aluminium sulfate

[kc7noa]

Has anyone tried replacing the electrolyte in a sulferic acid / lead battery with aluminium sulfate ?

If so .. what was the lowest voltage discharge before damage?

[greenenergyexperimenter]

I did that with a old lawn mower battery with a dead cell in December of 2012. The battery would not charge with the existing electrolyte, so I figured I had nothing to lose. The electrolyte was drained off, the cells rinsed out. I used hard water deposits from my water heater to neutralize the electrolyte and baking soda to neutralize the cells. I then added the alum electrolyte and trickle charged.

Even with the dead cell, it was able to start my riding mower even in cold weather. I normally used the battery for powering electronic experiments. After being over discharged repeatedly and overcharged with a capacitive charger, the battery finally failed in September of 2013. When I tore down the battery, I discovered that the positive plates had pretty much corroded away. I believe the cause of failure to be the overcharging, as problems started occurring after I attempted to desulfate with the capacitive charger.

Your mileage will vary. I'm pretty sure the battery would have had better results with a fresh sulfuric acid electrolyte. There's a lot of misinformation out there on using various salts to make a better battery. If you have trash batteries to play with, by all means see if you can bring them back. It is a cheap way to power lighting, but I wouldn't count on such a battery to store power for running anything really important. Keep in mind the safety concerns of messing around with lead and sulfuric acid. It might not be worth the risk.

[kc7noa]

im sure that it was destroyed by over charging ....

The voltage is reduced due to different chemistry ....  some loss of Ah too ...

Im wondering what is the safe DOD when using aluminium sulfate ....


Did you use 99% aluminium sulfate or was it "Alum" ( mix of aluminium sulfate , potassium sulfate and a few small amounts of other chemicals )

[greenenergyexperimenter]

I used alum. I've also done the same thing with epsom salt.

The chemistry is virtually the same as it still involves lead -> lead sulfate on the negative side and lead dioxide -> lead sulfate on the positive side. The key difference is when using salts, the internal resistance of the battery is higher than it was with the acid electrolyte. This, I believe, is the reason for a sometimes lower observed voltage and the more often observed lower capacity.

Because of this, I have yet to be convinced that using a salt electrolyte has any real advantage over sulfuric acid. Sulfation will still occur if the battery is left in an uncharged state. Shedding of active material will still take place. This means abuse and neglect will destroy a battery of the lead sulfate chemistry regardless of the electrolyte used.

Both alum and epsom salts sometimes can give temporary life to a bad battery in a pinch, but neither have represented a better battery chemistry than lead acid in my tests. Again, your mileage may vary as my sample of tests has been fairly small.

[kc7noa]

I used alum. I've also done the same thing with epsom salt.

The chemistry is virtually the same as it still involves lead -> lead sulfate on the negative side and lead dioxide -> lead sulfate on the positive side. The key difference is when using salts, the internal resistance of the battery is higher than it was with the acid electrolyte. This, I believe, is the reason for a sometimes lower observed voltage and the more often observed lower capacity.

Because of this, I have yet to be convinced that using a salt electrolyte has any real advantage over sulfuric acid. Sulfation will still occur if the battery is left in an uncharged state. Shedding of active material will still take place. This means abuse and neglect will destroy a battery of the lead sulfate chemistry regardless of the electrolyte used.

Both alum and epsom salts sometimes can give temporary life to a bad battery in a pinch, but neither have represented a better battery chemistry than lead acid in my tests. Again, your mileage may vary as my sample of tests has been fairly small.

If their was no difference to sulphuric acid ... then why does it make a positive effect .... wouldn't it be the same effect as adding sulphuric acid ? this may be true ....

at the moment i wish i had a hydrometer and ph testing equipment ....

well .. i do have the PH stuff some where .... i used to have a pool and id like to use that stuff to test the PH of a aluminium sulfate battery when charged.

The advantage my be in the DOD ..... if you can discharge a aluminium sulfate/lead battery to .8V per cell .... it reduces the chance of damage over that of a sulphuric/lead battery ....

[greenenergyexperimenter]

I think you hit the nail on the head - if sulfate salts help the battery, adding acid would probably do the same, if not better. Most of us will have alum or epsom salts around, so that is often the first thing reached for. EDTA is another chemical that can be used to temporarily boost a dying battery. It will actually dissolve sulfate deposits.

The PH will be less than 7. More toward the acid side of the scale if aluminum sulfate is used. Sulfate salts do not make it an alkaline battery, only a less acid one.

I certainly recommend trying it out with some old batteries that are being discarded. Ask around, you'd be surprised at how many people have batteries sitting in a garage. It is a lot of fun to experiment with and you can end up with some decent working batteries to boot.

[kc7noa]

yea ....

its all in good faith to discuss .....

im still looking for the safe Depth of discharge for a aluminium sulfate / lead battery .... guess i might just find out for my self .

I have a older battery out of my wife's car .... it was week but not shot by any means ...

Guess i should also know what is considered the safe top charging voltage too ....

[greenenergyexperimenter]

For some depth of discharge tests, check out the energenx channel on youtube. He's got several videos on the subject. I do not trust that particular individual, you'll notice a lot of the alum battery people like him are OU and conspiracy theorists types. You might find some of the information you are looking for on his videos, though. Take the information with a grain of salt, sulfate or otherwise 

Like you said, finding out for yourself is probably the best road to take.

[kc7noa]

Oh .. iv seen his stuff ... ben and chuck ....

Seen the alum / lead conversion .... but when he used a 12V light as a load to check Ah in to out and said you get 100% return ....

Then used a clock and charged for 1 min and got light for 2min out .... with no comment as to why .....  i knew his process was off .....

grain of salt (solution) .....

though the guy's are down right busy with all the videos ....

[dnix71]

I tried EDTA and all it did was eat the plates and make the battery deader. Sodium sulfite worked a little better. You can get food grade sodium sulfite cheap because it has legal uses as a food preservative. There is a photo grade as well.

If batteries weren't so stupidly expensive there would be no good reason to even attempt a resurrection. I took my neighbor to get a battery for his car and the local price for the cheapest car battery was $120. A good battery with a 3 year warranty was $160.

A couple of years ago prices were 30% lower.

[Mary B]

Going to get worse since Doe Run shut down, it was the last lead ore smelter in the USA. All that are left are the recyclers and that is a finite source of lead. So we will be importing raw lead now when supplies run low.

[kc7noa]

Sounds like a good reason to clean-up Courd'alne lake in Wa St / Idaho .. lots of lead and heavy in that water from the silver valley mines !!!!