Questions and Answers

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1. Why build an EV?
2. What basic steps are involved?
3. How much will a typical Conversion Cost?
4. How much will I save on gas?
5. Which vehicles are the most commonly used for conversions?
6. What driving range can I expect per charge?
7. How fast will my converted EV go?
8. How do electric cars work?
9. How do I determine the charge state of the batteries?
10. What can I do, to keep the cost per mile as low as possible?
11. How much do batteries weigh?
12. How should I care for the batteries to ensure long life?
13. How long do batteries last before they must be replaced?
14. Why can't I just use deep-cycle 12-V batteries to save space and weight?
15. Why use Lithium batteries?
16. What size cabling should I use for the high-current connections?
17. Should I use the wing-nut bolt or should I use terminal-post clamps?
18. Can I use an automatic transmission?
19. Why do I need a transmission at all?
20. What kind of meter(s) should I install so I can monitor as I drive?
21. After the conversion, will the vehicle be heavier?
22. Can I make my own adapters (motor-transmission mount, shaft-clutch)?
23. Can I still have air conditioning?
 
1. Why build an EV?
Today there are limited production electric vehicles (EVs) available, so converting an existing internal combustion engine (ICE) vehicle to an electric vehicle (EV) might be the best choice available to obtain an EV. Building your own electric vehicle (EV) can be a rewarding experience. A typical EV conversion will achieve a range of 30-60 miles with lead batteries, and 80-150 miles with Lithium batteries, for each charge. Studies have shown that 80% of commuters travel less than 40 miles per day, and 50% of commuters travel 20 miles (or less) per day. An EV conversion can meet those daily driving needs. EVs are a clean, efficient alternative to conventional vehicles - using technology that is readily available today! EVs produce zero emissions, and when you consider the full fuel cycle to generate electricity, are up to 99% cleaner than gasoline and diesel vehicles. EV owners enjoy the financial benefits of drastically lower fuel and maintenance expenses. You can be driving for as little as 2 cents a mile in energy cost if you use an electric outlet (or practically zero if you use solar panels to recharge!), as apposed to 20+ cents a mile with gasoline. And soon the gasoline prices could be MUCH, MUCH higher! Thus you will have a tremendous flexibility as to your energy source: from electric outlet, to solar panels, and only if necessary, a portable gasoline generator (still using less gallons per mile than conventional engines)! Thus EVs help significantly reduce our dependence on oil.
2. What basic steps are involved?
A.Define the purpose of the vehicle.
 Ask yourself the following questions:
 Why do you want an EV?
 Where will you drive it?
 How many miles do you require on a daily basis?
 How often will you drive the vehicle?
 Will your employer allow you to charge at work?
 How much do you want to spend?
   
B.Evaluate the vehicles manufactured.
 When you start to evaluate the different vehicles, you will find there are mainly 3 classes out there:
 1.Sports cars, such as the Honda CRX, Pontiac Fiero, Toyota MR2, Porsche 914, Fiat X-19, Nissan Pulsar, MGB or MG Midget. Sports cars have limited space and minimal payload capacity, but are lighter weight and will have better performance.
 2.Passenger cars and vans, such as the Ford Escort, VW Rabbit, VW Beetle, Saturn, Honda Civic and Geo Metro. The payload capacity for a Geo Metro is about 600 lbs.
 3.Light trucks, such as Toyota, Nissan, Ford, or Chevy. Small pickup trucks are a great choice because they can cary much more weight and many batteries, thus giving far greater range per charge. Another advantage is that a large generator can be added in the truck bed, making it a series hybrid with almost unlimited range (with enough fuel).
   
 Each of these classes have their own characteristics with respect to aerodynamic drag, curb weight, Gross Vehicle Weight Rating (GVWR), passenger compartment, and available space for batteries.
Table 1 lists typical vehicles under each of these classes and their range using various lead acid battery packs (6V and 12V). Range is a function of battery weight because the battery represents the fuel. Typically it takes 15-20 lbs of lead to achieve 1 mile in range, or 4 to 5 lbs of Lithium per mile. A Rule of Thumb is that 1/3 of the EVs weight should be batteries; the other 2/3 represents dead weight (i.e. frame, suspension, body, motor, etc). If you could decrease this dead weight to 1/2 leaving 1/2 for fuel, you would have superior performance.
   
