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The mauswerkz 300zx EV build

Posted: Sat, 20 Jul 2013, 17:20
by jonescg
Hey I recognise the hand-writing on those boxes :) Glad they arrived in good shape! Are you going to sink the cells down a bit into the parcel-shelf of the coupe? Would improve handling a lot and keep them out of the way a bit too.

The mauswerkz 300zx EV build

Posted: Sat, 20 Jul 2013, 17:33
by BigMouse
Weber: I plan on using a PWM controller on the steering pump on this too. I'd just rather have much more 12v power than I need, rather than cutting it close. At night, in the rain, with the fan, wipers, lights, and rear de-mister running, the load on the 12v system could be approaching 40a. With power steering on top of that... I just want to make sure the engineer is happy.

jonescg: They arrived in very good shape! I was impressed. There's even a hand-written note inside tell me to be careful not to let the terminal bolts bottom out if I don't use a terminal-mounted BMS (which I am). Very thoughtful.

The cells are going where the back seat used to be. The padding has been removed and most of the cells will be down near the bottom of the pan. I won't be cutting the metal to set them any lower though. The CG of the cells should be much lower than the CG of anyone who might have sat in those seats. The room for batteries back there is why I specified at 2+2 version of this car. We looked at a 2-seat version and I realized there just wasn't any room for them!

The mauswerkz 300zx EV build

Posted: Sat, 20 Jul 2013, 18:21
by jonescg
That would be my note Image

The mauswerkz 300zx EV build

Posted: Sat, 20 Jul 2013, 22:03
by BigMouse
jonescg wrote: That would be my note Image
Much appreciated!

The mauswerkz 300zx EV build

Posted: Sat, 20 Jul 2013, 23:23
by Johny
Rockby have a special on at the moment for 80 to 264 VAC Meanwell SMPS 12v, 20A for $80 each. You could use two and series the inputs like I do. Centre tap the pack to hold i/p balance.

The mauswerkz 300zx EV build

Posted: Sun, 21 Jul 2013, 01:13
by BigMouse
That's just about ideal. I have a chinese generic version of one of those and it worked fine on 360v when testing it before. I probably wouldn't even have to series the inputs.

I wonder if the 500w PFC version would work. It states the same input voltage range, but has a PFC front end. It also costs twice as much for twice the power. Bargain!

My criteria would be:
Fully isolated input/output
Runs on DC (whether putting inputs in series or not)
Adjustable to 13.8v output

Can you verify these items?

EDIT: For reference, this is the Chinese one I was using in my tests (http://www.ebay.com.au/itm/350W-13-8V-2 ... 56582cc948), and it meets all those criteria, though I only tested it to 360vdc. The input capacitors are rated to 220v and there are two in series, so (assuming the internal leakage between them is the same), it should handle 440v there. Further, the switching transistors D209L) are rated to Vces 700 and Vceo 400v. So 400v on the input absolute max. Luckily they are isolated so the inputs can be put in series. These are 13.8v 25.4a rated.

Here's a 500w version of the same brand: http://www.ebay.com.au/itm/500W-13-8V-3 ... 258014aed3

The mauswerkz 300zx EV build

Posted: Mon, 22 Jul 2013, 06:03
by BigMouse
Fabricated a bracket and mounted the hall-effect throttle box today.

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I actually picked up an Astra electronic throttle pedal for this, but the owner purchased this potbox and wanted me to use it. Oh well. I opened it up to fix the grommet (the cable had pulled out of it) and took note of the internals. It's just a very small PCB with a hall effect sensor mounted on it and break-outs for the three terminals. A magnet mounted in an arm attached to the lever moves across the sensor. Very simple. I've mounted it un-housed in the engine bay. This is right behind the right headlight and shouldn't see any air flow or water ingress. Looking around at other conversions online, most of these seem to be mounted in the engine bay without any enclosure, so I figure it's okay. While I had the box open, I sprayed some INOX on the board to help keep it from being affected by moisture or humidity. I didn't have any circuit board lacquer handy, and I didn't want to gum up the mechanism with it anyway.

The clevis is an RC part and I've "crimped" it on to the throttle cable. I'd like to some sort of bush to make the clevis fit a bit better. Right now it's about a 1mm diameter pin floating around in a 5mm diameter hole.

The cable was a very tight squeeze to install in the clevis, and so with the crimp, I doubt it'll be pulling out. The travel and pedal feel are just about perfect. Very smooth operation. I'm glad I managed to remove the sheath and shorten the throttle cable without damaging it.

The mauswerkz 300zx EV build

Posted: Tue, 23 Jul 2013, 05:52
by BigMouse
I update the pic of my potbox installation, but I didn't change anything. Just a better quality image (from a real camera, not my phone).

