Electric Porsche 944

Electric Car

A New Direction

by on Sep.28, 2013, under Electric Car

From the start of this build there have been countless changes, and with the exception of the donor car every single component has been revised/updated/eliminated due to testing/learning or simply something new becoming available that just didn’t exist earlier in the build.

I absolutely love the Warp 11HV and Soliton1 together, the torque is incredible and the car does 0-60 in 4.8 seconds.  I absolutely hate the brushes and brush dust in the 11HV.  (And the fact my 11HV requires repair/cleaning)   For this reason I finally have to agree with the OEM’s that some type of brushless motor is required for a daily driven, low maintenance EV.  The series DC motors still have a place right now simply because there are no high power AC systems available to the DIYer at a reasonable price.

When Azure Dynamics went bankrupt last year I picked up a DMOC 645 AC Inverter as well as an AC24LS AC Induction motor.  I never really had a plan for the set, however the AC24LS would never be able to give me the performance I’m looking for in the 944 without burning it up.  The motor that Azure Dynamics paired with the DMOC 645 was the Siemens 1PV5135 4WS14, an abnormally low voltage version of the typical Siemens AC Induction traction motor.  This motor should give me decent performance for daily driving.  I won’t have the 290-300ft-lbs of torque that I got from the 11HV but a more modest 220ft-lbs is still well above what the stock engine could produce.  The Siemens motor also rev’s much higher, there is good power out to 7500rpm, and usable power all the way to 10,000rpm.  I’m not sure how well the stock 944 Turbo transmission would like 10,000rpm on the input shaft, so limiting it to 7500 should keep things safe.

A new motor means a new adapter plate and coupler.  As it turns out the length of the existing adapter plate is pretty close to ideal, I’m going to add a 1/2″ aluminium plate that will adapt from the 11HV bolt pattern to the Siemens bolt pattern.  The Siemens motor is slightly shorter than the Warp so the extra 1/2″ does no harm.  The coupler will be much simpler, smaller and cheaper.  There is a steel coupler available that normally mates either the Siemens motor or a Remy motor to the Borg Warner single speed gearbox used by Azure Dynamics (and others).  This coupler is only $72US, mine is in transit but apparently it’s a good quality coupler.  This is only half of the solution though, I can now mate to the splines on the Siemens motor, however the 944 input shaft uses a different splined shaft.  For this I am using the center portion of a stock 944 Turbo clutch disc.

AC copuler

 

After grinding off the flange that normally attaches to the rest of the clutch I’m left with this small splined piece of steel.

The Siemens side of things is similar though a bit longer.  (image from the Vaxo website, click HERE to see more info from Vaxo)

0000212_300

 

The Siemens coupler is 40mm in diameter, the 944 clutch center is also 40mm in diameter.  I still need a pilot bearing, or to be more precise a piece to align the pilot shaft on the 944 input shaft, it doesn’t need to turn as both shafts will be permanently connected.  I don’t have a lathe, however I’ve been able to get good results using my CNC mill to make round parts.

siemens to 944a

 

Above is the aluminium piece that I milled from flat scrap.  It has a 15.15mm ID hole for the pilot shaft to align.  It has a stepped OD, one size matching the ID of the clutch center and the other matching the ID of the Siemens coupler.  This piece will be used for alignment of the steel sections during welding and remain inside as the pilot “bearing”.  It will also serve as a stop so that the coupler can not work it’s way off of the Siemens motor and along the splined section of the 944 input shaft.

siemens to 944c

 

The two pieces fit together nicely, it’s not quite as precise as could be done on a lathe, it would probably be better if there was a slight interference fit.  One day I’ll get a mini lathe to go along with the CNC mill.

 

siemens to 944d

 

The DMOC 645 also has some challenges, it’s CAN bus controlled meaning you can’t simply attach a throttle and other things to it directly.  There are a number of VCU’s in development from various people.  My favorite is in the final stages of development by Wolftronix.  This is a guy who is very familiar with both electric vehicles as well as Azure Dynamics/Solectria and because of this I believe his product will be the best first generation product out there.  Others will play catch up and likely incorporate some of  the features that come out in his first product.

DMOC adapter

The above image is from the Wolftronix website and I suggest you check it out for more information.

