February 2008

Zilla FAQ25 Feb 2008 11:30 pm

Q: Does the Hall Effect Pedal Assembly (HEPA) fit my car?

A: I don’t know.

The HEPA is a wonderful pedal assembly. It is rugged and smooth, but it will not fit well in all cars. You will have to examine the pictures (taken here with a 6″ caliper for reference”) to get an idea. Or you can order one to check the fit, if it does not fit well we will cheerfully take the undamaged unit back for a full refund and change your Hairball to a standard Pot input version.

Some cars have been proven for a good fit, I will list the ones I know of here. If you have pictures and a description of a car that it did, or didn’t fit well I would appreciate hearing about it so I can add them here.

The Corbin Sparrow.
Bob Schneeveis reports to me that the HEPA “looks like it was made to fit the Sparrow”. I have not seen it myself, but I believe that he made one fit with only a couple new mounting holes.

The Honda Insight.
I have put a HEPA in my Honda Insight conversion and it fit perfectly. It did require drilling two new mounting holes and putting rivet nuts in them, then one aluminum spacer later and I had a perfect fit. See the following pictures for details:

Hoda pedal 1

The original pedal, side by side with the HEPA.

Insight pedal 2

The two golden plated parts are the mounting threads that I added. The top one required a aluminum spacer to bring it level with the mounting area. Rivet nuts, metric bolts and spacers all came from McMaster Carr online.

Insigth pedal 3

In place the pedal is a perfect fit for the Insight.

Porsche 914:

Richard Rau of Northwest Electric Vehicles did a wonderful job of integrating the HEPA into a 914. It was not as simple as the Honda Insight, but the results are very nice. The pedal can fit in the 914 with just a simple bracket, and I have done this before, but the resultant pedal alignment ends up being less than ideal. Richard, being determined to do the job the best way possible, made a tool for clearancing the sheet metal above the pedal assembly. This gave room for the electrical connector even when the pedal is mounted in the optimum position by his custom metal bracket. See the following pictures for details:

Hepa in 914

Here it is installed in the car, very clean!

Hepa in 914 2

Here is detail of where Richard made room in the sheet metal above the pedal for connector clearance.

Hepa in 914 3

Here is a view under the hood showing the red 12V battery cutoff switch, and below it the added hump that makes room for the pedal inside.

2007 Toyota Yaris

The Toyota Yaris is a special case. The pedal that came with the car is already a drive by wire pedal. With some research and testing we have discovered that it can be wired directly to the Hairball with a HEPI option. If you are converting a Yaris, check that the pedal part number is 78110-52020 and order the -P option Hairball. Then contact Cafe Electric support for wiring details.

If you have information on how the HEPA assembly fits in your car, please contact me so I can report it here for others to benefit.

I hope this helps,


Zilla FAQ25 Feb 2008 10:28 pm

Q: Can I electrically reverse a series motor even if the brushes are advanced?

A: Yes.

If you are only using the reversing function for low speeds then the brush advance for driving (which turns into brush retard for reverse) will actually help you out. Lightly retarded brushes will give higher torque at low voltage, which is just what you need when backing out of a driveway. This would not be wise if you happen to like driving in reverse at 30 MPH, since brush advance is important to brush and commutator life when motor voltage (and speeds) get higher, but that is why the Zilla’s Hairball interface includes a reverse rev limit setting. You can set the reverse voltage and RPM limits low to insure that the motor stays in a safe operating area. I set reverse voltage at 60 Volts and reverse speed at 1500 RPM. I think those are reasonable values for most cars.

On the other hand, most people don’t want to spend hundreds of dollars on a set of reversing contactors (required for electrical reversing) unless they are running a single ratio direct drive transmission. If you are planning that, then be sure to review my faq on “Shift gears, or direct drive?“.

When electrically reversing a motor, I strongly recommend having a speed sensor providing motor speed pulses to the Hairball and having it properly configured in the Hairball. That way the Hairball will keep the driver from switching directions at more than 100 rpm and protect the motor, controller and drivetrain from the damage that would happen if it were reversed at higher speed.

I hope this helps,


Zilla FAQ25 Feb 2008 09:50 pm

Q: Can I upgrade from a Low Voltage model to a High Voltage model at a later date?

A: Yes.

