CHILL!!!

Man, has it been hot here in Austin. With highs approaching 110F, temperatures in the garage are in the low 100's during the day, so working on the Porsche has been a sweaty endeavor. We installed the Benling Air Conditioning compressor in the car early in the build process, but there were some things that needed to get done before it could be put into service. The car's cooling system, radiator and fans, needed to be uprated and I had to figure out how to mount and wire the controller. So here we are after almost two years on the road, finally ready to put a freon charge in the compressor and enjoy some cooler motoring.

New compressor in place.

Sadly, after doing the freon charge the compressor just sat there, inert and stupid. Can't know for certain, but I suspect that it was a victim of a known issue that I failed to account for in the initial installation. That makes me inert and stupid. Here's Jack Rickard's explanation in the first twenty minutes or so of this video from August 13, 2010. In short, the compressor's input capacitors work their little hearts out trying to run the car's motor! Except mine never blew a fuse, just burned out the inverter that's built into the compressor after two years of unprotected exposure to the traction pack. Expensive lesson learned.

New A/C contactor hiding under the two red cable boots

Thanks to Jack Rickard and Bill Bayer for shipping my replacement so quickly! This time I may have erred on the side of excess caution, but I completely redesigned the A/C circuit to include a spare contactor I had in a box of stuff and a 400 volt 100 amp diode to prevent any outbound current from the A/C unit. Since the compressor and charger share an input line from the battery pack, both are protected. 




The new compressor also came with the newer design controller which is not quite as ugly as the original. One of the delay factors in bringing the A/C online was my attempt (without success) to use the original dashboard controls to manage the compressor. I hate to chop holes in the dash or otherwise bastardize its classic look, so a suction windshield mount for an iPhone did the trick. I also added an on/off switch to the console in an existing hole to power the compressor contactor and controller simultaneously, keeping them both out of harm's way when not in use.

Speaking of harm's way, I had to crawl deep under the dash to pass the wiring through the firewall. I had fished some of the earlier wiring for the charger and dash gauges through without doing the contortionist routine and noticed that they were dangling in the path of the accelerator pedal mechanism and in some cases showed signs of chafing on the insulation. Another complete rework was in order and that slowed things down considerably. I'm happy with the results and especially happy that this time the compressor fired right up and pushed cold air through the vents as it was meant to.

With the ambient temperature showing 100 degrees F, at 50% compressor speed (which master mechanic Keith Jordan says shows ideal line pressures) the inside temp dropped to 94.1 in the first minute and 92.8 in the second minute. 

Probably more important, the chilled air blowing through the vents felt very comfortable and made the car a lot more civilized. The compressor is almost inaudible when running and its sound is masked by the radiator fans. In this short test, the motor and inverter temperatures held at around 39C, so the heat exchanger in front of the radiator didn't seem to have any effect on the running gear. Tomorrow we'll stress it a bit more and mix highway miles with some local traffic. It's forecast to be another 110 degree day, so we'll get a good sense for what it can do.

The PorschEV is inching towards completion and all-weather everyday use.

New Speedometer in the PorschEV

I chose an Intellitronix digital GPS speedometer for the Porsche conversion mostly because it complemented the blue theme on the Andromeda EVIC display. Click here to see that post. After it was installed and the car was on the road, I began to have second thoughts. It took a long time to lock in on a satellite and begin registering at all, and there was a significant lag in the display when accelerating or decelerating. It was mostly good at reporting speed if you kept it steady, sort of suggesting an average.

A couple of months ago, it gave me an excuse to replace it. First one and then another LED disappeared from the right digit. That made it a little hard to read, but with some imagination you could guess. Twos and fives are a challenge, though. Reading the online reviews, I've learned that this is a common problem.

I have used Speedhut custom gauges in both the eBugeye and the evTD and they have been superbly accurate and reliable. They're custom built and you can configure a huge number of variations; font, text, needle, and background color, even custom logos. I toyed with the idea of a blue palette, but instead opted for a look that's pretty close to the original Porsche gauges.

Even though both our Prius and the Leaf have digital speedometers, I still prefer an analog display with a needle that tells at glance both what speed you're doing and the rate at which it is changing. The Speedhut speedometer locks onto the GPS satellite quickly and registers speed in real time. It's actually quite satisfying and works simply and with no fuss. I consider it an upgrade and don't miss the old one a bit.

COOL!

Last summer I was complaining about the undersized cooling system in the PorschEV and how it would send the inverter into thermal limiting, usually at the most inopportune times. How does sudden loss of power at highway speeds sound? The good news is the inverter protects itself from heat damage, but it's pretty disconcerting when it happens.

