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Old 05-03-2012, 11:00 PM   #12 (permalink)
Ryland
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Join Date: Jan 2008
Location: Western Wisconsin
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honda cb125 - '74 Honda CB 125 S1
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People in our local EV club did a group buy of GBS batteries so they got a better price and I'm not sure what that price was, but if you buy a smaller quantity of them it looks like $6,000 worth of batteries should give you around 50 miles, around $120 per mile of range that you want to drive, there are of course cheaper batteries out there, A123 system pouch batteries directly from china are almost half the price before shipping, but they also are just in plastic pouches... no hard cases and if you don't compress them then they swell and stop working, the pouches also just have flat foil tabs on top, so you would need to figure out a way to bolt cables on to them.

In comparison, quality lead acid golf cart batteries are going to cost you about $30 to $45 per mile of range that you want to drive, but to get the kind of range you are looking for you are going to need 1,600 pounds of lead acid batteries stuffed in to an 1,800 pound car! those GBS batteries are going to weigh about 5.3 pounds for each mile, lead acid... 28.9 pounds per mile of range, so when I said you would save a ton of weight I was a little off, it's only half a ton!

Figuring out how many batteries you need for a given range is easy, you make an educated guess based off what others are getting as to how many watt hours per mile range you can get, then you look at the capacity of the batteries you are looking at, lead acid don't last very long if you drain them past 50% so you cut the capacity of lead acid batteries in half so they last longer, that way you still have good range as they age as well, a common mistake that people make with lead acid is to drive to 80% depth of discharge and wear their lead acid batteries out really quick.
Most lithium batteries do just fine to 80% depth of discharge, of course shallower discharges and they are happier and could end up lasting the rest of your life, but if you drain them to 80% don't freak out like you would with lead acid batteries.
If or when you do go to talk to someone at your job about charging, remind them that it's not going to cost a lot of money, around 2 cents per mile that you drive, so for 27 miles one way $.54 per day.
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