Front brakes

Old car stuff.  I knew the front brake calipers were from a ‘75-‘83 BMW 320i, and the brake lines were for a 2002tii booster, but I didn’t know the hubs were from a BMW 2002 standard. I replaced the rotors, one of them had warped.

Brake job

I was driving my friend home when the brake pedal went to the floor.  Where did the brake fluid go?  A failed slave cylinder.

Instrumentation

For four and a half years I've been operating without any battery instrumentation.  Professionally I work in the field of battery charge estimation, algorithms that decide whether to light 1 LED or 5 LEDs.  My cousin recently gave me a ride in his Tesla Model S and pointed out the irony to my lack of battery charge gauging.  I simply make sure I don't drive more than 40~50 miles on a charge.

When in a pinch I have read the voltage of a single cell with a voltmeter to get an idea, when fully relaxed these voltages are directly related to state of charge.

I've run out of charge only 2 times so far.  One time because I forgot to charge the night before.  And the other time is still a bit of a mystery.  I thought it was perhaps due to running the air conditioning over lunch break but that would not account for how much charge I lacked to get home.  Both times I simply called AAA and was done.

There is a communication port on my battery management system and I've used it for diagnosis using a laptop and to log data using an iPhone.  The iPhone was really too small to be practical and was abandoned.  My family recently upgraded from an old iPad to a Kindle Fire and I've adopted the iPad with cracked screen to up my game.

As a security feature it hides nicely under the passenger seat.  With this I can monitor and log voltages, temperatures, and current.  The app I'm using is called Get Console and is basically a HyperTerminal for iPhones.  I hope to do some more data collection and efficiency calcs soon!

flex disc

This is the 2nd flex disc this car has eaten.  What seems to happen is a few bolts work their way loose creating vibration that tears cracks into the rubber.  This is a piece that goes between the transmission and the drive shaft.

This time I'm using lock nuts.  While we're under here here are some new steer components required to fix a bad alignment that was starting to show on one of the tires.

The underside of this car is interesting to study.  The drivers side appears to have bottomed out severely at some point.  The floor pan is repaired with rivets and tar.  The drivers carpet gets wet when in the rain.

Finally, a shot of the power cables where they cross the drive shaft on their way to the trunk.

4 year aniversary

This post marks the end of my 4th year driving electric.  19810 miles total. 

repair ac again..

Repair ac again.  It is getting hot this summer so I had a local shop repair my air conditioning again and it is now blowing cold.  They reported to have found and fixed some leaks.  Windows up!

I tape this sign to my non-standard AC controls to help the mechanics.  

reflections

If I did this again I think I would use a higher nominal voltage, maybe 144V.  I chose 96V because I already had a motor controller for 96V (quickly fried it) and a charger (just replaced).  However, 96V is sluggish to provide current and I often need to upshift for acceleration.  I certainly would want a higher nominal voltage if I did not have the 5-speed transmission.  4th gear only gets me to ~55mph floored, less when uphill.  DC motor speed is dictated by voltage and power is dictated by current, but when you have the full voltage applied to the motor you're not going to get any more current.  So you have to upshift to lower the motor speed.  96V does provide a nice safety feature though, the shock is less painful.