You also have to factor in battery replacement costs.
Unless your commute is less than 10 miles, your battery pack in that Sparrow will not last much longer than 10,000-15,000 miles. You have to keep the depth of discharge low to get a reasonable number of cycles from the batteries. If you want a reasonable 30,000+ mile battery life using lead acid batteries, your typical daily usage has to discharge the pack to around 30-40%. If your daily amount of driving is 40 miles and you wish to minimize operating costs, you'd want a car with at least 100 miles range driven until the battery is discharged. It would still be ok to deep discharge the batteries maybe one of every 10 trips for that occassional longer trip, but it is not recommended as common practice.
The effect of depth of discharge on cost per mile is very large, and will mean either saving tremendous amounts of money over using a gas powered car, OR paying a lot more than using a gas powered car.
This pretty much leaves out the sparrow unless you have a short commute. The Sparrow's battery pack is 13 Optima D750 AGMs which go for $100 at the cheapest(Usually around $135!). That's a $1,300 battery pack. Given the Sparrow has a 30 mile range, if your typical commute is to go 20 miles to work, plug in, go 20 miles back home, your batteries will last roughly 10,000 miles. That is $.13/mile for batteries! Hardly a bargain, even at $2.59/gallon. If your commute is more like 10 miles to work, plug in, and 10 miles back, then you might eek out 20,000 miles. Then it will start looking good. But if your commute is that short, that's bike riding territory, and probably wouldn't justify spending such an excessive amount of money on a Sparrow.
However, if your commute is long, you can still save money(and lots of it) with an EV. The key is to build for long range, but to rarely use more than 30-40% of it before plugging in again.
Lets compare two theoretical EVs and their gas powered counterpart, one EV with a battery pack sized for 50 miles range, another with the same type of battery only sized for 100 miles range(and consequently more weight), and the gas version. What kind of car? Perhaps a 1989 Chevy S10 truck. Both use the same types of batteries, one will use 20 Trojan T105 batteries and the other will use 40 Trojan T105 batteries, each with a Zilla 1k controller, PFC30 charger, and Netgain WarP 9" motor. The typical daily usage for each vehicle will be 40 miles. The S10 with a smaller battery pack can have the pack built underneath the bed leaving all bed space intact, while the one with the large battery pack will not have bed space available.
Parameter...
Gas S10(4 cyl)...
Electric S10(small battery)...
Electric S10(large battery)
Maintenance Cost per mile...$.07...$.01...$.01
Fuel Cost...$2.59/gallon...$.08/kWh electricity...$.08/kWh electricity
Fuel Consumption...24 mpg...300 Wh/mile...350 Wh/mile
Battery Pack Cost...N/A...$1,700...$3,400
Battery Pack Life...N/A...12,000 miles...40,000 miles
Battery Charger Efficiency...N/A...92%...92%
Battery Charging Efficiency...N/A...75%...75%
Operating Cost per mile...$.1779...$.1864...$.1356
0-30 mph acceleration...7 seconds...5 seconds...3 seconds
0-60 mph acceleration...15 seconds...36 seconds...23 seconds
Top Speed...90 mph...70 mph...85 mph
Horsepower...90...40...80
Peak Torque(lb-ft)...100...220...220
Curb Weight...2,600 pounds...4,000 pounds...5,200 pounds
Cruising Range...320 miles...50 miles...100 miles
Look at the figures above. The truck with the small battery pack will cost you MORE to operate than its gas counterpart, the one with the large battery pack less. The truck with the big battery pack has a break even point with its gas counterpart if gas was $1.57/gallon. Gas hasn't been that cheap in years, and probably never will be again. So it's the best cheap transportation you'll find!
At an 80% typical discharge, you can realistically expect 300 cycles from a lead acid battery(even though manufacturers' specs might be double that). That's 12,000 miles battery pack life for a truck with a 50 mile range and 40 miles of typical use between recharges. At a 40% typical discharge, you can realistically expect 1,000 cycles(even though manufacturer's specs still might be double that), which is basically 40,000 miles battery life. This explains the battery pack cost per mile disparity between the two trucks. Due to Peukert's effect, the larger pack will see more deliverable capacity than the smaller pack due to lower current draws, even though the truck with the larger pack is less efficient due to more weight, so they will about balance out on amount of range per pound of battery.
As for performance, the Zilla controller can output up to 1,000 motor amps, but the 6V flooded lead acid batteries are only capable of delivering 500 amps before sagging to 4V per battery. So basically, the controller will only be able to make 1,000 amps for the motor until the moptor demands a certain voltage, and the batteries will be your limiting factor when it comes to horsepower. But, 1,000 motor amps is 220 lb-ft of torque for a WarP 9" motor, so your acceleration up to 25 mph in either electric truck will be very violent(like a musclecar), even if you might slug your way forward at higher speeds(slower than a Geo Metro).