The Siemens motor is also on route, it was purchased from “Steve” thanks Steve!!!  This picture is from his for sale listing and may or may not be the actual motor I’m getting, he had purchased a lot (10?) motors from the Azure Dynamics auction.

1425_18

 

If I didn’t already have a DMOC I likely would have just purchased the pair from Jack at EVTV, I think his combo price is quite fair considering he includes the required cables/connectors to connect the motor/controller as well as the main IO for the DMOC itself.  I would also suspect the connector for the GEVCU will be included when that is available as well.  Jack is also working with various groups on their versions of the GEVCU, I’m sure they will all catch up eventually but the feature set in the first generation Wolftronix is what I believe to be the best solution right now.  Jacks price on a single item is less attractive and I’m not sure if he would include any cables when only buying one piece.

 

Performance:

In some respects this change could be considered an “upgrade” I’ll have a water cooled maintenance free motor with regenerative braking.  Those are all significant pluses!  There is however a negative or “downgrade”.  The peak power of this system is rated at 118kw, the peak power of my Warp 11HV/Soliton1 right now is around 200kw, and could be higher when the remaining CALB cells are installed.  I have no doubt that the system will still provide an exceptional driving experience, but it won’t be a sub 5 second 0-60 car any longer.

Range:

I have more cells to install anyway, so range goes up, with the regenerative braking I will probably get a tiny bit more range.  I live on a bit of a hill so I should be able to recapture some energy on the way down instead of heating up my brakes.  More than anything, my peak power will be lower, which to a certain extent limits the amount of energy I can burn accelerating away from a stop sign or light.  With all of these factors combined I expect my Wh/mile to drop from 300-325 down to 275-300, not a significant difference but still a difference.  The DMOC also has a higher input voltage range, instead of 350v max like the Soliton1 it has a 450v max rating.  It’s nominal cell count is 105 where the Soliton1’s max cell count is 100.

I will have 100 cells once I add in my remaining CALB’s, I also have a few more A123’s that could be installed if I have the room.  Each cell adds around 1km of driving range and I could easily go up to 110 or 115 cells providing I have the space to mount them efficiently, it’s never been an option so I’ve never actually looked into it.

Another small but interesting fact is my 944 will once again have a water cooled german motor.

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It may be one of the hottest days of the year but I have heat!!

by on Sep.01, 2013, under Electric Car

I’ve had a bunch of posts over the years talking about heaters, some of them were planning, some were installing, some were testing, some were blowing up heaters.  I’ve finally planned, installed and tested what I hope to be the final version of my 944 heating system.  Surplus components from Think EV’s when they switched from the Mes-Dea RM3 fluid heaters to a ceramic or other PTC heater.  The combo includes a 200-450v RM3 heater along with a high quality bosch pump.  During the removal at Think the HV power wires had been trimmed rather short.  These wires were replaced in a previous post, ready for installation.

4kw heater 3

 

New wires above, heater installed below.

pump

Like most other systems in the car, it’s very important to me to retain the stock look/feel/function of the original Porsche system.  I’ve talked about it before, but a big thing for me was to NOT have a dedicated non factory switch to turn on the heater.  Some people have an aftermarket switch with some sort of label saying “heater”, this just doesn’t do it for me.  In the stock heating system there is a temperature dial, it’s blue on one end, red on the other, and has numerical values in between.  The most intuitive method of turning on the heat would be to turn this knob from blue to red or some value between, we can all figure this out if we get into a new vehicle that we’ve never driven before.  Why should it be any different in my EV?  In addition to simple operation I also wanted to maintain the “automatic” climate controls that Porsche was using in 1986.  It’s a simple system, it’s mainly vacuum operated based on some simple analog electronics.  To make this happen I installed two microswitches, one in the heater control itself, it’s basically a NC (normally closed) switch that only activates (opens) in the cold position on the temperature dial.  The second switch was installed on the vacuum operated coolant valve that would normally restrict the flow of coolant from the engine.  I don’t actually use this valve to restrict coolant flow, but the microswitch serves to turn off the heater.

wiring3

 

The vacuum valve with added micro switch, and installed view below.

