Roper ZAP PK Xero Existence Log for May 2007

L. David Roper

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ZAP Xebra PK review

tailgate chains, drag coefficient, PakTrakr, wiper quit, glove-box expansion

1 May 2007

I learned today that the Xebra will run if the charge switch is on. Apparently all that matters to keep the Xebra from running is that current is flowing into the charger. I pulled the watt meter out of the plug and then did a few more things before I got in the PK to drive to run some errands. When I started backing out of the garage I quickly realized that the 10' cord was still plugged into the PK. The watt meter caught in a hanging ladder and bent the ground prong of the cord; when I tried to straighten it out it broke. I tried to order a new 10' 12 gauge cord at the local hardware, but they could not find any in their catalog. Mark Higley has advised me to get a replacement plug.

I put some chains in the back of the bed to hold the tailgate horizontal for hauling long items, such a sheet of plywood:

These chains and point of attachment are not strong enough to hold heavy items sitting on the tailgate, such as a person sitting on it. They should work for long items that extend to the front of the bed. I wonder if the points of attachment will be in the way of the rear posts for the solar panel; I may have to move them when I get the solar frame.

1 May 2007

I am still having trouble keeping the cap on the brake-fluid reservoir. I have asked Mark about it.

I tried again at taking the steering wheel off to straighten it relative to the front wheel and to get the turn signals to cancel. It appears that I cannot have both.

Battery conditioning is leveling off at about 2.9 miles/kWh.

2 May 2007

I bought a 15-amp plug to repair the 10' power cord and it works.

I had the best miles/kWh day of 3.18 for 32.8 miles with a mid-day charge at home.

3 May 2007

Drove 3.25 miles on the 55-mph Blacksburg bypass today in light traffic and drove about 15 miles in heavy rain with puddles with no problem. The brake light came back on; the bleeding must have to do with moisture in the air. The hot-motor light also came on, although the air temperature was a cool 55 degrees. There may be moisture-induced bleeding in that indicator light, also.

4 May 2007

Drove to Advance Auto and got a cigarette lighter to install in place of the vestigial green-button "emergency switch", but it is too large in diameter. I need for ZAP to send me the one that was taken out when the "emergency switch" was put in. I see how I can tap into the wires for the other lighter to get power for it. I would like to be able to plug in my cell phone and a seat warmer or a fan at the same time.

When I installed the new rear-view mirror on 29 April I dropped the screw that holds the mirror on the piece of metal glued to the window and could not find the screw on the floorboard. I used another longer screw. Today I discovered the screw lying on the entry to the tape player; when I tried to retrieve it, it fell into the tape player. I use a magnetic screw driver and a grabber from my computer-repair kit to get it out.

Mark Higley called to tell me that it will take about 4 weeks before I get the frame and wire harness for the solar panel PK roof from ZAP. He said that he will try to find me a cigarette lighter to fill up the hole where the green button was.

I started removing the 8 screws to get the front off of the heater to try to wire the 2nd element to put out heat. I realized that I need a Phillips screw driver about 4" long with a narrow handle to get the top two top screws off, which I do not have. Should I wire the two elements in parallel? I asked on Yahoo/Xebra-EV for guidance, but no one has answered yet.

21 Wheels told me that I should get the Paktrakr soon, so that I can start monitoring the individual batteries in the cab.

5 May 2007

The daily log of my PK show that the miles/kWh is lower for days when I drive fewer miles. Is that because there is a temperature of highest efficiency for the PK drive?

Installed on the Powercheqs modules fuses that light an LED in the top housing if the fuse is blown.

Battery 1: 13.05; Battery 2: 13.04; Battery 3: 13.01; Battery 4: 13.02; Battery 5: 13.02; Battery 6: 13.02

Maximum difference = 0.04 volts. The total matches the voltage shown on the vehicle voltmeter.

6 May 2007

An aeronautical professor at Virginia Tech has agreed to calculate an estimate of the drag coefficient of my PK. I sent him pictures and dimensions today for that purpose.

