AGM Experiment

[Lin]

It seems my three Group 31 AGM house batteries really do not hold are charge anymore.  I was looking at getting some new ones and came across a place that sells factory reconditioned ones relatively cheap.  A little research into the subject showed that AGM's can suffer from fluid loss and be possibly brought back.  I popped the 6 covers on two of the batteries and found that they were way low on water.  It took more than a gallon to fill both of them.  They are on a charger now, and I will let you know if this did any good.

[Oonrahnjay]

    VW TDI batteries are not AGMs but they're "maintenance-free"; free from maintenance that they need because VW has put a couple of warning stickers over the caps that should be removed every once in a while to check water and add it, if necessary.  In my experience, cutting out the caps and properly servicing them extends their life 60 - 90%.  Maintenance free my big ole hairy redneck you-no-whut.

[belfert]

AGM batteries should be totally sealed with no way to add water.  They don't have vents.  They have safety valves that if they open means the battery is junk.  You sure these are AGM batteries and not maintenance free batteries?

[luvrbus]

Not all AGM batteries are sealed with the pressure valve,you can buy AGM batteries in vented or non vented

[Lin]

Yes, they are AGM.  They are sealed.  There is an outer seal that can be dug out, and below that is a threaded cap that can be removed with a socket.  I tried charging two together.  One is so bad that the charger did not recognize it.  I read that you can put it in parallel with another battery to get the charger to work.  It has been on it now for over 8 hours and that one is still less than 8 volts.  I doubt it is coming back.  I am leaving the other one charging through the night and will see tomorrow if it is any good.  I do not expect much, but it is worth looking at.

[Lin]

The experiment is not a failure.  It proved that these batteries are gone!  I checked this morning and the remaining battery on the charger was hot, bubbling, and only at 11.5 volts once disconnected.  Maybe if the lack of water had been dealt with a long time ago, it would have been helpful but not now.  I guess I should try to figure out why they lost water in the first place.  Could be that my smart chargers, like me, are not as smart as we think!

One benefit of this is that I will probably pry open my non-AGM, maintenance free start batteries and give them a drink.

[TomC]

AGM means Absorbed Glass Matt. This also means that even when the batteries are new, if you're able to open the cells, there should not be any visible water-hence the Absorbed part. Being absorbed is the reason AGM batteries can operate in any position (except upside down, preferably), and can be transported on an airplane (AMG batteries were originally made for fighter jets to with stand massive G forces and upside down flying). Good Luck, TomC

[luvrbus]

Life Line has sure change their installation procedure now,they need air space around the batteries and need to be in a vented area,the rep told me they do put off gas when charging but a controlled amount 

[Lin]

Obviously, my knowledge of battery technology is weak.  In my defense though, I was aided in this idea by stuff on the web.  Who could have known that there is some bad info there?  Anyway, since these bats are just good for exchange, I saw no harm in trying it out.  Generally, miraculous solutions do not work, but trying them can be interesting.

[chessie4905]

Parallel charging a dead ATM with one that has a charge will work sometimes, just use a manual charger, not an automatic one. Use should use some sort of timer if not closely monitoring.

[Oonrahnjay]

     And I'm not sure it will make any difference but I thought I'd add an experience.   The guy in the next storage space to mine had accumulated a fair stash of mosly 8-D batteries and a few Group 31s that didn't seem to take a charge.
     He tried all the "tricks" shown on YouTube and things suggested by the local battery shop; he did the drain-the-acid and replenish, the "fast hard equilization" charge, the multiple equilization charges, the repeated slow charges.  Here's what happened ...

1)  Some of them just never did anything.  They were dead and they stayed dead.  Off to the recycler.

2)  Some of them showed signs of revitalizing.  They'd accept charge and show good voltages plus responding well to the load mater but when you tried to use them, they'd die either almost immediately or pretty soon.  This is probably the largest %age of the batteries he tried to revitalize.

3)  A few would work well for a short while but began to slowly die after that.

4)  A very few would come back to life and work well for a good period of time.

    I guess all this adds up to the fact that batteries are finicky and unpredictable, but once they show signs of distress -- or if they just plain die -- you have some chance of getting them to work at least for a while, but not much.  Just mu observation in one situation, other people's experience may be different.