 

vacuum switch

I haven’t found a good program to create schematics but the system is quite simple:

Switched ignition +12v is connected to the NC microswitch on the temperature dial.  In any position above blue (cold) this switch applies power to a 12v relay which turns on the pump that circulates roughly 2L of coolant through the 4kW heater and stock heater core.  The same 12v out of the relay that powers the pump then goes to the 2nd microswitch connected to the vacuum valve that would normally limit coolant flow.  If the cabin temperature is lower than the temperature setting on the dial the valve is open and the NC microswitch applies power to the 12v terminal on the heater.  If the cabin temperature rises above the preset value the vacuum valve closes turning off the switch and removing 12v power to the heater.  The heater itself also has built in thermal limits that attempts to heat the coolant to 70 degrees celsius.  Any of these various systems will turn off the heater which should reduce the amount of power wasted creating excess heat and allow me to dial in the amount of heat I need or want while driving.

coolant tank

With a 4000watt heater the draw on the main pack is 12-13A while it’s “on”.  Only time will tell as to what kind of duty cycle I will end up with as the portion of time the heater is on vs off.  This duty cycle which will vary both with ambient temperature and the desired amount of heat and will ultimately determine the impact it has on my range.

I was going to make a short video on the operation and the various systems that control the heater however the ambient temperature this afternoon is too hot for the heater to even turn on.  There will be plenty of chances to do so in the coming months as the temperatures drop.  We have had some chilly mornings so time permitting I will demonstrate the system in action soon.

I still need to create some sort of indicator to make sure I know the heater is “on” and don’t have it on needlessly wasting power if it’s not required.

 

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A weeks work on a lot of little (and big) things

by on Aug.27, 2013, under Electric Car

I took a week of vacation to get some dedicated time to work on the car, I stayed busy the whole time and ticked a lot of check boxes off the to do list.  I also tackled a few things that weren’t on the list and didn’t imagine doing, but they are done and the car is better for it.

The week started with the manual steering rack, it turned out being a very simple and straight forward swap with no issues.  Since I had to remove the leaky rack I was up to my elbows in oily sludge which brought to my attention I was never able to pressure wash the motor bay before the install began years ago.

manual rack

 

The other very significant difference between removing the rack from the ’83 gas powered 944 and installing it on my ’86 electric 944 is the access to all of the parts, I had plenty of room to work with easy access to where I needed to bolt things up vs the incredibly tight dirty and awkward process in the gas car.

Since the ’83 is now just a parts car I’ve started looking at pieces that I replaced to get it on the road for my wife, as well as parts that are still in great shape that can either be sold or kept as spares for my own use.  Since I had recently replaced the front strut inserts on the ’83 and mine was in need I swapped the entire strut assemblies to the EV.  They are missing a couple of small clips that hold the brake wear sensor wiring but a zip tie took care of that.  The other good thing is that if I decide to buy performance struts and an adjustable spring kit I can install it on the original strut assemblies and then install the completed units back on the EV which could reduce down time.  (See how old this update is… I already have the new Koni suspension installed)

After solving the dc/dc converter fan noise issue, the next “loudest” item in the car is the vacuum pump for the brake booster and hvac vents.  To solve this (or at least reduce it’s annoyance factor) I milled a new mounting bracket that made use of the included rubber mounts on the vacuum pump as well as one of the unused motor mounts still in the car.

vacuum pump

 

This new mount has significantly reduced both the vibration and noise created by the pump, but not eliminated it.

One of the big things on the to do list was installing the heater.  Initially I had hoped to install it in an insulated box however the shape of the space I had to work with along with reduced serviceability forced me to reconsider.  Instead the heater is mounted out in the open on some simple brackets but I should be able to insulate the hoses/reservoir to hold in some heat.

 

Once again I was going to take some pictures to complete this post, but now it’s getting old.

 

The heater is completely wired and integrated with the stock controls.  I would like to make some sort of indicator light to show that the heater is “on” however I’m not sure where I would like that or how it should look.  Ideally it would be an indicator on the tablet and not require drilling a hole in the dash for an LED or something.

I also decided on the Momo Tuner 350mm steering wheel, again pictures needed!  The wheel is awesome and I found it for a very good price.  I was able to take the steering wheel adapter off of the ’83 and modify it to work with the late steering column.  The “tab” that kicks off the turn signal when the wheel returns to center is too short on the early version, otherwise it’s exactly the same.  I used epoxy and a metal bar to extend it far enough to work properly again.

