Sunday, August 30, 2009

We finally did install the main battery box in the Mini Cooper project. This box was quite a wrestling match but we have completed fabrication of the box and installed it in the vehicle.

Brian's "sliding drawer" concept to allow us to move the top box to gain access to the gas tank battery boxes works pretty well. The slides cost over $500, and I've never actually lived in a house with a kitchen drawer that works, so I was a bit skeptical. But these slides seem to do the trick, and they are rated for 1000 lbs. We will have about 375 lbs of cells in this box - about half of the total weight of our 40 kW pack.

I'm a little weary of battery boxes frankly. That's pretty normal. As I've said before, battery placement and box fabrication is easily over half the effort of converting a vehicle to electric drive. Still, time for a breather.

So I started a new project. Post my charge station tirade, I decided to build myself one. Given a clean sheet of paper, the question then becomes "What would a Jack Rickard charge station look like?"

I found the answer in Hickory North Carolina at the Finest Web Site for Gas Pumps. This guy is reproducing dozens of different kinds of gas pumps circa 1950's. They aren't restored vintage pumps. He makes them new. And they are not quite as solid as the originals. It is pretty thin tin and acrylic. But the result is eye catching, certainly nostalgic, and works quite well for our purposes. I wouldn't want to chop up a real vintage pump to make a charge station. But these reproductions are easy to work on and at $939, while not precisely a bargain, they add a bit of nostalgia to what is necessarily a pretty plain concept - an AC receptacle for an electric car.

Of course, it grew into a bit of a project. We dug a shallow ditch down the west side of the garage and ran some 1 inch electrical conduit the length of the building. I put in a 100 Amp 2-pole circuit breaker in our Square D panel and ran some 10-3 interior wire through the conduit. This wire consists of three 10-gage insulated wires and a bare copper ground. You connect the red and black wires to the two poles on the circuit breaker, and the ground and white neutral wire to the ground bus bar in the box. This will give you two 120 vac phases - the classic 240 vac service.

This 240 vac is what almost all U.S. boxes provide. In your house, you primarily use 120 vac circuits from this box, broadly balanced across the two phases. But heavy load appliances such as electric dryers, electric range, and air conditioners typically do use 240 VAC.

Running a 240 VAC circuit is actually pretty easy. It is painful to watch all the angst among the ever faithful and generally abused Tesloids, and now the BMW Mini-E guys, over simply running a garage circuit from the box. The circuit breaker is $45 or so. The wiring is actually a little expensive - I think about $1.50 per foot. ANd of course, the conduit is a good idea. So it does add up to three or four hundred dollars. But it's not rocket science.

While assembling the Texaco FIre Chief pump, we did do a few mods. We installed a NEMA 14-50 connector in the side and a hook for hanging electrical cable. We also wired in a 40 foot cable made of 10-4 service cord, which I terminated in a female 120VAC 15 amp female (wired for 240 VAC) that fits the Porsche charge connector.

But we also added a few other items. Notably two Tyco Kilovac contactors. These are the relays often used in the electric cars to switch high voltage DC. 240 VAC is easy for these heavy duty relays and does not pose the arcing problems you have with high voltage DC. We installed a simple toggle switch on the side of the pump to energize the relays.

In your house ,most switches switch ONE leg of the circuit, either the hot wire or the return. So the voltage is still there, either at the switch or the light. But because the circuit is "broken" by the switch the light or appliance doesn't run.

That's not precisely what we're after here. I don't want ANY voltage in the cord, or in the NEMA receptacle. So BOTH phases each get their own relay, and without the 12vdc coil voltage applied to the relays, both are ENTIRELY dead.

Where to get 12v was a bit of a problem. These relays do draw a little current initially, but the current to maintain the relay in the ON state is trivial. Every wireless router, camera, and other computer item I've purchased over the years has come with its own little wall brick power supply. Basically a little step down transformer with a very primitive DC bridge rectifier and regulator in it. I can never bring myself to throw these away. Finally a use for one. It puts out 1000 ma, or an Amp. And that's just enough to close two relays.

The big addition was of course a meter. We used a Conzerv Model 6433 - some $213 for the meter - we got it from Optimum Energy Products of Calgary Alberta. But to measure currents over 5 amps you also need TWO of the 100:5 tranformer rings at $40 each. You run the conductor for one of the two phases through this ring. As current passes through it, it acts as a little AC transformer and the resulting output can be used to measure current flow. The rings step 100A down to 5A.

