Branch's Alum Battery

[Branch Gordon]

I decided to start my own thread here so I can keep my progress more organized and have a better record. Hopefully JB will see this...

I tested my PH tonight with my new paper test strips. Results in video. Any suggestions anyone?

[John_Koorn]

Branch, I don't have the answer but maybe something to think about if you think you need to raise the pH.

What is the pH of the following 3 chemicals?

• Alum
• SO4
• Distilled water

What do you think you need to add to the mix to raise the pH?

John K.

[Branch Gordon]

Hey John K-

Yeah I thought about that previously remember. I posted a vid of me adding 1.5ml of distilled water in order the raise the PH. John B however commented that if I went the "water battery" route I would end up with a really weak battery. He has been saying this whole time that I need to add more acid.

That is the source of my confusion.

[John_Koorn]

Branch, what about Alum?

John K.

[Branch Gordon]

From what I have read, a 1% alum solution has a PH around 3. Have you read differently?

[Branch Gordon]

Here is my source: Alum (aluminum sulfate)

[Branch Gordon]

Here's another article discussing drinking water treatment: Drinking Water Treatment - pH Adjustment - eXtension

Here's the excerpt that applies:

"Acid injection treats water with a high pH by lowering the pH of water to around 7, which eliminates the soda taste and can improve the effectiveness of chlorination. This method also reduces the potential of pipe corrosion as water with a pH above 9 can corrode metals such as brass, copper, zinc, aluminum and iron.

Acid injection is a point-of-entry system. A chemical feed pump made from corrosion-resistant materials injects a solution of acetic acid (white vinegar) into high pH water. Citric acid and alum can be used instead, although they are more expensive. Weak solutions of hydrochloric acid or sulfuric acid also lower pH but these are more hazardous and require special handling. They are recommended, however, if the pH of untreated water is 11 or higher. After adding the acid solution, the feed rate should be adjusted until tap water reaches a pH around 7."

[Branch Gordon]

So it seems to me that adding alum is gonna make things more acidic.

[John_Koorn]

Branch,

i think if I were you I'd start over. Empty the solution out of the battery and give it a flush with some distilled water a couple of times and leave it upside down for a day or 2 to dry out.

Then make up a new solution exactly how JB has said in the other thread. Get an old blender and mix 60% Alum solution and add 40% SO4 solution slowly until mixed well. It will mix into a crystal jelly type of solution. Let it settle and then take off the scum on the top. Fill the battery above the plates with the solution.

John K.

[Branch Gordon]

I was really hoping someone would explain this PH thing better. Its really frustrating that I cant get an answer to this. John has said I need to add more SO4.....you suggested adding alum or starting over....and everyone agrees I need to raise my PH. But no one seems willing to explain how you add an acidic substance and raise PH.

I am obviously really wanting to learn here. I really dont want to start over until I understand.

If a 1% alum solution has a PH of 3, a 60% solution will be more acidic right? And then adding SO4 lowers PH even more.

Where is the PH of around 4 coming from? Is there something happening chemically that I am not getting? When the alum forms a crystal and locks up the SO4...does the alum mix then have a higher PH?

These are really important things to understand. Someone should be able to make adjustments and fine tune these batteries without starting over. I should be able to know from my PH, my curves, and my internal resistance that I needed more or less of something initially.

[James Milner]

Branch,
While I haven't yet had the privilege of playing with these batteries, ill do my best to help.
The thing to remember is whilst ph is important it isn't the most critical. From my understanding the most important thing, others please feel free to correct me, is that your proportion of ions are correct. The ph doesn't determine the effectiveness of the battery it is an indication of your ionic proportions. Ie H+ or OH-, acid & (alkali)or base.
What you are trying to achieve is having the alum disassociate in the water which is called hydrolysis. If it is alkaline it will produce OH- ions ( not what we want ). If it is acidic it will produce more of the H+ ions.
Adding H2SO4 is sulphuric acid. (Battery acid). And will increase the population of SO4 2-as well as H+. You can detect this with the ph as it picks up the H+.
This is one example of the reaction we are trying to create
4Al 3+ +6SO4 2- +30 H2O <> 4[Al(H2O)6]3+ +6H2SO4 + 3O2.
Please don't quote me on the balancing I don't have time to check it!

So to try and simplify things for you. First get your proportions right. Use distilled water ph 7 ( neutral) and check your Ph then. If the system is not working you may need to tip the scales more in the acid direction. This will affect the ionic molecules formed called oligimers. Large ionicly bound structures. These will vary in size and form and there are many. These structures transfer large charges.
From here on is where I don't have a clear idea because I have not made a crystalised mix. The crystal then gets locked up in zeolite when you know your proportions are right. That is get your alum mix at the right proportions first. Then once you've got that right, possibly by adding a little acid then lock it up into a crystal.
Remember ph is a relative indication of acidity and a guide as to where you stand it does not drive the battery capacity.

I hope that helps.
Anyone with some more practical exposure please feel free to correct me

[Branch Gordon]

Hi James-

Thanks for the response.

The distilled water isnt going to have a ph of 7 after being exposed to air. It ends up slightly above 5.

John B has said that we need to have a PH around 4 for the alum battery to work properly. However, he has also said that the cells can be balanced on both ends of the ph scale.

This info seems contradictory, and I have not been able to get clarification despite repeated attempts.

Through my own personal experimentation, I am seeing that my alum battery works a lot better at a lower acidic PH. I have been adding water to raise the PH.....each time the battery gets weaker.

[James Milner]

Branch,
My understanding is that adding water will dilute the ionic population. You want to add the least amount of solvent for the greatest ph change. Just to change the balance. I'm suggesting H2SO4 for the acid and Aluminium hydroxide Al(OH)3 for the alkali.
This compound is used as an antacid under names such as Alu-Cap, Aludrox or Pepsamar.
Aluminium hydroxide shouldn't contaminate your battery as NaOH might.
Thanks for posting how you are going.
Keep up the good work!

[Branch Gordon]

Ok I decided to post some of my recent curves to see what everyone thinks. My newest battery holds higher voltage longer....my old battery drops down and then holds a lower voltage for much longer. My old battery was refilled with a new stronger alum mix. I did not add any acid to it yet.

New battery standing voltage: 12.34
Old battery standing voltage: 12.03

My old battery, before refilling it, had a resting voltage of around 12.86. So just making a stronger alum mix brought the resting voltage near where it should be.

If I add acid to it now...will that bring the resting voltage up? How do these curves look?

[Branch Gordon]

I should add that these are the only two discharge cycles I have run on these two batteries since filling/re-filling. I'm sure they will get a bit stronger and become more consistent...