Archive for November, 2008

Batteries and Battery Racks

Restoring and Building | Posted by admin November 30th, 2008

One of the hardest tasks when designing an electric car is to decide on the battery pack. The batteries you choose are going to be the heart and blood of your car. Which ones you choose and how many of them you use will determine how fast the car will be and how far it will go.

There are a number of technologies available. Each has it’s advantages and disadvantages.

Lets start by saying what is required is what is called a “deep cycle” battery. These are batteries which can be discharged to within 25% of their power without damaging them. A typical car starter battery is not designed to do this. Deep cycle batteries are used for marine applications like trolling motors or golf cart batteries.

There are 3 types of batteries I considered for my project.

1. Wet Lead Acid – This is your standard car battery or golf cart battery. They are made of plates of lead immersed in an acid. They are cheap, easy to obtain, are reliable, and not easily damaged with charging. The down side is they are heavy, require adding water to the cells every now and then, and they must be kept upright so they don’t spill acid.

2. AGM – Absorbed Glass Mat batteries also use lead and acid, but the the acid is absorbed into a glass fabric so the acid doesn’t spill. These batteries are also typically sealed and do not require maintenance. Because the acid in embedded in the glass mat, they can not spill acid and can be used on thier side or even upside down. The disadvantage is that you must be very carefull not to over charge them. Doing so will damage the battery.

3. Lithium-ion polymer batteries – These batteries are an evolution of the standard laptop battery. They can be quickly charged, are light weight, and hold a lot of energy. The major downside to these is that they are still very expensive. Pricing out a battery pack to run the car was going to be between $20-30k. This is the technology I eventually want to run my car on, but it has to wait till the price comes down.

Weighing in price, weight, and size, I have narrowed my choice to either Exide Orbital 34DC 12 volt deep cycle or the Optima D34/78. These batteries have a 10 inch x 7 inch foot print and both about 55ah.

Based on these batteries I have begun designing the battery racks. The frame was modeled up in 3D Studio Max and used as a model for calculating out the battery positions and designing the rack. The rack is designed to not only old the batteries but also keep them from sliding forward in a hard stop or accident.

Frame loaded with 24 batteries

Frame loaded with 24 batteries

Battery Holders are in red.  Note the addition of a roll bar as part of the system

Battery Holders are in red. Note the addition of a roll bar as part of the system

Battery holder Side View

Battery holder Side View

Top View

Top View

Version 2 - Holds up to 24 batteries

Version 2 - Holds up to 24 batteries

Version 2 Racks

Version 2 Racks

Side View

Side View

Notes:

The electric motor is massed out in purple in these renderings. The transmission is in dark grey. The existing frame is in blue.

The frame is fabricated with 3 types of members, the roll bar is 2″ x .095″ tubular steel, the racks are fabricated from 2″ x .25 angle and 1″ x .125″ angle. Bolt plates are made from .25″ steel plate. The frames are all MIG welded.

1968 Valkyrie Specs and Brochure

Restoring and Building | Posted by admin November 28th, 2008

These are the original brochures from Fiber Fab on the Valkyrie. The body style of the kit that I acquired has been modified quite a bit by the previous owners to look more like the 2005 Ford GT40 with the deep front nostrils. I believe it was also originally a two piece body and was modified to be a 3 piece.

These are the specs for the Warp 9 motor that is going in the car.

Body Work

Restoring and Building | Posted by admin November 28th, 2008

Fixing the body.

The iPhone

technology | Posted by admin November 23rd, 2008

Just a note about the iPhone. This has been one of my most used tools in this project. The whole project actually started when I was sitting on the beach in Sarasota watching the sunset and surfing on eBay with my iPhone. It was then that I came across the Fiberfab Valkyrie that was for sale in Jupiter, Florida. That dream of taking on Detroit and Tesla and building a cool electric sports car for less took hold of me. One press of the bid now button and the journey began.

Since that time I have used the phone to take photos of what I was doing and email them to friends or experts to get advise or find parts. Without this ability to snap quick photos and carry them easily around the job would be much harder. It is very hard to explain to an autoparts employee what you need without a make and model for a car. But I would pull out my iPhone and show them the project and exactly where the part was going or what it was replacing.

And this blog has been written almost entirely with my iPhone.

The Doors

Restoring and Building | Posted by admin November 23rd, 2008

Like every part on this car, the doors are not going to be easy. The original manual calls for 1965 Mustang corner windows and a Ford LTD 4dr hardtop side windows. The car I purchased came with the corner windows but no LTD windows. That is going to require some searching. The latches were only partially installed and I don’t like the job he did.

