Aluminium Sulfate Lead Acid Battery Conversion

quick how to on aluminum sulfate electrolyte for lead acid batteries.

Step 1: Purchase Ingredients.

you will need aluminium sulfate, a hydrometer, distilled water and a two buckets.

also you will need a face mask. long sleeves, safety goggles and water on hand.

this job could cause death or serious harm from explosions and acid spills.

you will also need a battery charger, applicator bulb and common sense.

Step 2: Drill Holes Into Vent Caps or Remove Caps.

if you have a sla battery you will need to drill into the plastic.

use a pneumatic drill a regular drill could cause sparking or explosions.

you have two choices.
1.fully flatten the battery to sulfate the plates. this will produce a super saturated acid.

2. fully charge the battery. check with hydrometer that the electrolyte is 12.5 to 13.00. this indicates 80 to 100% charge.

Step 3: Create Saturated Aluminum Sulfate Solution.

you will need room temperature distilled water. add aluminium sulfate slowly to water while stiring. check with hydrometer.
it takes a long time but you should be able to get a reading of 12.5 or more specific gravity easily.

if you heat the water or add too much the aluminum sulfate will precipitate when the electrolyte cools.

Step 4: Tip Out the Acid From Battery.

pour out acid from the battery into a large bucket. be carefull not to spill any on yourself.

Step 5: Add Electrolyte

add aluminium sulfate solution to each cell. use a bulb designed for this purpose. about 5 bucks from auto store.

feel free to use any ratio. I have found 20% sulfuric acid to aluminium sulfate works the best.

100% tends to precipitate and provide low cca.

Step 6: Charging

you will need to charge the battery to 16.8v. this electrolyte solution doesnt off gas as much as battery acid.

gassing starts at 14.7v and gets rapid at 15v plus.

I use a turnigy charge set to 7 cell mode. it will cut out at 17.1v. but the battery only reaches 16.8v so you need to turn it off manually.

Step 7: Testing and Final Thoughts

I have mixed results. all my batteries were dead or used batteries and performed less than originally specified.

for example 710cca produces 540 hca. this battery is 90ah and 160 rc. I got 60 mins rc.

only notable improvement is less heat produced and less off gassing.

you can't buy sulfuric acid in Australia now but you can still buy aluminium sulfate which works ok.

pic shows resting voltage and cca rating of two batteries of the same make and capacity.

one is pure aluminium sulfate. the other has 150ml of battery acid added per cell (100ml of aluminum sulfate solution at 12.75 sg in each cell).

the latter has higher cca and lower resting voltage. the former has higher resting voltage and lower cca.

batteries converted with 20% to 60% sulfuric acid added seem to produce about the same CCA and about 80% the Ah capacity. not magical results but note worthy.

a resting converted battery that is flat will still read 12v. but when loaded will drop instantly. specific gravity only changed by 50 to 80 points between fully charged and flat. also sulfation doesnt appear on plates as dramatically as with battery acid.

I would appreciate real professional testing of this electrolyte. it is hard to produce meaningful analysis with the junk I am using.

try it out and post your results.