The 6433 has a number of features in an odd combination and with odd little menus. But we were interested in two functions, runtime and kWh. The run time simply totals run time where more than 10 ma flows in the cable - either NEMA 14-50 or the dedicated cable. kWh is a totalizer just like your house meter.

The meter is not anytihing great although probably fairly accurate. In fact , it is a little dated and the setup is a little tedious. But it is obviously not the latest design. That's a good thing for our purposes. It winds up with 14 mm digits in bright glowing red LED - a kind of obsolete display concept. But those large glowing red letters are perfect for a Texaco Sky Chief display.

We set it up to alternately display kWh and runtime. Using the arrow buttons, you could manually clear it each time. But we put it behind glass and so we can't really do much with it in that sense.

Why would we want to see kWh and runtime. Well runtime is pretty obvious. Everyone wants to know " how long it takes to charge the darn thing." We'll I can calculate that, and of course we have run numerous charge cycles while watching it. But most of the time I charge at night and I'm in bed at the time. The runtime function will tell me how long it took to charge last night.

In our cars, we have the EVISION kinda/sorta working with the Brusa chargers. So we can tell quite precisely how many kWh we have put into the pack. But that is the DC amperage and voltage from the onboard Brusa charger into the batteries.

While a kWh is a kWh, you'll find that doesn't match your electric bill. There are conversion losses in the charger itself.

By comparing the kWh used at the Sky Chief pump to the kWh going INTO the batteries from the charger, I can tell just what the efficiency is - about 88%.

We have further plans for the charge station. We'll probably add a GFCI circuit to the mix here pretty shortly. Everyone hates GFI (ground fault interrupt) because the cheapies in the bathroom receptacle blow at odd times for no apparent reason. Actually, there is a reason.

GFI works by comparing the current in each of the two phases. In a single phase, it compares the current in the hot lead to the neutral. As this circuit is a loop, you should always have as much current on the neutral return as you do on the hot leads. A GFI simply compares the two currents. If there is a difference greater than about 6 to 10 ma, it trips a circuit breaker.

The problem is that utility power is almost always different in one phase than the other. So the "inbalance" may be power company induced.

If the currents are not the same, this is SUPPOSED to indicate a leak. Basically, one of your phases may have found a ground. This is not good in a bathroom. But it's also not good in an electric car. If some wiring got chewed up or chaffed against a sharp metal edge, you could wear through the insulation and make contact with a metal car part. That could indeed put 120 vac on the frame of your car. If you then touch the car frame, you could get a shock.

GFI is supposed to disconnect the circuit within milliseconds when it detects this imbalance. But the cheapy units in bathrooms are famous for blowing WITHOUT a fault. We'll shop around for a good general GFI circuit we can wire into our relay system that will allow us to adjust the trip threshold.

And of course, there is the SAE J1772 plug issue. If this standard is finally approved and these become available, we'll replace the "hose" with a new cord and connector to connect to the car.

J1772 should specify a Control Pilot signal. This is a 1kHz 12V squarewave. The pulse width (duty cycle) of this waveform indicates the amount of current the charge station can supply. The circuitry also detects the voltage drop of the car's charger when it connects - the car is supposed to present a standard resistance to the waveform pin.

This works a little bit like our toggle switch to energize the Kilovac relays. If the circuit does not detect a decrease in output level down to about 9v on the squarewave output, it disables power to the cable. As soon as you plug in the cable to your car's charger, the waveform drops to 9 v and a circuit energizes the relays in the charge station to apply power to the cable. So you basically have a dead cable in your hand until its plugged in. As soon as the connection is made, the power to the car is turned on. Not a bad idea.

So that's about all there is to a "charge" station. We didn't get a permit. We haven't been inspected. We're not UL listed. I'm sure I've broken at least 17 local, state, and federal laws. But we're quite safe. And quite convenient.

Best of all, despite driving an electric automobile, we can still trust our car to the man who wears the star......

Tuesday, August 25, 2009

Charge Receptacles

The more I examine this electric car thing, the more I realize how Alice in Wonderland it has become. We're seeing the wider press, and by that I mean even those specific to electric cars such as Autoblog-Green, EVCAST, EV World, and others just go gaga over every press release put out by any automobile manufacturer about any electric model announcement. They all swallow every word hook, line and sinker with no critical thought as to what was being said, what was NOT being said, and what the likelihood is of any of it ever happening.