 

At the moment I’m driving the Infiniti again, (not by choice) I had a “Desaturation fault” in the controller, so it’s back at Evnetics getting repaired.  The people at Evnetics have been incredibly helpful and quick to respond to the problem.  I received an email back within 15 minutes on a Saturday when this happened.  More info to come.

 

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Gear ratio’s and a possible transmission swap

by on Jul.15, 2013, under Electric Car

When starting an electric conversion it’s tough to know exactly what gear ratio will perform the best and feel the best when driving.  I was happy that my car had the turbo transmission installed since it would handle the extra torque from the 11″ motor, however I really didn’t know what the ideal gear ratio would be, but having a free box with 5 to choose from is a good start.

After driving the car for awhile on 300v I’ve come to the conclusion that my ideal ratio wasn’t included.  The car does drive beautifully and it’s quite quick, however I wouldn’t mind a few slightly “shorter” gears to choose from.

First gear is too short (too high a ratio) and 2nd is pretty close to ideal but could be a bit shorter for low speed driving and fun acceleration.  3rd gear is also close to ideal but is a bit tall for a 0-60mph run or spirited but not high speed driving.  What I feel might be ideal is a 2.5 gear, with a ratio about halfway in between my existing 2nd and 3rd gear.  As it turns out Porsche did make that transmission, it’s has the tough internals like the turbo transmission to handle the hp and torque that I have, but has my desired 2.5 gear.  It came in the later 944’s namely the 944S and S2.  It also has a 2nd gear that’s shorter than my 2nd gear and would provide slightly better acceleration without being too short like my existing 1st gear which is too far in that extreme.

944 Turbo
1st – 11.81    34.5mph @ 5500rpm
2nd – 6.949 58.5mph @ 5500rpm
3rd – 4.725 60mph @ 3830rpm
4th – 3.490 60mph @ 2830rpm
5th – 2.798 60mph @ 2268rpm (top speed 5500rpm 145.5mph)

As you can see from the above speed vs rpm vs gear ratio my existing 2nd gear is almost perfect for a 0-60 run, of course I would accelerate through 60 for the best time which puts the motor slightly above the recommended maximum RPM.  So for a safe 0-60 acceleration I need to use 3rd gear, which is a bit tall.

944 S2

1st – 13.56    30mph @ 5500rpm
2nd – 7.979 51mph @ 5500rpm
3rd – 5.425  60mph @ 4400rpm
4th – 4.007 60mph @ 3250rpm
5th – 3.015 60mph @ 2445rpm (top speed 5500rpm 135mph)

944_S2_transmission_brand_new

The S2 info is above, and as you can see a 0-60 run in 3rd gear would take me to 4400rpm which happens to be around where the power starts to taper off anyway.  4th gear would also provide a nice RPM for highway cruising keeping the fan speed fairly high for good cooling.

I have many other things to work on first, but I’ll keep my eyes open for a good used S2 transmission for a future swap.
In the mean time back to suspension and motor updates!

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The Weights are in and some Suspension Decisions

by on Jul.07, 2013, under Electric Car

Early on the goal was to have a conversion that came in at the stock curb weight with similar front/rear weight distribution.  When I got to the point when I knew the A123’s weren’t going to be the solution I knew the car was going to get a little rear heavy based on the new battery choice.  Once I switched to CALB CA60FI’s I estimated the final weight at 2900lbs +/- 100lbs, well it looks like I just squeaked inside that estimate.  In it’s current state the car weighs in at 2992lbs with a F/R weight distribution of 43.5% Front and 56.5% Rear, this is much more rear biased than the original 50.7% Front / 49.3% Rear gasoline powered 944.  It’s still far from the ~39%F/61%R of the 911, and lands quite close to the new Porsche Cayman which is 44%F/56%R.  I think it’s a good number for now, but I may try to move some weight forward, I’m working on a new water cooled charger, and a water cooled dc/dc converter.  The new dc/dc converter will be completely sealed and go up under the hood (vs the rear side panel) and share the cooling loop with the Soliton1.  If I can make the charger sealed enough it will also go up front, but the required fan cooling for the inductors might mean it has to stay in the back.

near final weight

Above is the current appearance, you can see the front ride height isn’t bad, but the rear is a bit low.

porsche1

Above is a pre-conversion picture showing the front slightly lower and the rear higher (but still not quite level).  The final goal is to have both the front and rear level at a height resembling the pre-conversion stance.

