Rejuvenating Gel Battery

[runningman]

I have four 6 volt gel batteries that are ten years old. I just discovered that they have removable caps and the plates are dry. They are on their last legs, but is there anything I can do to help them hold out until a better time to replace them? I understand inverting them may help, or can distilled water be used to fill the cells?

[GordMay]

Greetings and welcome aboard the CF, runningman.

Gel Cells contain acid that has been "gelled" by the addition of Silica Gel, turning the acid into a solid mass that looks like gooey Jell-O.
Don’t add water.
Recharging gel cells requires a very exact regimen.
A 10 year life is pretty good.

[marc]

My gels are almost 13 years old, and so trouble free, that I almost forget that they're even there.
Marc

[capt_douglas]

It's possible that they were improperly charged somewhere in their very long life. While the battery has a gel/jello consistency, there is some moisture in the gel that can get cooked out if incorrectly charged.

If you want to attempt an resuscitation, I'd contact a battery supplier and chat them up. They may have some ideas, or possibly the equipment, bring the batteries back to life for a while. And 10 years is a very good life.

[noelex 77]

I have had great life from Sonnenschein gel batteries (18 years for the first set and 12 on my second yacht, with lots of abuse from the PO).
One trick that is worth trying is to test the batteries in the bank individually and keep only the good ones. They do not necessarily die at the same age.
I am still going with one of my original batteries it has about 60 % capacity left 18 months after the others died. I have new batteries, but the old one (seperated into a different battery bank) is still providing useful power.In fact it is all I have used for the last 18 months.

[runningman]

Thanks for all the advise; we are still working thru this.

[bobox]

I've got 225AH GEL batteries on my boat. Between the 3 of them I get about 120AH capacity (ie from 12.8v down to 12.2v) so they have issues.
They are almost 4 years old. Dont know how they were treated by the previous owner - not well based on there current state.
Nigel Calder suggests a number of options, one of which is to "kill the battery stone-dead". This means placing a 10a load on it until it gets to 1v and then finishing it off by short circuiting it and leaving it for a few hours. Then recharging it. He suggests this may recover some of the lost capacity.
I'm doing this right now to 2 of the gel batteries (I've got a spare cranking battery if it fails).
Just wondering if anyone has tried this and what were the results.

[FSMike]

bobox -
Had a friend who did that. Hooked up a 12v fan to the battery and let it run until it stopped. Then he hooked up a 12v light. It never did go out so when it got dim he shortcircuited the battery using a long screwdriver w/ insulated handle. He said there was a good sized spark, then nothing. He recharged the battery and it worked as normal. No idea as to how long it lasted, voltage readings, etc.
WARNING: If your battery blows up in your face it ain't my fault.

[hellosailor]

Gord, if the OP can actually SEE the plates, doesn't that mean the gel has in fact dried out, lost water, and shrunk down? So that adding just a little distilled water (and giving it time to rehydrate the gel) might be exactly what they need?

[bobox]

Aborted the battery kill procedure. I took a look at the gel and there are voids so I guess its been overcharged at some point. Can you add distilled water? There are opinions that you can and you cant. I guess people selling the batteries would say you cant. Has anyone tried it and did it work?

[hellosailor]

Well, if it doesn't work, what have you lost? Dead batteries? They already are that, right? Just add sparingly, and give it time to absorb into the gel.

[bobox]

Good point. I've taken a bit of the gel out and have added some water in a cup to see what happens.

[osirissail]

If you are in an area with access to Walmart's just go there and buy some new marine deep cycle batteries and be done with it. Reviving gel batteries is a short term loosing deal. There are much superior batteries around and even the liquid lead acid batteries now come "maintenance free" which means the caps are sealed. - - You only need "exotic" batteries if you are going sailing/cruising away from easy access to replacement batteries. The cost effectiveness of exotic batteries versus the standard liquid lead acid (sealed maintenance free) batteries is not very good. You can purchase a lot of new batteries for the price on one exotic battery.

[bobox]

Im at anchor at the moment so trying to keep the current batteries going until I can get somewhere to buy new ones. I found the gel did not absorb the water, it fell apart into grains, so I dont think its a go'er.
Have been tossing up between the liquid and AGMs. Here in Aus the difference between a liquid and cheap AGM is not much, particularly when your comparing it to the Trojen T105.

[osirissail]

Exide Corp bought up most of the battery manufacturing and brand names on batteries in the last decade. See if you can get their "Optima" Blue (Marine) batteries. They are AGM's but used in cars and trucks and are very durable and accept quite a bit of abuse. They are also priced very reasonable.
- - Normally your battery choice is constrained by the shape and physical dimensions of your battery boxes/storage areas.
- - The "maintenance-free" are the cheapest batteries as they are sealed and come in all the normal "auto/boat" sizes. At Walmarts the group 31 was $38 versus the same size marine AGM that was $380.
- - Next up is the quality Liquid-acid like Rolls/Surrettes, etc. Then come the marine AGM's that can vary from expensive to ridiculous.
- - IMHO, Gels are not cost effective and super-sensitive to abuse. The technology was revoluntary way back when but now the maintenance free and marine AGM have made the Gel's not the good choice for a boat. And the Optima series have put all of the small size batteries to shame.