When we started talking about the Mini Cooper project nearly a year ago, Brian and I had a little bet. He thought that if Mini was doing this experimental lease program, they were simply getting something "out there" and would be announcing an electric model certainly within a year - at least before the lease program was up. I told him it would be 3-5 years if they ever did it at all. And we had a spirited discussion about it. I said I put the chances of a production electric mini within 4 years at less than 20%. I should have said what I really thought - less than 2%.

IF we had ANY automotive manufacturer that really got religion and WANTED to produce a pure electric car, there are a couple of problems. And the chances of having one are about the same as having a railroad want to produce DC-3's, or IBM develop the Apple II Personal Computer, and all for the same reasons. But if they DID, there's a couple of basic problems.

The cost and time to engineer a new car model are pretty steep. Typically 5-7 years of engineering time and a half billion for a startup or over a billion for an established firm. Why is this?

The business is not quite what it seems. You would be stunned to learn what it actually costs an automobile manufacturer to manufacture your car - the parts, supplies and labor to produce it. A typical $35,000 car costs about $5,000 in parts and labor.

The design process is only partly devoted to the car. What they really have to design is a machine that makes that car. There is of course some design in the car itself, typically about a third. The other 2/3 are devoted to designing the assembly line, specing and procuring and integrating robotic welders and assembly machines, and specing and procuring each of the parts bought from suppliers. Those parts have to arrive at a particular gate, on particular days and times, in particular packaging, for further delivery to particular doors, for staging at particular areas of the line. And this goes for wheels, brakes, axles, seats, rear view mirrors, stereos, transmissions, bumpers, and many many other items they don't actually manufacture, but purchase.

This machine also consists of the factory workers, which type of worker stationed at what point and doing what task, in what order.

If you design all this, the actual parts and labor per car, your unit costs, can be very low. But of course it is all burdened by a huge overhead of engineering talent, not $45 per hour factory workers but $125,000 design engineers, in droves, who have to design this MACHINE that makes a specific model of a car.

So the business is kind of one of those threshold businesses. It can be operated at many levels, but it more or less works the same. You have to sell x thousand cars to break even, and it's typically a relatively large number. I call it thresholdy. If you make it across the threshold, it rains money. So if you can reach your 325,000 unit threshold, for EVERY car you manufacturer over that, you make 6X your costs - it literally rains money.

Of course, the other end of that is that for every car UNDER the 325,000 magic number, you LOSE an almost unlimited amount of money.

Last year's credit squeeze caused EVERYBODY to miss their number. That's why GM needs $80 billion dollars. Almost everyone buys cars on credit. And when credit locked up, so did vehicle sales. And they missed their VERY large magic numbers very badly. But the huge buildings full of engineers continue to eat money all the while.

The head of the autoworkers union was actually on television and said "look, if we agree to work for FREE for the rest of our lives, it won't get GM out of the financial bind they are in." Everyone laughed at the guy. We all know that the reason the American automakers can't make money is the ridiculously high "union wage" GM and Chrysler and Ford are forced to pay.

The irony is that the guy was exactly right and quite knew what he was talking about. The blond chippie chick "journalists" on TV howled with mirth, because they are so woefully ignorant of everything they report on, they can't tell fact from fiction.

But the labor costs are part of the $5000 unit costs. And what was killing the companies was the design engineering overhead.

So what has this all got to do with electric cars? Well, aside from the fact that a lot of the revenue streams kind of dry up with the electric car, it basically takes a huge amount of money and typically 5-7 years, to develop these lines. It's not about drawing a pretty car on a computer. So if an emergency was declared and they truly believed EVERYONE would ONLY want electric cars, it could be done in 4 years.

And that's about all there is to it. GM may indeed deliver the Volt by November 2011 - maybe about 500 of them. But it will certainly take longer to get the machine up and running to make sufficient numbers where you will be able to get one. There's no magic wand to wave here.

