Pack assembly

Right now I am grouping the cells together.  I was able to balance the capacities within ±0.15ah which is probably withing the uncertainty of my testing.

The most time consuming thing is peeling off all the stickers and getting all the pressure sensitive adhesive off.  PSA is not known for it's high conductivity.  :) So I get to sit in front of the TV with rag and some rubbing alcohol.

For making my connections I was able to modify a 3 hole punch with a simple MDF block to make all the holes in the tabs.

Works well but I might put a better spring in the punches because they often get stuck and I have to wiggle the cell to get it back out.

While I was away UPS left some presents

While I was away working in Spain for 2 weeks the UPS driver left a few boxes on my doorstep.  So after unpacking the bags it was time to unpack the new toys:

The first is the EMW EV Android Dashboard.

http://www.emotorwerks.com/emw3/product/ev-dashboard-by-emw-basic-edition/

It measures the current flowing from the pack to the controller in order to estimate the state of charge (SOC) of the battery cells.  Unlike other batter chemistries you cannot estimate SOC from the voltage.  Lithium has a very flat voltage curve from 10-90%.  Great for performance but it's hard to know how many electrons you still have in the tank.  This uses a hall effect sensor to measure the current flow.  It is designed to work with a android device so I was able to get a good deal on a new Toshiba 10.1 thrive tablet.   It has bluetooth to communicate with the current sensor and a GPS chip for navigation and a nice bright screen. It's not the best tablet in general because it's a little bulky and not the most robust case.  But none of that matters for me as I am mounting it in the center dash.

One other cool feature is that there is an output on the Bluetooth unit so it will drive the stock fuel gauge too. 

I need to play with it more but it doesn't seem to work in landscape mode. Hopefully this is something that I haven't figured out yet or will get added soon.  The other thing is that I wish the gauges were more adjustable as far as ranges and it would be really nice to add the option for warning lights (for high batt temp, SOC < 10% etc).  It seems like this would be easy to add but I have only used a android device for 15 minutes....

The second item was my BMS system:

I went with Lithiumate Lite, EV Li-Ion Battery Management System (BMS).

http://elithion.com/lithiumate_lite_overview.php

It monitors each cell group (in my case 3 cells in parallel) and make sure that the cell doesn't get over charged or over discharged.  I went back and forth on needing a BMS and I think bottom balancing a pack that has had the capacity matched would be fine.  But this is my first time with lithium and wanted the "insurance" of the BMS.  I knew I at least wanted monitoring of all of my gray market A123 cells and going to a full blown management system wasn't anymore expensive with the Lithiumate Lite.  Also on the bright side, not only are they made in the US, they are made here in Colorado!

To be honest having the EMW dash and the Lithiumate is redundant but I wanted to try out both and see how they compared.

Odds and ends

I have been so bad about positing updates I missed a few things and wanted to get it caught up.  This first is a minor change to depowering the rack.  When went looking for ARP flywheel bolts I found  http://www.miataroadster.com/ had the best price.  I ordered them but of course I didn't end up using them because of the thread issue on the adapter.    On the plus side when I ordered from Bill he was interested in my project read the blog and sent me a free set of rack depower plugs!

They are just block off plugs, but the custom aluminum plugs sure look nicer then my hack.

I am looking at a roll bar and noticed that Bill carries the Boss Frog MAXX double hoop roll bar:

http://www.miataroadster.com/boss_frog/boss_frog_roll_bars_doublehoop_retro_style_with_individual_hoops_behind_seats/bfmdsrx/i-411853.aspx

I was originally planning on building my own but these are bolt in bars that are FIA and SCCA legal.  All the other double hoop bars are not FIA or SCCA rated and mostly for looks but I want something that looks good and works to protect me (crazy thought).  The price is reasonable but I am still going back and forth on building my own.

I mounted my vacuum pump right below the brake master cylinder.  I am going to forgo a reservoir for now and to a few tests to see if I think it is okay.

I also wanted to say that these Dewalt pilot point drill bits rock!  I usually try to go "Made in the USA" for everything but German made cutting tools are pretty much impossible to beat.