 
Table 1
VEHICLEICE CURB WEIGHTVOLTAGE OF EVBATTERY MODELEDCURB WT (LBS)AVG RANGE (MILES)
SPORTS CARS
Pontiac Fiero25301205SHP336044
Honda CRX21751205SHP306047
Toyota MR22695144SCS225343040
Nissan Pulsar2025144SCS225286346
PASSENGER CARS
Ford Escort230096T-145345759
Geo Metro1695120SCS225245138
Honda Civic2260144SCS225306340
Saturn23001205SHP316542
VW Rabbit193096T-105296748
Notes
1. Calculations based on spreadsheet developed by Electric Vehicles of America, Inc.
2. Typically curb weight increases each model year.
3. Average range based on 1 percent grade at 50 mph - representing some traffic.
  
 Other Considerations
  
 Front Wheel Drive(FWD) vs Rear Wheel Drive (RWD)
 A FWD vehicle has the advantage of being more efficient; which improves range. However, front wheel drive vehicles typically have smaller engine compartments, which limit the location of batteries. Also, the front -wheel drive vehicle requires more weight (typically 60 percent) on the front axle.
In a RWD, the greater battery weight in the back tends to plant the driven tires more firmly against the road, thus enhancing traction.
  
 Availability of Spare Parts - Age of Vehicle
 Spare parts should be available. This availability is related to the production of that specific vehicle and which part of the country in which you live. Also the availability of after market parts for suspension upgrades can be important.
   
 Manual Vs. Automatic Transmission
  Most EV conversion vehicles are manual transmissions because they are more efficient than automatic transmissions and provide greater range, require less motor torque, require no transmission cooler, and are easier to convert. The problem with an automatic transmission is that it shifts at about 2000 rpm; the electric car motor is usually designed to operate efficiently between 4000-5000 rpm. If you buy a vehicle with an automatic transmission, you can replace it with a manual transmission, or you can order our adapter set for automatic transmissions. The additional cost to change to a manual transmission is $150 and up depending on the transmission and used auto parts dealer. Consider trading the automatic transmission.
  
 Power Steering
 Power steering is not recommended because of the continuous power required of the battery system. Even on many of the trucks that get converted, most people eliminate the power steering. The cost to change from power steering to a manual steering box is under $100 and less than 1 hour of work. The equal weight distribution allowed reasonable manual steering.
  
 Power Brakes
 Power brakes are a definite advantage if you increase the weight of the vehicle with lead batteries. Your goal should always be to have a safe vehicle. Power brakes unlike power steering are only an intermittent energy demand. A typical system requires a vacuum pump and a vacuum switch.
Curb Weight Curb weight is the weight of the vehicle parked at the curb. No passengers and no payload.
You must also consider where the EV components will be located. Where will the batteries be located; they are the bulk of the additional weight. Will the charger be carried onboard or offboard? How will this change in weight distribution affect the vehicles handling? In the 1973 VW, the majority of weight was on the rear wheels; this was great for snow.
  
C.Select a Vehicle to Convert
   
D.Look for an EV Kit for the vehicle you choose
 Kits will make the conversion significantly easier - they include all the parts, except batteries. A conversion kit will cost about $3,000 - $6,000 and the batteries, depending on how many you need, can cost from $700 - $4,000 , depending on the type you choose.
   
E.Gather the proper tools for the job
 Make sure you have access to the proper tools and supplies, and a place to do the conversion. You may need to rent equipment like engine hoists and contract out welding work.
   
F.Familiarize yourself with the EV parts
 See kit order form for detailed list.
   
G.Saftey
 Any project involving automobiles and tools has inherent risks. Be aware of these possible hazards to prevent damage to the vehicle and serious injury to you.
   
H.Remove ICE components
 Remove any ICE (Internal Combustion Engine) components, making room for the EV parts.
  
I.Install EV components
 Install the motor, components, battery box, and batteries. Install the wiring for propulsion (traction pack), auxiliary power system (12-volt system), and traction pack charging system, and displays and controls.
  
