V3.0?

[Randy Pollock]

Hi all,

V1.0 (2008) - I got my 914 running using the ElectroAuto AV kit. Ran ok for ~18 months before its emergency brake failed and it rolled out of the driveway and suffered a fair bit of damage.

V2.0 (2014) - Running again with lithium. Still not performance champ, but it runs much better after dropping a bunch of weight especially driving up the steep hill to my house (~1,000’ of elevation gain in a mile). Stopped working last fall with no obvious symptoms. Lots of debugging has not led to a solution and borrowing another DMOC didn’t cause the motor to spin. If I am reading the ccShell errors and the manual correctly, the ‘B’ phase of the motor is an open wire :-(

V3.0 (????) - Thinking about moving to DC motor and giving up on regen. Thinking about a Zilla 1k (only have 100 Ah batteries, so will never draw more than 200 Amps or so) and a Warp motor. Would like to splurge and get the Warp 11-HV so that I have good performance. Anyone know if that size motor will fit with the ElectroAuto battery racks? Also, anyone out there have pictures of how best to mount the Warp motors to the 914 motor mount?

Thanks in advance,

Randy

[Peter Thompson]

Hi Randy,

I've got a monster BLDC motor under the rack - I had to adjust the rack about 1/2 inch to make it all fit, but that was pretty straightforward.  I believe the motor is 13.5" - I'll check later today.

What sort of batteries do you have?  You mentioned 100Ah, but not the brand.  CALB can safely to 3C continuous, so that would let you produce 300A.  With a smart controller, you can limit the number of amps, and all will be well.  Oh - what voltage are you currently at?

Cheers, Peter

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[Randy Pollock]

Hi Peter,

That will be great.  I can’t lift the rack at all because the CALB cells are taller than the lead-acir cells that the system was designed for.  I’ve already slightly modified the engine compartment cover to make them fit at all.

And yes, I am using the previous generation CALB so I was going to start at 200 Amps and work up from there.  I have 56 cells so that puts me in the mid-180 V range.  I like the Warp 11-HV as it can handle up to 280 V so I am not running near the limit.  I know the Zilla can step down the voltage, but that will reduce the efficiency and I would like to avoid that if possible.

That said, I am interesting in hearing your experience with your motor.  So what are you using?

Thanks,

Randy

[Ben Apollonio]

Hi Randy,

The warp 11 may be overkill. I run an ADC 9" with a Z1K and 54x 100Ah Thunder Sky LiFePO4 in my 914 (the older pre-yttrium variant). I have the battery current limit set for 500A so I don't over-stress the pack, and I try not to take it even that high most of the time (but you know, sometimes my foot has a mind of its own...)

I can honestly say that the limiting factor seems to be the max power of the batteries, not the max torque of the motor. Launches are crazy -- it beats my Tesla S60 off the line; it's once I'm already up to speed and I hit my battery current limit that I start to run out of "go." I think I'm already putting too much stress on the poor 914 components -- I've shredded 2nd gear (still working on the rebuild after that one) and seem to have wrecked a CV joint. Granted, it's hard to tell what would have failed anyway after 40 years and 100k miles, but I don't find myself wishing I had an 11" motor.

On the other hand, if you are serious about that 200A battery current limit, I believe the Warp 11 will give you a little more torque for your limited battery power (200A * 170V = 34kW). If I remember correctly, the ESR on my 9" is 31milliohms, so 1000A wastes 30V at stall (=176A @ 170V ignoring controller and battery efficiency). So with a 9" your Z1k would be wasted almost as soon as your motor starts turning and producing back EMF. The Warp11, by virtue of being bigger, can achieve lower ESR for a given torque constant, which means you'll waste less of your precious 34kW in winding loss. It is difficult though to quantify what you could realistically expect, but even 100% efficiency still has you topping out at 1000RPM before torque falls below 9" levels (240 ft-lb * 1000RPM = 34kW)

Not enough to justify the weight and cost, in my opinion, but that's your decision to make.

My $0.02.
-Ben

[Randy Pollock]

Hi Ben,

Great feedback. That much torque sounds glorious after the Azure motor.

Part of my concern was putting the 180 V into the Warp 9. The Warp 11 HV is supposed to be good to 288 V, so that gives me nice margin against the limit. The Warp 9 spec sheet puts the limit at 170 V and I’ve read several places you should probably stay ~15-20 V lower to minimize wear on the brushes. Are you setting an upper voltage limit in the ZIlla?

Also, how did you attach the motor to the 914’s motor mount bar? I can see lots of places to order the adapter to the transmission, but nowhere to order the bracket to attach the motor to the car.

