Monday, May 21, 2012

Escaladus Interruptus and the Catellier Effect

This week, we were hard at work in the 2008 Electric Cadillac Escalade EXT conversion and we are at a very rewarding phase of the build where things move along quite quickly.

Tim Catellier of Chandler Arizona slipped in and mounted a small explosive device under the hood and this kind of wrecked our week.

Tim, an EVCCON 2011 attendee, and so of course a rank up in standing over "ordinary" viewers, inquired about a pleasant little puzzle he was having with his BMW Z3 conversion. He had been at EVCCON 2011 with his erstwhile assistant, his FATHER, and we were privileged to examine first hand and up close the particulars of this Zilla/Netgain build using CALB cells - excellent in all respects. He in turn claims the drag racing and autocross was the most fun he'd had in a car EVER with his pants on and no music.

It seems he had developed a "frame leak." I'm actually extraordinarily pleased with this. We had done a show that prominently featured our efforts to chase down a frame leak on the 2009 Mini Cooper Clubman. We described what they were, how you could detect them, why it was important for your personal safety NOT to have one, and how to chase them down. We have since had a regular flow of viewers who HAVE found frame leaks subsequently.
While most were minor leaks in the 30 ma range, some have been serious. So I'm kind of pleased this particular episode caused a lot of people to check their systems for leaks, and more pleased that they have largely been successful in addressing them. I'm not precisely a safety Nazi. Life's a bitch, and then you die, and ho hum. But this one has caused us some nasty shocks in the past and so it deserved some attention. Apparently the problem was not as rare as I thought. It wasn't just us. And so, as Marthaa Stewart says, "That's a good thing."

The check is simple. Connect a multimeter between any battery terminal and frame ground. You should see a varying voltage of 4 to 6 volts. It will probably jump around. This is because the pack "floats" separately from frame ground. If you read ANY steady voltage above a volt or so, you have a frame leak. If you read DIFFERENT steady voltages based on which battery terminal you measure to ground, you certainly have a frame leak.

If you connect a 12v light bulb between the terminal and the frame and it fails to light, it is probably a very minor leak of 30 or 40 ma usually through some of your instrumentation. If you get any light, you have a serious situation that can be life threatening in the right environmental conditions - like sweaty skin.

In any event, Mr. Catellier had one. ANd after carefully and logically troubleshooting the problem, isolated it to the MOTOR. DC series motors of course have brushes and a commutator. Carbon conducts. And a buildup of carbon dust within the motor is not unusual. Sufficient carbon dust can short the field windings to the case. Actually this is so common that a leak of less than 30 ma is not even considered a problem by the motor manufacturers. Tim's was more in the 800 ohm range which into a pack his size, is pretty stout.

He tried blowing the motor out with compressed air and failed to eliminate the problem.

George Hamstra, of Netgain Motors had previously rebuilt this same motor and wanted a clean slate on this problem. After examining photos of the brushes, he asked Tim to send in the motor and he shipped him a brand new motor from Warfield, complete with the latest Helwig H60 RedTop brushes.

It was a non-trivial amount of work to swap out the motor. But Tim again enlisted the aid of his erstwhile assistant, DAD, and they were able to do it in some four and a half hours. The frame leak was gone. And they reassembled the car.

He was back on the road and drove it to work and back the next day. But there was an interesting difference. Tim had kept careful records over the past 26 months and tracked energy usage, electricity costs, gasoline prices, and right down to the dollars dimes and ducats saved in not purchasing gasoline, all in a handy spreadsheet, just as a proper Computer Systems Administrator is wont to do.

The car averaged 380 Wh per mile for over two years. In fact, Tim and I had actually had a conversation earlier about this as we have a pretty strong rule of thumb that a car will use about 1 Wh of energy to move 1 Mile over time and average, for each 10 lbs of car. Tim's car weighed in at EVCCON 2011 at 3285 lbs. And 380 Wh/mile somewhat exceeds our rule of thumb. I was unable to account for this or provide a persuasive theory. Maybe my rule of thumb not so good medicine in all cases.

