morph999 said:
you are saying that it's cheaper to drive a car than ride an ebike?
that is not what i am saying at all. you asked about the cost of lead acid power vs. the cost of gasoline power, right? What I said was that you need then to compare the gas used by a moped to the lead acid used by an ebike, or you need to compare the lead acid cost of running a car to the cost of running a car on gas. If you do this, and use the current $2 a gallon for the price of fuel, I said that gas will win in both cases.
You cannot compare the cost of the lead acid batteries used to run an ebike with the cost of the gasoline required to ride around in thousands of pounds of automobile. You must factor in many other costs as well if you are going to try to put a relative cost on the two means of travel, and you must factor in the difference between riding on an ebike and riding in an automobile.
If you want to make a strict apples to apples comparison, let's say your ebike batteries cost $120 for 3 quality 12 Ah SLA batteries, and let's be very generous and give you 300 cycles of discharge to 8Ah. You will not likely get any more than that, and most people will likely agree you will get less. So assuming the only cost of running the bike is the battery and you get your electricity for free, let's say that you are quite frugal with the motor power, and you only use 20 Wh per mile. I use much more, many use much less. Your battery is providing 8Ah x 300 cycles = 2400Ah @ 36v or 86,400Wh which will take you 86,400/20 or about 4,000 miles.
Let's be equally generous to the moped, and say it gets 100 mpg. It will then take you 40 gallons of gas costing $80 to travel the same distance that you traveled on $120 worth of batteries. The break-even point in this scenario is $3 a gallon for gas. This of course completely ignores the damage to the environment from burning the gas or refining it, or the cost of oil, filters, etc needed for the moped, which adds the real value to the ebike side of the equation.
Now let's look at an electric car run on lead acid vs. a gas powered car. Let's be equally generous with the batteries and just scale the numbers. Let's be extremely simplistic and just for the sake of illustration multiply by 10, say you have 10x the batteries and the car weighs 10x as much as the ebike and takes 10x the power to get you around. Again this is very simplistic but I think it is still a useful illustration. It now costs you $1200 for your batteries and they take you only about the same number of miles because the car is so much heavier than the ebike, especially using lead acid batteries. Your little gas powered car can be tiny and light like the electric one, so let's say it gets 40 mpg. The car will take 100 gallons of gas to go 4000 miles, costing $200. Your batteries cost you $1200 to go the same 4000 miles. Gas now has to cost $12 a gallon to break even. These numbers are terribly inaccurate, but they are not off by a factor of 10. The small gas powered car will probably get >50mpg and the electric car will probably use a lot more than 200Wh/mile, electricity is NOT free, etc. so the errors add up in favor of the gas operated vehicle having the lowest fuel cost if one only compares the battery and gasoline costs.
The bottom line is that if you only look at battery cost vs. gasoline cost, you will never run a vehicle on lead acid batteries for less than the cost of running the same sized vehicle on gas unless gas costs much more than we have ever paid, or you get your batteries some other way than buying them retail. Lead acid is not the way to go unless you just need the cheapest thing that will work. The cycle life is terrible, the Peukert effect means you cannot get much of the capacity out of the battery at EV currents, they are heavy, etc. The real benefit comes when you compare running the smallest suitable vehicle to the cost of running a full-sized automobile. In our example, the ebike travels for a cost of about 3 cents a mile, and the electric car travels for about 10x the cost. The moped costs less for gas than running the ebike, but one must consider the other costs including the cost to the environment. Unfortunately one must also consider the cost to the environment of millions of lead acid batteries sitting in landfills leaching lead into the ground water.
Lead acid batteries are the cheapest in terms of initial outlay, but they are no longer a good investment now that there are lithium based batteries available that can provide much more power and much longer cycle life with lower weight. Riding an ebike powered by lead acid batteries still has a lower impact on the earth by far than driving in a gas powered car. Duh...
Just kidding of course, almost nobody is qualified to adopt these dogs.
