While I'm at it...

I just sold my 16 US125XCs last night. They'll have a good home, in another EV conversion up in Vancouver, BC! So now I work on Electro, waiting quite literally for my lithium battery ship to come in.

Since the batteries are out, I am taking the opportunity to improve a number of systems in Electro, such as better battery instrumentation (a fuel gauge device), some more appropriate HV fuses, and finally reinstalling the venting/heater/defrost system, this time as electric!

I kept the heater/AC core from the original cabby, and tonight started pulling it apart. I got the condenser out (or is it evaporator?), and the heater core itself out of the big box. The heater core is like a small radiator inside the car that is responsible for transferring engine heat to the passenger compartment. Mine is tiny - about 10"x6"x2" - and I believe I can replace the original antifreeze-carrying one with a ceramic heater element for a reasonable price. Pics soon!

Lithium cell balancing modules

Here's a picture of one of the 53 cell balancing modules I received last week from EV Works in Australia. Each module sits on a cell and monitors its voltage to ensure it stays within appropriate cell limits (2.5V-4.0V). Its signal wires (yet to be soldered on) are daisy chained to neighboring cell modules, and the whole loop is connected to a BMS controller. The BMS controller is inline with the AC line to the charger. If the charger does not taper current back when the cells reach the appropriate voltage during charge, the BMS can literally cut the charger off at the knees. There is also an audible alarm (although unclear how loud) the BMS has to warn of cell anomalies.

Note that this system only protects against over-charging. The Zilla controller already has configurable safeguards for over-discharge of the cells.

I guess I will start soldering wires this weekend. Lots of wires. Fun!

Lithium order increase, and BMS change

I was a little uncomfortable shelling out ~$2K for a Elithion BMS that had very little documentation and not a lot of explanation from the company, so I started hunting around. Folks that have Thundersky LiFePO4 batteries have also gone with a much cheaper battery balancing system from EV Works in Australia, here's the link:

EV Works BMS controller

This controller costs $AUD 350, which is around $315. Coupled with the 'cell balancing modules' ($AUD 16.90 or $15.21 ea), I should have a reasonable overcharge protection system. The Zilla already protects me from over-discharge, so no worries there. Based on this change, my BMS budget shrank to ~$1000, sooooo... I increased my battery order from 45 to 53, and that still fits in my car, and my budget.

The good news here is that 53 x 3.2V = 170V traction pack. Very close to my original peppy 180V voltage, but with much less weight!

These are the lithium cells I am buying (45 of em)

Sky Energy SE100AHA LiFePO4 cell info

My winter project: LITHIUM UPGRADE!

I just placed my order for 45 Sky Energy LiFePO4 cells from evcomponents.com. This new traction pack will be a third the weight of my current pack, and have at least twice the range. Oh, and the voltage will be higher (144V vs. 96V). Don't know when I will get them (they get shipped from China), but pics will be posted when they show up!

New 1.5 KWh battery coming from Panasonic

A new 1.5 KWh battery from Panasonic, debuting this month.
No idea on the cost, but the marketing fud indicates this might commercially popular. If it is reliable, then 10-12 of these would be all I need for Electro...

Panasonic Lithium Battery Press Release

Another image, minus background

Thanks to Lucky at the152.com for providing the MK1 customizer tool!
Here is a mini image of Electro!

Charging parameter experiment

I have a working hypothesis that I have been routinely undercharging my batteries, and not long enough on the acceptance charge. This would explain the low float voltage, and more limited range. Here are the guidelines I recently found from US Battery:

http://www.usbattery.com/usb_faqs.html

My usual acceptance charge is ~119V for a 96V pack (7.44V for each 6V battery), and only for an hour at that charge.

The guidance above says ~124V for a 96V pack (7.75V for each 6V battery), and 2-4 hours at that charge.

Doing that tonight, we'll see if the floating voltage is any higher tomorrow.

BTW, passed the 1900 mile mark. This car is a great commuter car!

1500 miles!

Electro just recently passed the 1500 mile mark of being on the road. Awesome!

Back on the road - tuning for temperature!

I finally received my replacement battery and put the traction pack back together. Electro has been great for the past few weeks, getting me to work and back. We've had a bit of a heat wave here in the PNW, and I didn't connect the fact that the Zilla motor controller was getting hot with the hotter ambient temperature.

