5: Motor Controller

I have opted for a DC motor controller to go with my ADC FB1-4001 motor (see page 4). Most of this blog is about DC motors. If you have opted for an AC system then it is fairly normal to have a matched motor and controller. Some popular makes include Siemens, AC-Propulsion, Azure Dynamics, Magna and Brusa. These packages tend to come in small, medium and large sizes for buggy/small car, large car/SUV, and truck respectively. There are some AC controllers that will work with a wide range of voltages for the battery source and a wide variety of motors.

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The picture below shows an old Siemens controller for an AC system. ----
The picture below show a Brusa controller that is available for a wide variety of battery supply voltages. Brusa also recommend their own motors to be used as a package.

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The picture below shows a Curtis 1231C controller. This is probably the most widely used DC motor controller in car conversions. This controller can operate up to 144v at 500A. This will give a reasonable acceleration at that voltage and current. These controllers are very simple to set up and will work with a wide variety of DC series motors. The power control comes through MOSFET (Metal Oxide Semiconductor Field Effect Transistor) that use a high frequency switching technique that controls the average voltage fed to the motor. This voltage corresponds to the position of a potentiometer in the throttle box connected. A potentiometer is a rotary variable resistor. These normal have three terminals; 2 are each end of the resistance track and the other is the wiper. The wiper is connected along the resistance track depending on how much the shaft it is attached to is rotated. This gives a variable resistance. This is the same as the volume control on a radio that has a rotary control. The throttle potentiometer is operated by pressing the throttle pedal. The controller then meters out the power to the motor through the transistor bank (MOSFETs). I am not sure if Curtis have resolved this, but there used to be a nasty whine when pulling heavy loads on initial pull away. This was one of the reasons I did not choose a Curtis Controller. The Zilla controller from Cafe electric is another DC controller, but the business side was a bit rocky, so supply of these controllers is tetchy. They are well sought after as there tends to be 1K and 2K versions that can deliver 1000A or 2000A respectively. This is a mighty lump of power and will put a big grin on the face of the lucky owner.
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The picture below shows the Zapi H3D DC motor controller and it's programmer unit. This was my controller of choice. Its delivers up to 800A at 120v. That puts a smile on my face. One of the selling points of this controller for me was that it has regenerative braking so I can re-charge the batteries when slowing down or braking. By way of a few control relays I was able to set up a sport / economy switch, so I could limit the driving current and provide bigger regen amounts (economy) or have full driving current and a small amount of regen (sport mode). The economy mode tends to be jerky, so I only use it when I am trying to eek out the range from the batteries. I also got this with a large heat sink for air cooling and forward / reverse and regen contactors as well as a main contactor. The Zapi controller was designed for retro-fitting a Fork Truck with a modern controller, so this provides some nice little extra features that can be used on a car. I use the auxiliary steering contactor output to control a 120v relay linked to the control of my 12v power steering pump and so I get power steering from when I first touch the throttle until 5 seconds after the motor stops. This 5 second delay is programmable. I tried different settings and 5 seconds seems to be about right for normal driving, useful little feature. There are many others too. As my conversion was my first, I wanted as many options to try out different driving situations and set-ups as possible. The Zapi controller gave me this. Be warned that Zapi recommend that you do not attempt a gear change with regeneration enabled as a sudden change in motor speed / load can damage the output transistors. That was what I was told, so I worked out some relay logic to disable regen whenever I pressed the clutch pedal therefore regen is only active when the drive is mechanically fully engaged. It was fairly straight forward to connect up to the motor.

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Before I installed anything into my car, I set it all up on my garage floor. I mounted a plank of wood on the wall and fixed the throttle box to this and some old light switches that could provide the key switch inputs etc. Then I got the whole system working. From that point on, it is just about figuring how to mount everything and repeating the wiring in the car. when I looked at the the system on my garage floor and then at the car, fear set in that it would not all fit in the car. This is understandable. The Ford Probe is quite low, so the height problem is exaggerated, but I got it all in after about 3 attempts. More about that later.

