David Heacock's 1985 Avanti EV Conversion (In Process)
A typical approach in an electric vehicle for providing a vacuum for the power brakes is to install an electric vacuum pump and a switch. The vacuum pump is tied to the electrical system so when you turn the ignition on, the pump comes on, builds up a vacuum and is then switched off when the vacuum is correct. When you use the brakes the vacuum falls below a set level and the switch turns the pump on again. The picture below shows the vacuum pump and the switch used for providing a vacuum for the power brakes.
The following picture was actually taken after the old batteries were removed. It shows the pump and switch installed on the side of the engine compartment. The picture also shows a bank of SB50 connectors I decided to provide for a number of reasons. At first I wanted to be able to measure the voltage of each battery from a central position. Since three of the batteries are under the rear battery rack, they are hard to access for measuring their voltage. However, I also wanted to be able to charge individual batteries when they became out of balance using a pack charger over time.
From a number of sources I discovered it is a good idea to place the major components of the electric vehicle on some type of board or rack. This allows you to be able to wire up the major components and then place the board or rack in the vehicle in one piece. It also allows you to remove the major components as a complete unit if necessary in the future. Not knowing much about the electrical components of an electric vehicle I spent lots of time reading information available and discussing issues with a number of friends. I then decided to make some rough drawings and ask the real EV guys to look them over and comment on them. At this point I can't say enough about friends who belong to the Electric Auto Association and their help during this stage of development.
The diagram below is one of my hand drawings of the basic electrical system. Note that it does not include fast transient suppression diodes that need to be added across the contactor coils that are required to protect the Hairball -- details to follow. I only show this as it helped me to understand how components went together and again gave me the opportunity to show it to others for comments.
I ended up making numerous changes and modifications and as these changes were made it became harder as the paper became thinner from all the erasing. I finally decided to use a drawing program so I could make changes easily and use the final drawings as a reference at a later date if necessary for trouble shooting.
After getting the main components on a drawing I decided I needed to figure out where I should place the major electrical components in the car. Since my arrangement of components was sort of strange with all the batteries in the front and the motor in the rear seat the solution seemed to be that I would place the board with the components near the motor to limit long cable runs. I determined I had room just behind the motor and transmission to place a board and the major components along with a way to mount it to the frame. It should be kept in mind that placing these components and high voltage cables inside the car is not a good idea as it presents the possibility you might come in contact with high voltage which is never a good idea. My plan was to enclose all of these components and the motor to make contact with the high voltage components more difficult.
The following picture shows the major electrical components mounted to the board. In this case the board also acts as an insulator from the frame. On the left hand side of the picture is a green box known as the Hairball. The Hairball is sort of the brains of the system and sends signals to the controller to make things happen. The Zilla controller is the large green box more toward the center of the board and is supposed to be able to send up to 1000 amps to the motor, that is if the batteries can handle that many amps. Between the Hairball and the controller on the backside of the board is the primary contactor which must to be turned on for anything to happen. Just in front of the main contactor is a fuse which was placed there as part of the protection for the controller. I also placed two other similar fuses in the battery pack in the front of the car. On the right side of the board is the forward / reversing contactors which are used to make the car go forward or reverse depending on the position of a switch located next to the driver. These contactors were necessary because I can't simply place the Harley transmission in reverse. Between the controller and the forward / reversing contactors at the front of the board is the shunt used in conjunction with the ammeter so the driver can determine the amount of juice being drawn by the motor. The idea in an electric vehicle is to keep the amp draw as low as possible to provide more range and longer life for the batteries, kind of like slowly depressing the gas pedal rather than stomping on it to save gas and your pocketbook. The other two components on the right are a fuse block and a small relay.
The next piece of the puzzle was to figure out how to connect a pedal to the electrical components on the board to make the car move. In many cases this is done using a mechanical linkage connecting the normal gas pedal to a pot box under the hood. My problem was that my controller and components were located behind me making a mechanical linkage more than difficult. The answer was a HEPI pedal which was electronically connected to the Hairball and would send electronic signals to determine how much juice the controller needed to provide. I actually like this idea as it makes things simple by connecting a few wires. My problem was that mounting the pedal directly to the fiberglass firewall was not going to work because the pedal would not be positioned correctly. Therefore after trial and error with cardboard mockups I came up with a mounting bracket. This bracket could be mounted to the firewall and then the pedal could be mounted to the bracket. The following set of pictures shows the various components including the bracket after it was first tack welded together, the wire connections and the competed mounting bracket and pedal. If you are asking yourself, is this like the pedal in vehicles in the news lately, the answer is yes.
After wiring up the main board, connecting the HEPI pedal to the Hairball and providing some additional wiring from the ignition key I was ready to see if pressing the pedal would actually turn the wheels. Here again I called on two very helpful friends who know way more about electric vehicles than I will ever know. We spent time one evening doing some testing to make sure things were correctly wired before we tried to step on the pedal to see the wheels turned. As it turned out, the first time we tried using the pedal, nothing happened. The nice thing about the Zilla controller is you can read error codes with the use of a computer or a Palm Pilot which helped us determine the pedal input was not being recognized by the Hairball. Solution, change the settings for the Hairball to recognize the pedal. And, after about two hours, the wheels turned for the first time in about three years.
Just for conversation sake, the picture below shows one of the main wire connectors inside the engine compartment. The problem here is that many of these wires were no longer needed but determining which ones became an interesting game of tracking down just where they came from. Some were easy as I had labeled them as I removed the engine but others were somewhat more difficult. I would imagine that anyone converting a gas car will have to deal with this problem sooner or later and you have to be careful to only remove the wires which are no longer necessary.
While we are on the subject of electrical I would like to share an unpleasant experience which should not have happened but did. I am only including this because everyone should keep in mind the high voltage /amperage in an electric vehicle can be dangerous and deserves respect. When first making the cables for connecting the batteries I made the mistake of connecting six batteries and then shorting the first with the last battery. The results are shown in the following pictures. What is not shown is the visit to the emergency room and the reasons for why this happened. I had made up a wiring diagram and the connections for each battery in the pack. As I was measuring each cable length I would use the diagram to make sure which connections went to which battery. However, this accident occurred because I looked at the diagram on one side of the car and decided to go to the other side to place the cable for determining the position of the lug on the end of the cable. In doing so, I contacted the cable from the last battery I hooked up with the terminal on the first battery because I had moved to the other side of the car without the diagram and was looking at the wrong battery terminal. On the way to the emergency room with a blackened hand and skin hanging off my fingers I just could not figure out in my brain what had gone wrong.
As you can see from the above pictures, high voltage in an electric vehicle can do a lot of damage to electrical components and people. After thinking about what had happened I decided at least three things could be done to prevent this type of accident. First, when using a diagram, always have it with you when looking at the batteries and cable connections and place it like a map in the correct orientation. Second, tape or cover all battery terminals before you begin making the cables. As you begin the process look at the diagram and then remove the tape or cover from the next battery terminal you will be working with. This should help to limit contact with the wrong terminal when you come back to place the cable or adjust the lug on the end of the cable. And third, check, recheck and recheck again before you physically connect or touch a cable to any battery terminal.