The second problem has to do with the concept of a true electric car. I've made no secret of my disdain for hybrids. Hybrids inherit the complexities and disadvantages of BOTH the electric drive train AND the internal combustion driver train, while pretty much negating the advantages of either. Not that either is partiicularly good or bad, but rather that in the act of combining them, you have to deal with the weight and low storage of batteries, while you have to deal with fueling and storage of gasoline and all the negatives of running a petrol motor as well. The main advantage of an electric car is that it has no internal combustion engine and related systems. The main advantages of an ICE vehicle, are their quick refueling, and extraordinary power. When you combine them, you wind up with inadequate electric range, and inadequate piston power.

But even the automakers who proclaim that they have religion - such as GM with the Volt, have a problem. And the problem is that we run out of gas. 10,000 of us a day do it. I've done it. Almost everyone has. With an ICE car, it's pretty much no harm no foul. You put more in it, and you can go on your way. With a battery driven car, there is harm, and it is foul. You destroy the battery pack. The $10,000 battery pack.

Now since childhood we have become acculturated to the concept of batteries. We got Christmas toys that wouldn't run because the batteries weren't included and no one thought to buy them and there is nothing open on CHristmas day. We played with flashlights and.... well you know what happens when the batteries run out. ANd as adults we have battled through laptops and cell phones, and we just know quite a bit about batteries...

And the big question all newbies have about electric cars is of course the "range" question.

So if you go to a dealer and talk about buying an electric car, you are going to have a couple of questions. The first will be about the range, (how long will the flashlight shine before the light goes out) and the second question is "how much do the batteries cost?

At one point, before the introduction of the Maglight, flashlights were basically free. The battery companies would INCLUDE a flashlight with a battery purchase.

So we know how this story goes.

The brlilliant answer, and actually the only answer that will result in a sale is really about the batteries, not the range. And the answer is that they are under "warranty". GM is now claiming a quite generous 10 years and 150,000 miles on the batteries in the Volt, which is odd since they haven't really fully developed, much less tested them.

And that brings us to running out of gas. If you warranty the batteries, you can't ALLOW them to run out of gas. So you add an ICE with generator, and monitor the pack voltage. When it gets down to a certain voltage level, you automatically kick in the generator to save the batteries.

We'll call it a "range extender" because that's the other question they are worried about. And if they don't mind putt-putting along on a three cylinder chain saw motor, they'll have plenty of "range."

Interestingly, the CEO of BMW went on conference call to discuss their less than stellar sales and earnings over the past two quarters. In the hopes of pointing to a brighter future, he pointed to the success of the Mini-E program. Actually the Mini-E program has been plagued by a host of technical and logistical problems. It was rather rushed to market in what is now being clearly seen as a move to cash CARB credits before the June 30 2009 deadline while taking advantage of a comical loophole in the byzantine CARB regulations.

But what was amazing was that he noted that what they learned from the Mini program would be very valuable for a brand new Magna City model they had planned for 2012. That year is another magic CARB date, by the way. But more importantly, he made NO mention of ANY plans to produce an electric Mini Cooper of any variant at all.

Cars such as this, the Mitsubishi iMiev, and the Nissan Leaf may indeed make it into production in two or three years. They will be comical little pieces of car, and I do not think they will be particularly well received by the public.

So who has the best shot at actually producing a desirable production car? Well, Tesla obviously, though in small numbers. And believe it or not, I think this Smart for Two car has legs. It is actually very cute, fully featured, (remarkably fully featured for a car this size) and they are experimenting with an electric model. I think it has legs.

But now to everyone's darling, Tesla. And the real heart of the dark side of electric cars. Proprietary Technology. EVERYONE wants to shut EVERYONE out of the game. The classic pig at the trough scenario.

Its really not a problem for us, because we are shitcanning the whole engine. But the 2009 Mini Cooper Clubman has an Engine Control Unit they call the DME. It' s a computer that monitors ignition, air intake, fuel flow, timing, etc to keep the engine running at peak performance and efficiency. But YOU can't program it. Only BMW service centers can. And in fact, this ECU is SERIALIZED and matched to the motor. A guy here in Missouri had a brand new car that was struck by lightning. The car really wasn't damaged but the ECU was smoked. He had to take it to the BMW dealer in St. Louis. They fixed it alright. And presented him with a bill for $3500 (on a $30,000 car - over 10% of the purchase price) for a new ECU. He told them to take it back out. And he subsequently sold the car for a fraction of what he paid rather than pay them this amount.

You basically cannot work on your MIni Cooper engine if it involves the ECU. In fact, you can't change the program, you can't replace the ECU, and you can't use your ECU on any other engine.

