ELECTRIC CAR PROJECT 9311 DIARY, DEC 96
Made sixteen 1-7/16" thick battery holddown blocks out of 1-1/2"
diameter wood rod and attached eight to the inside of each battery
box lid at strategic locations to keep the batteries from bouncing
around in the boxes.
Tried out the automatic battery filler on the dummy battery. Works
fine. Fills to just the right level then shuts off. Installed the
battery box holddowns. Set tire pressures to 35 psi. Adjusted the
front ride height per the Porsche manual. Took a few spins around
the driveway. Big fun!
Got the insurance activated. Found out what's required to get it
licensed. Inspection by State Patrol is required to verify electric
drive. Drove around the driveway a few more times then took it
around the block (about 1/2 mile). Drives like a tank. A bit slow
accelerating up the hill. Acceleration okay on the flat. Rent a pair
of Wheel Weigher scales. Weighed car, front wheels then rear wheels.
Total: 2740 lbs. Distribution: 1280/1460 lbs. 47%/53% front/rear.
Per the Owner's Manual, the original weight was 2425 lbs. with a
total permissable weight of 3086 lbs. and maximum axle weights of
1323/1852 lbs. front/rear.
Pulled the car out into the rain and sat for a few minutes to see
where the water would go. It would appear that the grille in the
engine compartment lid should be baffled to keep water from falling
directly on the motor. Made four "S" shaped 1" high brackets for
attaching a baffle plate to the outside mounting bolts of the rear
lid grille. Cut baffle plate out of 1/4" plexiglass and attached to
brackets with #10 hardware. Made and installed an "extension" on the
circuit breaker so that it can be actuated easily from the driver's
seat. Made a tether for the AC power connector's protective cap to
keep it from getting lost during charging. Noted that one of the
strapping corner protectors on the rear battery box is broken.
Replaced the broken corner protector. Had to remove the strap and
install a new one. It went fairly well.
Made a "right angle adapter" for the vent fan on the front battery
box that will allow the fan to be mounted vertically. This way, the
fan will protrude only about 1-1/2 inches from the side of the box
instead of 4-1/2 inches. This will provide a little more storage
space behind the battery box.
Reinstalled the front vent fan. Rerouted the negative cable where it
exits the box by relocating the nearest cable clamp to the rear of
the box thus looping the cable neatly around the new fan assembly.
Got vehicle trip permit.
Drove around the block several times taking different routes so as
to hit different hills. The trick seems to be to shift sooner on the
hills than "normal" so as to keep the current maxed out. Put the
charger on. After a few minutes, the house breaker popped. Dropped
the charger current to 12 amps. The batteries were fully charged in
about 6 hours. Prepared to drive car. No go! The start battery was
dead so put a charger on it. After about a half hour, removed the
charger. Checked the key-off load on the start battery: 0.66 amps!
May have left the map light on. Drove the car up to the State Patrol
to get it certified as electric. No problems. When returned, put the
charger back on the start battery and watered the front batteries.
Got new license plates and registration. Drove up the 116th street
to 128th street hill (c. 0.7 mile) on Des Moines Way and barely made
it to the top. Had to limp home. Only made about 9 miles on the last
charge! I hope this is because the batteries aren't broken in and
the temperature is around 45 degrees. After and hour or so, drove
around the block a couple of times then put the charger on. Set
charger current to 13 amps. Raised the tire pressure to 40 psi.
Watered the rear battery pack. Cell 1 of Battery 8 had lost enough
water to expose the tops of the plates. SG measurements in the other
cells of this battery using the "short" hydrometer that I purchased
at the hardware store were at the upper end of the fair range. Cells
in other batteries in the pack were in the middle of the green
range. Put Battery 8 on independent charge.
Checked the voltage and SG of Battery 8.
Drove around the block (various routes) for about 30 minutes using a
"light foot." Speeds were between 20 an 30 mph. Got about 8 miles
before hitting "poop out" (i.e., when the battery voltage is so low
that the battery can't supply 400 amps when accelerating). Charged.
Bought a battery tester. Pulled the cover off the rear battery box
and noticed acid on the top of #8. Used the tester on #5 and #8. It
showed #8 a bit lower than #5 but both were in the "green" range.
Checked fluid levels on #8. Cell 1 was way high and cell 6 was below
the plates. I am thinking that cell 6 is bad. This was the first
battery installed and it fell over on its side while being pushed
into position. Could that have damaged something?
Made a bracket out of 1/16" thick aluminum sheet and used it to
install an auxiliary throttle spring at the pot box. Installed wires
for the yet-to-be-built tachometer module. Tested the tachometer to
see if it would work with the signal produced by a simple transistor
switching circuit. It will. Put the rear of the car on jack stands
and removed the motor bracket and the rear floor plate support to
get to the rear of the motor. Drilled a hole in the center of the
rear motor shaft and tapped it for a 6-32 screw.
Found an optical sensor from a VCR in my goody drawer. This device
has two arms with a gap between them. A light emitting diode in one
arm is directed across the gap at a phototransistor in the other
arm. An object in the gap will block the optical path and turn off
the phototransistor. With proper circuitry, this can be used to make
a signal to drive the tach. Made an three-lobed interrupter plate
and attached it to the motor shaft with a screw and a spacer. Made a
bracket for the optical sensor that positions the sensor gap around
the edge of the interrupter plate. The bracket is attached to the
rear of the motor with a short #10 screw in an existing hole. As the
motor turns, the interrupter plate blocks and unblocks the optical
path three times per revolution. Designed the circuit and wired the
tach sensor assembly. Bench tested the finished assembly. It works!
Routed the tachometer wires from the pot/relay assembly to near the
rear of the motor and installed a 3-pin Molex connector. Installed a
mating connector on the wires from the tach sensor assembly. Plugged
the connectors together and tried it out. It didn't work! Redesigned
the tach module circuit slightly. The new circuit works fine. Used
RTV to crudely encapsulate the electronic components (four resistors
and a transistor).
Made a new interruptor plate out of a "For Sale" sign bought at the
hardware store (its 0.025" thick plastic sheet) and then installed
it using some of Loctite on the screw. Reinstalled the motor bracket
and floor plate support. Took the car off the jack stands. Finished
routing the tachometer wires.
Merry Christmas! Drove around the block a couple of times then put
on the charger.
Built a battery puller out of a 13-1/2" long 2 by 4, a large eye
bolt, two lag bolts and two pieces of 0.04" thick steel sheet about
3" wide by 9" long. One end of each steel piece was formed into a J
hook 3/16" thick and 3" wide. A hook was then loosely bolted to each
end of the 2 by 4 with a lag bolt. The eye bolt was then installed
in the center of the wide side of the 2 by 4. The plan is to attach
the puller to the crane with the eyebolt then "hook" the lip on each
end of the battery. Tested the thing with the dummy battery. Works
fine and will easily hold the battery weight.
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