Bonus gear discovered!

During driving of Electro over the last few months, I had noticed two minor problems with the gear shift pattern. First, the Reverse (up/left) was dangerously close to First (up/mostly left), and I even though I theoretically had 5 gears in the transmission, I could never get into Fifth. This was becoming more of a problem as I started approaching freeway speeds on my commute last week.

This weekend I set about looking through the VW shift linkage and connections, and found that my shifting rod part of the linkage (the rod running between the shifter and the engine compartment) was slightly misaligned. Its connected via a simple clamp and bolt, so after loosening, adjusting and retightening the clamp, I not only retrieved access to Fifth, but also fixed Reverse such that I need to push down on the shifter before up/left. Two problems fixed with one correction!

It's a little cold and rainy this week, so probably no commute trips with Electro (still has leaky roof), but I am considering taking some video of trips soon for the blog.

First week of commuting with Electro

I finished my first week of commuting to work with Electro - no issues! I have found a great non-freeway route as I break in the EV, and the distance is around 12.5 miles. I can recharge at work, so this is a great distance to break the batteries in on.

Clint Eastwood talks EVs on Letterman!

http://www.youtube.com/watch?v=QBmB32cfD4w&feature=related

Fascinating.

First full commute with Electro - success

I just returned from driving Electro to work today (10-12 miles each way depending on route). Lots of coworkers had wanted to see this electric jalopy - my one hour show at lunch felt a lot like an entry in a car show... hood up, explaining the car stats, people starting to put their fingers where they shouldn't =). During the commute, I was again concerned about Heartbreak Hill, a fairly steep hill that lasts about 1/2 mile. It is by far the biggest ass-kicker hill for any vehicle in the area, electric or otherwise. Electro attacked it like a champ, at a slower but respectable speed. Which reminds me - in my commute I don't go on the freeway (yet) but I do maintain a healthy speed of between 35-40 MPH. Electro really zips along nicely.

The facilities guy at my work says he bought an 'EV charging station' sign, and will post it on the light pole where I plug in during the day. Awesome!

Test drive #5: Heartbreak hill

To test out the torque capabilities on my 'lead sled', I drove it on a hilly 18-19 mile course, which includes a brutal 1/2 mile steep uphill climb halfway in. Electro made it back home with charge to spare, but on the brutal hill Electro had to be in second gear and ran at 25-30 mph. Reasonable, but I think I was hitting my Zilla battery current limit. I will be looking at increasing this limit from 600A to either 700A or 800A for short term torque needs.

You knew it was bound to happen! There will be an electric version of
the Smart Car soon. A partnership between Tesla and Daimler:

http://blog.wired.com/cars/2009/01/tesla-motors-jo.html

Tweaking almost done

My latest settings in the Zilla seem to be working great for drives:
Battery Amp Limit: 500A
LBV: 67V
LBVI: 71V

I have the current I need for hills & short bursts of acceleration, and I am not in danger of going below the under-load 1.2V/cell limit (57.6V in the 96V pack) which would damage the batteries.

I'll be driving 20 miles a day (or less) while I break the pack in for the next 500 or so miles.

EV Grin Time: Cost per mile for fuel

I just found out that the cost per KWh in this part of the country ranges from $0.08 non-peak to $0.10 peak (Puget Sound Energy). Let's do some fun math...

0.330 - 0.380 KWh/mi * $0.09/KWh = 3-4 cents a mile.

With a typical sedan of say, 20 MPG @ $2/gal => 2/20 = 10 cents a mile.

Cost is not a driver for me (pardon the pun), but it is cool to see that it costs less to fuel Electro than it does a "gasser". That makes driving an EV just that much more fun!

Simulated commute this evening

I drove Electro a typical commute distance this evening (~11 miles). Even though it was not the longest I had driven Electro, it was the furthest from home. I drove into an adjacent town, testing Electro at some higher speeds than my neighborhood (avg speed 35 MPH) and on some steeper-than-usual hills. The drive went great, and I expended 3.57 KWh on the trip - this entry lines up with my average energy running so far: 330 Whr/mi.