The options:

Reindex the torsion bars and tweak the final ride height with the built in adjuster.  This would likely correct the appearance, but wouldn’t address the fact the rear of the car has gained roughly 300lbs.  I also need to address the front end which has lost just over 100lbs.

Supplement the torsion bar system with rear coilovers, this would increase the load carrying capability while providing ride height adjustability.
Coilovers on the front would allow me to level the car and increase performance.
http://www.paragon-products.com/Coil-Over-Kit-Koni-Cup-p/koni_cup_kit.htm

Piece together an improvised coilover like system with add on adjustable spring perches.
http://www.paragon-products.com/Coil-Over-Kit-Front-p/944arhk-nr-xdo.htm

Replace the torsion bars with higher spring rate versions to carry the load, while setting the appropriate ride height.
http://www.paragon-products.com/Rear-Torsion-Bars-p/saw_944tb.htm

Initially the torsion bar looks like the most cost effective solution (simply reindexing the torsion bar may not be a solution, when considering the extra 300lbs), however I believe the front and rear shocks likely need to be replaced as well, and since I’m there replacing the front springs with a 1″ lowering spring could be worthwhile.

 

UPDATE:

Well as often happens with my posts, I don’t get around to finishing and publishing a blog post until things have changed.

I’ve already adjusted the ride height and I’ve purchased some larger torsion bars, and now I have a week off to play with the car, I’d like to get the new torsion bars in and the rear height adjusted to provide a suitable stance.  I’ve started to tear apart the ’83 944 which I bought strictly for the manual steering rack, but then replaced the engine and other stuff for the wife to drive it.  I had bought new strut inserts for that car so I’m simply going to swap them over to the EV.  They aren’t high performance struts, however they are basically new, and should let me evaluate the front spring rate better since the existing struts are starting to “bounce”.  This will help me decide what type of spring to put up front, or if I need to replace them at all.

I finally installed the manual steering rack today and it’s simply awesome!  A few short drives confirmed it’s got the feel and lighter steering weight that I’m looking for.  The stock steering wheel didn’t feel big enough to provide the required leverage on the depowered power steering rack, however it feels huge now and I could use a smaller wheel.  I’ve heard great things about the Porsche 968 Club Sport steering wheel, it’s a bit expensive so perhaps one day, although a nice Momo would actually cost less.

968wheel_1

 

I’m a fan of the Momo Tuner wheel which is similar to the Club Sport wheel above.

 

momo wheel

 

I’ve also done my best to level the car using the existing adjusters, and as it turns out it was lowered as far as it would go, so there was quite a bit of travel to bring it up.

near final weight ride height adjust

 

As it sits now before I change the torsion bars above, and to compare the pre adjusted level below.

near final weight

 

I’m happy to be at a point where car stuff is running in parallel with finishing the electric portion of this build.  The car itself is wonderful to drive and getting better every day as I address some of the normal car stuff, including the steering rack and suspension.

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Building another EMW 10kw Charger

by on Jun.23, 2013, under Electric Car

I’ve already built an air cooled version of the EMW and it’s working beautifully in my car. I was going to build a 2nd air cooled version for a friend, but because the kit was different enough I couldn’t use the same CAD files and panel designs for the 2nd charger so it was on to plan B.

batteries

Since I had to start from scratch (or at least revise all of the panels) I told my friend he was getting my air cooled version and I’m going to build a water cooled one.