Thanks,

Randy

[Ben Apollonio]

Hi Randy,

Both the motor mount bracket and the transmission adapter came from Electro Auto. They are the parts used for their original VoltsPorsche kit, though I did my own battery boxes and electrical system design (hence the Thunder Sky and Zilla). I am admittedly pushing the voltage limits of the motor, but I tend to stay below max RPM; the only time I dump full pack voltage across the motor is under heavy acceleration, and at that point my batteries are sagging to 140V or 150V so I rarely push the 144V rating by very much. The car has about 6000 EV miles on it and no motor issues so far. My biggest issue is actually the adapter hub; I was never able to get it to install perfectly straight, so it contributes significant vibration at higher RPMs. I've had the flywheel and pressure plate precision balanced and that didn't solve the problem. I have the car apart now to tackle the aforementioned transmission issue, so I'm hoping I can straighten it out this time.

In the interests of full disclosure, I did blow out my old T-rex controller - twice - and I suppose it's possible there was some brush arcing that contributed to it, but mostly I think it was just an old and crappy controller. There were some loose connections on the gate drive signals that would cause it to strand me on the side of the road until I literally punched the side of it, or else completely disassembled it to reseat the contacts. The Zilla has been rock solid, and I haven't seen evidence of damage on the commutator.

This is me: http://www.evalbum.com/4196

-Ben

[Peter Thompson]

@Ben: Love the color (same as mine ;) ).  

I ended up ditching the adapter from EA (along with most everything else) with the various upgrades. I used to have a bad vibration with the EA adapter, but with the new one, there is no vibration at all. It could be that the mechanic that put it together was super-meticulous, or that the new part was properly balanced - I'm not sure which. 

@Randy: As for my motor and controller - DON'T.  I bought this 85KW BLDC motor direct from China, and you should know by now what that means - NO support, almost NO information, and definitely no quality control.

If you want to upgrade, make sure you buy from a company with a good reputation.  Hard to go wrong with Zilla or Soliton.  AC motors have been using the Curtis 1238 with good effect.  I've heard good things about the Rinehart controller, too.  

I tried to crawl under the car today, but a sprinkler malfunction turned that area of the driveway into a small pond (bad thing to happen in California), so I couldn't actually measure.  According to the "manual", it is 11" in diameter. I also looked at the battery rack, and realized that we hadn't had to change the pack height at all.

Cheers, Peter

[David Shields]

I remember the pics you posted after your accident. It took guts to rebuild from there.
 
I've been having fun with my 914 EV lately. It's no fun in the winter in KY.
 

[jrmole]

Hi all,

V3.0 is now on the road (probably 200 miles so far over ~10 drives).  I ended up installing a HPEVS AC-51 that I bought from EV West:

http://www.evwest.com/catalog/product_info.php?cPath=8&products_id=172&osCsid=1cim0fp0762kjkdjukasut8uv0

Very happy with the motor.  Even limiting the controller to 300 Amps to protect my batteries, the car's performance is great.  At 65 MPH on the freeway, there is plenty of available torque to accelerate in 5th gear.  I can drive up hills in 4th gear that the Azure motor couldn't handle in 2nd gear.

Seeing about 250 Wh/mile efficiency which will put my range around 60 miles (without margin).

Working on the displays now so that I can monitor the batteries while I am driving so that I can start extending the drives past my 20 mile max so far.

Really, really happy with the car right now.

Randy

ps:  Had a few issues with the final installation of the wiring harness.  I made a mistake, but EV WEST and HPEVS were wonderful in helping to diagnose the problem.  Part of the confusion ended up being a problem in the initial configuration of the controller and HPEVS sent me (overnight) the hardware to reprogram it at no cost and told me to hold onto it for a few weeks in case something else came up.  Really impressed with both companies service.

[David Shields]

Good for you Randy.
 
I think I remember a picture of your 914 in its garage with the hill below.
 

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Date: Sun, 13 Dec 2015 16:39:19 -0800
From: ra...@alumni.caltech.edu
To: 91...@googlegroups.com
Subject: [914ev] Re: V3.0?

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[Richard Rodriguez]

Hi Randy,

Congratulations.

I remember reading your post of the parking brake disaster.  Glad you are back on the road with a nice motor and controller with LiFePh batteries.

I have the HPEVS AC-50 with 38 200Ah LiFePH Voltronic cells in my 914.

I have 53,900 miles driven as an EV.

My car has over 100 mile range still after 5 years.  (Originally 135 mile max range)

I get around 225Wh/mile.  My car weighs 2,300lbs.

if I go light on the pedal, I can do 195Wh/mile

Again congratulations.

Richard

[David Hale]

Very cool, Randy. Can't wait to see it.