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I hope this has provided some insight into my choice of motors, but yours is based on your own desires. Mine was most definitely not the cheapest solution. For AC and DC systems, more voltage normally means more ability to make the motor go faster. In order to push your car up to speed requires current. More current generally means more torque from a given voltage and this is perceived as acceleration. So for racing, you want a high voltage high current motor controller. AC systems are best here as the motors are capable of much greater speeds with minimal gearing. These systems are more expensive generally. Hub motors do not actually go very fast as they are connected directly to the wheels. However these motors can work at very high voltages too. These are also quite expensive generally. I have seen DC motors doubled up by joining the shafts of two motors mechanically and running from 2 Zilla controllers (checkout "white zombie" on YouTube), but this is not for everybody and can be very costly. Most people converting to electric just want an electric car to behave similar to a normal petrol car for their money, and not too much money either. If you really want to do things on the cheap then you must admire the efforts of forkenswift. A quick search will find details of this Geo Metro with the drive system and motor etc. from a scrap forklift truck. This has got to be the cheapest way to do an electric car conversion. However, this is not for the feint hearted. There is a lot more work needed to match things together and much more research required to track down parts etc. Of course the bonus is the cost. I believe that I have gone midway, ordering some parts at normal rates and getting some parts by arranging my own shipping, scouring salvage yards and eBay to save money.

I have given some examples of motor controllers that I know of, and there are many others that are worth mentioning, but a bit of searching on the web will soon reveal the characteristics and cost of these controllers. I can make updates to this page if you have specific questions. Please use the comments section at the bottom. If you believe that my commentary is in some way wrong or misleading then please use comments. If you have anything else that you want others reading this page to hear about then please leave a comment.

4: Motor

The motor is one of the key parts for your conversion and will have the most influence on what goes with it. First choice is gearbox or hub/wheel motors. There are many choices for hooking a motor to a gearbox, but for hub motors, they are nearly all DC permanent magnet motors or AC. I have no specific experience with hub motors, but many of the top speeders and sporty electric cars use in wheel motors. The Venturi Fetish uses the Michelin electric wheels. These are amazing for developing a complete new car as the wheel contains the motor, suspension and brakes, all you need to do as a vehicle designer is build a frame to fix it to. They are also very expensive. The Lightning car uses 4 AC motors for 4 wheel drive. These were a new design and also expensive, but huge performance comes at a cost. So the easiest and cheapest way to get a reasonable performance is what I want to focus on. For this blog, the design is continuing the theme of change as little as possible for the first build, then you can go back, redesign and upgrade later. At the same time I don't expect anything to be second rate, that has never been my objective. You need to be happy with what you have built. So in this way I will consider that you will keep the gearbox, clutch and flywheel from the donor car.

AC or DC
This question comes up a lot. So going through the gearbox, AC is more expensive and normally comes as a whole system with a matched controller and motor. These systems often offer a complete solution that also includesa motor controller, a DC-DC converter and 12V controls to hook directly to the donor car systems. This all sounds great and it is, but it comes at a price. Another advantage of the AC motor is that many systems offer motors that freely rev up to 13,000 rpm and this means it is easy to run a single gear ratio and ultimately replace the gearbox, clutch flywheel etc. with just a simple reduction box and a differential that are not too difficult to get hold of. Another advantage of AC systems is that generally they normally have regenerative braking to put charge back in the batteries at different levels when you release the throttle and when the brake pedal is applied. This also reduces wear on the mechanical brake pads and provides the drag that you would normally expect from a petrol engine when you release the throttle. DC systems can also have regenerative braking, but it is not so common. I have a DC motor and controller with regen braking, but I will explain more about controllers in another posting. DC motors are generally cheaper, but often limited to around a nominal 5,000 rpm and maxing at around 7,000 rpm by over-revving. So this makes the gearbox essential. I know from experience that I can drive comfortably from rest to 40 miles per hour in 2nd gear only. I can take this up to over 50 mph but the acceleration is much slower after 40 and that is about 5000 rpm, so it is over-revving. Changing into 3rd gear gives me a sharp rise in electric current, but the acceleration comes back in a lump and feels good. This then takes me up to a comfortable 55mph and can pull away from zero, but it can be a little sluggish on the initial pull away, but still drivable. 4th gear will give a good top speed, but pull away from rest is really poor and forces full current draw. 5th gear can be used on it's own, but the pull away is unacceptable I find. With an AC system revving up to 13,000 rpm it would be quite comfortable to have a gear ratio and differential equivalent to about 2nd gear and this could go from rest to a good high top speed. This is the sort of performance you could expect from a Tesla Roadster. The Tesla uses an AC motor.

