Corbin's Treehouse - Corbin Dunn, Santa Cruz, CA
Plug Bug

chargepoint energy stats for my bug

Since July of 2011 I’ve been using chargepoint for charging at free charging stations, and at work. Prior to my work getting J1772 stations, I would use a dryer plug outlet that was provided for EVs. Here is a screen shot of the stats for my use:

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10,673.912 kWh used in about 4 years. Mostly with the bug, but some with another EV (Jan/Feb ’15). This also doesn’t include other J1772 stations I’ve used that aren’t charge point (i.e.: the free stations downtown Santa Cruz), and it doesn’t include charging at home. 

The large gap from August to January was when the bug’s transmission was broken, and I was forced to drive another car for a while. The shorter gaps were probably vacations.


Bathroom cabinet: Free Sketchup model download!

Here is my downstairs bathroom cabinet design in Sketchup:

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A quick rendering:

Rendering cabinet


And placed in my bathroom setup:

Downstairs bathroom with vanity 2015 06 22 20115400000


Download the free cabinet sketchup model: Downstairs bathroom cabinet 2015.skp



Plug Bug: You are only as strong as your weakest cell

I had known for quite some time that I had a weak cell in my battery pack. My electric bug’s battery consists of 48 lithium iron phosphate cells. I use the eLithion battery management system with a custom display I fabricated along with some custom ardiuno code to show cell info from the CAN bus. I would routinely see one cell (number 9) sag heavily under load. 

One day I left work work (a 20 mile drive) with my pack at about 50% charged. At about five miles from work my low battery warning buzzer went off telling me that I had one cell that was fully discharged. That was my bad cell number 9, and I was only at 30% SOC once I arrived at work:

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The cell was down to 2.07v, which is well below the nominal 3.20 volts, and the “fully discharged” value of 2.7 volts. I had ignored the low voltage buzzer, and continued to drive car, taking more energy out and over-discharging it. I knew this might destroy the cell, but I was okay with that as I had a spare cell at home. 

Once I got to work, the BMS wouldn’t let it charge! It thought the under voltage condition was an error where it shouldn’t let any energy in (which is strange). Luckily, I could easily unplug the BMS connection to my charger, and let it charge for a bit:

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This pulled the voltage up to 2.70 volts, and let it normally charge:

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At this point, I knew that 30% state of charge (SOC) was my real world “battery empty” point. This one particular cell has lost 30% capacity in the 4+ years and 39,000 miles that I have been driven the car. I know the other cells aren’t as bad, as they don’t sag under voltage load, but this one bad cell is the limiting factor of my pack. If I continued to discharge it below 30%, it would cause the cell to die. That in itself wouldn’t be that bad, but I heard dead cells can sometimes reverse the voltage and suck energy out of their neighbors. I would also have to bypass it in my BMS, as it wouldn’t let the car drive with a dead cell.

I continued to drive the car for a month or so, and just didn’t let it get that low again, and it worked fine. But I really wanted that extra bit of range and capacity “just in case”. Plus, I had two spare good cells for this very reason.

Last weekend I finally did the work to replace the cell. I had previously used a volt meter to find out which cell it was (the numbering doesn’t seem to be related to anything I can figure out). It was a cell in the front trunk of my car, so I pulled out the module for it:

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I snapped the green strapping wires apart, replaced the bad cell, and then strapped the module back together.

This time, I used my engine hoist to pull the module out and put it back in:

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It was so much easier than trying to pull it out by hand (which I had done when I originally installed the modules!). 

The bug now has a bit over 39,100 miles. The transmission is leaking a bit of oil from the main shaft seal; I’m afraid it will eventually fail again.

Now, I need to do another capacity test with the pack and see how the other cells are doing. 30% loss over roughly 4.5 years isn’t that great…the cells forecast an expected 20% loss after 10 years of use when discharging to more than 20% SOC. I always did this, but I also always charged to 100% SOC (indicated by roughly 3.6 volts per cell). I think always charging to 100% has reduced the capacity. If I were to do the project again, I would write some smarter charger controlling logic to limit max SOC to 90 to 95% for most charging sessions, and only charge to 100% on the days I knew I would really need it, or would use the energy right away. Sitting at a high SOC for a long time isn’t good for the cells.




Photography: Nepal White Himalayas

The himalaya mountains are fabulous; I couldn’t stop staring at them. I can’t remember if this was early morning or early evening — but the mountain was just glowing from the sunlight, while myself and the surrounding area was engulfed in shadows. The moon appears on the edge. Notice how the skyline of the mountain pulls your eyes towards it.


Taken 4/8/15, ISO 640, f/20, 1/60, 70mm with a Canon EF 24-70mm f/2.8 USM lens and 5D Mark III.