I bought an 8″ x 8″ x 0.75″ aluminium plate for another purpose, however it’s just about ideal for the EMW.

http://www.youtube.com/watch?v=q3o26_hG3Oc

Test fitting the silicone gasket, I’m using a 220mm x 3mm gasket in a 1.9mm deep by 3.5mm wide channel.

cooling block 1

Drilling and tapping the G1/4 threads, since the rest of my cooling hardware is computer stuff, standard fittings will thread in.

cooling plate3

And a test fit of a 1/2″ barb fitting. I may go with 90 degree fittings, depends on the final mounting location in the car.

cooling block2

Both barbs and the silicone gasket. I still have tons of holes to drill and tap on the top and bottom as well as around the edges. The asymmetrical design of the cooling channel is to leave enough room for the mounting holes on the other side for the IGBT’s, diode, input bridges etc.

cooling block 5

Test fitting everything on the block.

cooling plate plus emw2

The final dimensions including mounting feet will be:
10″ x 8.3″ x 5.5″ This doesn’t include the barb’s or cooling hoses that will run out the side.

cooling plate plus emw

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Daily Driving and an Excellent Car Show

by on Jun.23, 2013, under Electric Car

With the motivation from The Future of Transportation Symposium and Car Show I was able to get the car in a complete enough, tidy, safe and drivable state.  So being the first day it was above zero I drove it to work.  The JLD404 wasn’t quite set up correctly, it was a decimal point off on the Current and AH’s, but it still gave me an idea of energy usage.  Since I don’t have the EMW deluxe dashboard hardware set up again I’m using the JLD404 as my only instrumentation.  So to implement the auto reset I’m simply using one of the built in relays and a voltage alarm.  My pack charges to about 317v (92 x 3.45) so I have set an alarm that when the voltage reaches 317v which is my full charge and the charger terminates very quickly after that point.  This will likely give me a small error since it will continue to charge after reaching 317v, to increase accuracy I could set a 2nd alarm for a low current level and put the relay contacts for the two alarms in series.  That would mean it would reset the JLD404 when current has dropped to zero AND the voltage is at or above 317v, the only time this happens is at the end of charge.  I’ll start with just the voltage alarm and reserve the other for an AH warning or disable function.  If this proves unreliable I will revisit using the end of charge signal from the charger.

Since it takes awhile for me to put these blog posts together I actually have had time to run with the auto reset on the JLD404 using only the built in voltage alarm.  Typically I have a reading of -0.01 to -0.03Ah on the JLD when I come back to the car, this is actually far more accurate than I had expected and should work very well long term.  I may have to see how this plays out at higher and lower temperatures, but it’s currently working perfectly and I am as close to 0Ah as I would hope.

I had my first “break down” this past Friday, but luckily it happened while I was at work, which gave me access to the resources required to patch the problem and allow me to drive home and fix the car.  This will mean more to the fellow 944 owners, the rear side panels behind the wheel wells have tubing and drains that allow water to flow through and out of the car.  I spent a lot of time ensuring that all of these were clear and the tubing was in good shape and connected correctly on the passenger side of the car.  The previous owner had a CD changer installed in the drivers side cubby, and for whatever reason I had assumed that the drains were working because the changer still worked.  I installed my DC/DC converter in this cubby and as you might be guessing the main drain was plugged.  We had a few days of heavy rain and that side panel filled up with water, well not exactly full but there was 4-5″ of water in it.  This meant the bottom 1 – 1.5″ of the DC/DC converter was actually under water.  This included the fan and the 300v output rail of the PFC section of the power supply.  When I turned on the car there was a very loud POP and the car didn’t turn on.  The pack voltage was fine but the 12v dash gauge didn’t read anything.  I quickly turned off the car, opened the hatch and turned off the maintenance switch.  I confirmed the pack voltage which was fine, but the 12v system read about 3v.  My 12v battery is the original battery that came with the car.  It’s been drained to zero volts more times than I can count, and it only stays alive because the demand on it is so low.  So there is no chance I could use this battery alone to power my 12v system and get home.  Fortunately we had a couple of 4P 100Ah thundersky battery modules that were used as a battery backup on one of our products at work.  I had checked them and left them at roughly 55% SOC for long term storage a few months earlier so I knew one would have plenty of energy to power the car and get me home.  I disconnected the dc/dc converter from the 12v and 300v batteries and temporarily connected the TS pack to my 12v system.  The voltage came up quickly as it brought the lead acid back to life.  I drove home without issue, though being much more conservative in my driving and use of the wipers/fan etc.