Spent a good portion of today messing around with the battery arrangement and trying to figure out the best way to mount them. According to NCOP14, the batteries need to be restrained against a forward impact of 20g. For the 74 cells I'm planning to have in the back seat area, at 2kg each, 20g is equal to nearly 3000kg! I'm having a hell of a time coming up with a good way to restrain them, though I have some ideas.

Here's a quick image from today. I was trying to get my head around where the batteries will sit and where the available attachment points are.
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The latest arrangement is something along these lines:
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Ignore the overlap on the models. The angle needs to be increased for it to fit, but for some reason my program crashes any time I try to change that angle. The layout is correct though. The lowest row is missing cells from the middle so that it clears the raised part of the driveshaft hump seen in the photo above. The top row is missing cells from the outboard ends to account for the fact that the available space is narrower at the top.

I was thinking about building a battery box to mount under the car where the fuel tank used to be. That would take about half of those cells out of the back seat area and make them easier to restrain. The challenge there is that I'd then have to completely waterproof the box, which would be very difficult to do. A box back there would also not be very easy to work on if I needed to do any maintenance or replacements on the batteries, battery management, or contactors that would also be installed in the box with them. Lateley, I've been reading too many stories on here of "this battery box is the worst", "it takes hours to remove", etc. I've been a mechanic of one sort or another for a long time now (cars and airplanes) and I love to curse the engineers for not designing with maintenance in mind. I don't intend to be cursing myself down the line ;-)

The mauswerkz 300zx EV build

Posted: Tue, 23 Jul 2013, 15:27
by Renard
BigMouse wrote:

Spent a good portion of today messing around with the battery arrangement and trying to figure out the best way to mount them.

I was thinking about building a battery box to mount under the car where the fuel tank used to be. That would take about half of those cells out of the back seat area and make them easier to restrain. The challenge there is that I'd then have to completely waterproof the box, which would be very difficult to do.


You are now grappling with what, in my opinion, is the hardest part of a conversion.

Securing the cells is important because the approving engineer will almost certainly be thinking 'mechanically'. Although my engineer checked that I had all my electrical elements, photographed the vacuum pump, the enclosures containing the fuse etc etc, it was nevertheless pretty much a box-ticking exercise. The only time he became detailed was when he checked up on the tensile strength, size and number of bolts retaining the battery boxes. Also I had shown him my calculations on the rotational forces exerted by the motor and their action on the mountings.
What I'm saying is that provided your electrics looks OK at least superficially, they won't cause any approval issues, but you have to insure your cell/box mounting is up to spec.

About the waterproofing, I don't think you need be unduly concerned. A sealed lid with silicone should serve. That's what I've done with my two under-seat boxes. (Which, incidentally, as you have seen from the photos in my thread, can be lowered from the car by simply undoing five fixings.)
I'd be interested to hear if others have had any issues with water.

The mauswerkz 300zx EV build

Posted: Mon, 07 Oct 2013, 20:51
by BigMouse
Okay, finally found some time to post an update. Installed the motor to the transmission last week. Here are some pics and a brief description of how it all goes together.

These three pieces required to mount the 300zx flywheel to the motor's output shaft
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The adapter hub and expanding bushing installed on the motor. The shaft had to be cut down to keep the thickness of the adapter plate to a reasonable value.
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The flywheel adapter installed.
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The transmission adapter plate was machined from a single piece of 50mm thick aluminium plate.
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Fidanza flywheel installed. The ring gear will likely be removed eventually to save on weight. It's no longer needed.
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High performance 6-puck clutch disk in place.
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Heavy duty pressure plate installed.
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It goes together like this. Everything lines up and turns easily by hand.
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Transmission reinstalled in the car. The motor mounts still need to be made, but this is pretty much how it will sit when it's done. The front battery pack will be mounted above the motor, and the mauswerkz motor controller will mount in front of the batteries.
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The mauswerkz 300zx EV build

Posted: Sun, 15 Dec 2013, 01:49
by BigMouse
Update!

Motor is mounted!
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The mounts will come off again to make the welds a bit nicer and paint them up for protection. The mounting is fairly rigid, which should transfer -some- motor whine in to the cabin. Hopefully that's a good thing.

I also finished up the watercooled base plate for the motor controller.
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I love having my own CNC mill. There will be another, thinner plate mounted on this one and glued in place with silicone adhesive. A block or other manifold will also be bolted on to direct the water in to the channels. I haven't decided which method it'll be yet. If I could weld aluminium, I'd weld short pieces of tubing directly to the plate and attach the hoses to those. More likely, I'll mill some slide-fit holes in to a block of aluminium, and slip the tubing in to them with some JB weld to hold them in place.