On that note, I thought it would be interesting to point out that 100% of all the components, parts, fasteners, etc that I have bought for this conversion were made in the USA.  EVERYTHING.  A great point to bring up when people doubt green tech's benefit the american economy.

It is ALIVE!

Well after triple checking everything I decided it was time to make the wheels spin.  The controller was all wired up but I still have to put my A123 pack together.  Luckily I happened to have a few old 24V SLA batteries literally lying around.  So I threw a battery in the the passenger seat and hooked up my jumper cables and slowly drove it out the garage!  :)

One battery was enough to make it move but not much more then that.  So I grabbed a few more batteries out of the backyard and whipped up a quick 96VDC pack.

I drove the car up and down the drive and slowly upped the limits for the motor voltage (120V) and current until I was spinning the rear wheels on the gravel.   Finally the fun ended when I got on the go pedal and the car lurched to a stop with a faint wiff of acrid spoke!!!!  My first concern was that I done something to the Soliton1 but I should have known better.  A quick check showed one of the batteries had shorted internally, the second battery my Soliton1 has sent to it's grave.  Not  too surprising considering they are 6 year old mistreated lead acid batteries.  I simply moved the jumper cables over and drove the car into the garage under 72VDC.

Controller Mounted

Well progress has been slow but steady and I am way past due for an update.  I have gone back and forth on the mounting of the motor.  I ran into several issues with my original plan for mounting the controller.  The original plan was the front of the controller would be supported by the strut tower brace.  Well I decided to flip the controller around so the motor terminals faced forward because I wanted to have the wiring connections on the passenger side.  I am using the stock wiring harness and the wires I needed to power the Soliton1, connect the tach output, etc were right there.  This made the clearance between the traction terminals and the hood too close for comfort and so I had to move the "strut brace" down which made it rather pointless for stiffening the tops of the strut towers.

The other challenge was the fact that the adapter had blind holes for all the bellhousing bolts.  I was going to use the bolts sticking out the front of the original adapter to mount a L bracket for the back of the controller.  I do really like the rebirth adapter but there are some parts of the plate style adapters I like better.  If I were going to do it again I think I might try the Jimerico adpater for $500 less.

http://www.jimerico.net/index.php?main_page=product_info&cPath=69&products_id=24

I bought my Soliton1 from them (Jim Husted + Eric Pedersen) and had no problems.  Again the Rebirth adapter is great but I had been planning around a plate style adapter so life got a little more complicated.  I did hear back from Steve and he said their drawing called out the right thread pitch on the hub but the machinist made a mistake.  He offered to send it back and they would fix it but I already have it in the car with the bolts I had found.

Anyway I then went through a couple design gyrations and finally decided to make a L-bracket that was mounted to the back of the bellhousing.

I then made a bracket that supported the front of the controller from the front of the 9" motor and mounted the throttle to the front controller bracket.

I  later cut down the throttle lever to go from 7%-73% travel on the pot.

As you can see I also made up the cables to go from the controller to the motor using the nice 2/0 cable and some molex lugs.



I then spent some time reviewing the Miata wiring manual and pull the leads I needed from from the wiring harness.  I also started trimming down all the unnecessary pigtails and cleaned up the engine bay.  When I cut the bundles I was careful to tap of each individual wire so I wouldn't cause any shorts.  I also installed my $27 strut tower brace that was nickle plated aluminum which happened to match the Soliton1.  :)

I turned all of the settings on the controller way down to get ready for the first test.  For instance I set a max motor voltage of 12V just in case something went wrong I knew I couldn't overspeed the motor.

Motor is in!

Well after a hour or two of driving around I was finally able to find the bolts I needed at Lowes.  M12 1.75 x 25mm Class 8.8s...

I torqued them to 75ftlbs in criss-cross pattern.  To hold the motor while I did I stuck a screw drive between the cooling fins and the fan (very carefully).  I originally was trying to hold the other shaft end but it wasn't working for me.  Probably not the best way but I was not sure how others do it and no harm was done.

Then a clutch install was pretty straight forward.  Without a pilot bearing in this adapter you can't use the alignment tool so I did my best to get the clutch centered.