Tesla. Everyone's darling. It's a Lotus Elise with an electric motor. Well done, but that's what it is. Their web site actually says that THEY designed the clay body etc. and that the Tesla shares less than 7% of the parts of the Elise. It's actually true, but it's not true the way they claim. The 7% includes the body, frame, chassis, suspension etc. Since the ENGINE has over 2500 parts, and the transmission a couple of hundred more, if you count the NUMBER of parts, it has less than 7% of the parts in the Elise. But it's a slightly modified Elise glider.

But the one that just drives me insane is the charging connector. They are now charging some $3000 for their "charging station", about $1500 for a 240vac extension cable, and $600 for a totally useless 120 vac charging cable.

Let's get a couple of things straight. First, the "charging station" is not a charger. The actual charger converts AC supply to a DC voltage to charge the batteries. It's built into their Power Electronics Module or PEM that contains the controller, DC-DC converter, and charger.

The "charging station" is a barely glorified AC power receptacle. It has a couple of items in it. A ground fault interrupt circuit. A control pilot circuit. And the cord. It's tied to wiring into your electrical panel. It can handle (and the Tesla can eat) 70 Amperes of current at 240 VAC.

This charge station DOES have another magic bit. It's an electrical connector that fits the car. Actually, this connector is made by Amphenol. Amphenol makes probably the best electrical connectors in the world and their major customer is the U.S. government, and virtually every DOD contractor. They make MILSPEC connectors primarily but they do sell versions of them for the civilian market. They are indeed expensive, but well worth it. And they have many standard connectors with four contacts in about that shell size that would work admirably. Tesla worked out a custom connector with them with the proviso that they NOT sell this connector to anyone but Tesla. A Proprietary charging connector?

The idea is patently absurd. They are advocating cities and other public and private entities to build charging stations where you can recharge your electric car. But they want a proprietary connector nobody can buy except through them? It is just ridiculous. Surely they do realize that SOMEBODY else is going make an electric car and the concept of them MONOPOLIZING electric cars in the future is a pretty far reach... Nobody is going to do charging stations with a DIFFERENT connector for EACH type of car?

The usual move is to open source your connector so that as many people start using YOUR connector before the standards bodies can establish standardized connectors. This is how the Hayes AT command set wound up in everyone's modems years after it made any sense at all.

The Society of American Engineers (SAE) is supposed to be out for balloting on the proposed J1772 standard as you read this. This is a five pin connector. It features two large pins for high current AC voltage, a neutral, an interlock pin to disable the car while the cord is plugged in, and the Control Pilot signal.

The Control Pilot is a bit interesting. This is a 1 kHz 12v square wave. The pulse width of this signal indicates what current the charge station is capable of supplying. Your charger is supposed to know and be able to limit itself to that amount of current. The signal is also used to detect the presence of an onboard charger in the car. The charge station doesn't actually turn on the current until the plug is connected and it has determined what level of resistance the charge circuit is presenting to indicate that a car is connected. THEN it turns on the power.

All in all, not a bad scheme. A ground fault interrupt circuit compares current levels in the two power lines. If one is higher than the other by about 10 milliamps, it reads this as a short to ground or the frame of the car. It will disable the charger. In the event there is some chewed or worn cable that does connect the AC to the vehicle frame, this will disconnect the power before you can really be electrocuted by touching the car.

Yazaki so far is the only one making the connector. We talked to them last week and they seem to have had some incident, problem or objection, and they are back to the drawing board on this one. This might indicate a delay with J1772 adoption, or it ight have just been a manufacturing snag.

In any event, a standard plug will happen, and we would think soon. Which makes Teslas activity with the charging connector on their roadster absolutely mystical. In fact, it is not even in their interests so I'm going to claim it is one of the stupidest moves I've seen by an electric car builder. They COULD have been the defacto standard just by filling the vacuum while all this was going on. Instead, they've alienated the people who were their customers. No news there. See Hitlers dilemma.

So we are officially retiring our advocacy of electric cars. Actually, we have refined it or replaced it with a new mission OPEN SOURCE CUSTOM ELECTRIC CARS.

