Saturday, September 3, 2011

Metal Work

Cleaning up one of my
uglier welds
New Toys
One of the great things about new projects is the opportunity to acquire new tools. One of the first things I did before starting the actual project was to install an air compressor for the garage.  I got lucky here and picked up a used industrial compressor for less than $100.  The impact wrench, cutoff tool, and die grinder I got cost way more than the compressor.  In fact, the material to install the compressor (had to run a new 220v line in the garage) was more than the compressor.  So now I have air in the garage!  I also added some other tools including a 4" grinder, essential for the metal work I've been doing.  I also borrowed to important tools from friend, a MIG wire welder and a chop saw.  I would be nice to have more metal working tools, like a drill press, band saw, etc. but I don't really have the room for them in my garage.

Motor Mount
My simple motor mount
The first order of business was to create a motor mount to hold the front of the motor in place.  Initially I thought I was going to have to fabricate a rather complicated bracket that attached the new electric motor to the existing motor mounts.  However, after dropping the new motor in place, I discovered the mounts for the steering arms were in an ideal location just in front of the motor on either frame rail.  All I had to do was make plates to match the existing bolt pattern for the steering arms and then weld an angle between them and drill holes for the bolts to the motor itself.  This worked out really nicely.

Battery Boxes
Battery "box" before installation
After some considerable thought and discussions with a number of other folks who had done EV conversions, I decided I didn't really need boxes for my batteries, just racks to hold the.  The plastic shells of the batteries are really robust, and I saved weight by just using steel angles to form the frames. The image at the right shows a typical box before it was installed in the vehicle.  The bottom is 1"x1" steel angle and the top is 1/2"x1/2" angle.  Threaded rods are used to bolt the top to the bottom holding the batteries in place.  Along the sides of the box are aluminum channels (2"x1") which are connected by additional threaded rods.  These channels are used to compress the batteries.  One characteristic of the lithium batteries is they can swell when they get hot.  The swellings causes the plates inside the battery to separate and this quickly ruins the batteries.  Therefor, some way of compressing the batteries is essential.  A lot of folks use steel or aluminum plates with tie rods.  I chose the channels because they were easy to cut and the channels are stiffer than a flat plate with much less aluminum.

Bracket fabricated to attach battery
box to the truck frame
Getting the boxes mounted in the vehicle took a good deal of creativity and and a lot of work.  The basic technique was to create brackets from additional steel angle and attach the brackets to the boxes and the truck's frame.  The brackets were welded to the boxes, but I tried as much as possible to avoid welding on the frame.  Since I'm not a very good welder, I didn't want to screw up the frame with a crappy weld.  The image at the left shows the used to attach one of the boxes to the truck frame.  In this case I was able to attach the bracket to an existing set of bolt holes originally used to hold the gas tank in place.  I was often able to use existing holes as bolt locations for the brackets.  In other cases I had to drill new holes in the frame and in two cases I had to weld tabs onto the frame. Once I got the technique down, things went steadily (if a bit slowly).  The final configuration is shown below.  There are 29 batteries in the back of the truck in three separate banks of 12, 12 and 5 batteries each, plus one bank of 7 batteries up front under the hood.
Three rear battery banks

Front battery bank and motor

The next step is to design the layout of all the electrical equipment that goes under the hood.  I'll need to fabricate a box to hold the motor controller and associated gear and figure out a way to attach that under the hood.  Then will come the serious wiring work.


  1. Is your transmission mounted with a mount that includes one or more rubber isolators? If so, the fact that the transmission can move around on that rubber, but the hard-mounted motor end cannot is going to put some unpleasant stresses on the motor housing.

  2. Thanks for the observation, Too Many Parts. I've designed a modification that will solve this problem. Will post it when I get it done.