J.Safety Testing
 Test the battery charger; check the wiring and fuses, connections. Then take it out for a spin and notice the quiet, smooth ride. Be sure to show it off!
  
3. How much will a typical Conversion Cost?
Not counting the cost of the donor vehicle and labor, you will spend between $4,000 and $11,500. It depends on the type and number of batteries, and which controller you choose. The total cost also depends on how much metal work you can do yourself.
4. How much will I save on gas?
Gas Guzzler - Assumptions 
 Milage:20 miles/gallon
  Cost Per Gallon:$4.00 (US Ave.) / gallon
 Cost Per Mile:$0.20 / mile
   
Clean Electric -Assumptions 
 Electricity Cost:$0.07 / kWHr (Kilowatt Hour)
 Recharge Cost:Aprox. $0.84 / charge (12 Kw-hr / Charge)
 Vehicle Range:Aprox. 50 miles / charge
 Cost Per Mile:1.68 cents / mile
   
Savings -Assumptions 
  Savings Per Mile:($0.20 - $0.0168) = $0.1832 / mile
 Annual Miles Driven:12,000 miles / year
   
 Annual Savings:$2,198.40 Per Year
* Annual Savings Do Not Include the reduction in annual maintenance expenses! So, you could save more than estimated above.
5. Which vehicles are the most commonly used for conversions?
Vehicles most often converted have a 4 cyl. engine and a manual transmission.
Heres a list of some of the most common:
VW - Bug or Beetle, Jeta, Golf, Rabbit, SciroccoVW BugDodge Rampage
Dodge - Colt, Shadow, Rampage, Daytona
Ford - Escort and Ranger
Porche 914Ford EscortPorche 914
Honda - Civic
Datsun Pickup
Plymouth - SundanceHonda CivicGeo Metro
Pontiac - Fiero
Geo - Metro
    
6. What driving range can I expect per charge?
Of course it all depends on the conversion - vehicle type along with the number and type of batteries. However, most people who drive electric street vehicles say they get between 30 and 60 miles per charge with lead batteries, and up to 4 times that with Lithium batteries (which is about 100-200 miles)! Keep in mind that driving habits impact distance.
7. How fast will my converted EV go?
Depending upon your vehicle type, set-up and application the average top speed is anywhere between 50-85+ MPH (miles per hour)
8. How do electric cars work?
Electric cars are something that show up in the news all the time. There are several reasons for the continuing interest in these vehicles:
Electric cars create less pollution than gasoline-powered cars, so they are an environmentally friendly alternative to gasoline-powered vehicles (especially in cities).
Any news story about hybrid cars usually talks about electric cars as well.
Vehicles powered by fuel cells are electric cars, and fuel cells are getting a lot of attention right now in the news.
  
An electric car is a car powered by an electric car motor rather than a gasoline engine.

From the outside, you would probably have no idea that a car is electric. In most cases, electric cars are created by converting a gasoline-powered car, and in that case it is impossible to tell. When you drive an electric car, often the only thing that clues you in to its true nature is the fact that it is nearly silent.

Under the hood, there are a lot of differences between gasoline and electric cars:
The gasoline engine is replaced by an electric motor .
The electric motor gets its power from a controller .
The controller gets its power from an array of rechargeable batteries .
  
Inside an Electric Car
The heart of an electric car is the combination of:
The electric motor
The motor controller
The batteries
  
 
 A simple DC controller connected to the batteries and the DC motor. If the driver floors the accelerator pedal, the controller delivers the full battery voltage to the motor. If the driver takes his/her foot off the accelerator, the controller delivers zero volts to the motor. For any setting in between, the controller chops the battery voltage, thousands of times per second to create an average voltage somewhere between 0 and Full Battery pack voltage.
  
The controller takes power from the batteries and delivers it to the motor. The accelerator pedal hooks to a potentiometer (variable resistor), and this potentiometer provides the signal that tells the controller how much power it is supposed to deliver. The controller can deliver zero power (when the car is stopped), full power (when the driver floors the accelerator pedal), or any power level in between.
  