On his drive to work and back, Tim noted an energy usage of 280 Wh/mile. This is kind of dramatically better.

He describes this somewhat better than I do on his blog at

I received an e-mail message regarding this. In discussing the issue, he refined his results with total driving over the past 680 miles - 332 Wh/mile average. At 3285 lbs, I like this number for by now obvious reasons.

I initially suggested that the only thing I could imagine would cause such a DRAMATIC disparity in two otherwise identical 11 inch motors was the advance timing. The Netgain motors come marked with alignment marks for CCW, N, and CW timing. This corresponds to counter clockwise as viewed from the drive end of the motor, neutral, and clockwise respectively.

Most explanations of electric motor theory are technically correct as far as they go, but of necessity incomplete. First, some of the factors are difficult to explain. And second, after 150 years some of them we really don't know exactly. For some reason, "square" motors - that is motors with a certain ratio between diameter and length, run better than others. A certain amount of mass of iron in the case is simply required for efficient operation. We CAN make motors lighter. That's not necessarily a good thing. We know that the field windings set up a magnetic field that causes armature rotation. But were you aware that there is an interaction where the armature rotation then affects the magnetic field - in fact rotating it in the direction of the armature?

This is termed the armature effect and actually we DO know quite a bit about this. In the Netgain Warp 11HV, they employ inter poles to counteract the effect of this, and this is how this particular motor can handle higher voltages without arcing.

In the ordinary Netgain Warp 11, the CCW position literally rotates the brush ring a few degrees in the direction of armature rotation. This moves what is termed "the neutral plane" that same number of degrees. And so the brushes are only truly at neutral when the motor reaches a couple thousand rpm and the armature effect comes into play. Since it is OUT of neutral at low rpms, you would think this would cause arcing on startup. But in fact, the actually applied voltage to the motor is very low at that point and so arcing isn't as much of a problem. Under power AND RPM, the voltage is higher, and so that is where we want the brushes to truly be in the neutral plane.

And so we refer to this as ADVANCE TIMING. My theory was that if Mr. Catellier had his first motor accidentally at N or worse CW timing position, this would cause severe arcing during acceleration - and probably a LOT of carbon dust. That could seriously undermine his Wh/mile and explain his frame leak.

Unfortunately, brilliant though it sounded, it was another case of my trying to type myself smart in a fashion that would make the DIYElectric crowd cheer with pride.

Tim had of course noted and recorded the position on both motors. CCW. Theory busted.

Leaving what? The brushes. I'm accustomed thinking of brushes as just brushes and that their main characteristic is their life span, based on the hardness of the material. This also becomes a factor in seating the brushes, as they can take longer or shorter amounts of wear to properly seat in. But once they are in operation, there is little to choose between them other than how many miles you get before you get to change them. The technology is 180 years old. What's to know?

But in the spirit of rational inquiry, what else is there? That was the notable change between the two motors.

I happened to have a Netgain Warp 9, and an ADC 8 motor on a bench I had cleared off. We reassembled the Warp 9 using the new Helwig H60 Redtop brushes and painted the motor. The ADC took a little more work, we bead blasted the end bells, (and the armature unfortunately), revarnished the armature, and replaced the brushes and the entire brush mounting ring. I intend to use it on a lawn mower.

But we looked around and found the old brushes from the Netgain Warp 9. I wired up a JLD404 meter and a digital voltmeter with a contactor, one of our A123 13.5volt modules, and a switch. And we ran the motor with the new brushes, that had about 10 hours of seating on them. Then we changed the brushes to the old brushes. As it turns out, these aren't Helwig brushes at all. They are marked ML1683 and ML1684 H8 with a stylized chevron with a capital N in it. I have not determined who the manufacturer is, but Tom Brunka advises that it is a low voltage brush used on fork lift motors typically at 72v and below.

