04-08-2012, 10:20 PM
A good way to look at this is by power used either in HP or watts. There are 745 watts per horsepower and I use about 20 amps of power in my boat to go 1.5 mph and it's a 12 volt system. So using P=I*V or power (watts) equals current times volts means I use 240 watts which is .32 horsepower. If there is wind then I use lots more power to maintain 1.5mph. The variables are then motor and engine rpm and prop pitch.
Now on to the thermodynamics side of things. Gasoline has about 45.7 MJ/kg or 19660.6 BTU/lbm. Lead acid batteries have 25 to 35 watt hour per kg. which makes them have about 95% less energy potential. Compare with the inefficiency of gas engines then gas engines still win by a long shot. I just don't like the noise. I do love the smell of 2 stroke exhaust in the morning though.
[signature]
Now on to the thermodynamics side of things. Gasoline has about 45.7 MJ/kg or 19660.6 BTU/lbm. Lead acid batteries have 25 to 35 watt hour per kg. which makes them have about 95% less energy potential. Compare with the inefficiency of gas engines then gas engines still win by a long shot. I just don't like the noise. I do love the smell of 2 stroke exhaust in the morning though.
[signature]