The controllers job in a DC electric car is easy to understand. Let us assume that the battery pack contains 12 12-volt batteries, wired in series to create 144 volts. The controller takes in 144 volts DC, and delivers it to the motor in a controlled way.

The very simplest DC controller would be a big on/off switch wired to the accelerator pedal. When you push the pedal, it would turn the switch on, and when you take your foot off the pedal, it would turn it off. As the driver, you would have to push and release the accelerator to pulse the motor on and off to maintain a given speed.

Obviously, that sort of on/off approach would work but it would be a pain to drive, so the controller does the pulsing for you. The controller reads the setting of the accelerator pedal from the potentiometers and regulates the power accordingly. Say that you have the accelerator pushed halfway down. The controller reads that setting from the potentiometer and rapidly switches the power to the motor on and off so that it is on half the time and off half the time. If you have the accelerator pedal 25 percent of the way down, the controller pulses the power so it is on 25 percent of the time and off 75 percent of the time.

Most controllers pulse the power more than 15,000 times per second, in order to keep the pulsation outside the range of human hearing. The pulsed current causes the motor housing to vibrate at that frequency, so by pulsing at more than 15,000 cycles per second, the controller and motor are silent to human ears.

9. How do I determine the charge state of the batteries?
A simple way to measure state of charge is to measure the voltage of the battery bank a couple hours after you have driven it - and before you start charging, of course. The chart below is an example of one used to determine the percent charge remaining. You can make your own chart for the number of batteries you use. The third column, Individual Bat. Voltage, is simply multiplied by the number of batteries to create the first column. Many say that measuring the specific gravity is the best way to determine charge level, but who wants to mess with battery acid!
 
State of Charge - Unloaded
Battery Bank
Voltage - 96V
(16 Batteries)
% ChargeSingle Battery
Voltage
Specific
Gravity
(80°F)
101.901006.371.277
100.96906.311.258
100.00806.251.238
99.04706.191.217
97.9260 6.121.195
96.80506.051.172
95.68405.981.148
94.56305.911.124
93.28205.831.098
92.00105.751.073
 
10. What can I do, to keep the cost per mile as low as possible?
Use low rolling resistance tires and keep the tire pressure up.
Do not be a lead-foot. Its the same as a gas guzzler - take it easy.
Learn to coast a lot - you are traveling for free when you coast.
Use a high-efficiency charger so as not to waste energy while charging.
Plug into the neighbors house instead of yours when charging. (Just Kidding!)
  
11. How much do batteries weigh?
The 6-V golf cart batteries are around 65 pounds each. The 12-V deep cycle batteries are usually about 75 pounds each. Lithium batteries for the same capacity are 15-25 lb!
12. How should I care for the batteries to ensure long life?
Use a quality charger that has three charge phases: constant current, constant voltage with decreasing current and a lower constant voltage for the final phase. The final charge phase is often called the finishing phase or the soak-in phase. The charger should also provide a manual equalization charge mode that you can use at wide intervals to restore balance to your series connected batteries. Equalization removes sulphate build-up on the plates and helps restore performance.
Keep the batteries charged.
Do not routinely discharge the batteries down to 40% or less of remaining capacity .
Check water levels in the batteries at least once per month, especially during hot weather. Only add water after charging, not before.
Never add acid to the batteries.
Inspect the battery terminals to ensure they are tight. A loose terminal connector has contact resistance that will create a large amount of power loss in the form of heat and even melt the lead terminal post down.
13. How long do batteries last before they must be replaced?
It depends on many variables. On average lead acid batteries last about 3 - 4 years.
Lithium batteries can last up to 15 years!
14. Why can't I just use deep-cycle 12-V batteries to save space and weight?
You can. Realize that these are not 12-V automobile batteries. They are deep-cycle batteries intended for golf cart and other electric vehicle use. 8-V golf cart batteries are also available as a design option. Again, Lithium batteries will give you about 4 times the performance of lead batteries at about 1/4 the weight!
15. Why use Lithium batteries?
Lithium batteries are approximately 1/3 to 1/4 the weight of lead batteries, and can deliver up to 4 times the range. They last on average 3-5 times longer than lead! They are 5 to 7 times more expensive, but given all the advantages, they are a BETTER value, cost-wise, in the long run.
16. What size cabling should I use for the high-current connections?
#2 should be the smallest cable size that you use to interconnect the batteries, high-current fuse, circuit breaker, high-current contactor, current shunt, controller and motor. #4 and #6 are smaller diameter sizes that should not be used - too much power loss and heating. Visit your local welding supply store to obtain a flexible welding cable of size #2, #1 or larger.
17. Should I use the wing-nut bolt or should I use terminal-post clamps?
Terminal-post clamps are best because they offer more contact surface area to handle the high current and will stay tight. If you decide instead to use the wing-nut bolt on each terminal post, make sure you use the correct size cable terminal end, usually a 5/16 in. hole and that you use a spring-type lock washer under the wing nut. If you fail to use the lock washer, the wing nut will become loose, contact resistance will increase rapidly, heat will increase dramatically and the terminal post will melt - not pretty.
 