We advocate true electric cars. And we do not limit ourselves to funny little true electric cars like the GEM and the MIEV. But rather to cars you might WANT. Corvette electric cars. Volkswagen electric cars. Porsche electric cars. Lotus electric cars. Even 1965 Datsun pickup electric cars. Basically Custom Electric Cars built by individuals or conversion shops as the CARS YOU WANT TO OWN AND DRIVE. Neil Young has a classic Lincoln electric car. So can you. And we advocate the advancement of OPEN SOURCE components. I don't care if they publish the schematics or software. I mean parts and components that anyone can buy for money without having to qualify as an OEM and enter some secret backroom deal to screw the American public into the floor. An END to this proprietary parts madness. Your "qualification" for a component for an electric vehicle should be your willingness to PAY for the thing. Not your prospects to order 100,000 of them. Five years from now, if you want to upgrade your batteries, you should be able to chose from a NUMBER of vendors who can compete on power, quality, life, price, or whatever they want to offer as an advantage. If they are trying to offer you a MONOPOLY on a part, they should be brought up on charges, fined, and imprisoned.

This goes for batteries, controllers, motors, wiring, and yes, the charging connectors. A 14-50 connector costs $6.97 at Lowes. It will handle 50 amps at 240 volts. If you want to design something that will do 80 amps and has nearly TWO FREAKIN DOLLARS WORTH OF PARTS IN IT to make a 1 kHz square wave, great. That's not a $3000 item partner. I think everyone that touches electric cars should make a profit. I have no problem with profits. Monopolistic "tricks" where "you were stupid enough to buy our products, and now you are going to pay, read the fine print" seem enormously counterproductive to building a loyal customer base.

Jack Rickard

Monday, August 17, 2009

New Video Postings

The juggling of electric car conversion issues, video shooting, and video editing has been a bit of an adventure. Long time friend and business partner Phil Becker used to say:

1. I know how to parachute.
2. I even know how to make parachutes.
3. I have all the necessary components of a parachute.

So this should be simple. All we have to do is jump out of the plane, sew up a parachute, put it on, and pull the cord, before we hit the ground.

In any event, my wife is off to Jacksonville to help her daughter and visit her grandson, and so this weekend I did some video editing. Actually we have a LOT of footage lying around. And we're making good progress on the car. I'm quite excited about it I think it's going to be very good - once the usual set of small problems is overcome.

In any event, Brian's stepson Kurt is actually enrolled in a video production program over at SIU Carbondale, and although just starting out, he's been with us this summer acting as camera man.

I just posted a one hour video on Front End Disassembly. This is basically disconnecting various wires and hoses from the engine and dismantling the front bumper/headlights/radiator to reveal the engine. BMW calls this final assembly position. Incredibly, you have to do all this to do almost anything to this engine. Like change the alternator. Or air conditioning compressor. Or starter. You can't really work on ANYTHING on this engine without completely dismantling the front end of the car. And it is nontrivial. It involves evacuating the airconditioning system, draining the radiator, etc.

In any event, when complete, we should have full access to virtually all components of our system without all this front end removal, or that is my intention.

I have also completed editing another one hour segment on engine removal. At the end of this one, we will have the drive train completely removed from the car, the engine and transmission demated, and it features a discussion of the electric motor and controller we've selected for the car, and points out some less expensive options.

Hope you enjoy.

Jack Rickard

Wednesday, August 12, 2009

Passenger Seat Battery Box

The passenger seat battery box is quickly growing into a "battery module". The more we chew on this one, the more work this one becomes.

We received the Blue Sky 100 Ah batteries from EVcomponents last week.

A lot of good news and some not so good. The specs for the cells are all off size wise. They list very different sizes from the Thundersky 90Ah cells. They are not different at all. They are the same case, and EXACTLY the same size as the Thunderskys. I have no idea why the discrepency.

This doesn't pose MUCH of a problem. The listed specs are larger than the Thundersky's. For example, the THundersky 90Ah cell is 61 mm thick while the Blue Sky is listed at 67 mm. It's not. It's 61mm. Since we had gone ahead and sized for the 67 mm, our box is too large. But not by much. In fact it's kind of nice to have some slop. We can stuff it with foam padding.

The cells tested out very nicely. I pulled a random cell and charged/discharged it twice. I got 106 Ah the first time and 111.83 Ah the second. If anything, the curve is sharper at the two ends than the Thunderskys, and flatter across the middle. It is supposed to be a lower voltage. You charge at 3.6 volts (odd, we were doing that with the 4.25 volt Thunderskys), and you can discharge all the way down to 2.0 volts.

