Battery Repair

[Zookrider]

Hi All, Last weekend, one of my batteries broke free and got banged around pretty good. I managed to chip off a corner at the top and revealed a hole about 2mm square, which was enough to eject a surprisingly large volume of acid. Anyhow, I did a bush repair using a self tapper screw and wrapped the top half in plumber's tape. Seemed to stop the leaking.
The battery is a white sealed marine style (of unknown brand).

My plan is to top up the level by injecting distilled water back through the hole and then melt the surrounding plastic around the hole and seal it back up that way. Will that recover the battery? or do I need to inject acid in?

Also, I found the 1.3lt motor which normally runs off an oily rag, drank like a Patrol. So does the altinator bear greater resistance when the battery is drawing more load? Normally, I would never think about it in a normal car, but when the motor is dwarfed by 2 giant batts and and a big honkin' altinator, it gives me pause.

[Dooley]

My plan is to top up the level by injecting distilled water back through the hole and then melt the surrounding plastic around the hole and seal it back up that way. Will that recover the battery? or do I need to inject acid in?

That's a dangerous idea. There is a risk if you bring heat or a flame to the battery of an explosion from the hydrogen. From what I've read up, mostly eye injuries from the acid sprayed after exploding.

[Zookrider]

That's a dangerous idea. There is a risk if you bring heat or a flame to the battery of an explosion from the hydrogen. From what I've read up, mostly eye injuries from the acid sprayed after exploding

Yer I had thought of that, I think I'll be ok by resting the battery before hand and using a soldering iron. Naked flame very bad. Safety first I always say.

But there's no point if sealed batteries don't respond in the same way from being toped up as serviced batteries! I have no clue what the chemical differences are (if any)?

[Foo on patrol]

I think you need too talk to a battery building place, to be safe?

Would hate to read that you had a battery blow up/throw acid back over you.

[DamTriton]

Hydrogen is only produced when the battery is being charged.

If anything the cell would need to be topped up with the same fluid it lost, ie dilute battery acid, not water, as this was a mechanical loss of volume and not a chemical reaction leading to loss of volume.

x2 on the take it to someone with the tools and knowledge to do it properly

[Dooley]

Hydrogen is only produced when the battery is being charged.

It's a damaged battery though, I wouldn't rule out some residual hydrogen or something along those lines.

Just don't think it's a good idea.

[DamTriton]

Hydrogen is only produced when the battery is being charged.

It's a damaged battery though, I wouldn't rule out some residual hydrogen or something along those lines.

Just don't think it's a good idea.

Hydrogen is so light it would be displaced by the heavier air and escape out of the vents given there are now "two ends" to the vent. There would be no residual hydrogen if it has been left exposed to air and no attempt had been made to charge it.

[Zookrider]

I didn't get round to checking it out this weekend, but I'll try to access the vents under the top cover to ensure the thing is well vented. But I'll see when I get there. I'll turn the soldering iron right down so it only just melts the sorrounding plastic.

But I have done a lot of homework, the last Chemistry I did was in YR12.
Here are my results, and feel free to correct me:

Big Thanks to Wiki!
In the charged state, each cell contains electrodes of lead (cathode, -) and lead oxide (Anode, +) in an electrolyte solution of sulfuric acid.

In the discharged state both electrodes turn into lead sulfate and the electrolyte loses its dissolved sulfuric acid and becomes primarily water.

So the sulfuric acid is absorbed into the plates and this is why the specific gravity increases with charge, because the sulfuric acid is disolved into the solution. Pure water having a SG of 1.

THE MASTER PLAN
So I'm going to top off the battery with distilled water incrementally and charge it, I can't just fill'er up, as the sulfate dissolving into the liquid increases its volume and can over flow. So my goal is to pull as much sulfate off the plates as possible.
Then I can check the voltage achieved and SG when its almost full. Then adjust in any acid as necasary right at the end.

State of Charge / Specific Gravity:
100% charged 1.265
75% charged 1.239
50% charged 1.200
25% charged 1.170
Fully discharged 1.110

Also, I think I might have found out why so much acid came out such a little hole! Sealed batteries are pressurised to about 4psi, to help the hydrogen and oxygen gas recombine into water (hense they don't loose as much to evaporation). But when the pressureised vessel got a hole it released the pressure and may have taken some liquid with it.

Professor Zookrider

[Dooley]

Hydrogen is only produced when the battery is being charged.

It's a damaged battery though, I wouldn't rule out some residual hydrogen or something along those lines.

Just don't think it's a good idea.

Hydrogen is so light it would be displaced by the heavier air and escape out of the vents given there are now "two ends" to the vent. There would be no residual hydrogen if it has been left exposed to air and no attempt had been made to charge it.

Yes hydrogen is lighter but in a sealed battery should it not stay in the cell unless there is sufficient pressure to cause it to vent ?

In that case is it not possible that in trying to repair it he may cause gas to vent and may possibly ignite it ?

[DamTriton]

Hydrogen is only produced when the battery is being charged.

It's a damaged battery though, I wouldn't rule out some residual hydrogen or something along those lines.

Just don't think it's a good idea.

Hydrogen is so light it would be displaced by the heavier air and escape out of the vents given there are now "two ends" to the vent. There would be no residual hydrogen if it has been left exposed to air and no attempt had been made to charge it.

Yes hydrogen is lighter but in a sealed battery should it not stay in the cell unless there is sufficient pressure to cause it to vent ?

In that case is it not possible that in trying to repair it he may cause gas to vent and may possibly ignite it ?

Maybe I'm missing something, but I thought it already had an "unintentional" vent that he's trying to fix....

I also doubt that using a hot metal surface (soldering iron) to reshape the plastic as distinct from ANY source of open flame, would be a significant ignition issue.

I would still be taking it to a trucking/heavy machinery battery repairer to make sure it was done properly.

[Zookrider]

UPDATE:
I spoke to a battery rep about this repair. He wanted to sell me a new battery (of course), but said it was such a small outlay to try fixing it ($10 from Autobarn for a bottle of acid and water), I would be crazy not to give it a go. He said that he's seen fully cracked batteries with fiberglass patches and working fine.
Also to take into your safety conserns, I rang Selleys and asked them for some advise, they suggested I use a product called "Knead It", its apparently like a pliable putty araldite typ stuff that would plug the hole nicely. No heat, no BOOM!

I also wanted to clean up the battery before putting it in my daily drive, so I took a stab at disolving a buch of Bi-carb of soda (alkalie) into water and splashing it over the battery and now bare metal battery tray (with bright orange surface rust already). The battery foamed up and fizzed pretty good to show the reaction was taking place to counter the acid. I also washed my hands in the solution after handeling the battery.

[tehekho]

Knead it is good. I've used it to um....regenerate part of a rocker cover before!

[Zookrider]

CONCLUSION:
After trying to remove cover on the vents, found out the cover is actually 'part' of the vents. So battery is completely fcuked. YAY!

It may be possible to get 'insert' vent caps, but I'm over it.

So, need a new battery. Any suggestions for sub $500 battery? I know, already covered elswhere, but topic already up.