The cooler was a dual core Derale with one coolant loop for the motor and charger and the second for the inverter. With two Pierburg pumps and a 10" electric fan, it was adequate for the cooler months, but this is TEXAS and in the Summer (that's 2/3 of the year) it just didn't cut it.

A bit of Googling turned up a higher capacity aluminum replacement for the stock Porsche 924S radiator that was bundled with two 10" electric fans. Unfortunately, those fans  didn't fit so I wound up ordering a pair of 9" fans that did the job. I also found silicone 90 degree Elbow Reducer hoses that connect the 1.5" radiator outlets to the rest of the 5/8" system.


Here's a comparison of the two coolers. We're clearly adding capacity with the new system.

Mounting the new radiator had its own set of challenges. Long story short, the lower 3" of the radiator support was cut off at some point in its lifetime, so the original radiator was sort of dangling, held in place by some creative application of zip-ties. I devised a more secure if equally creative support involving angle iron and eye bolts. It feels secure and at least it's all metal.

The plumbing went together fairly easily using what was already there and rerouting the hoses so the pump output goes first through the inverter, then through the charger and finally through the motor before it passes through the radiator and then back to the catch tank for the pump.

One pump and catch tank was removed (set aside for the next project) and I think I'll use the space for a windshield washer fluid reservoir. Only one change was needed to attach the inverter output to the charger input. With everything on one cooling loop, I hope there is enough capacity to keep it all cool calm and collected.

The first short test is encouraging. With ambient temperature in the low 100's F (up to 104 in the sun on the road), a short 5 mile run around the neighborhood had the inverter steady at about 46C while the motor showed anywhere from 50 to 90C. At stop lights, the temps dropped to about 43 for the inverter and 48 for the motor, well below the 55C max recommended input temperature.

We're checking off the list of annoyances little by little. Next item is to get the air conditioning charged and working. How did we ever get along without it?

Update: 6/28/2017

I had experienced some coolant overflow on charging with the old system, so I was anxious to test it on a full charge starting at 366 volts. I have the fans set to run during the charge process and the temperature held at 34C (93F) with an ambient temperature around 33C (91F) in my garage. It's noisy but cool with no coolant loss. Happy times!

It's Always Something

You may be old enough to remember the late great Gilda Radner and one of her stable of characters, Rosanne Rosannadanna. If not, maybe you've seen it on old SNL reruns. Anyway, her trademark line,"It just goes to show you, it's always something — if it ain't one thing, it's another" seems to apply to my EV projects.

Saturday I took a little jaunt down to Barnes & Noble to kill an hour browsing. I can generally speed skim a book in about five minutes and get the gist of it, so I rarely buy any. It's an enjoyable diversion, especially on days like last Saturday when the wife has flute students stacked up at the house all day.

So I'm driving the PorschEV and thinking: "Wow, this thing is running especially smooth this morning." Uh-oh! That usually means something's not right. Sure enough when I stepped on the brakes it was clear that the power boost was missing in action. The good news is the brakes still worked but with much higher effort, so I drove home without incident.

You may recall from my Road Test video that I was complaining about how noisy the power brake vacuum pump was. It seemed like a good idea at the time since it was a Ford product from the same eTransit Connect that supplied the Siemens motor and Azure Dynamics inverter. It was a diaphragm type pump, and when it was in service it made a huge clickety-clack racket. Mounted directly over the passenger footwell, I think the noise was magnified by the sheet metal of the battery tray and no amount of Dynamat was going to dampen the sound to my wife's satisfaction.

I pulled the offending part and tested it with my bench battery. Click - nothing. DOA. Casters up. Pinin' for the fjords. Pushin' up Daisies. Good riddance. 

I'd been looking at options for a quieter vacuum pump and settled on a HELLA 009428081 High Performance Electric Vacuum Pump. Ordered it Saturday afternoon and it was on my front porch Monday afternoon, free shipping with my Amazon Prime membership. Based on reviews and such, it seems to be OEM for current Subaru and Volvo as well as some GM models. It's smaller and lighter than the Ford unit and as a centrifugal pump, it promises to be quieter as well.

I reused the mounting bracket including the rubber buffers, so the new pump is double damped but still made a pretty noticeable whirring sound on the bench. The good news is that the sound gets mixed with the cooling fan and power steering pump and all of that is just background noise. The clattering vibration is gone and the brakes are back to normal so we'll declare a small victory on this one.

