We had an incredibly full day today, packed with information & work.
We began with an introduction to our visitor John Yecker, who had driven his converted electric vehicle the 'Blue' Ranger 79 miles (many of them highway) from his home in Lancaster PA to join us. This is just about the limit of his range -- he spent the day with us, and by the end of class his batteries were fully recharged and ready for the drive back!
John's Ranger (photos farther down in the post -- we gathered around it later in the day) is his daily driver. When Bill & I met John at last year's Energy Fest he had just recently converted it. Recently he replaced his lead-acid batteries with lithium-ion and upgraded his controller and a few other components. He is thrilled with the results, and we were thrilled that he came to visit (even though he didn't quite break his range record). We knew he would be a wonderful resource for this group -- he knows a ton and he is incredibly good at explaining it in a way that even people like me can understand while also being able to engage the more technically-minded.
I was sad that he didn't pass it around for everybody to handle but he had to scootch out and there was work to be done in any event -- lots of work!
I had another box to ceremoniously open & unpack in front of everybody -- this one was from Brandon and contained the installation manual prepared by Bob Batson of EVAmerica for our entire kit. It was pretty funny that it arrived on the 2nd to last day of the workshop! We then debriefed on the various tasks accomplished yesterday. Everybody knew exactly what they wanted to get going on so we quickly broke back into hands-on for the rest of the morning.
A battery management system, or BMS, is a computerized monitoring device to make sure that lithium cells are balanced during charging and give information about their performance under load. (Elite Power Solutions, which manufactured ours, calls it an Energy Management System.) I had turned up the manual EPS sent me in my old email the night before and printed it out, but when I say Dan was raring to get working on it I'm not kidding -- he had found the manual on the company website and brought in a copy of his own!
Richard couldn't work on the front battery wiring until the batteries were loaded so he took advantage of the time to ask John lots of questions. I know for a fact that in this picture they are discussing impedance.
With the charger installation complete, Grant joined John & Dan in pondering the BMS
This is an unfortunately blurry picture of Chris bending steel with his bare hands! Note also all the tidy split-loom tubing and zipties bundling up the low-voltage wiring thanks to Glenn!
and here AT LAST are the rear batteries in the box (they somehow appeared there magically w/out me taking a picture) and the very sweet threaded-rod bolts that run along the top groove of the batteries to lock the strapped pack into place.
I had the usual trouble getting everybody to stop working and go eat lunch.
When we got back from lunch we went to meet John's 'Blue' Ranger, charging up on 240v in the body shop.
John discussed his decision to run without a BMS on his lithium pack. There are differences of opinion in the EV world as to whether a BMS is worth the investment.
At first I thought to my horror that we would just have to unscrew all those little chips that Ben had been working on! Upon further discussion, however, our intrepid & unstoppable BMS team announced that we would still get some of the balancing benefits for our cells even if the ribbon cable wasn't wired, so installation of the BMS chips proceeded.
Dave & Richard sharing online resources
Our poor terminal bolt holes were beginning to show signs of strain from all the assembly and disassembly and stripping inside. Dave taught everybody this clever little fix of stuffing them with a few strands of copper from the interior of one of our high-voltage cables, he called it making your own helicoil inserts.
I asked Dan what he was doing as I took this shot and he said, "Making a little cable." He really wants to wire up at least a few of the batteries to the BMS so we can all take a look-see and he thinks he can muster up a work-around that will accomplish that.
Julie got to use a low-torque wrench to put the brand-new low-rolling resistance tires on and she loved it, too. Bill also had her re-install the center console between the seats in the Miata so the interior is looking a lot more put-together.
Dan and John designing our partial BMS.
By the time we debriefed at the end of the day the back battery box was completely wired except for the high voltage connections. We are starting out tomorrow quite close to our goal: a rolling EV! I confessed to somebody today that we were farther ahead than we'd ever been before on the last day of the workshop, as recorded for posterity in 2007 and 2009. Can't wait to see what happens tomorrow!