Electric Vehicle Conversion Help

THE MOST INFORMATIVE WEB SITE FOR ELECTRIC VEHICLE CONVERSION

Conversion Tips

If you have a conversion tip you want to share, send it to mail@evhelp.com I’ll add it here with recognition.

Welding

If you don’t know how to weld, it might be worth your time and money to buy a welder and learn how to use it. You can get a decent welder and supplies for under $300 – the cost of the battery rack(s) alone will more than cover that expense. Here’s what you can make and save money:

Battery rack(s) (save $500 - cost of materials)
Motor mount (save $250 - cost of materials)
Tow-bar tangs welded to frame (save $100 - cost of materials)
Tow bar ($100 - cost of materials)
Bed mounts (save $200, if you fabricate a new bed to save weight)

You can get your angle iron and flat iron raw materials from a local scrap yard, metal machine shop or local home improvement store.

Engine Removal

You are going to need a hoist to get the engine out and it’s a good idea to have someone help you. Don’t get in a hurry. Be safe. I made a wooden frame on wheels with a 12-V winch on top. It was easy to maneuver and had plenty of lift power. Place a small jack or blocks under the transmission to hold it in place until the electric motor is in place and secured to its mount.

CAUTION: Do not start hacking away at the wiring harnesses! Only cutoff engine wires that you are sure you will not use later. Label wires that you want to identify later, such as tachometer and temperature sensor wires (I don't use either one of these.). Do not cut off any ground wires. Simply move them from the engine to the firewall or chassis. If you lose a ground, something won’t work right. All ground wires are important. Don’t disturb wires that go to the transmission – one set of transmission wires is for the speed sensor for the speedometer and odometer and the other set is for the reverse switch that activates your backup lights.

You will most likely have to keep the computer so your speedometer and odometer still work.

Motor Mounting

The electric motor mount is actually four main pieces: the part that clamps around the motor (upper and lower half) and the two motor-to-chassis mounts, one on each side. You don’t have to keep the rubber engine mounts for the conversion. There is no motor vibration that you must isolate from the frame, not like a gas or diesel engine. It’s better to remove the rubber (rip and burn) and weld metal flanges to them. See the photo below.

Power Brakes

You must purchase a 12-V vacuum pump with vacuum switch (a kit) to provide the vacuum to your power brakes and vent system. It is easy to install. Some people make vacuum tanks to store the vacuum, thinking that the pump will run less. My experience with this has shown that this is not needed and the vacuum pump comes on for short times when the brake is applied. Make sure you use the rubber mounts that come with the vacuum pump to mount it. If you don’t, the vibration through the frame and vehicle will be intolerable.

Power Steering

If you want to retain your power steering, 12-V hydraulic pumps are available. A popular source for this is the electric hydraulic power steering pump in the Toyota MR2. However, these pumps will add to the drain on your 12-V system battery, up to 80 Amps when the steering wheel is turned hard right or left. Using an electric pump requires that you also use a hefty DC to DC converter to keep the 12-V battery charged from the HV battery bank. If you decide against power steering, a manual steering gearbox should be available for your vehicle. I discovered that a 1993 manual steering gearbox replaced my 1998 power steering gearbox without any modifications or surprises.

Automatic and Daytime Running Lights (DRL)

I decided that I don’t want my headlights and running lights coming on during the day automatically. For most Chevy vehicles, running lights and headlights come on automatically when it is starting to get dark outside. During the day, the high-beam lights come on at half voltage, even in bright sunlight. The DRL circuit places the bright lights in series to share the 12 volts. If you wish to disable all automatic lights, first, remove the light sensor and replace it with a 1-kohm resistor – simply plug the wire leads of the resistor into the sensor socket. For the Chevy S10, the light sensor is located on the passenger side sticking up through the speaker cover - a dark glass ball shape. Second, open the hood, remove the fuse block cover and remove the DRL diode, which looks like a plug-in fuse but is black and has a white diode symbol on it. That’s it. Now you will not have this drain on your 12-V system as you drive.

New Bed for Trucks

My stock truck bed (6 foot) weighed 320 pounds. That is equivalent to 5 batteries. So, I decided to scrap the original bed and make one with an aluminum frame and ABS plastic sheathing. You can see that in the photo on the home page and some details on the S10 Conversion page. I used 2” aluminum framing that is used for patios and found the ABS sheathing at a local plastics company – it was only $45 for a 4’ X 8’ sheet 3/16” thick.

Battery Placement

The batteries are heavy, in the neighborhood of 65 lbs each. You will need at least 20 of the 6-V golf cart batteries or 10 of the 12-V batteries for smaller vehicles (45 to 75 lbs each). Therefore, you must place them so the weight is distributed fairly front and rear, side to side. A truck conversion is easy. Place 16 to 24 batteries just behind the cab in rows. Four of those batteries can be placed in the engine compartment where the radiator used to be. That way, the weight is distributed fairly evenly front and year.

Battery Watering (See the Battery Watering System page.)

Number of Batteries

Most people who convert light-weight pickup trucks use 20 six-volt deep-cycle golf-cart batteries. This provides a range of about 40 miles and a top speed near 80 mph. So if you are planning on driving the freeways, use at least 20 batteries. Actually, if you drive the freeways, 24 batteries is best. Even so, your range will be shortened because of the high current drain while on the freeway. Because of the heavy constant battery drain, driving on the freeway is not a good idea for lead-acid based vehicles.

Power = Current X Voltage

Voltage = Power/Current

Current = Power/Voltage

It's important to understand that it is power that makes your vehicle move. The motor converts electrical power to mechanical power. Electrical power is the product of voltage X current. For example, 96 V X 400 Amps = 38,400 Watts of power. This is the approximate amount of power that you will need to accelerate briskly. Note that a nominal 96 V is 16 batteries in series. Now, what happens if you use 24 batteries? For the moment, let's assume that the added weight will not affect the amount of power that you need for acceleration. Ok, 24 six-volt batteries is a nominal 144 V. Now that the voltage is higher, the amount of current that is drawn from the batteries to produce 38,400 Watts of power is less. Divide 38,400 Watts by 144 V and you get 267 Amps of drain current. You can see that having a higher battery voltage reduces the drain on the batteries for a given amount of needed power. Therefore, your range increases. There ya go! However, the extra weight does figure in causing the need for additional power during acceleration. However, overall you are still ahead with a higher voltage.

Consider this example. Let's say that a Chevy S10, with its 16 six-volt batteries, requires an overall average of 15,000 Watts of power during use - more during acceleration and nothing while coasting. The average current drain on the batteries is 15,000 Watts divided by 96 V, which equals 156 Amps. Now, if we increase the number of batteries to 24 (144 V), the average current drain required for an average of 15,000 Watts is 15,000 Watts divided by 144 V, which equals 104 Amps of drain on the batteries, much better than 156 Amps. So the drain on the batteries has decreased by 1/3 allowing nearly that much increase in range.

The Reality: Keep in mind though that adding batteries adds weight, which means it will take more power to accelerate with the same vigor. In this case, we are adding 8 more batteries for an added weight of 520 pounds, then add rack weight. With this much added weight, you may have to beef up the suspension. Estimate an increase in range of 1/4 or 25% instead of 1/3 or 33% because of this weight and increased need for power.