The first photo below is an ADC FB1-4001 from Advanced DC Motors and this is one of the most commonly used motors in electric car conversions. This is what I have in the Probatron (http://www.probatron.blogspot.com/). The second photo would have been my preference and is the Warp 9 motor from Netgain. It is a little bit more powerful than the ADC motor, but also a little more expensive. Being in the UK, I decided to arrange to have an ADC FB1-4001 shipped over from America and I arranged the shipping myself. I could not do this for the Warp 9 as they have a UK distribution network that stock them and wouldn't sell direct to me. ADC have a UK sales rep that basically takes my money and arranges the shipping for a small commission. I saved several hundred pounds this way. Both of these motors will run up to a nominal 5,000 rpm and can rev up to about 7,000 rpm, but this is not recommended. The ADC is rated at 19kW continuous and 176kW peak power. I believe the last time I looked the Warp 9 was rated at 22kW continuous and I would expect slightly more peak power than the ADC motor. Both motors are rated at 144 Volts, but can work comfortably at 156v. My system works at 120v, but I would like to have a higher voltage. The voltage is almost like the engine size. Higher voltages make it much easier to develop higher power as greater efficiency is possible. This is another advantage of AC motors, the efficiency is slightly better than DC motors. All electric motors can typically produce efficiencies of over 80% while petrol engines are hard pushed to make 25%. The problem then is down to battery weight and cost. Again this is the subject of another posting.

The third photo below shows an AC motor that comes with one of the Azure Dynamics systems. This is rated at 55kW, but these tend not to have such a high peak power and this is due to a flatter efficiency curve. Originally the Ford Probe 2.5L V6 engine that I had was rated at 164 Horsepower, and the ADC motor equates to 135 HP peak, but it is not delivered like that. I have an 800 Amp motor controller running at 120v, so the most I can develop is 96kW, and this equates to about 128HP. That is what it feels like, but the delivery of the power is completely different to a petrol engine and much smoother as it has just one electric motor instead of six thumpers to turn the crank. My advice to keep a good level of power and keep the cost down is to buy a DC motor and my choices are shown here. I would like to delve into AC systems, but cannot afford this right now.

3: Car

My Probatron !

Which car should you choose? If you fancy the idea of converting a car to electric and you don't already have a car to convert then here are some thought starters.

• Will you feel good, cool, respected and proud of your ride
• Will it look good in all situations
• Will it be light enough
• Will it satisfy your functional needs (2 seats / 4 seats, 4x4, sports coupe etc.)

It is important that having read the previous blog about budget that you understand that you are going to spend a lot of money on the conversion. The cost of the car itself doesn't need to be excessive, but don't use an old crapper because it is already sitting in your back yard or at the end of the conversion it will be an electric old crapper. Quite often these are better scrapped for the weight of metal to go towards a car that you convert for the reasons shown above.

My story goes like this; around 2005 I was discussing about converting a car to electric with my wife and I said that I would get a little Fiesta or something else that's going cheap. My wife asked me if that was a good idea and that I should feel proud of what I am driving, not just adequately satisfied, and certainly not embarrassed. One thing about owning an electric car that has been converted is that you need to expect to show it off regularly. So my wife said why don't you get something a bit sporty looking, but can sit 4 people so we can go out as a family. I have a daughter so I would need 3 seats at least. She suggested a Ford Probe and I had liked the look of these for some time. So I started looking. I wasn't too worried about a noisy engine or leaks as all this would be removed. So that gave me a lot of scope for haggling. In the end I picked up a 1996 Ford Probe 2.5L V6 for £700 (about $1120). I knew it would be some time before I could start the conversion as I needed to build up some finances. I ended up driving the car for 3 years and it was coming up for it's annual MOT test and the road tax and insurance was about to run out when the exhaust fell off. That was the time I parked it up and took it off the road ready for the conversion to start. I always said that I would squeeze as much out of this engine as I could and ended up naming my car Christine as it just wouldn't die. Apart from topping up the oil and water from time-to-time I did nothing to the engine and it was still going strong when the exhaust broke. I also managed to sell a load of the engine parts on eBay and weighed in the block.