The first part of the job was cleaning up the door handles.  They are handles off of a what appears to be a 1965 Ford Falcon. The previous owner had put masking tape on them and left it on.  I am not sure how old this tape was, but it was baked on good.  2 or three layers worth.  The latches were also a bit rusty and needed a good cleaning.

Here it is all cleaned up.

This latch was mounted, but it needed to come off and all of the rust removed.

The trianglular vent windows had also been covered in layers of masking tape that was baked on.  These took a while to clean up.

After quite a bit of work adjusting and working on the latch and connecting rods, the handles and latches were now mounted and working properly.  I still need locks though.

The Motor

Electronics | Posted by admin November 17th, 2008

The motor for the car is a Warp 9 DC motor. At a hundred twenty five pounds this motor is a little power house.

It is a 9.25″ diameter, series wound DC motor with a double ended shaft.

Standard Features

  • 9.25” diameter, series wound DC motor
  • Weight, approx. 156 pounds
  • 32.3 HP (72 Volts, 335 Amps)*
  • 70 Ft. pounds torque*
  • 5,500 RPM’s
  • Double or single ended shafts
  • Advanced timing – factory set for CCWDE (CWDE available)
  • Industry standard mounting and bolt configuration
  • Commutators key locked onto the shaft
  • High quality, large style brushes, factory preseated over 90%
  • Exceeds Class “H” insulation
  • Drive and tail shafts keyed with pilot bearing hole
  • Delivery – from stock

Brakes

Restoring and Building | Posted by admin November 17th, 2008

Upgrading the front drum brakes to disc and installing a dual master cylinder and booster. The booster will be powered by an electric vacuum pump.

The front drum brakes were converted to disc brakes for added stopping power. This was easily done with a conversion kit.

The rear brakes are the original Corvair drum brakes.

An emergency brake handle was found at the junk yard that works perfectly. I fabricated a peice of steel plate which bolts to the frame to hold the brake.

The emergency brake uses two cables which come off of the brake handle and go to the back brakes.

The local U-Pull-It junkyard is a great source for parts. In this case, I found an older model Camero with a perfect dual master cylinder and proportioning valve system for the car.

A special mount had to be made to mount the cylinder so it would angle slightly to miss the nostrels and also align with the brake pedals properly.

Here the plumbing for the breaks has been installed. The local NAPA autoparts store was terrific in helping me with this part. My thanks to the guys there. They supplied me with a special kit which included a special tubing that was bendable by hand but rated for high pressure brake lines. This saved a lot of time and was a lot easier that bending steel tubing. The kit also came with all the fittings.


The interior

Restoring and Building | Posted by admin November 17th, 2008

Designing the interior.

Transmission

Restoring and Building | Posted by admin November 17th, 2008

Transmission and linkage.

Rebuilding the front end

Restoring and Building | Posted by admin November 16th, 2008

The front end suspension on this car is from a 1967 Corvair. When I purchased the car, the front end was completely rusted out. The cross member was rusted completely through and lacked any structural integrity.

Corvair front end rusted out.

Corvair front end rusted out.

Rusted!!

Rusted!!

Taken completely apart and inspected. Some parts could be restored.

Taken completely apart and inspected. Some parts could be restored.

Sandblasted, rustproofed, and painted.

Sandblasted, rustproofed, and painted.

A new cross member was purchased from Clark’s Corvair which was frieghted to me. Though covered with light surface rust, the new cross member was in good shape. A quick sandblasting, rustproofing, and paint and I was ready to assemble all the parts back together.

The steel had arrived for the front nose as well. After carefully measuring and leveling, the new steel was welded into place. A new support for the rack and pinion was also fabricated.

The next step was to mount the fiberglass nose of the car. I was going to fabricate some hinges but needed a good firm mounting point. To do this I would attach two steel plates that I could weld the hinge onto.

The final hinge welded and mounted in place.



The front nose now hinged forward.

The back hinge I also had to fabricate.


Preparing the frame

Restoring and Building | Posted by admin November 16th, 2008

When I recieved the car it had been sitting outside in the elements for a number of years.  The frame hadn’t been properly rust proofed so it was in bad shape.  Once all the suspension and transmission had been removed, the body was lifted off so the work could begin.

The Frame with the body removed.

The Frame with the body removed.