The whine seems to be louder since I changed the gear oil on 29 April to half Lucas Heavy Duty Oil Stabilizer and half 80/90W Lucas gear oil. So, I decided to follow the directions in the Xebra mechanical troubleshooting document and change it to 100% Lucas Heavy Duty Oil Stabilizer. I seemed to pour more than 8 oz in it and it still did not come out the top hole. So I then put a little 80/90W oil in and it came out the hole right away and then much of the LHDOS came out, also. I let it drain fully before I put the plug in the top hole. I could not tell much difference in the whine after the change.

7 May 2007

I bought a "trash bin" for storing music tapes and taped it at the top of the center cover behind the front wheel; I now have two containers there. Drove to Tai Chi class on the lawn at the Duck Pond at Virginia Tech. The instructor and another student asked many questions about the PK. Many people wave or gawk as I drive around.

John Gipson sent me pictures and detailed information about wiring the second element of the heater to make it work.

Since a gallon of gasoline contains about 36 kWh energy and I pay about $0.075 per kWh, I am paying about the equivalent of $0.90 per gallon, assuming the the EV is 75% efficient and a gasoline vehicle is about 25% efficient at converting the energy into the vehicle's motion.

8 May 2007

I drove to the University Mall, where a young acquaintance looked over the PK.

Was complimented by the president of the Habitat for Humanity of the New River Valley affiliate for leading the community in information about energy-efficient vehicles.

9 May 2007

Information about the drag coefficient of the ZAP Xebra PK from my friend, Professor James Marchman, of Virginia Tech:

Based on the photos and existing data on a range of wheeled vehicles I am going to estimate a drag coefficient (Cd) of about 0.65.  It could be a little higher but I think this is about right based on a well rounded front end, a single front wheel and an open bed.  This Cd would be used with the frontal area (I would estimate that as about 21 square feet) and it would give a drag of about 44 pounds at 35 mph at sea level conditions and would increase or decrease as the square of the speed.

The dynamometer at the Ware Laboratory at Virginia Tech is not in working order, so I cannot get a torque vs rpm test done there. I am going to check to see if the Virginia Tech Transportation Institute has a dynamometer.

Drove to Blacksburg Community Band practice for the second time in the PK. Still getting comments about it from band members.

11 May 2007

Drove to various places to recycle materials. PakTrakr came in. Dale Schutt will help me install it next Tuesday.

Temperature is in the mid-80s today. I find that rolling both windows down all the way gives a good cross breeze for passengers.

12 May 2007

Drove to downtown Blacksburg and to Crow's Nest nursery in heavy Virginia Tech graduation traffic. Three people asked me about the PK.

Information in front window:

I badly need lumbar support on the driver's seat. Install such:

I have the seat all the way forward so that the seat back can lean back as far as possible.

Starting installing the PakTrakr:

This shows the Paktrakr remote box just inside the bed frame on the most negative battery. The 7 battery wires with lugs are at the top right and the wire to the Paktrakr display is on the left through a hole I drilled into the cab. The 8' wire between the remote and the display is not long enough to go under the cab beside the brake line and then through the firewall of the cab. The wire needs to be 10' long to do that.

The wire from the remote to the display is taped under the driver's door.

The Paktrakr display attached by velcro to the dash.

I ordered the PakTrakr automatic-logging serial interface and the current sensor.

The front-hood prop needs to be about 2" longer to hold the hood up higher to make it easier to work under the hood. I kludged a 1.75" extension.

I checked the steering and I do not seem to have the problem recently reported. A washer is between the nut and the ball joint. Should I add another washer?

14 May 2007

Hauled about 600 lbs of mulch bags about 10 miles today. The back tire looked pretty squished on the bottom, so I stopped at a gasoline station and put some air in them. After I got home I measured the air pressure in them and it showed 50 psi. After cooling they showed 46 psi; I reduced them to 42 psi. It sure rode nicer with the heavy load!

I removed cotter pin in the steering nut and tightened it one notch.