You can read the rest of the story at http://www.probatron.blogspot.com/ where the conversion is described in great detail with photos etc. I shall re-use some of these photos in this blog.

Land Rover Defender

My personal preferences are towards sporty looking cars or rugged types. The problem with rugged types is they are normally quite heavy and don't get the same performance as some of the electrical energy is used just to get the extra weight moving. I have considered a Land Rover Defender or mk1/mk2, but these are either rusty on the frame or really expensive. Other cars that I looked at were the Toyota MR2 or Celica Supra, Nissan 300zx or 200sx, Mazda MX6 or RX7 and the Audi TT. It is unfortunate that there aren't many home grown English cars that were suitable and affordable, but most are ordinary family cars or hatchbacks. The Japanese cars seem to have the most indulgence in cheap sports cars that mimic some top brands like Ferrari, Jaguar and Aston Martin. Even the Ford Probe was made on the same production line as the Mazda Mx6 and 626. The Haynes manual covers all three cars.

My best advice is to choose a car that uses only a small part of your budget and you would be proud to show it off as an electric conversion.

Leave comments about your choice of car and your reasoning. I cannot say there is a right answer that suits everybody (except maybe the Tesla Model S), but I am happy to help with discussion about your ideas and preferences.

Tesla Model S

2: Budget

Here is a subject that nobody wants to talk about, but the reality is that if you don't have a budget to get the car legally on the road as a first objective then it is highly likely that it will never get there.

I set a ball park figure of around $13000 or £8000. This is based on my experience. You may think this sounds like a lot to find at the start, but you can start with about half of that and build up your finances while you have the conversion going on. This is like a minimum, and is based on converting a car to be about the same as it was before the conversion and for general use on local journeys up to about 40 miles. Any of these factors can be improved upon, but then you will need even more money.

Generally the cheapest and easiest conversion is to have a DC motor with Lead Acid Batteries through the standard gearbox, flywheel and clutch. This would have a basic motor controller, a basic DC-DC converter, cheap chargers etc. Some parts you just can't get cheap unless you know the right people or get second-hand, but this can sometimes cause more problems than it solves. If you have the patience, then you can make some of the sophisticated parts yourself. I have seen kits for building your own motor controller for example. Throughout this blog I am not planning on discussing how to build the parts at this point in time, but may get round to as I take on more things like this in future.

Generally the things you are going to need to buy consist of the following:

• Car
• Motor
• Motor controller
• Battery pack
• 12v battery mains charger
• Battery pack mains charger
• DC-DC converter

As you will be removing the internal combustion engine you will be taking with it some power sources that you will need to add to run an electric car. Here is a list of other parts you will need to add to keep your car driving like it was before:

• Vacuum pump for the brake booster
• Hydraulic pump for the power steering
• Pump for AC if you want it.

As well as these essentials you will also needs lots of other smaller parts:

• Cable, and loads of it
• Lugs for connecting the batteries
• Switches, relays and contactors
• Tape and heat shrink sleeving
• Metal for making structures to support everything and wood to make models.

So there is the first blog and some ideas about what you will be spending your money on.

In future blogs I will examine each of the items here to help you make the right decisions for your conversion to get what you expect from it. When you have your converting head on and have built up some money, then you can start. It is worth having a stock of major parts before you start taking the engine out of your car as you will need to figure out how you are going to fit it all in the car. If you lose your momentum for lack of parts, then the conversion will take a very long time. I fell quite ill while doing my own conversion with a real bad dose of flu and I was itching to get back on with my car but couldn't do much for a while. We had a bout of bad weather that stopped work until I worked out a cover for my work space. Another period of time I was having some parts made to mount and connect the motor to the gearbox and this process took about 3 months, but if I had the parts it would have been done in one week. I had to kick myself back into action, but as I got closer to putting my car on the road the excitement mounted and my work effort went up again as I was setting myself deadlines.

My best advice is that if you are getting wound up or angry with your build then walk away and do something else for a few hours, or leave till the next day. When you return to the task you will see things differently. You are going to spend a lot of money on this project, so don't settle for a crap job. If something needs putting right then do just that.

1: Project EV Convert, In The Beginning

Welcome to the EV Convert blog.

The purpose of this blog is to go through all the steps to convert a normal car to electric only.