But as we approached the all-time record this last week of 103 F, I noticed the check engine warning light from the Zilla would come on earlier and earlier in the drive. I used to just connect that light with battery low warning, but found out that it is also when the Zilla is approaching thermal cutoff of 100 C. Closer watching with ZillaView during driving showed that I was getting upwards to 80 C, which cuts back on the current, but doesn't completely cut out. Anyway, I checked my liquid cooling system, and things are fine, but the mini-radiator/reservoir storing the coolant can't get cool enough on its own, especially when the days get hot. So I installed an extra 12 VDC computer fan, mounted to the radiator to help expedite the heat dissipation. I would prefer to expose the radiator to RAM airflow, but there isn't a convenient space for that.

Tested the new cooling arrangement the other day on my 'devil's run' test hill (1/4 mile extreme grade uphill). The temperature rose predictably, but leveled off at 70 C and recovered to a lower temp fairly quickly! The warning light still flashed at me, but I think that is going to be a fact of life on extremely hot days.

Whoops!

I had another one of those 'marvel at the power of electricity' moments this weekend...

On a leisurely Sunday drive, the power suddenly cut out on me, never a good thing. Luckily I was at a place near home where I could pull over, call for a quick tow, and all was good. After I got back home, I started checking voltages. I thought at first a fuse has gone out again, but I was wrong - waaaay wrong.

One of my battery posts had melted to about half its original size. Check it...
After being amazed at the melted post for awhile, I started working a theory of why it happened. Most likely a loose connection, coupled with high current draw, equals arc, and further deterioriation, which leads to further arcs, more heat, and MELTING!

The reason I think this happened was because I am using non-flexible cable, and during motion of the car, these connections between batteries, no matter how tightly they're cinched down, will come loose with the vibration of these battery boulders.

The battery in question seems okay voltage-wise. I will be looking into getting the post repaired, and also looking into replacing some of the more at-risk cables with their flexible alternatives.

Live and learn!

Price analysis on Lithium Batteries

I found this site:
http://ehsmanager.blogspot.com/2009/04/happy-9th-birthday-lithium-ion-battery.html

and the following experience curve on Li-Ion batteries...


I would probably jump in at the $400/KWh point on the curve. For the type of batteries I am looking for in Electro, that would run me $6000.

Enter Electric Hellfire

Well, Electro took me about a year of evenings and weekends to complete. Electric Hellfire took me exactly one. This kit, from GoldenMotor.com, took a couple of hours to fit to Matt's mountain bike. Here is a pic:



The motor is very subtle - a larger than usual hub on the front wheel. Everything fit perfectly, and although no instructions came with the kit, the PDF from the website and the color-coding of the wires and connectors helped make this assembly a cakewalk. Here is a picture of the controls:


Cruise control and horn on the left, thumb throttle on the right. The kit came with brake controls that hook into the normal brake cables. The only difference with these is that the brakes also are wired into the controller to signal stopping cruise control if it's on.

The installation components are very well manufactured. The wheel went on with no issues (albeit minor brake caliper tuning, which you would do with any new wheel), and the battery box fit easily as well. The only downside to this kit was the motor controller, which arrived with no enclosure. I didn't have an electrical enclosure this narrow to house it, so I made due with some tupperware for now.

The first test ride went flawlessly. Hellfire goes FAST. At full throttle, it can approach 25-30MPH on the flats. It takes hills easily, although super steep hills are still an issue - the draconian hill in our neighborhood was the acid test, and Hellfire made it 3/4 of the way up before conceding. Note: this was while taking Big Daddy up the hill - Matt made it to the top just fine!

I'll try getting a video or two of riding Hellfire posted soon. I also want to test range of the lithium pack.

New EV project looming for the summer: E-Bike!

I am interested in eventually replacing my lead-acid battery pack with a LiFePO4 pack, which will decrease weight, increase range and speed, all that good stuff. But since LiFePO4 batteries are much more pricey and are managed differently, I thought I'd start with a smaller EV project that uses them, to better understand how they perform.

Enter the E-Bike project!

I bought a donor bike off of craigslist, and have just ordered a DIY E-Bike conversion kit from goldenmotor.com in China. The kit contains a 36V/750W hub motor, 36V10Ah LiFePO4 battery pack, motor controller, throttle, wiring, etc. Should be here in about three weeks. Can't wait!

