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There are vast resources on the web re lead acid batteries. Key parameterrs are provided below a loom around the internet and sorting the good references from the not so good would be a helpful part of your necessary education if you are going to do what you suggest.

The vanadium redox battery exploits the ability of vanadium to exist in solution in four different oxidation states, and uses this property to make a battery that has just one electroactive element instead of two. The main advantages of the vanadium redox battery are that it can offer almost unlimited capacity simply by using larger and larger storage tanks, it can be left completely discharged for long periods with no ill effects, it can be recharged simply by replacing the electrolyte if no power source is available to charge it, and if the electrolytes are accidentally mixed the battery suffers no permanent damage.

Lead acid voltage per cell, as in any battery chemistry that you will probably encounter, is very largely a function of the battery chemistry, with other factors making a vey small difference to the cell voltage.

There are vast resources on the web re lead acid batteries.
Key parameters are provided below. A look around the internet and sorting the good references from the not so good would be a helpful part of your necessary education if you are going to do what you suggest.

The vanadium redox battery exploits the ability of vanadium to exist in solution in four different oxidation states, and uses this property to make a battery that has just one electroactive element instead of two. 
The main advantages of the vanadium redox battery are that it can offer almost unlimited capacity simply by using larger and larger storage tanks, it can be left completely discharged for long periods with no ill effects, it can be recharged simply by replacing the electrolyte if no power source is available to charge it, and if the electrolytes are accidentally mixed the battery suffers no permanent damage.

Lead acid voltage per cell, as in any battery chemistry that you will probably encounter, is very largely a function of the battery chemistry, with other factors making a very small difference to the cell voltage.

• Charge efficiency 40% - 98% very muh dependant on application circumstances.

• Cycle life 100 - 1000+ cycles very much dependant on construction and usage patterns.

Useful paper on charge efficiency

http://en.wikipedia.org/wiki/Lead-acid_battery

http://wattsupwiththat.files.wordpress.com/2011/11/ridley_rsa.pdf

• Charge efficiency 40% - 98% very much dependant on application circumstances.

• Cycle life 100 - 1000+ cycles very much dependant on construction and usage patterns.

Useful:

• paper on 3.3 amps/100Ah battery capacity charge efficiency
  Note: real world solar charge currents go up to 35 amps/100Ah.
• http://en.wikipedia.org/wiki/Lead-acid_battery
• http://wattsupwiththat.files.wordpress.com/2011/11/ridley_rsa.pdf

Your idea sounds like great fun, but is unlikely to be practical or useful. Your question about voltage and cell size suggest that you are more likely to be playing games with the question, than that you are likely to be serious, but I'll play the game, as the summary is liable to be of general value.

There are vast resources on the web re lead acid batteries. So much so that it's not worth spending the effort listing high value ones as the value obtained in sorting the good from the not so good would be a helpful part of your necessary education if you are going to do what you suggest.

There are vast resources on the web re lead acid batteries. Key parameterrs are provided below a loom around the internet and sorting the good references from the not so good would be a helpful part of your necessary education if you are going to do what you suggest.

Energy able to be stored in your water tank if it was converted to a large lead acid battery can be roughly determined from the Wh/l figure that I give further down.

• Energy density = 60 - 75 Wh/l

VANADIUM REDOX BATTERY - Energy stored in liquid !!!

• The main advantages of the vanadium redox battery are that it can offer almost unlimited capacity simply by using larger and larger storage tanks,

For a battery where the liquid IS the energy store and where adding more liquid adds more capacity see Vanadium Redox battery.

They note:

• The vanadium redox (and redox flow) battery is a type of rechargeable flow battery that employs vanadium ions in different oxidation states to store chemical potential energy.

The present form (with sulfuric acid electrolytes) was patented by the University of New South Wales in Australia in 1986.

There are currently a number of suppliers and developers of these battery systems including Ashlawn Energy in the United States, Renewable Energy Dynamics (RED-T) in Ireland, Cellstrom GmbH in Austria, Cellennium in Thailand, and Prudent Energy in China.

The vanadium redox battery (VRB) is the product of over 25 years of research, development, testing and evaluation in Australia, Europe, North America and elsewhere.

The vanadium redox battery exploits the ability of vanadium to exist in solution in four different oxidation states, and uses this property to make a battery that has just one electroactive element instead of two. The main advantages of the vanadium redox battery are that it can offer almost unlimited capacity simply by using larger and larger storage tanks, it can be left completely discharged for long periods with no ill effects, it can be recharged simply by replacing the electrolyte if no power source is available to charge it, and if the electrolytes are accidentally mixed the battery suffers no permanent damage.

The main disadvantages with vanadium redox technology are a relatively poor energy-to-volume ratio, and the system complexity in comparison with standard storage batteries.

LEAD ACID: