James Milner

Yoderll,
I believe you have a shorted cell. Or two!
I ran an alum battery in my car for 6 months and cell voltage was about 11.7+ v resting. It struggled with the lower voltage but would turn over and always start. Under charge it should still rise to the set alternator voltage. Usually 14.5v. It will return to its standing voltage with about 10-15 min off charge

As far as I can remember JB used aluminium ammonium sulphate. But said that aluminium sulphate is just as good.
I experimented on a number of sulphates. Sodium sulphate works as well. PH is acidic and I suspect over time can soften the lead paste plates, but may be useful on dealing with stubborn sulphation.

The aluminium sulphate has some special hydrolysis properties. PH can be mildly alkaline to mildly acidic. Although it generally is acidic. It can form very large complexes hence transport large quantity of charges with each particle. The ammonium ions I believe form aluminium complexes of slightly different shape but the sulphate will carry more charge. The chemistry relating to the aluminium complexes is very complicated but there are some publicly available scientific papers available if you are really interested in the detail.
My advice is charge your batteries with the sg and recondition as best you can before you substitute the acid for alum. Expect to lose about a volt off the standing voltage and exercise the batteries. DO NOT USE TAP WATER to mix your alum. It introduces other metals which contaminate your lead plates. Use distilled water.

Branch, an air compressor would be a better resource than you would expect. I've seen some pictures/ videos of air engines. That is engines driven by compressed air. If you could translate that to a usable car, you would have a very valuable fuel. What's more every gas station provides your fuel for free . They just think you're pumping up your spare tire. It's definitely worth investigating further. Maybe look at converting a regular gasoline car.
Cheers
James

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,
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