Another reason I wanted to simulate commute distance was to see what the recovery charge time would be for a typical commute. I have a Kill-A-Watt on order, so I don't know if I am pulling max 15 amps current during the recharge, but regardless, the complete recharge (including 50 minute taper) took 4.5 hours. Not bad!

My employer is allowing me to plug in at work when I start commuting with Electro! Sweet - free fuel for the trip home!

Battery voltage vs. charge

Battery voltage FAQ

This FAQ has a nice table equating average battery voltage with percentage charge remaining.
According to the table (and extrapolating for 96V):

100% = 2.12V/cell = 101.76V
80% = 2.07V/cell = 99.36V
50% = 2.01V/cell = 96.48V
20% = 1.93V/cell = 92.64V
10% = 1.89V/cell = 90.72V
0% = 1.75V/cell = 84V

This is not to be confused with low voltage under load, which is during current draw. In those cases, voltage may (and does) dip temporarily to 72V or lower (on hills or when accelerating).

Today during the 8.6 KWh test drive, I periodically took readings of average battery pack voltage. If I use the above table and my recorded voltage measurements:

5.1 mi => 80% charge left
13.3 mi => 50% charge left
18.4 mi => 20% charge left
24.7 mi => 10% charge left

Still reconciling this conclusion with the theoretical data. At one hour of use, my US125s are capable of 145AHr, and this equates to 96V*145Ahr*0.80 = 11.1 KWhr should be my actual capacity. So it looks like with fast driving, I get about 24 miles on a charge.

More testing later this week.

Another distance record broken!

I took Electro out for a test drive with the new Zilla settings of LBV=71 and LBVI=77. I drove around town so as to stay near home, but was not bashful with acceleration and hills. 26.3 miles! A new record for Electro, which expended 8.6 KWh on the trip. I am pleased to report that acceleration was great. No spinning tires, but good for merging with traffic and getting up hills.

I was collecting data the whole time using ZillaView. On average, Electro expends ~4 Ah/mi, and 330-380 Wh/mi in city driving, depending on terrain. Acceleration is good, and I could have driven further, but I was starting to notice acceleration on the slow side. I could still get up to fast speeds, but not very quickly.


I'm excited at the distance progress! Let's see how long it takes to recharge after this drive. Also, in the coming days I think it's time for a longer loop trip!

Tweaking stage

I have been adjusting the settings of the Zilla for the new 96V pack voltage and using the new flooded US125 batteries to get an optimum driving experience. One of the things I noticed was that this pack has quite a bit more sag in the voltage during high current draw, due in part to the higher internal resistance of these kind of batteries. Because of this, my previous low battery voltage limit of 80V in the Zilla would get 'touched' during acceleration or going up hills. This would lead to the Zilla dialing back current (what it's supposed to do at the limit) and embarrassingly slow speeds!

After some experimentation and data gathering using ZillaView via a laptop connected to the Hairball's data port, I determined that a low battery voltage setting of ~72V (1.5V/cell) works much better, allowing the voltage sag without limiting the current I need during acceleration/hills, which can be as high as 500A from the pack in short bursts (this is my battery current limit).

More test driving tonight!

It's Alive (again)!

I took Electro for a distance calibration spin with the newly-charged pack this morning. Just gently breaking in the pack, checking my new voltage & current settings on the Zilla, and measuring voltage depletion over distance.

Fantastic!

I easily went 21 miles with no problem, handily beating my previous distance record of 15 miles with the Exide Orbitals. Although I could have, I elected not to go further on this first run, as I am trying not to beat on the pack too hard. The good news is, I can go on a longer trip next test run.

Electro was more sluggish than before, no surprise given the fact that I have an overall heavier weight and lower pack voltage. I will see about modifying the Zilla settings to give an overall increase in instantaneous current and top speed. I definitely won't be able to squeal the tires like I did before, but my hope is that I will be able to have a much larger range with acceptable acceleration and speed.

Stay tuned for more results, and perhaps some pics of me at certain spots with Electro!