Lessons learned #347: LRR Tires

OK, EV fans. If anyone ever tells you that Low Rolling Resistance (LRR) tires are one of the key pieces to your vehicles energy efficiency, LISTEN TO THEM.

I recently bought a used set of low profile tires off of craigslist that made Electro look supercool and be very energy inefficient. Let me explain.

The stock tires for Electro were 185/60/14, which translates into tires that are 185mm wide and go on 14in wheels.

The new "supercool" wheels/tires I bought were 205/40/16s, which means they were 205mm wide, low profile, and had extra big wheels (16in).

Driving the same distance with the wider tires made a HUGE difference in the amount of energy I was using, which is extremely important in an EV. For a trip where I would normally use 7.1 KWh, I ended up using 9.3 KWh. That's 30% more energy - to look cool.

I am going back to stock wheels/tires for now until I can go the other way and find a narrower set of LRR wheels and tires. Hopefully I will find some that will get me significant range increases!

Electric motorcycle dragster video

Check out this lightning bolt. Power band? We don't need no stinkin' power band!

http://www.youtube.com/watch?v=eNkJCdEEzpM

Ford's new electric debuting in 2011

Designed and built almost entirely by an outside supplier - in Canada!

http://money.cnn.com/2009/03/20/autos/ford_electric/index.htm?postversion=2009032005

Another article about Better Place, an electric car infrastructure company. They're all about replacing gas stations with charge stations.

http://www.cbsnews.com/stories/2009/03/16/sunday/main4869332.shtml

Power brakes are back!

Today I installed a new switch for the brake booster, and put a shock absorber between the brake booster motor mount and the battery rack - basically a thick rag. My theory was that, with movement and vibration, the old switch would get stuck on, and run the motor constantly, which was VERY annoying - the vacuum motor has to be the loudest thing in the car at this point. The new switch doesn't get stuck on, but before I installed the rag it did seem to stay on a LONG time before shutting off.

If it is only on for short stints to replace the vacuum in the reservoir, then it is tolerable, and I am now at that point with the shock absorber - yay! Power brakes again - I love it.

I also took the time to check the front batteries for voltages, fluid and hydrometer readings (rear batteries tomorrow). All 8 look good at 6.5V / ~1.250 sg. The overall rest voltage for the pack is 102.5V, which implies ~6.4V for each of the 16 batteries. Either I have some voltage drop across the 2/0 cables (expected), or something's fishy in the one or more of the back 8 (NOT expected) - more tomorrow.

If it's decent weather tomorrow, perhaps I'll make a video of driving Electro around!

The Equalizer!

Now that the inclement weather has disappeared (again), I am again driving Electro to work. I have noticed some changes in the power while driving, and I suspect it may be time to equalize the battery pack.

I had read that an equalization charge was needed once in a while, but the frequency of the equalization charge varied in who was talking. The common wisdom is once a month.

Equalization charge for a flooded battery is driving the voltage up to 2.6VPC, or 124.5V for a 96V pack. The purpose is to make sure all cells (even the weaker ones) are fully charged. It is hard on the cells, hence the low frequency. So tonight I am the Equalizer. We'll see how it goes.

Good news, I found my video camera after losing it. This means I can post more videos in the weeks to come - stay tuned.

Check out the new Electric Mini Cooper

http://www.jaylenosgarage.com/video/video_player.shtml?vid=1052621

They don't mention cost, but I heard that they lease for ~$800 each. Yikes.

Electro is now Legally an Electric Vehicle

The big question that many had as I was doing this conversion was, what do you do when you get the smog-check notice for Electro? It would be pretty amusing to go to the emissions check place and watch those guys try to figure out where the exhaust pipe was, but more likely than not I would end up getting a fail because they wouldn't know what to do, and then I'd have to react by scrambling through a bureaucratic maze at the Department of Licensing with my rather esoteric problem.

My tabs don't expire until later this year, so I decided to proactively attack the problem. After a few phone calls, I found out that I just needed to revise the car title to specify 'E' powered instead of 'G' powered. All this without a vehicle inspection or anything. Cost me $19 and the time to wait in line at the local DOL office! I did have to sign a statement saying that the car is no longer gas-burning, and they said the revised title would be sent out in a few weeks. Easy!

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!