SF Uni Tour

Going through some old pictures on my hard drive and ran across this one that Daniel Inouye took of me on the San Francisco Unicycle Tour back in 2011:

Corbin  sf  uni  303821 10150287938626472 517731471 8339798 191102521 n

I like the composition; my head is centered in the top third of the picture, with my body in the dead center. It conveys a ton of movement. 

WWDC 2015: Improving the Full Screen Window Experience

For the past 10 years I’ve given a talk at every Apple World Wild Developer Conference (WWDC). Well, except for one. That was 2007 when I was busy working on UIKit for the iPhone 1.0.

Apples is now posting our videos online without requiring an Apple developer account. So, everyone can check out my video for this year’s session #221 on their site:

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 I talk about how to implement Full Screen in Cocoa desktop applications, including some new tiling features in OS 10.11. Most the full screen information applies to all OS X versions that support full screen (I think 10.7 and higher). I also discuss Title Bar Accessory View Controllers — this feature requires 10.10 or higher. During the second half my colleague Taylor Kelly comes up and discusses how to do some cool dynamic layouts.

We also have a demo app showing off the features: Exhibition – An adaptive OS X App

Hacking duolingo to make flashcards with sounds using Anki

Use Anki to learn a language with sound enabled flashcards.

0. Buy a Mac if you don’t have one already

1. In Safari’s Preferences, turn on the Develop menu item (Advanced tab)

2. Visit duolingo, and go to a lesson

3. Click the menu item: Develop -> Show Web Inspector (note: this may have changed in later releases)

4. In the web inspector, expand, and you should see an “Other” section in the Resources tab:

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If you don’t see an “Other” section, reload the page. If that doesn’t work, hit the reload button that is shown in the screen shot (in the table’s first row, on the right side of the row). Eventually it shows up.

5. Hover over some text to hear just that word. When you do this, duolingo loads the sound from an amazonaws or cloudfront server, and you can see the link in the Other section with the name of the word.

6. Double click on the word; this opens it in a  new window (and plays it)

7. Right click the sound and download it (it might say it is a Video, but it isn’t).

8. Now in Anki you can create a new Card (called a Note), and use the paper click icon to add the sound:

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You will now have a card with a sound embedded in it. Awesome!

On learning languages…

I’m working on learning Italian. When I was a kid, I hated learning languages, and had the terrible monopolistic language view that everyone should speak English. I have long since realized that was a really stupid opinion, and it really hindered me from learning another language. In high school, we had to take two years of a language as a graduation requirement. I wanted to take German, just because I thought it would be cool, but they stopped teaching it the year before I reached high school. So, the options were French or Spanish, and I heard Spanish was easier and I took that. I generally had terrible teachers with the worst teacher being Mr Nava. Ironically, you would think he would be the best, because I believe he was an immigrant from Mexico. He simply made us memorize verb conjugations, and we never spoke Spanish in class. I memorized, and I got an A, but I didn’t learn.

Now I really want to learn Italian, and at 37 it is becoming more difficult for me to learn new things — especially things like languages. I tried self-teaching myself German back in my early 20’s, and I know a few words, but I can’t really do much with the language. I decided I really want to learn Italian though, since Costanza is full fledged Italian.

Unless you’ve been in the dark, I’m sure you have heard of duolingo. It is an awesome website, and I’ve reached “Level 11″ in Italian. I do a lot of lessons on my phone, and some on the website while at my Mac. I also listen to Pimsleur audio books on the way to work. They utilize spaced repetition for learning, and I really like the technique. I also ran across a great app called Anki for the Mac. You can make flashcards with it that utilize the Pimsleur spaced repletion techniques. And, as an added bonus, you can add sound. So, I combine the two techniques by “borrowing” sounds from duolingo.

I’ll do a post on this soon on how I’m hacking it to learn in a way that works well for me.

Plug Bug: Killing Chargepoint Charging Stations

Well, my bug wasn’t killing the charging stations, but it was giving them an internal error. It seems that the newer charge point stations with a large display weren’t compatible with my car’s J1772 port for some reason. There are rows of them at my work, and I’d plug in and it would give an error: 

IMG 2387

Error Code #303-RSC, RELAY STUCK CLOSED. I couldn’t find any information on this error, and both phone calls and emails to ChargePoint went unanswered. The phone people just assumed it was a problem with the station, but I told them my car caused it and I wanted to know WHY it happened. Still, no info.

So, I really wanted to use the closer chargers at Infinite Loop instead of walking across the street to the older style. I started poking around and discovered the two pins were leaking voltage to ground. The ground is the 12v ground of the car, and I had known about a ground leak for quite a while. Pack voltage is usually isolated from the car’s normal ground system and chassis. On cars, the chassis is used for the 12v negative side (the ground). Yet, if I compared the plus side of an amp meter to my negative most terminal on my pack, I would read almost my entire pack voltage!

I knew this. It went away when I unplugged the controller/motor, and I assumed it was the brushes in the motor and not a big deal. Sometimes dust builds up in the brushes and causes a leak (or so I’ve heard). 

I figured this might be causing the charging station issue. It was easy to test; I drove to work, unplugged my controller/motor (it is on a BIG anderson connector), and sure enough — it worked!

When I got home I had to figure out where it was leaking. If I disconnected just the motor the leak still happened. I finally traced it to the controller. The Netgain controller has two high voltage “pre charge” wires. They are orange wires from the controller. They go to the contactor that the controller controls. One goes to the pack voltage side, and the other goes to the other side of the contactor that is “on” when the contactor is closed (providing power to the controller). The controller does some type of voltage check on both sides to pre-recharge things.  For some reason, the side on the non-open side of the contactor caused the problem; disconnecting it fixed the problem — well, almost, as the leak was only 2 volts or so. It was leaking “out” for some reason from here, and it is some problem in the controller. Swapping the orange wires didn’t matter (they were interchangeable). If I removed the pack voltage side wire, then of course, the leak went away entirely.

So, I was hoping I could put this pack voltage wire on a relay that comes on only when the key is on. This way, the charger works when the key is off.

I found a good relay on DigiKey and Mouser, and a better price on Amazon (especially with free Amazon prime shipping):

This is an Omron MKS1XT-10 DC12 relay. The details on Amazon are poor, and Mouser’s specs stated: 10 amp contact current (more than enough for that wire thickness), 220 VDC switching voltage (my pack is 154V nominal, and way less than 200V ever), and the relay runs of 12VDC (or 24VDC). Perfect! Amazon says $20 now…but it was $26 when I bought it (d’oh!)

I also got a terminal mount for it, so I could easily mount it in the car:




 So, for about $40 I’d be good to go! I got them, tested it, mounted it in the car, and the car’s controller still worked when I was doing this switch. I was afraid the controller might pre-charge on key-on *BEFORE* the relay kicked power to it, but it seems to work okay.

And, now it works at the charging station without having to unplug the main battery pack. Excellent!


Adventures in Solo Camping: Desolation Wilderness, Lake Tahoe

I got really excited about an upcoming backpacking trip in Desolation Wilderness with Costanza and some friends, and decided to jump the gun and do a solo trip by myself a bit earlier. I drove my electric car up to Tahoe from Santa Cruz and decided to do some backpacking into Susie Lake. Even though I love the outdoors, and love camping, I had never actually been backpacking where you hike in with all your stuff and setup your own campsite. I also don’t have a proper backpacking backpack, so I sewed on some straps to my travel backpack to turn it into one:

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This worked reasonably well, but I would love to get a real one like any one of these Osprey Backpacks.

I got a $5 overnight permit into Desolation Wilderness from the ranger station off of Highway 60. It was a Sunday night, so it was easy to get whatever location I wanted. I got a permit for the Susie Lake area, because I heard it had good fishing, and I had just got my fishing license in the mail the day before. I entered at Glen Alpine trailhead, at the end of Fallen Leaf Lake, seen at the middle right side of the picture below (blue arrow):


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The 4’ish miles to Susie Lake went very fast; about 1.5 hours. I am not much of a hiker, and I was pleased that I could do it in a fairly quick time. I setup a camp by the lake in a nice little spot:

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I didn’t bring a sleeping pad, but I brought my extra warm sleeping bag. In hindsight, I would have rather had my summer bag and a sleeping pad (although, I don’t have a small enough one to take backpacking yet!).

After setting up camp, I walked around the right/north side of the lake doing some fishing with a lure. I didn’t catch anything; not a bite or nibble, but it was fun exploring. I saw one other person fishing who had walked around the lake and also didn’t get anything. It was really windy out, and too early in the day at about 3pm.

I headed back to camp and ate some light dinner. I decided to toss my line back in, and ended up getting a really nice sized brown trout!

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The picture doesn’t do it justice; it was big! I fried it up and at most of it, but my pan and frying technique was terrible, and it didn’t cook the top part all the way through. I’m a firm believer of understanding where your food comes from and understanding the aspects of eating meat, and catching your own food is a great way of really understanding the whole process.

Here’s a selfie pic:

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and the view I was looking at:

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So gorgeous! 

Unfortunately, the wind never let up. It was so windy all night, and every gust would jostle the tent and wake me up. I hardly slept at all, and work up extra early. I ate breakfast, hiked around a bit more, and then did an early hike out, getting back to the trailhead and my car around 10AM.

It was an awesome short adventure.

(c) 2008-2015 Corbin Dunn

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