So we ran the motor again with the old brushes. The difference was astounding. For the same 129Ah of energy, the new brushes ran for 3 hours 38 minutes and 54 seconds. The old brushes ran for three hours, one minute, and 25 seconds.

So we reran the new brushes again. Along the way, we began recording RPM and commutator temperature along with current and voltage. The results are shown below.

If you clear out all the chaff, the new brushes use 485 Wh per hour to turn the motor at 2652 rpm while the old brushes require 535 Wh per hour to turn the shaft 2053 rpm. This is such an astounding difference that there must be something HUGE wrong with our methodology.

Except it rather persuasively reflects, in both direction and amplitude, what Tim Catellier reports.

I really have no further explanation for this. Here is the data and we would be very interested in direct attempts to reproduce either refuting or supporting. In the meanwhile, if you are driving a Netgain Motor a year old or more, you might invest in a set of Helwig H60 RedTops. Baseline your Wh/mile, change the brushes, and measure again. We would be very interested in what you find.

The current Helwig part numbers are:

For the Warp 9 = 10-621117-674-3-01
For the Warp 11 = 10-621117-674-3-02

I think Netgain is offering these brushes now at $150 per set of eight brushes. We will try to do the same on the EVTV online store as soon as possible.

We have also chased down the XSTURBOS guy and ordered 10 of his Garret blowers. We'll put together a little kit with the blower, the shroud for the motor to mount it on, and a relay at $495. George Hamstra of Netgain has already spoken for one for his Bricklin build that we are hoping to see at the EVCCON 2012. But hopefully we'll have these up on the web site this week or next as well.

Why? The main defense you have to carbon dust buildup in the motor is the motor fan. The newer motors actually have an improved fan on the drive end and these fans do a pretty good job at moving air through the motor, both to cool it and to clear the inevitable carbon dust. The problem is, that works real well at 3000 rpm. It works not so well at 300 rpm. And at 20 rpm it doesn't do squat. We have routinely begun using these 434 cfm blowers on all our Netgain motors. Any more heat you can remove is a good thing. And at low rpms, you still have fairly impressive air flow to remove carbon dust as well as heat.

Many people have run Netgain motors for years quite handily without an external blower. So this is overkill EVTV style. Still we recommend it.

Additionally, there are many less expensive blowers that are out there that will do just fine as auxiliary blowers for the motor. These look cool. For what i'm spending on the Escalade build, looking cool is kind of required.

Your mileage may of course vary....

Jack Rickard

Sunday, May 13, 2012

Messin with Wires.

This week we mostly deal with wiring issues on the 2008 Cadillac Escalade EXT Electric. The motors are in and we spun them up using a 12v A123 battery module. Very quiet and vibration free.

We mounted two glycol fill bottles, one for our Soliton liquid cooling system and one for the electric heater. It has been over a year since we did the segment on our tankless water heater we are using to heat both cockpit and battery boxes. We'll repeat a lot of that in the next few weeks as we install it. But the big breakthrough is the realization that we could use the windshield washer heater switch to turn it on.

The Cadillac actually has a heater for the windshield washer bottle. I've never heard of this before. And I don't quite get it. The idea of dumping hot windshield washer solution on an iced up windshield gives me a chill, so to speak, windshields costing what they do. The thermal contrast between the heated solution and the ice is pretty great. I would think they would have some problems with fracturing windshield glass.

The system IS under recall, but for another reason. IT has burned a couple of Cadillacs to the ground. The problem is, they don't fix it in the recall. THey just disconnect it and you no longer have a heated windshield washer. We haven't exactly done the recall, but I do intend to disconnect the power to it. It goes through a 60 amp fuse on the fuse block.

Leaving a rather unused, but really quiet prominent switch on the console right below the environmental controls. And so we are going to steal this signal and use this switch to turn on our electric heaters.