To prepare for installing the Paktrakr I lifted the bed up while the batteries were recharging and noticed that three of the Powercheqs were actively balancing between the batteries. After charging (0.12 amperes) the voltages were 13.54, 13.48, 13.44, 13.45, 13.47. The next morning they were 13.08, 13.07, 13.03, 13.05, 13.05, 13.05 and the red LED on all 5 PowerCheqs were dimly lit. The red light is supposed to indicate bad batteries or incorrect wiring of the PowerCheqs. Is there something wrong with my PowerCheqs? Later the red lights dimmed out.

Finished reading Electric Dreams: One Unlikely Team of Kids and the Race to Build the Car of the Future by Caroline Kettlewell, a very inspiring and interesting read.

15 May 2007

Dale Schutt came to help me install the Paktrakr:

Note the black square remote box at the bottom left of the 5 batteries and the 7 wires extending from it.

Drove to the Ecumenical Environmental Effort meeting.

16 May 2007

Drove to several meetings today. Had fun watching the PakTrakr display. Longest driving day yet: 31.7 real miles and the best mileage yet: 3.24 miles/kWh. The average is up to 2.80 mile/kWh now. I think part of that increase is due to being in less of a hurry on my part.

I drove for the first time with the Paktrakr working this morning. After driving over 20 miles the Paktrakr showed SOC as 100% for the entire time. I contacted Ken Hall at the Paktrakr company and he said to that it is possible that the Paktrakr thinks the batteries are 8 volts instead of 12 volts, and that I should reset the system (disconnect the black lead for a few seconds and then reconnect it. I had forgotten to tell him that it showed "12 fault" a few hours after I first connected it. I then did a reset and it did not show the fault again. I will do the reset tomorrow.

On one of my drives I started driving in a light rain and the wiper was working fine until I started experimenting with the different positions for the wiper stalk. They jerked a bit and then came to a halt at half window. It didn't sound like a fuse, but, after I took the Prius to the meeting, I opened the fuse box and the 5A fuse looked ok. I traded another for it, anyway, but the wipers still do not work. (Interesting that the fuse is 5A, whereas the cover on the fuse box shows it as 15A!? Mark Higley later told me that the fuse should be 15A.)

I do not see how one can get to the wiper mechanism to work on it. It appears to be enclosed in a box welded to the cab. On closer inspection there is an opening to the box under the dash. Tomorrow I will use a volt/ohmmeter to check out the wiper circuit. Mark Higley sent me some advice and a picture of the wiper system under the dash:

I want to get an electric bed lifter asap. The Rhinoliner underneath and the Xtremeliner on top have increased the bed weight, making it harder to lift. The solar panel system will increase it at least by 40 lbs. There is more room for it to replace the bed jack on the left side of the bed than on the right side:


Now I need to find an electric jack that will work. Perhaps the two jacks should remain and a new electric jack be placed in the center. I wonder if one of the bed-lift kits sold by Cycle Country would work.

17 May 2007

Left Sun Roper with South Main Auto today to try to fix the wiper, to wire the heater so that both defroster vents put out heat and to fix the brake-reservoir cap so that it latches on both sides. I asked them about doing the contactors rewiring and to figure out how to install a bed lift, but they declined both.

18 May 2007

South Main Auto called to tell me that the wiper motor is bad. Its fuse is not the one marked 'Wiper Motor', but is the one to left of it marked in pencil 'Inside Lights'. That must be the reason that the one marked 'Wiper Motor' had a 5A fuse instead of a 15A fuse. I left the PK with them over the weekend so that they can work on the heater next Monday. I told Mark Higley about the wiper problem and he is going to send me a another motor.

I got the current sensor for the Paktrakr today.

23 May 2007

Received wiper motor, brake-reservoir cap and 2nd cigarette lighter from Mark Higley today. Took them to South Main Auto to have them installed.