The frame showing the rust

The frame showing the rust

The frame was flipped over to get the underside.

The frame was flipped over to get the underside.

This section was rusted out.  The rusted metal was cut out an new steel was welded in.

This section was rusted out. The rusted metal was cut out an new steel was welded in.

The section removed and remaining metal rust proofed.

The section removed and remaining metal rust proofed.

New metal tack welded in.

New metal tack welded in.

The new metal welded into place.

The new metal welded into place.

This process of replacing metal was repeated on a few other sections that needed to be replaced.

Painted silver.  I debated the frame black, but wanted a higher tech look.

Painted silver. I debated the frame black, but wanted a higher tech look.

The frame was finished except the front nose.  Th metal there was really rusted and the welds done by the previous owner looked horrible.  I had ordered a couple of new pieces of steel that I would weld in there.

Almost finished but right side up.

Almost finished but right side up.

Hanging the transmission

Restoring and Building | Posted by admin November 16th, 2008

Hanging the transmision.

Choosing a controller

Electronics | Posted by admin November 6th, 2008

If the blood of an electric car is the batteries, it is the controller which is the heart.  This unit controls the amount of electricity that is feed to the motor controlling how fast it will go.  Selecting the right one is important.  After carefull research I chose the Cafe Electric Zilla.  This company has been building the best controllers for years and all of the fastest electric cars on the race circuit use them.  Unfortunately the owner has decided to shut down the manufacturing of the units and only a few remain.  I have a deposit on one of the last ones.

Below are the specs from the Cafe Electric site.

Zilla Z1K

Zilla Z1K

The Zilla is by far the most powerful motor controller available for Electric Vehicles.
Exceptionally high power density has been achieved by a novel design which pays careful attention to maximizing efficiency. Many years of development, extensive testing, and using only the best parts insures reliability.
The result is a race tested reliable package like no other.

In addition, it’s a controller that can make your EV wickedly quick.

While designing the Zilla series of controllers much attention was given to safety. From carefully monitoring that the controller comes up to voltage, communicates properly and checks the integrity of the output stage before engaging the main contactor, to the dual microprocessors that cross check and each have independent means of shutting the system off, there is no other DC EV controller that approaches this level of security.

The Zilla is the only controller that allows adjustment of multiple limits on battery voltage, battery current, motor current, motor voltage, RPM and more. These are not only important for going as fast as possible without blowing up motors and batteries, but also allow adjustment of the unit to prolong motor and battery life in street applications.

The Zilla works excellently with single motor systems, but realizing that many of the quickest EVs use dual motors, the Hairball interface also has a option for safe automatic Series/Parallel shifting of dual motors for even more power and efficiency.

It is no surprise that all of the worlds quickest Electric Vehicles use Zilla controllers, but the safety features allow them to also excel in street applications. The Z1K in particular has become very popular for street conversions due to its superior feature set and low price.


Zilla Specifications

  • Maximum nominal input voltage range for Lead Acid batteries: 72 to 348 volts.
  • Absolute maximum fully loaded input voltage range: 36 to 400 volts**
  • Maximum motor current at 50°C heatsink temperature: 2000 Amps for Z2K, 1000 Amps for Z1K
  • Maximum Battery Current at 200V: 1900 Amps for Z2K, 950 Amps for Z1K
  • Maximum Battery Current at 300V: 1770 Amps for Z2K, 885 Amps for Z1K
  • Maximum Battery Current at 400V: 1600 Amps for Z2K, 800 Amps for Z1K
  • Continuous motor current @ 50°C coolant temp & 100% Duty Cycle: over 600 Amps for Z2K, 300 Amps for Z1K
  • Peak Power: 640,000 Watts for Z2K, 320,000 Watts for Z1K
  • PWM frequency 15.7 kHz
  • Power devices IGBT
  • Voltage Drop: < 1.9 volts at maximum current.

** At this time we are suggesting not exceeding 375 volts on the EHV models, we hope to bring that back up to 400 volts with further testing


Features of the Zilla controllers

  • Simply, the most powerful controller in the industry, by far.
  • Backed by over fifteen years of experience making the worlds quickest controllers, plus a factory warranty.
  • Water cooling for sustained high power operation.
  • 2000 motor Amps available with proper cooling for Z2K, 1000 Amps for Z1K.
  • Multiple Microprocessors which cross check for security and safety.
  • Full motor current limit control with smooth temperature cutback.
  • Silent high frequency operation.
  • Compact size.