"It just goes to show you, it's always something — if it ain't one thing, it's another"

Ancient History and Interior Updates

Absent mindedly scrolling through Porsche 924 videos on YouTube (actually looking for customization ideas), I stumbled across a video that looked hauntingly familiar.

Yes, it's the PorschEV with a video walk around by a previous owner. He comments on the bra hiding some body damage. All the details right down to the wear on the driver's seat and the aftermarket radio leave no doubt that this is my car. Nice bit of archival information, what Antiques Roadshow might call "provenance".

Did I mention the radio? My wonderful kids pitched in to get me a new sound system and voltmeter for my upcoming birthday. The radio portion of the old one worked ok, but the CD player was non-operational and it lacked the Bluetooth connectivity I've come to appreciate so much with my Leafs. The new unit is a JVC KD-X330BTS with the Bluetooth hands free phone and music streaming features I was looking for. I figured that as long as the center console was opened up for the radio, I might as well replace the useless oil pressure gauge with something that actually registered some worthwhile information. The Bosch Voltmeter filled that niche very nicely. Both were available at our local Pep Boys store.

The clock on the right still keeps perfect time, so it stays. In the center are the air conditioning controls and I ran a set of wires from the temperature rheostat for future use as an input to the PWM A/C compessor when I get that charged this summer.

These projects are always an educational opportunity and I learned that the Kenwood brand is manufactured by JVC. That meant the wiring connector was a direct plug-in for the new radio and I didn't need to rewire anything. It did seem like a good time to replace the shop-worn old radio antenna with a modern rubber mast style.





The microphone for the hands-free bluetooth phone link is mounted to the stationary steering wheel housing and seems unobtrusive enough. I called each of the kids on the hands-free to thank them for their gifts. OK, it might have been a bit of a victory lap as well.






I'm very pleased with the results and feel like it really dresses up the center console. 

PorschEV Charge Monitor

It's been a while since there has been news to report on the PorschEV. We had another mechanical challenge just before Christmas. Motoring merrily down a street in my neighborhood, there was a clattering noise, then the motor spun up to redline and the car slowed to a crawl. After a flatbed ride over to Pro Automotive, Robert Juarez opened the access panel for the motor coupler and found the driveshaft spline had separated from the coupler flange. The good news is they were able to extract it from the rear by dropping the transaxle so I wouldn't need to disassemble the entire motor bay. The weld held just fine, but the metal just outside the weld let go. Robert fabricated a new flange from thicker higher strength steel so I'm hopeful that we'll get more than a year out of it. Unfortunately there are no photos of the new piece, but here's what the old one looked like. That jagged hole used to be the drive shaft spline fitting. Once again the electric stuff is no problem, it's the mechanical bits that bite you.

While the PorschEV was out of commission, I spent some of my holiday planning for the charging monitor I mentioned in the last post. Not surprisingly, just the right electronic bit turned up on eBay. This Dual LED Digital DC600V 100A Voltmeter Ammeter Voltage Amps Meter+SHUNT ships from Hong Kong and arrived shortly after New Year's about the same time the PorschEV came home. No free shipping this time, but $5.99 from the other side of the world is remarkable! 


As usual, the documentation is in pretty sketchy Chinglish, but I found this wiring diagram that helped (not sure where). I learned later that I needed to reverse the leads on the shunt to get it to display the Amps.

The shunt is rated for 100A and 75mV, so I couldn't just wire it into the existing traction pack wiring. I had a spare contactor and I used that to control a parallel
negative charging line so the shunt is out of play when the car is running.


With so much more going on in the rear compartment, I added another charge control relay in the same housing as the meter. It looks a bit messy since I used spade taps to attach multiple lines to the relay connections, but the function is pretty simple.

It is switched on by the relay in the AVC2 module when the charge cable is plugged in. It then passes 12 volts to close the negative line contactor and power the meter. It also energises the charge control relay in the front that closes the mid-pack contactor and powers the charger, DC/DC converter, and forward coolant pump.

It sounds complicated, and I should put together a wiring schematic so I'll remember all of it if something goes astray in several years. But for now, I'm delighted to have a means of checking the progress of a charge.

With the wiring and shunt tidied up, this area may look crowded,

but since most of it is black, it will disappear in use. The normal view of the charge monitor will be through the rear hatch glass.

I watched one charge cycle last night and it works perfectly. The voltage display increased through the constant current phase until it reached the 400 volt target, then held as the amp display moved down during the constant voltage phase until it reached zero. Checking the controller output with the laptop at that point indicated the charge was complete. Unplugging the charge cable removes power from the entire charging circuit including the charge controller, so it is reset and ready to start the next time the charge cable is plugged in.