6. DC to DC converter
1200 Watt converter as delivered:
This unit converts the 700 VDC battery pack output down to the 12 Volt level to maintain the charge in the existing automotive power system just as the alternator did with the original gas engine.
Being electronic, it will allow using lights and accessories independantly from driving, because it is always connected to the power source (as are all other functions, i.e. heating, cooling etc.)
I had originally planned to thermally mate this heat sink directly to the face of the water cooled charger to allow sharing the liquid cooling resource, but this was too much volume to fit the unused 12V battery location under the hood along with the charger. This would have removed the need for the electric fan.
Therefore, it will go here in the trunk, above the 12V battery, which it is connected to.
I will now have to run traction pack HV power outsite the motor compartment, somthing I was trying to avoid. This means I will simply have to protect the wires very well, such as in a conduit pipe and careful routing to minimize possible hazzards to rescue crews in the event of an accident.
Update Jan 26, 2010
The BMW engineers were thinking of me again, as luck would have it; The two studs you see holding the electrical box were just there, waiting for a use, exactly where needed.
The extra pass through grommets are for future aux battery pack/range extender I/O
This is the finished mount (yes, it is really mounted and has simple access to 12 V battery):
This is the only EV component that will be visible in the BMW Interior/trunk zones.
