Roper ZAP PK Xero Existence Log for September 2007


L. David Roper

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ZAP Xebra PK review

wheel drag, reverse problem & desulfator install

4 September 2007

  • Returned home from Atlanta and picked up Sun Roper. The axle was replaced with no trouble by South Main Auto for $162.50 with instructions provided by John Gipson.
  • Have a slow leak in the front tire. South Main Auto could not find it.

6 September 2007

Drove up the steepest hills yet to Preston Forest outside of Blacksburg:

The elevation increase from the bottom-right red circle to the top-leftt red circle is 525 feet.
The distance between the two circles is 1.4 miles.
The Sun Roper speed got down to 18 mph on the very steep hill about half way up.

7 September 2007

A long-time advocate and researcher in solar energy at Virginia Tech drove Sun Roper today.

12 September 2007

Sun Roper is getting poor mileage when I leave it sitting for two days. I think that it is the PakTrakr using energy. So, now I am turning off PakTrakr except when I want it specifically.

13 September 2007

On a few occasions drivers behind Sun Roper exhibit impatience at his slow speed going up hills. So I have put the following sign at the top of the solar-panel frame:

15 September 2007

Since I left Sun Roper for 3 days fully charged getting the axle put in I have been getting about half the mileage I used to get. It still takes about the same amount of energy to charge.  I ran out at 13 real miles today on my way home from showing Sun Roper at the Car Cruise-In at the Christiansburg Wilderness Trail Festival; I had to stop at Jerry's Garage for an hour to get home. I am going to check the amount of charging again tonight.


17 September 2007

Mark Higley suggested that I check the right-rear wheel for ease of turning. Sure enough, it has a large drag compared to the left one. The left one will not make a full turn either when I spin it with as much torque as I can muster. I cannot remember what it was like before, but I think it had less drag. Also, there is a clunking sound in the area of the differential when I quickly change the direction of the spin of either wheel. Is that norma? I do not recall hearing such when I spun the wheels before. I will call South Main Auto tomorrow about fixing it.

18 September 2007

Got Sun Roper back from SMA. The problem was that the emergency brake was too tight. I had tightened it inside the cab about the same time that the new axle was installed. They said that they loosened it at the cable junction underneath. They also found that the slow leak in the front tire was due to a bad valve stem. I wonder if they made the e-brake cable tighter on the right-rear tire when they installed the new axle. The price for the job was $57.43. They told me that ZAP needs to send me another axle for the left side, as the patch I put on the inner CV boot did not hold and the outer boot is cracked about ready to break open.

19 September 2007

Mileage was back up to 2.80 kWh/mile for 12 miles of traveling. Tomorrow I will travel farther, so should get near 3 kWh/mile.

20 September 2007

  • Gave a talk on Global Warming to the Montgomery County Kiwanis Club.
  • Mark Higley told me that ZAP is sending me another axle for the left side, since both CV boots are bad.
  • Still having trouble with the right wheel dragging. I barely was able to crawl home today after less than 20 miles. I jacked both sides up and could cause the left wheel to turn a full turn after I let go turning it, but the right wheel would turn only a half turn. I called SMA for me to take SR there tomorrow to put it on the rack and show them the problem.

21 September 2007

Took SR to SMA and put it up on the rack. The mechanic and desk clerk watched as I spun the two back wheels. Again the right wheel would only go 1/2 turn or less. The right e-brake was dragging again. (This could have been prevented at manufacure by inserting a compression spring between the cable housing and the lever near the wheel; I am going to look for such springs to put there.) The mechanic loosened the right ones some more. He pulled on the cable up under the cab several times. When I got in the vehicle to back out I could not get it to contact in reverse. It would contact in forward, but not reverse. What could be wrong? I drove it home without reverse working.

22 September 2007

Put Sun Roper on two stands at rear so that I could get underneath to try to find any wiring problem that might be causing reverse to not work. I took some pictures:

Picture of the system switch under the cab:

Place under the cab where the emergency-brake cable emerges and divides to go to the two back wheels:

Place under the cab where the wires from the emergency brake switch that turns off power to the motor when the emergency brake is on::

23 September 2007

  • Tried to find the problem with reverse not working, but no success.
  • I bought 6' of 10-gauge electric cable and end plugs to make a cord to add to a 25' 12-gauge cord so that I can charge Sun Roper at a driveway location that is not in the way of other activities.

24 September 2007

  • I took SR off of the two jacks and drove it to some meetings.
  • The following posts on yahoo/zebra-ev indicate that the reverse contactor is bad in SR:

Posted by: "Norm", Mon Sep 24, 200711:16 am (PST
Dave, something else you might want to check - if the little red reverse light stays on when you set the switch to reverse and press
the reverse button, then leave the E-brake set and take a look around at the back of the vehicle at the reverse lights. If you put the
vehicle in reverse and you hear clicks and the little red light stays on indicating reverse, and the backup lights and beeper (if yours is
connected) are on, then you can pretty much stop looking upstream of the contactors under the bed. The problem is pretty much narrowed
down to the reverse contactor if all the other pieces of the puzzle are there. Norm
Posted by: "Mark Higley", Mon Sep 24, 20072:26 pm (PST)
I just spoke to Brad at ZAP and he thinks Dave's problem is the reverse contactor. Brad said the click Dave is hearing when the reverse button is pushed is the main contactor, not the reverse contactor. He said Dave's contactor might have been on it's way out before he did the contactor mod. For you new people, the contactor mod is done at the factory now and is no longer an issue. Mark Higley

25 September 2007

  • The desulfator came today, which was very easy to install. I attached it to the top of the 12-V battery. See picture below.
  • At Mark Higley's advice I took the top off of the reverse contactor. It looked very clean. One of the two bakelite bases was broken. I think that the two cables on the bottom of the contactor nearest that bakelite piece, including the added shunt for the contactors modification, contributed to the breaking of the bakelite piece under it because of a downward force they were causing. My son-in-law, Steve Oliver, came over and helped me put the top back on the reverse contactor. We put the broken piece back in straight and the top back on the reverse contactor and then reversed worked again! Mark Higley says that he will get me a new top, although all that is needed is the broken bakelite piece.

Reverse contactor pictures: left: top piece (spring should be in the center); center: bottom piece; right: broken bakelite piece:


26 September 2007

Yesterday I drove 25.2 miles and used 7.15 kWh for a mileage of 3.03/kWh. So I have conquered the low mileage problem!

27 September 2007

Put a house switch on the 72-volts desulfator, so that I can turn it on/off only while charging the battery pack:

I drilled a hole in the tab sticking up on the edge of the vestigial 12-volts-battery container to attach the switch.

Note the orange fins of the desulfator at the upper right.

28 September 2007

I put a file on yahoo/xebra-ev about how to take the top off of a ZAP Xebra contactor.

29 September 2007

Here is a picture of the emergency-brake cable showing the gap that needs a compression spring and a picture of springs I bought at Home Depot for that purpose, two springs together since I could not get one long enough. What is the best way to put the springs in the gap?

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