The Tesla Model S battery system in my car consists of 14 individual modules
(a real model S usually has 16). Each are 27 by 11.5 by 3.5 inches in
dimension and weigh 55.8 pounds. They consist of 444 individual 18650 battery
cells with 74 cells in each voltage cell and six of these voltage cells in
series.
|
|
A single Tesla Model S battery module (444 batteries arranged into six
74 battery "cells" in series)
|
The battery cells are most likely Panasonic NCR18650BE cells or close
equivalent of nominally 3200 mAh capacity and 3.6vdc. These cells consist of a
nickel cobalt manganese aluminum oxide cathode and a graphite silicon anode.
This gives the module a 74 x 3.2Ah or 237 Ah capacity at the nominal voltage of
3.6v for a total power storage capacity of 5115 watt hours and a module nominal
voltage of 21.6 volts. These modules are designed to produce up to 1155
amperes of current for brief periods. With 14 modules, the result
is 71.6 kWh of energy storage -- enough for over 200 miles of range.
|
|
Individual nickel cobalt manganese aluminum oxide cathode batteries used
in a Tesla battery module, each providing about 3.6v DC and 3.2
Ah.
|
Finding room for 14 Tesla Model S battery modules in a smallish old BMW is no
small feat. You'd think that with the gas engine and transmission out of
the engine compartment there'd be plenty of room up there but the size of
these modules makes them difficult to place.
|
|
Each module is roughly 27" x 12" x 3"
|
Originally, I was hoping to keep the original brake master cylinder location
in the engine compartment, replace the large stock booster with a smaller
hydroboost unit, and fit batteries around it. But there just isn't
enough room. That meant loping off the brake mounting tube from the
steering column mount in order to free up some space. Again, no going
back now.
|
|
Testing fitment with foam batteries. Eventually, the brake booster mount
and 12v battery tray will need to be removed.
|
I took the foam packing from the batteries and fashioned them into blocks the
exact size and height of a battery module and played around with how to fit
them physically into the engine compartment.
Once I had a plan for what would work, I moved over to CAD and drew up a
battery box that holds 10 modules, 2 low in the middle where the oil pan would
normally be, 4 on the passenger side, 3 on the driver's side (working around
the steering gearbox), and finally one crossways on the top rear where it will
clear the closed hood.
|
|
Battery layout in simple CAD
|
That means 4 more modules need to go in the back of the car. But Tyler
immediately started in on the front battery box and it all worked out as
planned.
|
|
Battery box under construction. The original 12v battery tray had
to give up its life for the cause.
|
|
|
Test fitting the top battery
|
|
|
Proof that 10 modules fit. This is the electrical end of the
modules
|
|
|
This is the end with the cooling ports
|
|
|
Coming together, now with lifting points. I tried to fit the
original radiator but it is too tight.
|
|
|
The steering knuckle clears, just.
|
