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Hi,
Bear with me, this isn't easy to communicate. How do you figure battery cost into the equation? As in, does battery cost figure into gasoline cost (since I assume recharging is much cheaper than refilling)? For example, if batteries cost $3000, gas is $3 a gallon, an ICEV gets 20MPG, and battery life is 4 years, you'd have to drive 5000 miles a year (100 miles a week) to break even. Make sense?

Thanks,
Kurt
 

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Hi,
Bear with me, this isn't easy to communicate. How do you figure battery cost into the equation? As in, does battery cost figure into gasoline cost (since I assume recharging is much cheaper than refilling)? For example, if batteries cost $3000, gas is $3 a gallon, an ICEV gets 20MPG, and battery life is 4 years, you'd have to drive 5000 miles a year (100 miles a week) to break even. Make sense?

Thanks,
Kurt
What battery life are you refering to, lead acid or lithium. TS cells are rated at 3000 or so cycles depending on how much percentage that the cell is discharged at.

So for sake of simplicity lets say you have a lithium pack of 100ah cells that gets you 100 miles, and if the batteries last 3000 cycles, in theory you could get 300k miles. I know this probably not a real world situation, but you get the idea.

If your talking about lead acid, I wont even comment, for every time I hear someone building an ice vehicle and putting lead acid in it, my eyes gloss over.

Roy
 

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"battery life is 4 years" "It could be any type of battery, but I'm thinking FLA at the moment."

Do we have anyone driving 100 miles a week that has accomplished 4 years out of their FLA and still able to get 20 miles per day(5 days/week), or whatever your range goals are? 20,000 miles from a PbA pack of any type?

I keep seeing threads where people say they have their pack working great and it is a year or two later and they are either trying to upgrade to "better lead" or lithium. 20,000 miles at even $4/gallon and 20MPG is $4,000 but then you have to add the cost of the next pack at the end and continue the cycle, this isn't considering watering your pack if that time or hassle is worth anything to you.

If you are doing an electric conversion to save money, swapping cars to a more fuel efficient one is probably cheaper than going with lead-acid. If you are doing an electric conversion for any other reason, that reason probably trumps the cost.

If I converted a car to lead-acid, it would have to begin as an efficient body, lightweight, and aerodymanic. The lead-acid will weigh a whole bunch but on a flat road without many stops, traffic, high speeds, or distances that bring the car deeper than around 50%, it might make sense. Voltage sags a bunch so I'd have to do a higher voltage to drive on the highway. It doesn't make sense for my needs, but if you can realistically manage the low DOD% and light loading to keep FLA batteries happy you might get lucky with a long life, I don't know about 4 years though and the way you need to drive to get good life from lead IMHO is quite boring. I'd rather flog an undersized lithium pack for 20 miles range than buy lead-acid but that is just my opinion.
 

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One way to compare would be to look at batteries plus electricity used to charge the vehicle and compare than to fuel plus routine engine maintenance (mostly oil changes.)

In few cases do you save money by building and driving an EV at this time. These are hand built, one off "hot rods" (even if they are not fast) and it's hard to beat mass produced (cheap) that way. If your only motivation is to save money I suggest you look into cars with better gas mileage. If you want that EV grin and a unique vehicle too then building an EV may be for you.
 

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What battery life are you refering to, lead acid or lithium. TS cells are rated at 3000 or so cycles depending on how much percentage that the cell is discharged at.

So for sake of simplicity lets say you have a lithium pack of 100ah cells that gets you 100 miles, and if the batteries last 3000 cycles, in theory you could get 300k miles. I know this probably not a real world situation, but you get the idea.

If your talking about lead acid, I wont even comment, for every time I hear someone building an ice vehicle and putting lead acid in it, my eyes gloss over.

Roy
Roy; Here in the other world not all of us have access to unlimited funding to purchase the latest & the greatest. I am keenly interested in lead acid as my aged pensioner budget limits me to the occasional Trojan from the scrap merchant. My current(pun intended) project may never exceed its 4.5km range or its 45kmh top speed on level ground,but it is a mentally refreshing way to spend time. My eyes glaze over at the high-tech articles and it is enjoyable to read simple, and most importantly, affordable solutions. Best Wishes.
 

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"battery life is 4 years" "It could be any type of battery, but I'm thinking FLA at the moment."