The heater assembly we created has pump, TWO contractors, and two heater elements all in one box. We'll use the signal from the switch to turn on the pump and the heater elements. Relays and thermostatic switches will be used to cut OUT each of the heating elements in turn as the temperature of the system rises..

In this way, we'll turn them both on initially. When the temperature gets to 45C, we'll cut one of them off with the thermostat. As it continues to rise, at 55C we'll cut the other off as well. As it falls to below 50C, that thermostat should turn it back on. So it will seek around 50-55C on one heater element.

The pump will pump the fluid first through the cabin heat exchanger. This should provide quite a heat drop to warm the large passenger area. The fluid exiting the heat exchanger will be routed to the battery box where it wanders through a series of loops of pex tubing beneath a false aluminum floor in the box. After leaving the box, it will pump back to the fill reservoir.

The glycol should be much cooler on the batteries than on the passenger compartment, but still warm enough to maintain battery temperature.

I know the universal advice is that these batteries need to be cooled. They do not. They do not under any imaginable load cycle. Instead, what we've found is pronounced improvement in all parameters up around 35-40C. Worse, what we've found is pronounced decrease in both capacity and power at anything below 0C. In fact, it has become evident you should not charge these cells AT ALL below freezing.

And so we are going to heat them. We're also going to heat them in the garage while charging, but with a much lower power 240vac heating pad that we will probably affix to the fill reservoir. This won't do much really. But it will be in a garage when we are charging. And it will go on all night. We think a couple hundred watts will very gradually heat the battery box. The side effect will be a warm cabin on entry in the morning.

The vehicle features a remote door lock and even a remote starting system. We're hoping to retain that functionality. Of course, there isn't much to remote start with an electric car, but if it can get the air conditioning or heating going, that would be cool - or....err.... warm.

We used a Ferraz Shawmut A50QS-1200-4 fuse. This monster is the size of a large orange juice can and costs about $350. Sizing these is a pain, and explaining them, even more so. They are a FAST blowing fuse - that blows slowly. No, this makes no sense at all. Neither does the application guide from Ferraz Shawmutt, at least to me. Basically, this fuse will do 2500 amps for about 18 seconds and 4000 amps for 2 seconds. 1200 amps it will do continuously. This does not sound very "fast" to me. I have contacted one of their applications engineers seeking adult supervision on how to size these and how to explain this. So far, no help.

We're mostly using Champlain Cable COmpany's 4/0 shielded cable on this build. This is 4/-0 of copper wrapped in the using poly insulation, then a steal braid, and finally another layer of insulation. I like this for a couple of reasons. The obvious is the decrease in radiated emissions and noise that can affect other components. We do not have the EMI requirements of Europe, but on the other hand banging 2000 amps of 192volts of energy at 8 kHz is going to put out some stuff. One less thing.

Secretly, the reason I would pay $12 per foot for it is that with the layer of steel braid and another layer of insulation, this cable is much more resistant to abrasion. It's going to be very difficult for it to rub through to the copper and connect with frame. It is surprisingly flexible for what it is.

The Solitons already have TWO contractors in each of them. But I caught Sebastien Bourgouis with another pair in his 911 at EVCCON 2011. When asked, he noted it was just redundancy. Ok. Me too then.

And here's why. With other controllers we do usually have a contactor, but we also have a hand switch in the passenger compartment to break the connection to the controllers manually if necessary. I haven't really worked out a way to do that in the Cadillac cockpit. There is this enormous center console between me and the passenger, and no floor space or bulkhead I could conceivably reach.

I'm really NOT a safety Nazi. Prudence is good. But pontificating about safety is not really my thing and some of the extremes espoused by the wannabe experts and poseurs just seem over the top to me. But we have a failure mode with DC motors that is sufficiently rare to be hardly mentioned, but sufficiently possible to pose a danger. And the danger is kind of frightening.