18. Can I use an automatic transmission?
Most EV conversions are manual transmissions because they are more efficient than automatic transmissions and provide greater range, require less motor torque, require no transmission cooler, and are easier to convert. The problem with an automatic transmission is that it shifts at about 2000 rpm; the electric motor is usually designed to operate efficiently between 4000-5000 rpm. If you buy a vehicle with an automatic transmission, you can replace it with a manual transmission. The additional cost is $150 and up depending on the transmission and used auto parts dealer. Consider trading the automatic transmission.
19. Why do I need a transmission at all?
This is a very common question. If a transmission is not used, a gear ratio that allows the motor to start easily under load must be used. The idea behind this is to ensure that the motor is not over burdened when moving the vehicle from a dead stop. With such a starting and fixed gear ratio, the vehicle will reach a top speed that corresponds to the top safe RPM of the motor. For example, I can start off in 2nd gear and accelerate to about 30 mph. If the ratio of my second gear is to be used for a fixed gear ratio, my top speed will be about 30 mph. To get higher speeds, gear shifting is needed. Gear shifting allows for increased speed as the electric motor stays within its rpm design range.
20. What kind of meter(s) should I install so I can monitor as I drive?
Most people install both an ammeter and a voltmeter. The ammeter helps you determine when to shift gears and how to optimize the use of the gas pedal and conserve energy. The voltmeter is of little use at all because it will vary widely as you accelerate and coast. The voltmeter cannot tell you the true state of charge until the vehicle has rested for a couple hours. Unless it is a digital voltmeter, it will not be accurate enough anyway. So, an inexpensive multimeter can be used to measure your bank voltage until you are familiar with the discharge and range capabilities. If you have some extra money, you may be able to find a computing meter that keeps track of discharge and shows you what is left.
ex. Embedded Ammeter replaces the fuel gauge
21. After the conversion, will the vehicle be heavier?
That depends on what batteries are used. With Lithium, your vehicle will actually be lighter! But, with lead, the good news is that it is usually below the chassis and suspension ratings. The weight should be evenly distributed between the front and rear. For smaller vehicles, the suspension system will be challenged, especially with passengers. Booster springs or shocks with coil springs can be added if needed.
22. Can I make my own adapters (motor-transmission mount, shaft-clutch)?
Many people have done so. However, you need access to a metal lathe and other precision tools. It is not too difficult of a process but requires correct balance and alignment. As part of our kit we provide you with blank parts and instructions how to do it effectively.
ex. Typical Motor Adapter Assembly
23. Can I still have air conditioning?
Some people do try to keep the air conditioning. They use a motor that has a shaft sticking out of both ends. The front shaft interfaces with the flywheel and clutch assembly. The shaft sticking out the back end is used to mechanically connect to the airco compressor. Keep in mind that if you do this, you will have no airco when the motor is stopped, which as it turns out is a lot of the time during stops and coasting. Also, the energy needed for this airco comes from your battery bank, shortening your range by about 8%-10%. A second option for AC is to add a small 1-2 hp DC motor that runs the compressor from a second auxiliary battery. This gives you AC all the time!

Still have questions? Visit the Q & A section at Wilderness EV.

 

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