The mauswerkz 300zx EV build

Posted: Sun, 15 Dec 2013, 02:42
by EV2Go
Very nice, can't wait until it is finished.

The mauswerkz 300zx EV build

Posted: Thu, 26 Dec 2013, 23:57
by BigMouse
The rear battery box for the 300zx EV is nearly complete. The box is mounted in the car and the batteries have been put in place. Battery management and interconnects are next, along with some braces or a lid across the top to hold the batteries in place. The project is getting close to the point where the motor will be run in the car for the first time!

Here's the rack installed in the car. The two strips of steel welded across the box are there to restrain the batteries in the forward direction in the event of an impact. They are tied through to the floor pan of the car by bolts. The sides of the box and the middle part of the front are mounted to the original seatbelt mounting points. The two remaining straps on the upper back corners are mounted to the locations where the fold-down seat back latches used to be.
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Here you can see the batteries installed. They fill the rack nicely. I'll likely install a plate on the two ends of the box to keep the cells from swelling and help clamp them, but it's already a fairly tight fit.
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I also updated the image of the motor mounted on my previous post. The mounts have been re-welded and painted.

The mauswerkz 300zx EV build

Posted: Fri, 27 Dec 2013, 02:52
by jonescg
Looks great! Best spot for a battery pack in a coupe. Shame you can't sit them lower, but it looks like it's a rear wheel drive. Nice one! I think we'll start to see some more builds make progress with the holidays upon us Image

The mauswerkz 300zx EV build

Posted: Fri, 27 Dec 2013, 03:11
by BigMouse
jonescg wrote: Looks great! Best spot for a battery pack in a coupe. Shame you can't sit them lower, but it looks like it's a rear wheel drive. Nice one! I think we'll start to see some more builds make progress with the holidays upon us Image


Yeah, we specifically chose the 2+2 version of this car so we could put most of the batteries there. The remaining cells will mount above the motor. It's RWD, yeah.

The mauswerkz 300zx EV build

Posted: Thu, 09 Jan 2014, 03:14
by BigMouse
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Assembly of the motor controller has commenced! Here's a photo of the 3D model of the controller compared to the physical assembly which was created from that model. The yellow cylinders on the model have been replaced with the white boxes on the actual controller. The circuit board was designed to allow capacitors to be installed on the board (see photo below), or along side as is being done here.

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This assembly is nearly ready to be installed in the car and connected to the battery pack and motor. It won't be long before the wheels are spinning!

The mauswerkz 300zx EV build

Posted: Thu, 09 Jan 2014, 14:50
by coulomb
Impressive.

Are the big film capacitors at the left going to connect to the IGBTs through some fancy bus bars?

The mauswerkz 300zx EV build

Posted: Thu, 09 Jan 2014, 15:22
by Stiive
Nice one!
What IGBT bricks are you using? Have you done much high power testing yet?

Did you end up getting FOC working, or are you still using scalar/slip?

The mauswerkz 300zx EV build

Posted: Thu, 09 Jan 2014, 21:27
by BigMouse
coulomb wrote: Impressive.

Are the big film capacitors at the left going to connect to the IGBTs through some fancy bus bars?


Yes, very fancy bus bars indeed, in a sort of criss-crossing arrangement. Hard to explain in words, but I'll have a photo of them soon. I've already finished one of them.
Stiive wrote: Nice one!
What IGBT bricks are you using? Have you done much high power testing yet?

Did you end up getting FOC working, or are you still using scalar/slip?


I'm using CM600DY-12NF bricks. Beefy units.

I did implement FOC but I haven't run the controller since March last year. I lost my testing battery pack to a software glitch that caused the controller to lock up and short the batteries through the motor. The circuit breaker didn't open, neither did the contactor, since it was controlled by the controller which had locked up (rather than the BMS which would have detected the voltage drop and loss of communication with the controller).

I've enabled the watchdog timer now and it should fail safe. I also have fuses instead of a circuit breaker.

One kink I haven't quite ironed out with my FOC algorithm (I wrote it from scratch based on the theory) is how to handle field weakening. I had it so that the voltage vector magnitude was limited within PWM saturation by reducing Vd, but without reducing the Id setpoint, the decoupling is lost and the currents become uncontrollable. I need to implement another controller in the software to drive Id such that Vd does not allow the output to become overmodulated. Shouldn't be too hard.

I also need to implement a rate-of-change limiter to prevent the motor spinning up to max if the throttle is applied without the gearbox engaged, and also to prevent the motor from stopping suddenly due to regen during gear changes when the throttle is released. This could also be used for launch control ;-)