IGBT's can fail SHORTED. Most of the time they just burn up and are destroyed. But it IS possible, though very rare, for them to fail in a short. In the case of a PWM controller feeding a DC eeries motor, this is like connecting the battery pack directly to the motor. With our motors, and this battery pack, that could be 2000 or even 3000 amps OR MORE. When you break an arc at a voltage of 150 and that kind of current, it tends to vaporize metal, and arc weld contactor contacts. Frankly, our manual switch could well be useless too. And that gives rise not to a sunburn, but a vehicle screaming to go at top speed with 300 or 400 kw of power. Not an attractive spectacle for me.

By adding a second set of heavy contractors, using hydrogen dielectric and magnetic blowouts, IN SERIES with the ones in the Solitons, things are maybe better. The arc welded contacts of one contactor set will not really carry current as well as clean contacts and the immediate, almost simultaneous breaking of a second set stand a good chance of breaking that current flow. And if not, the heat generated in the contractors will within a few seconds cause them to go hand grenade anyway.

So that's the theory. We are using two 500A EV-250 kilovacs each capable of breaking 2500 amps. This in addition to the little EV200's in the SOlitons. We'll connect the 12v actuating signal through a big red slap switch on the panel beneath the steering column. I won't have to bumble or look. It's the only switch there, and all you have to do is hit it to disconnect the 12v from the contractors.

We are using TWO Megapacs on the Escalade at 15v. And in addition to our diodes, we are going to add Jeffery Jenkins recommendation of a 100 uh 14 amp inductor to the input to each, along with a 30 amp high voltage fuse.

So that's what we did this week. This is an enjoyable part of a build. The big stuff that takes weeks is over. Now we see progress every day. Little wiring things are fun for me.

Yes I'll try to schedule a private class for Brian on wireless microphone batteries sometime this week if I can find time.

Jack RIckard

Monday, May 7, 2012

Tang Zhengping and John Allen - Brothers from Another Mother

This week we begin the more pleasurable work of installing pieces and wiring them up on the 2008 Cadillac Escalade EXT.  Some mounting issues.

We installed the two Soliton1 controllers at angles above the motors much after the fashion of the old Ford flathead V8.  This allows access to all the terminals and still access to the motor terminals underneath.  We mounted the Solitons on a piece of our aluminum aircraft decking honeycomb material, and by angle aluminum to the upper mounting bolt on each of the engine mounts.  This held well enough, but allowed a little wobble.

Brain installed some brackets to tie the decking to the rear Garret turbocharger fan and to the top bolt in the transmission adapter.  This left them rock solid.

We also mounted a Vicor Megapac in place of the lead acid battery on the battery tray.  This unit features six 5v 40 ampere cards and two 15v 10 ampere cards.  We strapped these up to produce 15 v at up to 100 amperes.  It reads right at 15.05v unloaded and our systems in the Escalade should work very well at that voltage.

We mounted the throttle body inverted on top of the Megapac using a couple of pieces of bathroom plumbing.  It is inverted so that the butterfly valve, which is not entirely necessary, can clear.  I want to retain this as it gives me a good visual indication of what the ECU is doing with the throttle, and I can reach in and give it a twist myself for test purposes.

We added a diode to the input of this device.  I'm reasonably certain this was what was causing the Chennic DC-DC converter failures - back flushing the input caps into the batteries.  As one viewer pointed out, the Vicor already has a rectifier in it so the diode should be redundant.  That makes sense, but we're still going to use the diode.  I don't know exactly WHAT is in the Megapac, or in what order.  I know the power goes through a fan first, which seems to work from AC or DC indiscriminately.

We are going to buffer the throttle position signal with an LM1458 operational amplifier.  We bring out the ground and the 0-5v from the throttle body, tie them to the LM1458 along with our 15v supply.  The LM1458 can operate from +/-18v. And we bring the same ground out with the LM1458 output to the Soliton throttle inputs.