In practice, not so much difference. The curve is from 3.3 to 3.0 volts, almost identical to the Thunderskys. There is nothing there from 3.0 to 2.0 volts. Two amp hours maybe.

But we did graph temperature. At a 99 Ah discharge rate over the course of a little over an hour, the Blue Sky because noticeably warm - 40C. Warmer than the Thunderskys.

Our largest box, which will now be on rails over the passenger seat, holds 55 cells.

This makes for a pretty "dense" pack of cells. In the Speedster, almost all our cells were in small boxes, and by far the majority hung out in the airstream below the car. So we didn't need to worry about cooling.

On this box, with this density of cells, note that the cells in the center of the box are quite insulated from the edge of the box by the other cells. And, the box is in still air in the car interior, no exterior air flow to carry away heat.

Heat is a funny thing. These cells start to suffer at 55C. With 40C with an hour of 100 Ah discharge, this sounds like we are in fine shape. We aren't. With the packing of the cells close together, and no air flow, we have just built a perfect way for heat to build up in the center of our box and it is quite cumulatiive. If you don't give it a way to escape, it just keeps building up.

With a number of cells in smaller boxes where the gas tanks were and where the spare tire is, THEY get plenty of cooling from the air passing over the surface of the box. And no cell is very far from the aluminum surface of the box.

What this sets up is a huge thermal differential and it is a RECIPE for cell imbalance.

So we have to cool the cells somehow.

The solution is to add a cooling fan to the box.

On the BMW version, they added cooling fans to the top of the battery pack. I'm not happy with that. First, we have a LOT of batteries in the gas tank area and spare tire area that BMW didn't use. This will give us a much lower center of gravity than they enjoy, and I assure you a HUGE impact on vehicle handling thereby. But more importantly, our box over the passenger seat then doesn't stack nearly as high as theirs. Even with the rail system, it will sit about a foot above the rear seat bottoms.

We are going to have a large flat surface to the top of the box, basically a LID on it. This will actually work fantastically to augment our cargo space. We are going to retain all the rear cargo space we already had with the Clubman, but we lose the additional space you get when you fold down the rear seats. This is partially offset by having this flat sturdy lid 10 inches above where the back seat bottoms would have been. This makes a perfect shelf for a brief case, small purchases, jackets, purses, wine bottles, notbooks, etc etc. And it allows us to load longer items like a two by four or something from the hardware store from the rear of the car. So I don't want a fan there. I want it flat and strong.

We have rails on both sides of the box. I don't want a fan at my elbow on the front edge of the box. So the ideal placement would seem to be in the rear cargo area at the rear face of the module.

And the fan needs to be substantial. We selected a COMAIR model JQ12BA available on eBay

This is not a little computer fan. It is a 25 watt unit drawing about 2.5 amps at 12 vdc. It puts out 235 cubic feet per minute and is about 150 mm square. It has some nice bearings in it resulting in a fairly quiet operation at 54 dBm. They run a little over $20.

We'll mount this on the aft end of the box by building a little diamond plate enclosure with some aluminum screen over it. This is mounted to the box and a hole cut in the box end panel to allow flow. We mount the fan so it sucks air INTO the box.

I'm not really sure how much heat will be generated, and under what operating conditions. I know it won't generate any while sitting at a stoplight, and quite a bit while accelerating, so we're guessing here. Let's not guess.

We'll put it on a thermostat. Again we found a very nice Hayden Automotive Model 3653 fan switch on eBay

This unit is actually a bit more expensive than the fan itself. But it allows us to set the turn on temperature anywhere between 32F and 240F and it features a remote sensing probel. Designed to be put on the radiator of a car, and to drive a radiator electric fan, this unit is well able to handle the 2.5 amps current we need to drive the fan. Better, we can mount this unit on our fan enclosure, and drill a small hole to route the PROBE into the battery box. We can then put this temperature probe dead in the center of the battery pack.

In this way, we can set the thermostat to turn on at about 100F, and when the battery case temperature reaches this, it will switch on the fan, which will then PRESSURIZE the box.

Why are we doing it this way? Well, the next step is to drill some very small escape holes in the aluminum bottom of the box. And by clustering these holes mostly in the center of the box, we direct the cooling flow past the center cells more than to the cells on the edge. We'll sprinkle a few along the edges as well.

