bear in mind that AGM batteries are 99% saturated with electrolyte. They are designed to be non spill able, in the event that a case gets cracked the electrolyte is supposed to stay suspended in the matting. Adding water seems like it would dilute the electrolyte to a lower specific gravity than a fully charged battery would like to see.

[Paul Land]

I have a total of 8 batteries so I went ahead and added 30ml of water per cell (that was yesterday). Tried to charge them up a bit (they got about 4kwh) today in a string of 4 batteries. 4 of them showed voltages of 16-19V while charging so those are no good. Kept rotating the bad ones out and of the remaining 4, one of them is giving me 15V, the other 3 seem be charging normally.

Disconnected them now and will test again tomorrow morning after which time I will charge them individually and do further testing.

Don't really know if the water did anything but hey it's worth a try rather than dumping them.

Reading SOC without LOAD can be deceiving a batt looks great till load is applied: no load 12.8-13v after load applied 10.5-12+-v
soc2.JPGsoc1.JPG

[davethedrummer]

I have a total of 8 batteries so I went ahead and added 30ml of water per cell (that was yesterday). Tried to charge them up a bit (they got about 4kwh) today in a string of 4 batteries. 4 of them showed voltages of 16-19V while charging so those are no good. Kept rotating the bad ones out and of the remaining 4, one of them is giving me 15V, the other 3 seem be charging normally.

Disconnected them now and will test again tomorrow morning after which time I will charge them individually and do further testing.

Don't really know if the water did anything but hey it's worth a try rather than dumping them.

[Paul Land]

[QUOTE=sdold;n392744]What does "2 yr warranty/cycle" mean?/QUOTE]

2 years covers manufacturers defects
cycle (Life Cycle) means, lets say in very critical setting ie: Tsunami warning buoys batts must be changed out due to wet, salt, heat, cold and vibration damage . If not thats why they fail and 100s Die.
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[sdold]

These are the batteries I have, they just mention VRLA, nothing about AGM... http://www.northstarbatteri.com/PDF%...r/NSB-AP~1.pdf

The specs in the cut sheet imply AGM. I wouldn't expect to get any service out of them.

[davethedrummer]

These are the batteries I have, they just mention VRLA, nothing about AGM... http://www.northstarbatteri.com/PDF%...r/NSB-AP~1.pdf

[sdold]

...and they have 2 yr warranty/cycle when there new....

What does "2 yr warranty/cycle" mean?

I think with batteries in the OP's state, any charge will be an over charge. These are a couple of Liberty LS12-100s that we recently pulled from service, left on a float charger well past their prime. At first glance they seem fine, but if you look closely, you can see what I believe are signs of oxidation (swelling) of the positive plates. These were installed 22 years ago and just pulled out of service.


libertys.jpg .

liberty batt 2.jpg

[Paul Land]

And does not mind bad batteries pushed beyond the end of their service life and blowing up. At end of life, AGM batteries are prone to thermal runaway while being charged.

Mike, you will find these Batts way up on-top that Mt, behind your house and they have 2 yr warranty/cycle when there new. they are a zero touch zero maint, back-up batts.

[Mike90250]

It's still useful. You just have to find a system that runs on 10 volts.

And does not mind bad batteries pushed beyond the end of their service life and blowing up. At end of life, AGM batteries are prone to thermal runaway while being charged.

[Paul Land]

I don't have the answer but I'm sorry your first post resulted in an unhelpful/unfunny answer. Stick around there are lots of good people helping out here and one of them more knowledgeable will help you out.

It's still useful. You just have to find a system that runs on 10 volts.

[davethedrummer]

AGM batteries are susceptible to sulfation, just not as readily as FLA. Loss of water (only) from the electrolyte will cause loss of capacity but NOT reduced open circuit voltage after full charge. Your voltages and lack of response to charging are most likely the result of irreversible sulfation, not overboiling.
As such, the door stop idea has merit, but the value will be greater as lead scrap. Any AGM battery over five years old, used or unused, is suspect.
However, I do not know of any AGM (sealed) batteries to which you can add water without drilling or using a hypodermic and then resealing to hold gas pressure.
I may try looking the battery up.
Old FLA, especially ones that have been sitting uncharged are unrecoverable because of sulfation. Door stop recommendation still applies.
IF (and a big if) electrolyte was actually spilled instead of boiled off, adding electrolyte rather than water might get you some very limited use.
If the tops of the plates were uncovered for any length of time, the battery will have lost capacity.

OK, that part number is indeed sealed AGM, so there will be no way to add water, period. That is why AGM batteries should never see an Equalize cycle with a high enough voltage and current to cause venting.

Thanks inetdog.

The batteries I have do have venting holes and upon taking the cover off there are 6 holes with thin rubber caps on them.

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