As long as we don’t make major changes to the design in the future, you will be able to send a LV or HV model Zilla to the factory for an upgrade to a HV or EHV model. The cost is the same as the difference in MSRP cost of the units plus shipping charges. We will ship the same unit back to you with internal modifications. Usually this can be completed in a few days. Contact our sales department to arrange an appointment and for a RMA number.


Zilla FAQ18 Feb 2008 10:24 pm

The best diagnostic tool when a car under-performs is to read the “Operating Status” that the Hairball can spit out using the DAQ (Data Acquisition) display. The DAQ display is a diagnostic tool that was originally only made for development so it is not terribly user-friendly, but many people have learned to use it despite that.
To view DAQ data, you need a serial terminal connected to the Hairball that you can carry with you while driving.
The DAQ display, when running, feeds out ten new lines of data per second. By watching the display line on the bottom of the screen it will look like one string of values that automatically updates. If the the issue of concern happens while driving (such as low power) then this should be done with a helper to view the DAQ while another person drives.

When using the Palm Pilot to view the DAQ with the original setup, the lines can get longer than 32 characters (especially when using other that DAQ4) and will line-wrap, making it hard to read the display. In order to avoid this, the line width setting in the Ptelnet Terminal menu can be set from 32 to 64. When this has been done then the screen will scroll left, center and right by tapping on the left, center and right side of the display. When switching to a 64 character line with, the screen will go blank if you tap the right side of the screen when the data displayed is not long (such as a menu), so, if the screen is unexpectedly blank, be sure to tap the left side of the main display to return to the left side of the display.

Basics of using the DAQ are covered in the owners manual where it says this:
Start the DAQ in the Special menu by typing “Q1” or “Q2” etc., followed by a return.
DAQ data is displayed 10 lines per second in Hex format with spaces between data. Data is approximate and the scaling values vary.
Press the space bar to exit DAQ mode. DAQs may change with new code versions.

For our purposes of diagnosis we will use DAQ4. When starting DAQ4 with the car off, it will display something like this:

State: 1311
How may I help you?Q4
41 00 01 00 00 0B 00 1E 20 SFSV
41 00 01 00 00 0B 00 1E 20 SFSV
41 00 01 00 00 0B 00 1E 20 SFSV
41 00 01 00 00 0B 00 1E 20 SFSV
And so on, until the whole screen is full of lines of data.
The 9th value, 20, just before the jumble of letters at the end is the Operating Status. This is the most important number to us. If we look up 20 in the Diagnostic Trouble Codes in the Hairball manual we will see that it equates to “waiting for key”.

Next we turn on the key and the data on DAQ4 changes to:
41 00 01 00 00 0B 00 1E 21 SMFSV
Again, the 9th value concerns us, it is 21 which equates to “waiting for start signal”, So we turn the key to start and get this:
41 00 01 C8 00 93 00 1F 23 SOMFS
where the 23 indicates that it is waiting for throttle input. Unless we happen to have a faulty throttle potentiometer or are resting our foot on the throttle in which case we get:
51 00 01 C8 00 93 00 1F 22 SOMFS
where the 22 indicates that it has not yet seen a zero pot and therefore will not run. This is a feature that protects the vehicle from driving away uncontrolled on startup if the potbox is maladjusted.
As we get underway on the road, we may see something like this:
55 0B 07 C8 07 8E 07 27 30 OMFS
The 30 indicates that there are no active limits on the controller aside from the duty cycle requested by the pedal position.
As we drive we will likely see some of this:
A0 07 58 C8 22 86 1B 29 27 OMFS
where the 27 indicates that a standard motor current limit is active. This is either because the motor is drawing the amount of the motor current limit setting, or if we are at low throttle positions then the throttle current limit is insuring a smooth driving experience.
Another common mode is this:
BF 08 64 9E 26 83 1E 29 26 OMFS
The 26 indicates that the battery voltage limit is active. In this case the battery voltage has sagged to the limit set in the battery menu. If the car is running slower than expected at this point then either the batteries are soft, or the voltage setting is too conservative. Of course, trying to get too much power out of batteries can destroy them, so adjust with care.
Other codes are also possible, those should be self explanatory when looked up in the Hairball manual.

The other values in the DAQ can also be useful but being in hexadecimal format are a bit more confusing to decipher. For more details of the value scaling, please see the FAQ entry titled “What are the details for using data from the DAQ?”