By tying the LM1458 output back to the inverting input, it becomes a voltage follower.  Whatever voltage we put in, we'll get a pretty close approximation of that as an output.  So why do it?  The input to the opamp is on the order of 10 to the 12th power ohms in impedance.  It acts as a buffer to avoid loading the throttle position signal output to the ECU.

I get a lot of comments about the parallel motors and controllers.  We tested this a year ago and it's just not a problem.  The two motors are on a single shaft.  The outputs do not precisely fight each other.  Rather like batteries in parallel.  That current would vary between the two is first not an issue, but the load existing equally along the shaft tends to even out the currents anyway, regardless of any discrepancy between the two controllers.  It just isn't a problem.

Brian reinstalled the air condition compressor and power steering pump on the front adapter plate of the motor.  We have not installed the belt as we want to run some motor tests without aimlessly running the pumps.

We have put transmission fluid into the transmission and connected up the fluid cooler.  It will take a bit to work fluid into the empty torque converter.

Much work remains, but we are at the part where things start to move more quickly.  The heavy work of battery boxes and motor installation and mounting are behind us.  It's now a matter of finding cunning places for contractors, disconnect switches, terminal bars, the heater, etc and hooking them up.  We also have to devise a liquid cooling system for the Solitons.  We already have this hanging on the test bench so most of it will just be moving it.
We'll want to add a relay and use one of the Soliton outputs to run the pump only when cooling is called for by the Soliton itself.  A welcome feature in the more recent software releases.

John Allen continues his series on his Toyota rebuild.  I'm fascinated by this rebuild as John does not appear to be a master fabricator, and he is very value conscious as to his components.  His battery heater appears to work well despite all the warnings from the armchair builders, although I admit even I cringed when I saw all those resistive wires together in his junction box.  It appears it is a gentle heat.

John failed in this video, and on multiple fronts.  His controller blew up on him apparently, and his magic number on his motor adapter appears to have been off sufficiently that when he disengaged the clutch his flywheel gouged out a fairly impressive ravine in his motor adapter plate.

So why is he smiling so broadly.  Well, he just finished his first run in the SAME Toyota that used to have about a half ton of lead acid cells in it.  Only now it doesn't.  The result doesn't feel like an improved car.  It feels like a DIFFERENT car.  He's going from zero to 80 mph in better fashion than the Toyota could with the ICE engine and he still has pedal left.  Instead of a ponderous climb, it is a delightful acceleration.  And you just never get over it.  But there is NOTHING like that first roll. Ergo the EV grin even WHILE facing some major rework.  Gotta love it.

This is what its about gentlemen.  For those of you watching and planning and hesitating, you don't HAVE to be a master fabricator.  And the personal satisfaction of making a car GO on battery power from one of these conversions is just not something I can type yourself smart about.  You have to feel it.  It is gynormous.  It's a head rush beyond what drugs can deliver.  ANd it lingers for days, weeks, even years.

It will cause you to rip that motor that you took weeks installing out in four hours just to get it fixed and back on the road.

And it is quite universal.  Our Chinese builder of the week, and faithful EVTV viewer Tang Zhengping invested the equivalent of $1600 in ducats in his 90 mile range creation.  For those who don't speak Mandarin, what he is saying in the video is that he built a freakin electric car himself and he feels really really good when he drives it and f*** a bunch of oil companies.

It's springtime and I'm driving around in the ivory Speedster Part Duh we did two years ago.  It's not just that I can't get over it.  Every stop at Lowes Hardware, the grocery store, anywhere involves an inevitable discussion with perfect strangers that are just bowled over by the car.  When they find out it's electric, - cranial detonation right in front of you.  The front of their head just implodes.  We've gained enough notoriety locally that they are becoming much more aggressive.  "Your the guy with the electric cars...right?"

I am indeed the guy.

Stay with us.

Jack RIckard