Thursday, July 10, 2014

Volt battery modules

Here are the videos from the tear down:

And here are some close-up pictures and information to go along with it:

This is the charger connector.  It is fused with 2 30amp fuses

Wednesday, July 9, 2014

Chevy Volt drivetrain

Things have been busy and I haven't updated the blog in a while and a lot has been going on.  I actually bought the entire EV drivetrain from a 2013 Chevy volt with 7k miles.   After 3 attempts of buying a new volt battery ended with, paying for, waiting months, and then getting a refund from the dealer, I just went with a scrapyard unit.  A few weeks ago I started tearing apart the Chevy volt pack and video taped the tear down.  Here is a picture of the drivetrain sitting next to our daily driver volt (32,000 miles and going strong):

And here is a link to the video of how it works:

When I bought all the parts I made sure to get all the important wiring bits.  

The motor and inverter are very interesting, the motor is actually 2 motors.  One is nested inside the other in a coaxial setup and the inverter is actually two in one as well.  It will take quite a bit of work to figure out how to talk to the inverter and very likely outside my capabilities (I am a ME not a EE for a reason :).  But a 111kW AC drive system for well under $1000 is a big opportunity for the DIY community.

Here is the engine side of the gear box.  And on the bottom you can also see where the passenger side axle shaft comes out:

The Volt pack has a disconnect mounted on top.  It is not the easiest to pull but I am pretty sure it is fused.

The pack cover is easily removed and the the whole pack is easy and straight forward to work on.

The pack is configured in 3 modules that are made up of 48V and 24V modules.  The pack measured 370VDC total and is likely near a "full" charge.  Keep in mind that chevy's version of a full charge is actually 80% SOC.

There is a hall effect current sensor located in between the front and middle modules

I took video of the whole process and will post it up on youtube once I get it all edited.  The modules are pretty easy to breakdown and I will upload the pics from that process next week.

Tuesday, May 13, 2014

One Soliton1 or 2 juniors?

"Hi Kerry,  I seem to remember you favoring the Soliton 1 controller because of the 1000A rating and the fact that you could use it to drive two motors. I thought that these motors can be run intermittently at >600A, to get to their peak ratings of 200 HP (or whatever they are). Would using a 1000A controller limit you to an intermittent rating of 500A per motor or do controllers have short-time ratings as well?
Do you see any disadvantage of buying a Soliton Jr (which I think is somewhere around 650A) and later upgrading to a second motor and Soliton Jr to double the power?"

Depends on a lot of things.  I am assuming you are keeping the transmission?  Do you plan on doing 2 motors or is that a slight chance?

The motor torque is proportional to the current.  So with 600 amps you make 60% of the torque as a 1000amp.  This torque will be constant from 0rpm up until the back EMF from the rotating motor becomes a limitation.  The warp 9 has a mechanical speed and voltage limitation that mean with a junior you will not go more then ~160 on a single motor.  This puts your peak power at input at 96kW (128hp).  Assuming ~85% eff that means 109hp at the "crank".  It's deceptive as it will feel like more power then a 109hp gas engine but it won't be a rocket ship.

If you go to dual motors then you can almost double the voltage and thus almost double the power to 200hp at the shaft.  But you need a battery pack with high voltage which is not necessarily a bad thing, just something to be aware of.

A single motor with the Soliton1 will let you do 1000amps at 160V giving you 187hp at the shaft and my experience is a good amount of power for spirited driving

Running 2 soliton jrs is possible but it will be a grand more expensive then one Soliton1 and more complex.  

Both the motors and the controllers have duty cycles but I really doubt that either of the evnetics controllers will be the limiting factor. 


Sunday, February 9, 2014

The ev30 project begins

In December is started the next project a 1984 BMW 318i known by it chassis designation E30.  The E30 is well known for being a great handling chassis and is very popular for racing.  After MANY month of searching I can across this owne owner car that was almost exactly whayt I wanted.  It has the 3.73 LSD, 2 door, that is in great shape and I love the color combination.

It ran and drove fine but as my 5 year old son kept saying: "Yeah but it runs on that icky gas" so out came that little 4 banger:

Clean-up at bay 1!

Hmmm.... what should I put back in there?  Something that can take 300kw!

Saturday, December 22, 2012

What did I buy?

So I picked up a couple of the AC24LS motors that are available for so cheap now after the Azure Dynamic's bankruptcy.  they are brand new and normally ~$300 but you can get them for a couple hundered right now. I picked up one C-face version of the motor and one with prioritary face designed to work with a custom transmission that I can going to play with on the bench.  I am comfortable with DC but when it comes to AC motors I have some learning and a cheap motor like this is perfect. I had a free hour today so I decided to pull one apart and take a look.

I'll start by saying the motor is really simple and pulling it apart and putting is only a few bolts but there are a few things that you need to pay attention too.  I took pictures and posted here as reference for anyone else who bought one of the hundreds of motors that are on the market right now.

 I pulled of one end by removing the 4 long bolts that run the length of the case.

The red wire is for sensing the stator temp and the black wire is the signal from the encoder.

Here you can see the PN for the bearing with the integrated encoder

And here are the wire colors

 These washers look like belleville washers for the axial preload.  Make sure you put them back in the right orientation.

Here you can see the two pins that retain the encoder.  Make sure these are capturing the signal wire at the very last step before you tighten the 4 case bolts up.

I made 4 marks (in blue) on the outside of the end cap to show where the tapped holes are for alignment of the housing.

This big "screw" looks to be for compressing the belleville washers and provide the axial preload.  I didn't have the right tool so some tapping with a strategically placed screwdriver.  I need to look up and see if I can find the torque values for this and the 4 case bolts.  I also pulled the connectors outside the housing for bench testing.  The factory wiring harness runs into a potted box, with the connectors out I can access the wires directly.