Then it was time to put the motor into the car.  The goofy grin come from holding a 200lb motor while someone says smile to take a picture.  BTW I recommend most people use a hoist, or at least steel toe'd boots. :-)

The motor went in easily.  I just dropped it into the cradle and slid it home.  It fit in nice but it took some wiggling to get both dowel pins lined up.

A couple things I noticed when I wen to bolt everything up.  The first was the adapter is tapped so the bolts have to install from the rear, just like the ICE.  I was originally designing around the plate adapter so I was planning on having the bolts install from the front with a nut on the back.  With the tapped holes this isn't a option.

This lead to the second issue was I was having problems tightening all of the bolts.  I would start them by hand (you do NOT want to cross thread the aluminum adapter) and pretty easily tightening the bolt but then it would start feeling like it was binding.  At first I thought I didn't have the adapter quite lined up so I spent an hour fiddling with the adapter then it dawned on me that the problem was the holes are blind tapped and I was bottoming out the bolts.  I was checking that I wasn't running out of grip but hadn't thought about the OAL.  Not sure why I am bottoming these out (which are the stock bolts) but it's back to the hardware store tomorrow.  So far installing the motor I have spent more time tracking down bolts then actual turning a wrench.  :) But hey it's in... (mostly)



More batteries and some progress on the car

Well I just got back in town and realized I am way past due for a blog update.  I was out this past week for a seminar on energy storage at Ohio State University for work that was presented by EWI.  While I wasn't working on the car during the week (my excuse for lack of progress), I got to hear a lot about lithium based batteries and electric vehicles (among many other things).  Ohio State/EWI has a very impressive program with some interesting results on battery life testing/modeling, methods for building packs, as well as talking to the staff about thir ECOcar and the very impressive buckeye bullet (current EV land speed record holder), and finally a presentation from Ford on there take on the EV market.

Before I left I did make some progress on the car but most of it was centered on cell testing.  I have actually put together a testing procedure/lessons learned that I hope to release this weekend.  But as of this post I have just over 200 cells tested.  I think I should be done testing early next week!

I did complete the mounting for the Soliton1, the vacuum pump for the brakes, and the throttle is just about done.

The mount for the controller was made from some scrap steel using a torch and a hammer.

I think in a previous life I was a blacksmith.  :)

For the throttle I ordered the evnetics one which was backordered and just came in.  Like the controller it is a really nice piece of CNC work.  The TPS is a automotive one and the even included a weatherpack connector with a pigtail ready to wire.  Now that evnetics is making the throttles I wonder if their next controller can/will have a built in the throttle?  This would reduce a lot of the faults/noise that people get when wiring it up themselves and are not careful enough.  Anyway for my installation, I enlarged the outer hole just a little bit and cut two notches so I could slip the stock Mazda cable in.  Anyone familiar with bikes will recognize this method for connecting brake cables.

 I am going to mount it to my strut brace/controller mount.  Why have one part only do 2 things when it can do 3?  :)

I have been also been spending time reviewing wiring diagrams.  My plan right now is to utilize the stock wiring from the motor to pull of the few pins I need for the EV components.  I found the wiring diagram online which made this pretty easy.  

www.madracki.com/miata/wiring.html

When testing I did notice that I am getting 2-3VDC with the key off.  This probably explains why the previous owner kept having the battery die on him.  I also found it interesting that the back of the cluster wa labeled at the connectors which made wiring easier.

The adapter was a little delayed from Rebirth because they couldn't get the dowel pins from Mazda in time.  So they jut made some for me.  Unfortunately it arrived while I was in Ohio so It has been sitting in the box waiting for me to return.  When I got home I unboxed it and what a nice piece of engineering and CNC manufacturing. 

It's almost a shame it's going to be hardly seen. 

I did run into one problem when I tried to bolt on the flywheel.  The hub is course threaded and the miata crankbolts are fine thread.  I am not sure if there was supposed to a set of hardware included as I didn't get bolts for the motor interface either (I did get the key and the other parts that I ordered) Or was the hub supposed to be tapped for fine thread.  I emailed Steve at rebirth and i'll see what he says but I will be making a trip to ACE to see what hardware I can find there.