Do we have anyone driving 100 miles a week that has accomplished 4 years out of their FLA and still able to get 20 miles per day(5 days/week), or whatever your range goals are? 20,000 miles from a PbA pack of any type?

I keep seeing threads where people say they have their pack working great and it is a year or two later and they are either trying to upgrade to "better lead" or lithium. 20,000 miles at even $4/gallon and 20MPG is $4,000 but then you have to add the cost of the next pack at the end and continue the cycle, this isn't considering watering your pack if that time or hassle is worth anything to you.

If you are doing an electric conversion to save money, swapping cars to a more fuel efficient one is probably cheaper than going with lead-acid. If you are doing an electric conversion for any other reason, that reason probably trumps the cost.

If I converted a car to lead-acid, it would have to begin as an efficient body, lightweight, and aerodymanic. The lead-acid will weigh a whole bunch but on a flat road without many stops, traffic, high speeds, or distances that bring the car deeper than around 50%, it might make sense. Voltage sags a bunch so I'd have to do a higher voltage to drive on the highway. It doesn't make sense for my needs, but if you can realistically manage the low DOD% and light loading to keep FLA batteries happy you might get lucky with a long life, I don't know about 4 years though and the way you need to drive to get good life from lead IMHO is quite boring. I'd rather flog an undersized lithium pack for 20 miles range than buy lead-acid but that is just my opinion.
Building a car to operate economically of PbA is heavily dependent on designing it to where its typical daily use discharges it to 20-40% of max depth of discharge. Thus, a long range EV, is actually cheaper to operate, per mile, than a short range one, under the condition you drive it enough to put enough miles on it to see savings, as the batteries also have a limited shelf life.

Whether or not there is a BMS is also a very important factor. Without a BMS, Mike Willemon's Deka 9A31s only lasted 6000 miles in his electric Mitsubishi. He cites the lack of balancing on charge/discharge as the primary reason for their short life.

AGMs do have a high shelf life; John Bryan's Optimas lasted for at least 8 years in his Karmann Ghia(they may still be in use; I last checked 4 years ago). I don't know how many cycles or miles.

Rich Rudman's Optimas in his Fiesta, "Goldie", lasted thousands of cycles, but the vast majority of them shallow ones. He had a shunt-based BMS. They may still be operational; I last checked in 2006.

Brian Methany had an electric Chevrolet S10 with 40 Trojan T125s in it. It had 120 miles range at 60 mph to 100% DoD, but did not regularly see that deep of discharge. His pack lasted 45,000 miles before the truck was destroyed in an accident, and the pack was still delivering more than 80% of nameplate ratings. Given the price he paid for the pack at the time, he broke even at about $1.60/gallon gasoline. It probably had ten thousand miles left in it, or more.

Paul MacReady understood this when he designed the Impact. The EV1 that spawned from it had 100 miles range with its Panasonic AGM lead acid batteries, and before the EV1s were crushed, some of them had more than 30,000 miles on them still delivering nameplate ratings. To be fair, the Panasonic lead acid were more advanced than anything we can readily buy, but the basic principle is the same.

If you want the EV to save money, you must design it for that purpose. Most 30 mile range conversions will yield very poor economy. The secret is having such long range that your typical discharge is shallow, and for AGMs, having a BMS and appropriate charger to go with it to keep the batteries balanced.

Most conversions aren't capable of handling the battery weight for this. Because of this, some of the most economical EV conversions are trucks. Trucks loaded with a ton of lead. Many examples on the EVDL had operating costs that broke even at under $2.80/gallon gas.

Sports cars and econoboxes are only economical if they are sufficiently aerodynamic and can handle 40% of their weight in lead. Not many donor choices can yield those results, but they are out there. Look for Honda CRXs, Triumph Spitfires, Datsun 1200s, VW Karman Ghias, and the like. Geo Metros, Dodge Daytonas, and other econoboxes will also work wonderfully *if* you use LRR tires and aeromods to improve your range(thus lengthening battery life), but if you ignore either of these things, you will have just another 30-40 mile range conversion with a lead acid pack that goes tired after 15,000 miles or less.

If you want your EV to save money, its operating cost has to be a design parameter, and you have to make the right kind of design for it to work! And save money it can do well... under the right circumstances.
 
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