BMW 3.0 CSE

Picking up from " Danger Low Voltage! ".... After the batteries drained while sitting I decided to make some improvements to the battery box.  The acrylic see-through top was neat but it was unnecessary to see through the sides of the " aquarium " and the acrylic panels weren't very strong and cracked easily so I decided to change to aluminum everywhere except the top.  

Almost all of the EV conversion work is now done.  A few of the things recently taken care of: On the test drive the brake pedal went to the floor.  This was because the pedal itself rotated on the pivot point.  I thought it was secured at the factory and all pivoting happened at the pivot tube but I was wrong so had to TIG weld the pedal to the pivot.

I've successfully transplanted all the components from the donor Tesla Model S into my 1973 BMW 3.0 CS coupe.  The last organs to be inserted were the 10 battery modules up front.  Now, all 14 batteries are in place, the motor, inverter, and differential unit is installed, the iBooster is operational, and even the Tesla electric air conditioning compressor is in place.

Building a box to hold batteries sounds so simple.  It isn't. The batteries have been in and out of my front box many times now.  The latest reasons for disassembly were to relocate the BMS and plate the buss bars .  While plating, we decided to do the buss bars in Paul's car also since the battery box is out of the car while the car is being painted. My box on the left, Paul's on the right It is interesting to see the two approaches to battery fitment side by side.  Figuring out how to get 14 Tesla Model S battery modules fitted into a car designed for a gas engine and transmission is always the most difficult part of the EV conversion process.  The big rectangular batteries just don't want to fit into the curvy voids of a normal car body.

Hoses and brake lines are a challenge on this Frankenstein project.   Brake lines a combination of metric DIN bubble flares and ISO imperial double flares, with a super odd metric double flare on the Tesla master cylinder.  Plus, the original ATW front calipers have two redundant circuits so the original master had 5 ports.  The Tesla iBooster only has two.  And the original rear-mounted proportioning valve isn't practical with this new setup.

Recall from the post on fitting the Tesla batteries, the cells are made of a nickel cobalt manganese aluminum oxide cathode with a graphite silicon anode.  The cathode chemistry of these cells is such that gives off free oxygen at a fairly low thermal temperature of perhaps 180C - very low by lithium battery standards.