Monday, January 19, 2009


One of my Christmas gifts was a shiny new ammeter. I already have the voltmeter, motor temperature gauge, and overheat warning installed in the dashboard, so this may be the last gauge I have installed. Some EV converters also use a state of charge gauge, but I'm going to see if the voltmeter alone will suffice.

The left and center dashboard are pretty tight on space, but the right side has plenty of room. One issue though is the metal support behind the wood. Luckily there is already a perfectly sized hole in a great location.

I held the wooden dashboard back in place and traced the hole on the back. It looks like the last mechanic to pull the dashboard apart was patriotic.

I then used a 2 1/8" bit to drill a hole for the ammeter.

Very nice. I also had to trim the light plug and mounting bracket for the gauge.

And the final product with all the electric vehicle gauges in view!

I sat in the driver's seat to check visibility. The "0" and "100" are blocked, but the graduated marks are very legible. Ideally the gauge would have been a couple more inches to the left, but it works just fine where it's at.

Saturday, January 17, 2009

Motor Mount Pt. 2

Today I finished mounting the motor in the car! Using the wood template built a couple weeks ago, I traced out the design on a 3/8" aluminum plate.

Looks pretty good. I then took a small flat head screwdriver to etch my lines in the plate just in case they are wiped away from the WD-40 (learning from past experience...).

I went to Home Depot to pick up a fresh set of jigsaw blades. This time I bought the coarser blades, and wow, what a difference. It was like night and day cutting with the beefier blade, but it still made a nice clean cut. Don't get the super fine blades; they aren't necessary, but they are very slow.

Drilling the mounting holes...

And the finished motor mount!

Mounted in the car...

Good clearance between the bottom of the motor and the steel frame. It's difficult to see in the pictures, but I wanted to make sure the bottom-forward electrical connection of the motor was not touching the frame of the car. I'm not sure how critical it is to keep them separated, but I don't have any desire to pump 120V 400 Amp anywhere near the car's 12V.

Overall I'm pretty happy with the motor mount. The bottom left mounting hole unfortunately had to be notched for the bolt. Fairly surprising that there was such a significant discrepancy between the design from 2 weeks ago and how it actually fit in the car. I think the 3/8" aluminum plate should be sufficient for the torque from the motor but only time will tell. I won't be drag racing anyone so I'm not too worried.

Sunday, January 11, 2009

Parts On Order / Precharge

No mechanical work on the car to update on, but I have been finalizing electrical components and making orders.

My controller will be the ElectroCraft EVMTC60-192V 400 Amp. Estimated delivery is 5-6 weeks. The company isn't well known in the EV community, but they've been very responsive to my questions, offer a 1 year warranty, and have a great price. I've decided to try them out as opposed to established older designs that get more expensive by the month or other newcomers that have serious questions in reliability. Also, this controller has built in over-speed protection (when in neutral) and should easily handle a fully charged Lithium Phosphate battery pack.

For Christmas I got a second contactor (with auxilary connection for status light)...


and novelty horn. The car's nickname is Bumblebee, so I'll have to record the Transformers theme song into the novelty horn to play at car shows. :-)

I also ordered a few other components. A 400 amp fuse with holder (which is huge by the way)...

and a precharge resistor (1k Ohm, 50W)...

Taken from the website... "The PWM motor controllers common in EVs have a sizable bank of capacitors on their input. When you apply a Voltage across a capacitor it initially appears to be a short-circuit, that is, the Voltage across the capacitor is zero. If there is very little resistance in the circuit, e.g. a closing contactor with no precharge, then the current will be very high. Nearly all of the traction pack voltage will be across the closing contacts. The large Voltage difference and sudden high current (known as an inrush current) can cause damage to, and in extreme cases, welding of the relay contacts. Also of concern to some is the stress on the controllers electrical components caused by the inrush current. This can all be prevented by the use of a precharge resistor across the contacts of the main power relay. The precharge resistor allows the capacitors in the controller to slowly charge BEFORE the contactor closes. This means that there is less voltage across the closing contacts and little or no inrush current."

I'll use 2 contactors with my setup. The first contactor will be triggered closed by turning the key to "on". The second contactor will be triggered closed by the key "on" and by pressing the foot pedal. The precharge resistor will be across the terminals of the second contactor. After I turn the key to on, the precharge for the capacitors will begin. Then all I need to do is wait a few seconds before hitting the gas (as most people do anyways) to let the controller slowly charge up. Another option is to have a delay timer to wait a few seconds to charge before the car will go - I'll decide later on if I want to go that route.

My wiring diagram is basically done, but I think I'll wait until I get the controller and all the smaller components in before I post it. Little things may change until everything is in my hands.

Friday, January 2, 2009

Motor Mount Pt. 1

Christmas / New Year's break is definitely nice for working on a project! 3 updates in 3 days!

Luke and I installed the motor for (hopefully) the last time this morning. We covered the coupler and shafts in CV boot grease (not ideal, but acceptable - it's what I had lying around) before bolting everything together.

Now it's time to get this motor mounted as opposed to just resting on the car's frame. I stared under the hood for a good hour with a pen, piece of paper, and ruler trying to get dimensions for the mount.

Building a prototype adaptor plate out of wood was so helpful I decided to do the same with the motor mount. It takes seconds to cut a piece of 1/2" MDF board; it takes minutes to do the same with aluminum.

I test fit / trimmed with jig saw / test fit / drilled hole / test fit / etc. several times to find a good shape.

I'm pretty happy with the final design, although I will be adding an extra 1" strip along the top to attach the controller/electronics base to. Pay no attention to the multiple holes drilled right next to each other - that's why it's called a prototype! :-)

When speedymetals opens on Monday I'll put in my 3/8" aluminum plate order!

Thursday, January 1, 2009

Motor Coupler Pt. 3

Despite the coupler being inside the car for only a month, the steel surface developed quite a bit of rust. It was always the intention to take out the coupler and apply a protective coating, but I wasn't expecting just how fast the rust would form... (Especially in Phoenix!)

Taking apart the coupler...

I used Rust Dissolver jelly to clean up the parts.

Once all the rust was removed, I applied several coats of Rust Inhibitor onto all the metal surfaces.

The pieces look shiny and new once again!

Similar to the adaptor plate, the coupler is held together via a lock washer, a regular washer, and threadlock fluid.

I'm aiming to get it back in the car tomorrow!