dc-dc toast

The dc/dc converter that I use is similar in concept the the Vicor Megapac that many people use, it’s a PFC front end that will accept AC or DC input over a wide range with a motherboard style layout that allows you to install a number of different modules for your desired usage.  The motherboard was toast (literally) but luckily all of the modules were just fine.  I plugged these modules into a spare motherboard I had on hand and the dc/dc converter was back up and running with no downtime.  I also took this opportunity to “Fix” the fan in the dc/dc converter that sounded like a small jet turbine and the noise/airflow was driving me crazy, as it was by far the loudest thing in the car.  I played with the voltage to the fan and found a nice compromise between airflow and noise.  The car is much nicer to drive now.  There is a good chance I will be able to repair the motherboard and lowering the fan noise was a big win so all in all this “break down” wasn’t a bad thing.

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First 300v charge! And The Future of Transportation Symposium and Car Show

by on Apr.21, 2013, under Electric Car

Progress has been very slow lately, it’s been cold, I hurt my shoulder, (insert 20 other excuses here). Now the shoulder is basically better, and to add some outside motivation there is The Future of Transportation Symposium and Car Show coming up next weekend.

FOT v2

http://solaralberta.ca/events/future-transportation-symposium-and-car-show

For anyone in the Edmonton area, I encourage you to attend!  I will have the car there in running condition, but not “complete”.  It should be a great show, and there should be a lot of great cars and great people.

 

In preparation for the show I have to get the car to a level of completeness that is both safe and informative to the show attendees.  First step was sorting out the battery and charging system to ensure that I can charge the car.  The 2nd was to mount and wire the dc/dc converter, it turns out I was able to reuse the mounting holes for an aftermarket CD changer that was installed in the side cubby, this serves to plug the existing holes and mount the converter all in one shot.

A short video of the beginning of the first charge is below.  The pack started off at the bottom balanced 255v and quickly increased to around 280 as you can see below, it continued to increase quite quickly to around 300v from there it increased very slowly.

first charge

 

The first thing you’ll notice is the very high “runtime” count, this is what happens when you need to charge a 300V pack off of a 120v 15A ciruit, to maintain a safety margin on the circuit (the garage lighting is also on this circuit) I’d like to keep it below 13-14A, but I also never intend to run the pack this low ever again.  This reinforces the need for a high current 240v circuit in the garage.  A 240v 50A circuit would allow me to make use of the full 10kw and charge the car in less than 2 hours from completely empty (vs 15 hours for the charge I just completed).  In the future I will likely build a new version of the EMW charger, they are in the 15kw range now and water cooled, this would allow me to mount it in the side panel opposite the dc/dc converter which would allow me to install 8-11 more cells.

 

First charge finished

 

During testing I measured my smallest cell at 61.08Ah so as the charge was coming to completion I watched that cell along with a few of the other “small” cells.  Sure enough, at 61.2Ah my smallest cell was coming up on 3.65v and the charger terminated shortly after as the cell got close to 3.7v.  I think this is the perfect charge level to fill the cells, however I may visit undercharging a bit more as that would extend the life of the cells with a small decrease in maximum range.  The front pack of A123’s is significantly undercharged as the smallest cell groups are around 76Ah, but only charged to 61, they also won’t be discharged too deeply which uses them in the middle section and should make them last for a very very long time.

I have a lot of small things to do before next weekend, including installing the wiring harnesses that I showed in previous blog posts.  Make new brackets to install the fan/radiator and pump for Soliton cooling.  Since I will be towing the car up to the show, it just needs to make it on and off the car dolly and to and from the parking spot at the show.

 

 

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Fixing an image issue with the Blog.

by on Feb.11, 2013, under Electric Car

I don’t always fully test the blog after I make a post, I just noticed that images were not working correctly with the pop up gallery.  I have fixed the problem and tested the last few posts to make sure images work as they should.  I also updated the plug in that controls the images and enabled a couple of the new features.  The gallery will now cycle through all images in a single  post in a continuous loop either by clicking on the image or using the arrow keys.  Escape now closes the image taking you back to the blog.  Hopefully this corrects the poor interface where the images were linking to a new page then clicking that image would bring up the full size image but requiring two back clicks to return to the blog.  Sorry!

porsche3

If you notice a problem with the blog let me know and I’ll fix it right away.

