Tuesday, January 31, 2017

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.


Sunday, October 9, 2016

Revamped Charging for the PorschEV

I have been so pleased with the new charging arrangement on the evTD that it finally got me motivated to rethink and rework the charging for the PorschEV. To recap, although I had plans to consolidate both the charge controller and the DC/DC controller in a single box, space constraints forced the DC/DC converter to the hatch area near the batteries, so the controller went along with it. Probably as a result of too much handling and user error, the DC/DC controller failed early on and Jack Rickard kindly replaced it with a newer version which has worked perfectly. The older version Charger controller has done its job just fine, but loses its configuration from memory between charges. That means that for every charge, I have to open the hood, drag out my trusty MacBook, plug in the USB cable, and reset the target voltage and termination amps before plugging in the J1772. It's a nuisance and pretty much negates the possibility of convenience charging while I'm out and about. Ideally, I should be able to simply plug in the J1772 like I do with the Nissan Leaf and now evTD.

Jack Rickard of EVTV told me that the controllers are all programmed to support the Volt Lear Charger, the Volt APM (DC/DC Converter), and the UQM Lear Charger and have enough processing capacity to run all three concurrently. Here's how he described it on the EVTV Forum:




Well, he did say "you could PROBABLY run all three at the same time", so once again I think I'm on the bleeding edge of what has actually been put into service. If not me, then who? I say go for it! Disassembling the Charger controller, it was clear that there were two sets of Can Hi and Can Lo connections, so that wiring harness will need to be thought out. 

There are also three separate 12v+ connections going to the connector, so it's clear that a junction box will be needed to organize the connections up front.  It turns out that the original black plastic housing for the controller will do just fine. The terminal post on the left is provision for a traction pack negative connection for a volt/amp meter for monitoring charge progress. More on that in a future post. The white and brown wires on the top are the CAN connections to the control box in the rear. The main reason I put this project off is once again twisting this old body into unnatural positions while snaking the CAN wiring through the firewall, behind the dashboard, through the console, under the arm rest, and through the rear seat upholstery and trim panels to keep everything tidy and mostly out of sight.


Once the wiring gets to the rear, it's threaded through the gland fitting into the rear controller and simply added to the screw connectors for Can Hi and Can Lo. The terminals are well marked on both versions of the controller, so it's pretty easy to make the right connections. Once everything is hooked up, it's time to test. 

I'm pleased to report that it all works as Jack described, "certainly" more than "probably"!


Here's a screen grab showing both the DC/DC (APM) and Charger active at the same time. I do want some visual feedback on the charge process without hooking up the laptop. The Leaf has three blue lights and the evTD has the JLD404, so I'll be adding a volt/amp meter for the traction pack that is only active during charging and visible through the rear glass near the charge port. More on that in a future post. Stay tuned ...

Saturday, September 3, 2016

evTD Refinements

WARNING! ACHTUNG! Long and involved post ahead. You have been warned!

Truth to tell, the final days of construction on the evTD were pretty frantic. I had a deadline to leave for EVCCON 2012, and I might have taken a few shortcuts. I've also learned a thing or two in the four years since she became roadworthy. This became most apparent several months ago when I had a gentleman from Germany who was very interested in purchasing the car. The deal fell through as we learned that the German Dept of Motor Vehicles was intent on making it impossible to register any imported one-off vehicle. As part of the process I wrote a user's manual to support the sale. Documenting the steps for each simple action it became clear that things weren't so simple:

Charging


  1. Pull out the Emergency Stop Switch to close the main contactor
  2. Connect laptop computer to Charger Controller with USB cable
  3. Using an ASCII terminal program as outlined in the TC Charger User Guide, check and reset the charging values if necessary. I generally charge to a Target Voltage of 256 volts (approximately 3.55 volts per cell), a Target Current of 20 Amps, and a Terminating Current of 5 Amps.
  4. If charging from the Alternate NEMA L6-20 Inlet Port, connect both ends of the charge cable before turning the white auxiliary charging switch to “ON”. This prevents arcing at the plugs when applying power.
  5. If charging from the J1772 Inlet Port, open the cap on the inlet and insert the J1772 plug until the catch snaps into place. Ensure that the NEMA L6-20 plug from the J1772 inlet is plugged into the alternate inlet port, then turn on the white auxiliary switch. Finally, turn on the toggle switch on the J1772 Inlet box to begin charging.
  6. When charging is complete, turn off both switches on the inlet boxes and push in the Emergency Stop Switch to open the main contractor before removing the charge cord.
That's a far cry from my ideal scenario - just plug it in.

The Law of Unintended Consequences now comes into play. The AeroVironment TurboCord  made the NEMA connection redundant, so out it came. In its place, I installed a nice sealed 12 volt battery for a Mazda Miata that fit really nicely in that space. I'd been running on the DC/DC Converter only since I had installed the NEMA box, and it seemed that it would reduce wear and tear if the battery supplied the power for those things that run even when the car is off. Those things are called parasitic loads for a good reason - they'll suck the life out of your 12 volt battery in no time at all.  One startup failure showed me it's not good to let your auxiliary battery run down to 3 volts keeping the radio, GPS speedometer,  JLD404 volt/amp meter, and AutoBloc AMP fuel gauge driver powered up. 

Then there's the emergency switch. You may recall an earlier mishap with this thing. At the time I rewired it so it wasn't carrying the full 12 volt load, but it was still an extra step to pull it before turning the ignition switch or charging and push it back in when you're done.