Keep in mind the following equations:
Horsepower = (Torque * RPM)/5252
Watts = Volts * Amps
Horsepower = Watts * 1000 * 1.35
Also understand that 40 kilowatts from your batteries will roughly equal 40 horsepower at your motor counting in motor/controller losses.
Want more power to keep the acceleration hard after 25-30 mph or top 120 mph(with right gearing)? Swap out the flooded batteries and use more expensive AGM batteries. The potential for 0-60 mph in < 7 seconds using AGMs and a Zilla is certainly there. But the extra battery pack cost will make your cost per mile go up. Want a performance vehicle and still save money over gas? You'll need to spend a lot more time and effort on converting an aerodynamic sports car and obsess on every last detail, as opposed to a cheap and easy but heavy and unaerodynamic truck. The unaerodynamic shape of the truck makes cost to operate go up, but likewise, the small battwery capacity of the sports car keeps range short and discharge high making costs go up. You'd have to find a lighweight sportscar with lots of battery room and good aerodynamics, not an easy task but a very worthwhile one wioth the right donor and one of the cheapest possible EVs if done right. Otherwise, a truck is the best way to get both long range and reasonable operating costs but at the cost of performance.
Further, extensive aero mods on either truck(aeroshell, covered wheel wells, grille block, bellypan, side skirts, frontal dam, ect.) would improve its range by 30% due to increased efficiency. LRR tires would see another 20% improvement in range. Synthetic transmission oil another 2%. Correcting dragging brakes and 0 degrees camber alignment could cumulatively yield another 8% more range. Given how they will lower the discharge of your battery pack for a trip of given length and lower your energy use per mile, they are worth every hour and dollar spent and will pay themselves off many times over in savings, and potentially allow the 50 mile range truck to have maybe 70-80 miles range and then save money over its gas counterpart, negating the need for a large battery pack and the sacrifice of the truck bed.
The truck with the large battery pack with extensive aeromods and LRR tires could get around 150 miles range! Top speed from reduced aero drag might increase to around 110 mph(if it has the gearing for it)! Add in other improvements such as synthetic transmission oil and 0 camber alignment and range could go up to 170 miles. That would be a very practical vehicle, with half the range of its gas counterpart!
To see a Toyota T100 truck with aeromods, look here:
http://www.evworld.com/view.cfm?sect...le&storyid=870
Instead of plunking $35k+ on a Sparrow, you could build an electric truck with far more usable range for roughly $10-12k. Take the S10 examples, for instance. Here's a cost breakdown for each:
Truck with small battery pack:
-WarP 9'' series DC motor x1 $1,395
-Trojan T-105 6V flooded lead acid battery x20 $1,700
-Zilla 1k Controller(72-156V DC, 1,000 amp max) x1 $1,950
-PFC30 Charger x1 $1800
-CC Power Electronics 200W DC-DC converter(Headlights, wipers, radio, ect.) x2 $700
-Steel for battery racks $100
-Battery Cable $100
-EV200AAANA contactors x2 $150
-L25S-500 Littlefuse Safety Fuse(250 V, 500 amp) x3 $120
-Curtis Potbox(To control acceleration) x1 $75
-E-Meter x1 $235
-Solid-State Ceramic Heater Core x1 $75
-Adaptor Plate x1 $1000
-Miscellaneous components(Heat shrink tubing, ect.) $800
Total: $9,850
Truck with large battery pack:
-WarP 9'' series DC motor x1 $1,395
-Trojan T-105 6V flooded lead acid battery x40 $3,400
-Zilla 1k Controller(72-300V DC, 1,000 amp max) x1 $2,495
-PFC30 Charger x1 $1800
-CC Power Electronics 200W DC-DC converter(Headlights, wipers, radio, ect.) x2 $700
-Steel for battery racks $100
-Battery Cable $100
-EV200AAANA contactors x2 $150
-L25S-500 Littlefuse Safety Fuse(250 V, 500 amp) x3 $120
-Curtis Potbox(To control acceleration) x1 $75
-E-Meter x1 $235
-Solid-State Ceramic Heater Core x1 $75
-Adaptor Plate x1 $1000
-Miscellaneous components(Heat shrink tubing, ect.) $800
Total: $12,445
They may not be as 'unique' as the sparrow, but they'll certainly be much more practical, and may actually allow you to save money over a comparable gas car.
So, do you feel like driving an EV? Be aware that first time EV users usually kill their first battery pack due to improper charging or watering. Be warned. Diligent attention could prevent this, and people have cared properly for their first pack. If you kill your first pack, don't become discouraged. People usually learn their lesson quickly when dealing with this amount of money. EVs pay themselves off in savings in roughly 3-5 years if done right, and continue reaping in savings well after. But the key is to design for cheap operating costs, which means lots of batteries.
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