Charge - Discharge - CHarge - DisCharge ...

[BobZilla]

Dominus,
If they have been sitting a long time you do want to push them up to 15 at least a few times to help clean the plates. One suggestion would be to charge them at your normal rate but when they get up to 13.5 or so increase your power a bit to drive them faster don't worry about your efficiency on the primary, you are just trying to condition them without gassing off to much. That should minimize the gassing period a bit by bringing them up faster. Just don't do it too much or you will dry them out as previously discussed.

[John_Koorn]

No, don't go higher than 14.8 with gel-cells or they off-gas too much and dry out.

John K.

[BobZilla]

I guess we disagree John but I said only a few times or they will dry out.

We went over all of the nuances earlier in the post. If they have been sitting for years than they are sure to have a good build up on them that will need to be cleared or he will never get capacity back out of them.

[Dominus]

Thanks guys!
I wasn't even sure about these 14.8 - yes, the difference can be heard from 14,9-15V up.

I'm using John's chargers as my SS are waiting one transistor+crocodile-clip experiments, and my SG-wheel is approaching it's final building stage.
The 10A12 is more gentle at pushing the voltage at the top than the 2A12-3. Less amps mean better structure on the plates...

D.

[BobZilla]

Cannot comment on the chargers. Just to make sure you follow me don't push those things up past 14.8 on a regular basis if you decide to do it at all. It will mess them up. I was more suggesting you do it a few cycles is all.

Especially with GEL cells it can be beneficial to bubble them only once and awhile. The reason I say that is because the "GEL" is thick inside there and when you do partial charging from a normal charger you will develop tiny air pockets in the gel from where it starts to bubble occasionally. These can create tiny little voids at the plate surface area where the actual electrolyte is not touching the plate because of the air pocket. When you bring the voltage up it will liquify the gel and let the trapped bubbles escape the plate surface and recombine. Of course if you do it too much you will just boil out the electrolyte.

Ever made cookie dough or seen it being made. You know how you slap the tray down on the counter a few times to get the bubbles out, kind of like that.

[Dominus]

Gel cells and rejuvenation techniques are quite contradictory...

You'd like to push them very high but they start making bad digestion sounds

Too much and they'll boil dry. On the other hand you get more water into the Gel-mass by desulphating, because it´s stuck in the chemical structure!!
I should build a window into the side of these batteries to see how it looks like

Some years ago I heard that when you boil them, the bubbles stay in the gel and mess it up

[BobZilla]

Yea,, That is why everyone agrees that flooded batteries are the best for the type of projects we work on. GEL/AGM are too finicky. Gels are even stranger than AGM in that regard.

Just give me a battery that I can simply add more water if I need too and be done with it ;-)

[Dominus]

Anyway, nice info about Gel's

Now I know really well why I have to stay far far away next time I stumble upon such a maintenance free sucker ^^

[Dominus]

I have a set of gel cells and they are jello compound trapping acid. They are Lead Acid. When these batteries need to be reconditioned this means that some of the gel is probably missing from the plates. I add ALUM, I don't care why I am not suppose to do it, I did it and it works.

Gel cells will start working better if you add electrolyte, or else why would my cells have very large screw off caps right? Add acid if you must I don't.

I never read anything and just added ALUM to the cells, when they are charged the Acid leaves the top in overflow and if need be I will overfill and charge and let them run over till I have what I want.

ALUM BATTERY that was an ACID battery.

Try it, the worst that can happen is that the battery will do alot better. My gel cells were overfilled and set on constant current til the plates are reforming. The ALUM must be heavy and the ACID must be lighter because like I said what runs over is ACID released from the gel.

I recently did this to two 50ah gel cells and two 30ah. They all went up the long slow way that all converted ALUM batteries do this is how I know it worked.

Mikey

Hi Bro, what a surprise to have you jumping in

Not sure about doing the Alum conversion to them yet.
I know Alums have lower voltage and deliver current much more steadily across the discharge voltage curve. That makes them pretty useless for powering loads with an inverter.

Is there any good link for these questions?
1. Do ALUM conversions increase the Ah?
2. (And/or) What makes an alum conversion superior to lead-acid?
Yes: http://www.hho4free.com/bedini_alkaline_battery.htm

Anyway, when discharging the batt, it stabilizes @8.5V or even goes up and down there while under load. The next charge takes longer, as well as the consecutive discharge.
Manufacturer recommends very long charging times at 14.1-14.4V
I´m making a pseudo topping-event at 14.8, by this I mean I disconnect the charger.
Both methods won´t give them a topping charge, but capacity is rising by going up & down.

This is the battery


And this is how the caps look like. Will have to find a tool that fits in there, eventually..

[BobZilla]

Keep at it and hopefully they will come back.

The main thing is to cycle them anyway regardless of the fancier technique's I would start with a light load at first like whatever the c20 rate is, do half that. Long slow discharges will help.

I have some big AGM's that are similar, 100AH from PowerSonic. Those look like telecommunication rack batteries and they are well worth the trouble if you can get them working decent. They will run inverters fantastic.

[Dominus]

Thanks Bob,

Here is some interesting info about gel electrolyte n cells: http://www.ehow.com/how-does_5041186...tery-work.html

I´ve opened the caps, it´s very interesting to have them around 15V and see no bubbles coming out (or are they just being trapped in the GEL? haha)

D