So does it take almost 4000 lb of lead to= 1 gal. of gas?

[roflwaffle]

Originally Posted by 3dplane

I've got several automotive lead acid batteries that actually state the A/h rating on the sticker.

So I started weighing them and calculate the Wh/lb. They are all pretty close to about 18 Wh/lb.

According to what I can find,energy in a gallon of gasoline is 36.6 Kw/hr.

36600(W/hr) / 18(W/hr) = 2033 lb. Let's just say 2000 pounds. But that's calculating with the 20 hour discharge A/hr rating of the battery!

So unless we want to drive around at 0.5 mile/hr in super granny gear for 20 hours to justify the 20 hour discharge rating of the batteries,I think it's about half of the Amp/hour rating is what is an appropriate capacity for a one hour discharge? Is that about right?

In that case can we say that it takes about 4000 pounds of lead acid batteries to eaqual the energy available in a gallon of gas?

Just an interesting comparison if I did it correctly.

That's right, but they only do the same amount of work in terms of thermal energy. The electricity has a lot more exergy than gasoline, so it can do a lot more useful work per unit energy. For instance the best a Prius is at is ~30+% efficiency over a driving cycle, while an EV can be well over 70% efficiency, so you can get more than twice as much done with electricity compared to gasoline.