Sunday, November 23, 2008

Batteries ordered

After months of debating which batteries to buy the deed is done and there is no going back. I originally started this build with the idea of using the typical LA(Lead Acid) battery as the power source. After doing the math and seeing what other EVs range seemed to be it didn't seem LA could really get the range I was looking for, at least not without making my car weigh in a 4,000 lbs. I ordered 45 of the ThunderSky LFP-160Ah modules at $264 a pop, not cheap. On top of that the charger and BMS system added another $3,000. The full setup was ordered from Elite Power Solutions.

The amount of money up front for this setup is scary but after doing the math the investment should be well worth it in the long run. First off I can get about four times the capacity out of them as LA pound for pound. The setup I ordered will add 550 lbs. of lithium to the car which should keep the overall weight of the build at or maybe slightly below the original weight. This compared to most EV conversions needing the suspension beefed up to support the extra weight. Lighter will also mean faster acceleration than with the LA and also less power required to accelerate.

A standard LA battery last around 200 charges. Some of the higher end cells can go as much as 400 cycles. Cycle life of the lithium cells start at 1000 and go as high as 3000 cycles for 70% DOD. If I used flooded LA and got 200 cycles out of them I would still break even if I only got 800 cycles out of the lithium cells so I shouldn't have any trouble getting my moneys worth if the cells hold up....we'll see.

Hurry up and wait. So now that I finally committed to this purchase I get to wait for 5 to 9 weeks for them to arrive. UGH. I'll take this time to work on the electric systems of the car and hopefully have things ready to go when the cells arrive.

Sunday, November 16, 2008

12v Test Video

It's just too cool to see the car moving that words can't describe. I got my neighbor to video as I backed it out of my driveway up the street a bit and then back in. I edited the video to shorten it up since at 12volts it wasn't moving very fast if there was much of an incline.


video

Sunday, November 9, 2008

Installing the motor

After taking a nice vacation to Oregon for some quad riding in the dunes and getting over a nasty cold I was finally able to get back to the project. First I needed to hoist the motor and transmission down into the car so I could start measuring things and figuring out how to build the motor mount. I knew this would be a two man job even with the hoist so I grabbed my neighbor again for some help. The top center bolt of the adapter plate to transmission turned out to be perfectly balanced for the setup.

Here is another closer shot to show what we have to work with. You can see the original two motor mounts that we need to eventually tie into. Still plenty of room in here for other things later such as batteries.

Here is a top down view just to show another angle. My neighbor had a good idea of using this strap to support the motor weight so the car could easily be moved around if needed.

A quick note about the rotation of the motor. It turns out that all Honda engines do not rotate counter clockwise like I read. At least the S2000 rotates clockwise. This effects where the front motor mount holes need to be so make sure your motor is setup correctly before making your motor mount.

Let the work begin. Here I am making my first cut of the project.

Here is one of the brackets made to set against the adapter plate and utilize those bolts to build a frame around the motor. A plasma cutter makes these custom corners a breeze. The metal used here was 3/16" x 3" flat bar.

That same mount shown in place.
Next I welded 1/4" x 1 1/2" angle to the plate.
I made another plate for the other side of the motor. These couldn't set at the same level on this side and are slightly higher overall because the closest bolt to the center is below the angle iron in this shot and can't be seen.
Here is the finished support frame. The front bracket was also 3/16" x 3" flat. The center was notched out for the secondary output shaft of the motor. The two ears were added to bolt to the front of the motor. We'll see how all this fits a bit later.
Finally on the frame assembly two holes have been drilled on each side to mount the brackets that attach to the old motor mounts. These must be bolted on and NOT welded because the motor mount bolts are at an angle and the motor will not drop in properly if it's all welded together.
Here is one of the two motor mount adapters. It's hard to see here but there is a bend to metal to transmission from the angle of the motor mounts to the level frame support. The larger center hole on the left is a 1/2" hole and existing motor mount bolt goes here. The slightly offset hole from there is an alignment hole where the motor mount has a tab sticking up. The two smaller holes are for the mounting to the frame support. I used 3/8" bolts here and drilled the holes one size up from there. The most important feature of these adapters is the small strips of metal on each side. They create a triangular shape and add a great amount of support against the weight that will be pushing down on them.
Here is a quick shot of the whole assembly before we take it out for paint. It's much easier to the angle of the mount adapters in this shot. At this point I've probably installed and removed pieces of this a dozen times as the measurements were made and it was all built.

Here is the whole assembly again after a primer, two coats of semi flat black and one coat of clear.

Here is a shot from the back side of the assembly.

Here are those two ears I was talking about earlier. These are the only two spots on the motor. Depending on how you build your plate and fasten it to the motor these two bolts could end up anywhere. You do have the option of rotating them in 90 degree increments though by rotating the motor on the adapter plate. I didn't feel like taking everything back apart and didn't see much benefit from a rotation so I worked with what I had.
Here we have the completed and installed motor mount from the right side of the car. The largest bolt on the plate connecting to the adapter plate originally called for 47 foot pounds and that was reused here. The motor mount nuts were torqued to original spec of 40 lb/ft and the newly added 3/8" bolts were torqued to 35 lb/ft.

Here is a shot from the right side of the car. You can see here that bolt is just below the angle iron and a tight fit. Make sure you give yourself enough clearance to get a socket in there. Also I mentioned earlier this side had to set slightly higher. You can't really see it here but I crafted two 1/4" x 1" x 3" spacers to set between the frame and the mount adapters to make up the 1/2" difference.
Here is a shot of the entire assembly installed.
With this done I finished installing a few last things on the transmission (shifter, console, etc). Next I jacked up the rear of the car and put the transmission into 1st gear. I then tried the old 12 volt test again and the back wheels started spinning forward. Make sure to keep an ear out for any strange noises or vibrations. Things should be fairly quiet or something is wrong.
So then I couldn't resist. I lowered the rear of the car and ran the motor again. I was amazed at the torque from only 12v. The car immediately lunged forward and begin moving fairly quickly. I'm pretty excited at this point as things are slowly falling into place.