Finally, what's with the charging controller losing its memory settings so the laptop is necessary for each charge? I had wired the positive lead to an unswitched 12 volt and the little computer chip set was apparently subject to some surge issues while the car was running that erased its settings.

So here's the plan: build a little circuit box that takes over the control of the 12 volt battery, the emergency switch, and the charge controller. All of that is predicated on rewiring the emergency switch to a switched circuit so it will automatically energize the main pack contactor when the key is switched on. That eliminates the Soliton1 controller error that causes an annoying error light when I forget.

This all took a great deal of head-scratching time and one important little electronic component.

Found this on Amazon and figured for $15.00 how could I go wrong? It's an XINY Voltage Control Relay. It's one of those amazing Chinese gadgets that does all kinds of magical things with free shipping and absolutely no documentation. A bit of Googling around turned up a few documents in Madarin and this one in English. You're welcome.

The function I use is the voltage triggered relay that engages when the voltage reaches a preset lower value and then disengages at an upper value. I have it set to kick in the main pack contactor when the voltage drops below 12 volts which runs the DC/DC Converter until the voltage reaches 13.4 volts, then removes power from the contactor.

While I was at it, the same thing can be done with the charger, so I added some circuitry to manage that as well. I have a Tucson EV J1772 Adapter Box that I bought back in 2011 for the eBugeye. It has a simple toggle switch controlling the J1772 pilot signals, so I moved that function to a relay so the switch could also control power to the Charge Controller. Since the hood must be raised to charge anyway, one switch didn't seem so bad. I may move to an AVC2 controller in the future, but for now this is fine.

The circuit winds up looking like this:

I know it's not SAE spec, but it works for me figuring out logically what goes where. In real life, the box wound up looking like this:

The black box at the top is the J1772 Pilot Signal relay and the smaller black box below the terminal block is the diode to prevent the charge controller from getting power during other operations.

The XINY voltage control relay is mounted to the lid and wired to the terminal strip inside. I'll build a housing for the XINY that shows only the voltage LED, but for now it's still a pretty tidy installation.


Sunday, July 17, 2016

evTD Gets LED Headlights


I'm still trying to get the 12 volt system under control on the evTD. Whenever the cooling fans and pump are running (most of the time here in Texas) and I turn on the headlights, the voltage sags below 12 volts. There's a momentary shudder and error light from the Soleton1 controller due to current inrush to the sealed beam headlights. Even after it recovers, the lighting still seems dim and yellowish and the high beams pull down the voltage further and cause the controller error light to flash. I replaced all of the secondary lights with LEDs a couple of years ago with limited success, so it's time to have a go at the headlights.

I ordered a set of Truck-Lite LED 7 inch round headlights. The prices have come down significantly over the last couple of years, but they are still a bit pricy compared to sealed beams. These are advertised for Jeeps mostly, although they do reference "other classic cars". They have a standard plug connection that is compatible with the old sealed beams and they are an easy and direct replacement.

Here are some before and after photos:

Sealed Beam Headlights

Sealed Beam Pattern
LED Headlights

LED Pattern
I am very pleased with the optics of the new lamps: the light is whiter and more intense than the old sealed beams. It makes night vision much better and I think I'll put a set on the PorschEV just because of the improvement for driving after dark. The voltage sag results are a mixed bag: no more controller shudder when turning on the lights and the voltage holds just above 12 volts with the cooling system running, but with high beams voltage drops below 12 volts and turns on the error light. These lamps are rated for 1.8 amps draw on low beams and 3.6 amps for high beams so at this point I think I need to look at the cooling fans and pump to see if I can cut back on the current draw and subsequent sag they are causing, Stay tuned ...

Sunday, June 19, 2016

Visual Tour and Road Test Video

This is a follow up to our last posting, once again shown as part of Jack Rickard's EVTV.ME video, this time the June 17, 2016 episode. My segment starts at about the 33:40 mark.


There is lots of fascinating (geeky) information about Tesla drive trains and the next version of the GEVCU (Generalized Electric Vehicle Control Unit), also a look at the inside of a burned out Tesla inverter. It's a worthwhile hour and forty five minutes, but if you'd like to have a look at just the PorschEV segment, here it is:


Thanks for watching!

Sunday, May 29, 2016

Project Summary Video

I shot a short video this week for Jack Rickard and EVTV.ME that covers the year long build-out of the PorschEV in a seven and a half minute segment. Here's Jack's show of May 27, 2016. My segment starts at the 6:57 mark.



Jack's explanation of the EV adoption curve and his new Chademo fast charge station is very interesting, so I'd encourage you to watch the whole thing. All of his shows are archived, so you can go back and watch them here.

If you'd rather just watch the PorschEV segment, it's available below:


I plan to produce a live walk-around and road test video soon, so stay tuned ...

Thursday, May 26, 2016

Pulling It All Together

There have been separate blogs for each of my Electric Vehicle projects, and it seems like a good time to pull them all together in one place, along with the commercial EV's that have also been in the mix. So this page, Adventures in EV Land, will be the source for news and information for all of the family EV's going forward. All the individual project pages are linked at the top of the page.

The first news item regards the Second Annual Cedar Park High School Cross Country Car & Motorcycle Show held May 21, 2016. The show was organized by my friend Robert Juarez, who did all the fabrication, body, and paint work on both the evTD and the PorschEV, and benefited the Cedar Park HS Cross Country Team. It was an honor to show both cars, and a thrill to win "Best in Class" for the evTD. Truth is, mine were the only entries in the EV class, so how could I lose?


Here is a sampling of the other cars in the show: