Archive for May, 2011

…with Girlventures!

The Elithion Lithiumate BMS uses a serial cable to talk to the computer. That’s kind of a pain to see additional information that the SOC display doesn’t tell me. It is also nice to see how the batteries are doing “on the fly”, or when I’m charging at work.

I bought a WiSnap and made a little case for it:

The red/black cord is for a 9v power supply, but it doesn’t need it as it can get its power from the RS-232 input. I can now connect to an adhoc Wifi network with my iPhone (dubbed “PlugBugBMS”) and see all the serial data from the BMS controller. Pretty cool!

I still want a better display, and eventually I want some easy software that displays cool battery status in a nice graphical package. I thought the serial port might be good to do it, but it won’t work. I need to tap the CAN bus line and somehow emit the data to my phone. Bluetooth would work, but the bluetooth connection kit (and SDK) for the iPhone is not free. I’m also not sure if the iPhone can connect to more than one bluetooth device, and I really want it to always connect to my hands free headset and car stereo. Now…only if that bluetooth device could tap into the CAN bus and report additional packets of information to a custom app on the iPhone…

I got my charger back from Manzanita last thursday and put it in the car Friday night. They weren’t sure why it busted, but the bridge rectifier had to be replaced, and they did some general tune ups. Unfortunately, it was out of warranty, so I had to pay out of pocket for it. But oh well…I’m still saving money on gas!

Here’s a picture of my charger’s bracket to allow me to mount it horizontally:

I also got my Belktronix DC-DC converter to replace my ailing IOTA DLS-55. Good news from IOTA is that they are taking the issues I brought up to heart, and apparently now have a prototype IOTA DLS-55 that is ruggedized and specialized for EV use! Cool! Evolve Electrics is helping them test it out.

Here’s the new DC-DC converter (the big hunk of aluminum):

No fans, so the car is now dead silent again. Yes!

Some other mods an recent issues. My brakes started leaking and went soft one day. The rear line I installed was rubbing against this member and got a small hole that let it leak out:

I replaced it and bent it better.

I had moved the radiator underneath and inline with the car, and covered it by some white screen to protect it:

It didn’t seem to cool the controller quite enough, so I moved it directly into the flow of the air. This involved some new pipes:

A new bracket:

And mounted:

The fans are still on it, but I may not need them anymore. They are still controlled by a temp switch:

A cool picture from my trip to Madagascar in 2009.

Lemur Eating

I now have over 3000 miles on my car. Up till today, the only problems I have had have been with the IOTA DC-DC Converter. I’m supposed to have a replacement soon, as my IOTA may fail again at any moment.

Now that I have some driving experience, I have a better idea of the range. It’s not good to say that an electric car gets X mile range, since X various by many factors. Those factors are: how heavy you are with the pedal to accelerate, how hard and often you brake, how many hills you drive up and how fast you drive. I have one big hill on my commute (or, when I go *anywhere*), so I can never remove that factor, and I always want to drive at least the speed limit. But I can control how “soft” I drive.

If I drive the car “soft”, meaning reasonable acceleration and driving at the speed limits on the freeway (usually 65 mph), I could get a 100 mile range to 0% State of Charge (SOC). Last Sunday I drove 64 miles according to my odometer (or, about 62 miles according to google maps). The BMS said it took 122.3 Amp-hours and the SOC was at 39%. This drive was mostly at 65mph, aside from the 2 miles driving up my “driveway”, and then going 50-55 up and down highway 17. I had maybe one stop light each way on my trip. 122.3Ah * 48 (number of cells) * 3.2V (nominal voltage per cell) = 18785 Watt-hours (18.8kW). 18785.28Wh / 64 miles = 294 Watt-hours per mile. The batteries are rated at 200Ah. So: 200Ah*48*3.2 = 30720 Watt-hours of energy in the battery. 30720Wh / 294Wh/mile = 104.5 miles.

So, a good “soft driving” estimate for my bug, including a large hill and mostly 65 MPH on the freeway, is 104 miles. Generally, I don’t want to do this, as taking the battery lower than 20% is not good for cycle life. I also don’t have my BMS setup to limit power when voltage drops to a certain level, so it is dangerous (meaning, I could cause damage to expensive cells).

If you are doing a bug conversion, use about 300 Wh/mile as an estimate for what you can get. I rarely get better Wh/mile, but that is because of my huge hill I drive up. Wh/mile would be better if I didn’t live in the Santa Cruz mountains.

Now, if I drive “harder” I can get about 375 Wh/mile. That’s about an 82 mile range. So, I can probably safely say my range is from 70 to 100 miles per charge, but I probably won’t want to go more than 80 miles to keep it “on the safe side”.

Today when I went to grab my car at lunch I discovered that the Manzanita Micro PFC-30 charger wasn’t charging. I looked at it, and the BMS (Battery Management System) also wasn’t on. The BMS is turned on along with the charger when I plug it into an outlet. So, I realized the 50 amp / 240VAC circuit breaker must have tripped. I plugged the car into another nearby 50 amp circuit, since I couldn’t reset the breaker and there was another charging station right next to where I was. The BMS came on, but the charger wasn’t charging. It also had flipped its little breaker on the charger (also known as the power switch), so I flipped it back on, and it went “pop” as it immediately flipped back off . It also tripped the 50 amp main breaker on that outlet too. Ah, bummer!

So I emailed Evolve Electrics and Justin is having me mail the charger back to Manzanita. I have followed the instructions to the T, so I’m hoping it is covered by warranty. I’m also quite curious as to what is wrong, since I’ve charged the same way nearly every day.

I also took a look at the BMS stats; 812 kWh have been put into the battery pack. I think the BMS got reset once when I had it upgraded.

Hopefully I remember how to pump gas!

Yesterday I drove a 6 hour round trip drive to do a unicycle criterium (crit) race in Auburn, CA. It was the first time I’ve had to pump gas in several months, but it was worth it!

The Auburn Journal did a nice write up and took this cool picture of us starting:

From left to right: me (Corbin Dunn), Stephen, Tom Holub, Nathan Hoover, John Foss, Robert, Wiley, Jim and Austin (the last three are sort of hidden in the back).

There is also a thread on the unicyclist forums about it.

I got first, which was cool, but I also really enjoyed the race. It was the third crit I have done; the first was during “Ride the Lobster” a few years ago in Canada. The second was last year at UGames in San Francisco. Both of those crits were on flat ground around a block and just making right turns. This one in Auburn was a blast because it had an uphill, a flat section, a steep downhill into a left turn, and the usual right turns. It was nice to have the variety and I really enjoyed it.

Robert Allen’s daughter also snapped a picture of me cruising by on one of the laps:

Afterwards, we did a 10 mile “coker muni” ride that really wore me out. I’m somewhat out of shape for sustained distance riding, and the hills tired me out. But it was really fun blasting down the single track in high gear.

The next event coming up is Strawberry Fields Forever — a casual rode rode of 100km. I hope I’m in shape enough to do it….after the 13 miles of riding yesterday (10 + the 3 mile crit), I was dying.