[dcb]

nerys, It was not at all obvious (buried in the verbiage somewhere perhaps) that you wanted to purchase batteries to recharge at home to make hydrogen while you drive.

Simple experiment for you

1. Charge up a battery

2. use battery to make known quantity of hydrogen (inverted beaker in tray of water or something)

3. plug in killawatt on battery charger and recharge battery, compute cost to recharge

4. compute energy stored in the quantity of hydrogen to equivalent (btu) energy worth of gasoline.

5. determine cost of that equivalent amount of gasoline that has same amount of energy as the hydrogen generated.

The cost of the electricity to the cost of the gasoline should give you the cost conversion factor.

Factor in cost of equipment and lifespan of batteries, as well as how much hydrogen you can reasonably produce per charge (plus fuel metering changes)