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Creating wiring harnesses, and working on the little things

by on Feb.11, 2013, under Electric Car

Although I’ve driven the car for a few months it was never 100% complete.  With the installation of the CALB’s in the rear and the A123’s in the front for the first time the battery system is finished.  I do have one cell to keep an eye on, but that can be replaced very easily without having to remove the entire pack.  I could have started driving the car again with temporary wiring and unfinished pieces but I’ve decided the best thing to do is just complete the car properly.  There is a to do list about a mile long ranging from creating wiring harnesses and installing connectors to building an insulated box for the fluid heater and installing the aluminium channel the length of the car to protect all of the wiring for the HV pack as well as 12v and signal wiring.

I finally installed all of the final ring terminals with proper heatshrink for the battery system, I have a a bit of work left  in the motor loop then all of the high voltage / high current wiring is complete.

A portion of my product line with RW Audio is custom cables.  These are high quality audio cables that look better, last longer and sound better than your typical radio shack variety.  I will be using these same techniques to assemble wiring harnesses and cables to complete the EV wiring in the Porsche.

rcacable

sencable

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I’ve started with the “14 pin” connector near the firewall that allowed me to use factory wiring to interface with most of the required connections on the Soliton1.  That worked well for testing, but wasn’t finished and had many unused wires dangling all over.  Below is the old messy wiring.

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Below the water pump for the Soliton1 cooling loop, the 14 pin harness that connects to the Soliton1 and other terminal blocks, as well as the 8awg cables to connect the charger.

wiring

Close up of connections including the cheap 2 pin weather proof connector I bought on ebay for the pump, and will be using for a few other items that need an easy disconnection method.

wiring2

The replacement harness uses the stock connector, but new wire and terminals that are protected by techflex and heatshrink.  There will be a few new harnesses in the car, all using the same assembly style and provide plenty of protection while being serviceable.

With the new 4kw heater that’s replacing the Kats heaters I also decided I should build an insulated “heater box” so that as much heat as possible makes it into the cabin and I’m not wasting heat in the engine compartment to the cold ambient air, especially while driving.

heaterbox

The top and bottom of the box are made from an aluminium extrusion I had laying around, the sides are made from raw double sided FR4 PCB boards that I use for prototyping using my CNC router.  This makes for a very light yet strong box that should work well with some 1/2″ foam insulation.  I still need to decide on what to use for the ends, perhaps a couple more pieces of extrusion since they are the correct width.

heaterbox2

I used the CNC router to drill the holes in the PCB material as well as the extrusion so that everything would line up nicely.  I will need to do further machining on the top and bottom panels to make cutouts for the reservoir, wire glands and drain hole.  This box will be mounted on the passenger side of the engine compartment beside the motor.

As I get closer to installing the heater system permanently the question comes up of how to turn on the pump and 4kw heater.  They simply require 12v, however I was not looking forward to the idea of some sort of “out of place” switch with a cheesy label saying “heater”.  To make the heater behave just like the ICE version I should just be able to turn the temperature dial from cold to hot and the system just works.  So to make that happen I had to remove and disassemble the climate controls which involves desoldering the main switches from the PCB.  Once it was all apart I found just enough room near the temperature dial which is simply a 10k potentiometer to mount a microswitch.  When the temperature is set to cold the switch is closed, so by using the NC contacts on the switch, in any dial position other than cold, the switch is “on”.  This will trigger a relay to turn on the pump and heater.  The car has “automatic” climate controls, meaning that once the cabin reaches the preset temperature the system then controls the flow of coolant through the heater core to maintain the preset temperature.  It uses a temp sensor in the dash and a vacuum operated valve.  Since I don’t want to interrupt the flow of coolant I’m simply using the vacuum valve to control another microswitch that will turn off the heater once the cabin reaches the preset temperature.  This switch closes when the valve would close to cut off the coolant flow, so again using the NC contacts to run the heater only the system will turn on and off automatically as it tries to mimic the original function.   When the valve opens to increase the temperature of the cabin the heater turns on again.  The pump and fan will continue to run during this time drawing more heat out of the coolant.  I don’t have to worry about a fan interlock since the fan comes on low as soon as the ignition is turned on.

wiring3

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