Sunday, May 29, 2016

Adventures in EV Land

I've consolidated this project blog with my evTD and eBugeye pages so there is one point of reference for all of the family EV's, including the commercial ones, from now on. The old pages will stay for reference, but new activity for everything will be posted to:

Adventures in EV Land

Thanks for your interest!

Tuesday, April 19, 2016

Berthing Arrangements

Now that the new Leaf has come home, it was pretty clear the time had come to rearrange the garage for best utilization. The Porsche EV project is nearing the phase-out stage where it doesn't need a full side of the garage any more. A threatening weather forecast with the possibility of two inch hail pushed the garage to the top of the priority list.

There had to be a way to get all three EVs in this one space and I tried more than a few things that were either unworkable or marginally dangerous until this bit of out-of-box thinking struck. What says the cars must park straight? If the evTD is angled into the nook at the front of the garage, the Porsche and Leaf can be slightly splayed to the outside and Voila! Room to spare!

Of course there needed to be some serious rearranging of the crud that tends to accumulate in a garage just so you can do things like open the door after you park. After three EV conversion projects there are scraps and odds and ends that need to be either stored away or pitched, likewise with a twenty year accumulation of Flute teaching material (mostly untouched for the last ten years) and antique computer projects. That's on the todo list for another day, but right now I'm pleased to see the three safely under cover.

All three are within easy reach of the charging station and there's walk space in between the cars, so I can get to the workbench and outside trash bins without rearranging the fleet. This has me thinking of fresh paint and garage decorations, maybe even that cool flecked epoxy floor finish. So when the day comes to sell the homestead, we can legitimately advertise the three car garage.

Thursday, March 24, 2016

Seriously, This is Getting Old

Yes, another fried contactor, this time the rear mid-pack unit. It's clear that there is something fundamentally wrong with the precharge setup, and I've changed the circuit scheme three times and still welding contactors shut. One thing that hasn't changed is the precharge resistor. Even though it's been replaced once, the 500 ohm 100 watt unit I've been using may be mis-sized for my 400 volt pack. I still have the precharge resistor and relay that came with the battery pack, and surely it must be a match. Only problem is that I welded those contactors on my first precharge mishap. 

Fortunately, the Panasonic contactors used in the Better Place pack can be found from time to time on eBay, and I picked up a couple from a Canadian seller at a very reasonable price. I like the packaging on the Better Place contactor/precharge module and since I designed the mount for it in the first place, it went back on pretty easily.

 I took the opportunity to ground the shielding on the inverter cables and revise the wiring to the time-delay control relay. This setup certainly looks cleaner than the former one, and all of the terminals and connections are safely contained inside the plastic housing.

We'll test this in the neighborhood for a bit before we go too far afield, but I'm hopeful that this will solve the precharge challenges. There is lots more I want to do, but this needs to be stable and reliable before moving on.

Monday, February 15, 2016

Tidying Up a Bit

I like to keep things neat and organized, but to a certain extent, things got out of hand with this build. For one thing, it's rather more complex than the last two projects with Siemens AC power and the supporting DMOC inverter and GEVCU controller. The electric air conditioning compressor and its plumbing are a challenge yet to be addressed. The OEM charger and DC/DC converter also have their own controllers, leading to an upcoming consolidation project. Then there is the spaghetti monster in the wiring box.

To disguise that mess, a cover was constructed with 1/4" plywood skin over a 5/8" marine plywood core that was clearanced to allow for the height of the wiring bundles coming from the harness. A little black spray paint makes it disappear, and it's secured with a velcro strap. Not only does it clean up the appearance, it also protects the wiring and terminal blocks from accidental shorts. The GEVCU has been relocated  to the top of the DMOC, held in place by two inch wide industrial strength velcro. I had to unplug the connector to add a terminating resistor, and simply didn't have enough room or leverage to plug it back in where it was previously installed on the back of the DMOC. There's a surprising amount of hood clearance, so it works well and certainly is more accessible.

Here's the view from the other side:

I'm not entirely happy with the GEVCU cable, but it's a dark color and could be worse. 

On the other side, I plan to enclose the contactor and precharge circuits as well now that I think I have that sorted out. With Spring in the air here in Texas, I think it will be time soon to have the air conditioning system charged and get that working before the summer heat sets in.

Tuesday, February 9, 2016

More Precharge Challenges

The precharge circuitry on the Porsche has been a challenge since day one. I'm appreciating more and more the well integrated design of the Soliton1 controller in my evTD. I never had to even think about precharge on that because it was built in. Sorry they've left the EV scene.