17-25 May 2007

Sun Roper was at South Main Auto (SMA) having the following work done: Replace the wiper motor, replace the brake reservoir cap, rewire the heater so that the second element is heated and put the second cigarette lighter back into its slot. (The lighter was removed by ZAP to install the green emergency button, which is not needed for Sun Roper's 72V ignition system.) Mark Higley sent me the replacements as soon as it was determined by SMA that they were needed. The vehicle was off of the charger that entire time. Even though they had the PK for 8 days, they did not take the heater out and rewire it. The charge was $32 (the minimum mechanical charge at SMA) for replacing the wiper motor and brake cap and installing the cigarette lighter. I am going to try another auto-repair place when I get the rear springs from Norm Woodward.

26 May 2007

I tried to installed the current sensor for PakTrakr; the hole in it is too small to fit over a PK battery cable:

I contacted PakTrakr and was told that I need to get a short bus for the sensor; they are sending me one and a new remote, as mine always registers 100% SOC.

I hope to get the two rear shocks/springs from Norm Woodward soon. He has a 90.2 megabytes video about how to install them.

Sent the old wiper motor and brake reservoir cap back to Mark Higley. I ordered two bumper stickers from

I drove to the Blacksburg Farmers Market this morning and several people gathered around Sun Roper. One said that he is very interested in getting one for his Dept. at Virginia Tech. Another was a contractor and is interested in possibly using one for his work in Salem VA.

27 May 2007

I ordered the LED side markers from Grants Pass EV and the Fluke TL225 for detecting ghost voltages from luv_2_climb on eBay. (I am apparently getting a ghost voltage of 48 volts across some of the contactors terminals when the power is turned off.)

28 May 2007

Drove to Warm Hearth to play in the Blacksburg Community Band for a Memorial Day ceremony; I drove 3.5 miles on the 55-mph bypass because the traffic was light. Coming back I drove 1.15 miles on it. In late evening I drove to Tai Chi practice at the Duck Pond on the VT campus.

Got needed connectors at Radio Shack and wired the 2nd lighter to the vestigial "power" switch to use with the 12-volts directional fan I bought to attach to the tray on the floor. Then I removed the glove box (made easier by removing the right dash bolt) and then removed the front of the heater to supposedly wire the 2nd element. However, the 2nd element was already powered. I had a difficult time getting the heater back together because of the intricate fit at the top, but finally I did.

Now I am planning to cut the bottom off of the dash below the glove box and use some thin wood I have to extend the glove box down about 2". Then I will follow the example of my Tai Chi instructor, Jim Alexander, and put everything in the box in a large zipped plastic bag, so it can be taken out to make it possible to quickly see what is needed.


I cut off the bottom of the dash below the glove box and the front and two sides of the bottom of the glove box to bend the bottom out at about 45 degrees. (The heater does not allow the bottom to bend back more than 45 degrees.) Then I used the wood shown on the right above to extend the glove box down about 3 " in the front and angle the bottom to the back:


I liberally used Elmer's wood glue to attach the four pieces of wood together temporarily held together by black tape and sealer to seal the three drill holes used to start the three bottom cuts. I wrapped the extension in blue duct tape:

It is not very neat, but it works:

Notice the two bolts that attach the front piece of wood to the box.
This is not a perfect job; those more skilled than I am should be able to do it better.

Jim Alexander, my Tai Chi instructor, pointed out a problem with the dash surface at the right of the windshield:

It will be very difficult to get glue under it because of the steep backward slope of the windshield; anyway I don't think that glue would hold it. Jim suggested that perhaps a long rubber tube could be jammed up to the windshield rubber seal to hold the cover in place. The problem was there before I removed the right dash bolt when working on the glove box; perhaps it occurred when South Main Auto removed the three dash bolts and pulled the dash partly out when they installed the wiper motor. I got a 5/16" plastic tube and used it to force the cover under the windshield; it is not perfect, but much better than shown in the picture above.

29 May 2007

I did the glove box work described above.

30 May 2007

Drove 27.2 odometer miles today running errands and going to meetings and band practice. Several people stopped me to talk about the PK. The best miles/kWh = 3.32 was achieved.

31 May 2007

This completes the first two calendar months of driving the PK. I will not report the daily mileage record beyond this date. I will now start reporting the monthly mileage record.

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