You may recall that the first time I powered up the Porsche, I fried the contactors. Then I did it again. Third time is the charm, you say? Well, after 200+ miles I came close to another wholesale contactor replacement. This time, after a jaunt up the MOPAC (that's a highway here in Austin, so named because it parallels the Missouri Pacific railway line), I parked it and came back a few minutes later to run an errand, turned the key to see only 6 volts register for the pack! That just can't be, so I spot checked some battery cells - all fine - then  pulled the contactors yet again to find they worked ok after cycling them a time or two, but the precharge resistor was dead - no reading on the multimeter in the ohm setting. So once again, even though it was in the circuit, no precharge was taking place. The contactors likely would have welded closed if I had put them through one more startup sequence.

I had wired the precharge resistor using this diagram from the GEVCU manual:

So my guess is that I either had a defective resistor, or it didn't like being in the circuit full time. After receiving a replacement resistor, I reworked the arrangement adding the yellow high voltage precharge relay to energize the resistor only on precharge and keep it out of play at all other times.

After a quick spin around the block, things seem to be back to normal. We'll give it a more extended test run tomorrow.

Monday, January 18, 2016

Baby Needs New Shoes

Checking out from Pro Automotive after the drive shaft repair, Keith noted that the rear tires were showing sidewall cracks and he sure would hate to see a blowout and the trail of sparks when the battery boxes drag the car to a halt. As usual, Keith is right, so we paid a visit to the tire store over the weekend for new shoes. Turns out all four tires were the same age (2009 vintage) and the fronts would be showing signs of dry rot soon enough, so I had all four replaced.

The replacements are the same model 195/65 r15 Falken tires that came off. That size seems to be a bit odd and not available from every manufacturer, also  sadly unavailable in low rolling resistance tires. Due diligence on Google turns up that Falken, although it sounds vaguely Scandinavian, is the performance brand for Sumitomo Tire company, and pretty well rated on the review sites. I don't know how many miles may have been on the old set, but they showed very little wear for seven year old tires.

I was pleased with the way Discount Tire handled the whole affair. They let me drive the car into the service bay so I wouldn't have to explain the startup process. They used hand tools for removal and installation rather than pneumatic impact guns, then hand torqued the lugs. They wire brushed the studs and wheel mount areas and even asked where I wanted the balance tape mounted.

It's probably psychological, but the car seems even smoother, so between the new drive shaft and new shoes, we're making progress toward a more civilized ride.

Thursday, January 14, 2016

Getting the (half) Shaft

Happy New Year!

I haven't updated this blog for a while, been waiting for resolution on a mechanical issue that reared its ugly head just before Christmas.

The Porsche had been running GREAT! I had put two hundred miles on it and was using it as my daily driver, running errands around town and buzzing down the highway for appointments downtown. Bit by bit, we were fixing some of the rattles and clunks that always seem to go along with a custom build. As my confidence grew, I figured the time was right to get the wife on board and share the EV grin with her. We drove it out to meet a friend for dinner at our local Applebee's, enjoying the time together and the conversation. As we left the restaurant and turned onto the frontage road, it sounded like a coffee can full of rocks and there was no power going to the rear wheels. The trip home was on the back of a flatbed wrecker with the wife having one of those "I told you so" looks on her face. The tow truck deposited the Porsche in my garage (these guys are good!) and there it sat until the Christmas and New Years activities subsided, all the decorations were put away, and all the leftovers consumed.

I was fearing the worst, as I tend to do, thinking the likely culprit was the weld on the motor to driveshaft coupler. Finally last week I pulled the inspection plate off the top of the coupler housing (no small feat) and was relieved to see that the coupler looked perfect. That was a huge happiness because I really didn't want to disconnect everything and pull the motor out and then re-engineer the coupler. So the next line of thought and a good bit of Googling led to the suspicion that the driveshaft to transaxle coupler may have worked loose or stripped its splines. That was only slightly less distasteful in that the transaxle would have to be pulled to make that replacement.

This morning I had the car towed over to Pro Automotive to have the experts put it on the lift and work their magic. Bob just called and told me the right hand axle shaft had failed. I'm delighted! Not only can the motor and transaxle stay where they are, it's really a pretty straightforward repair.

We've ordered a replacement that is a bit pricey, but is an OEM quality German manufactured part as opposed to the "remanufactured" ones that I had sourced when we did the conversion. In this case I fear that "remanufactured" is an industry term for "cleaned the gunk off a used one and sprayed on some Rustoleum".

A recurring theme among the community of EV conversion guys is the frequent breakage of something in the driveline after the conversion is complete. You may recall that I had a transaxle graunch in the evTD, and the same sort of thing has happened with alarming frequency to other EV conversions. No drag racing this time, but with the strong regenerative braking on the Porsche, it's no surprise that there's more stress on the driveline than its thirty year old parts can handle.

I'm anxious to get the car back in service and already have some plans for improvement. Stay tuned ...

UPDATE Friday, January 15, 2016

Bob called to let me know the Porsche was done and ready to be picked up. They shipped the part overnight from somewhere in Illinois and Robert had it installed by 10:00am! Probably couldn't have gotten one from a warehouse in Dallas any quicker. The car runs great and feels smoother than before. It's good to have it back on the road.