The cells themselves feature a ribbed structure that creates channels just for the flow of such cooling air.

By having the fan blow in, the heated air will be expended DOWN into the cavity where our gas tank boxes are. While this may heat those cells a bit, probably not. This area is open to the underneath of the car, and those batteries are in the airstream.

In this way, we avoid bringing heated air into our passenger compartment, when we very well may be spending more energy to run the air conditioner. And by clustering more holes in the center of the pack, we can modulate which cells get how much flow to some degree.

Finally, the temperature probe is metallic and offers the potential to short some of our cells. So we have to sheath it in heat shrink tubing and put a hot air gun on it to create an insulating area over the probe piping. We'll leave the end probe itself bare, and stick it down between the battery cases in one of the channels formed by the cell ribs.

In this way, we can draw air from our passenger compartment, circulate it between the cells, and exhaust the heated air DOWN and out of the car. Our rail system still works. Our flat top cargo area on top of the box is intact, and the system only uses power if cell heat becomes a problem. If I was wrong and heating just isn't an issue, it will never come on.

But I'm not usually wrong. The 235 cfm may be over kill. The entire box is 9 cubic feet. But we are going to obstruct the fan with an aluminum screen, and the batteries themselves. It's doubtful it will actually put out 235cfm in operation. And overkill is always appropriate.

Finally, I'm still not onboard with the shunt BMS issue and most of the monitoring circuits out there. But we have a LOT of cells in this pack - 112. And not only can my thinking change, but the available BMS options seem to be growing and some show some promise. So we've decided to go ahead and wire the car from the get go with 16 gage wire to every cell in the pack. What we are going to do you may not want to deal with. It's a bit expensive. But we are using some 19 pin MILSPEC Amphenol connectors. We'll mount these to the boxes with the wiring running to each cell within the box This will allow us to PLUG INTO the box with an external maintenance shunt balancer, future BMS circuitry, or just a measurement box. My initial plan is to build a small box with a huge Soviet rotary switch and Digital Multimeter with a couple of connection terminals. This wll allow me to quickly cycle through the cells checking voltages, and If get to one with two little or too much in it, manually connect a load to bleed off some energy, or manually connect a small 12v charger to add some energy to individual cells.

I'll make this box with a plug to connect to these heavy duty amphenol connectors. Amphenol 97-3102A-22-14S to be specific? Why this one? We got a deal on 60 of these at $55 on eBay. They run about $24 apiece on Digikey and indeed we had to buy the plug full price. There is no magic on 19 pins. I suppose if you get to a size that would accommodate 56 pins, to do it in one connector, the pins get too small to carry any current. And if you have a smaller number of pins, you need a lot of connectors. It's just a judgement call. But in truth, the eBay deal on a sack full of them was what drove the decision.

Jack Rickard

Tuesday, August 4, 2009

More Batteries and Boxes

I also completed a new battery box for the rear cargo area. This 34 1/2 inch x 18 inch box is only 10 inches deep. We cutout the lower section of the cargo area where the spare tire tub is and cutting it out was quite a little task. We use a thin carborundum blade on a little DeWalt 4 inch grinder to do such work. But this hole, complicated by the round tub extending downward to accommodate the tire, had Brian and I taking turns at the terror.

We put some 1.5 inch aluminum angle iron on the front and rear long edges of the box at the top. We pushed the box up against the hole from the BOTTOM, and lipped a piece of aluminum stock over the front edge from the top. This allowed us to drill some holes and basically make an aluminum sandwich across the car at the front lip of the hole.

On the aft end, we could not access the top for a bolt because a member under the door jamb is formed. We drilled a 5/16 hole and tapped in 3/7 bolts - five of them, to hold the back edge flush. Then we took some pipe strapping and ran straps from the structural member on each side, lengthwise under the box. This should be reasonably sturdy.

The box will hold about 265 lbs of batteries, or some 39 cells. That's a 14 kWh pack just in the spare tire area. And this leaves room for some Brusa chargers on top, and then the standard cargo area floor panel.

At this point, we could almost put the rear seats back in and have an untouched interior, with all cells below floor level. The 24 cells in the rear seat area total 8640 wH so we have 22640 wH in the car entirely below floor level. Not bad. That's about the size of the Porsche 356 entire pack.

And indeed, that would give us a range of about 75 miles and a working voltage of 226 volts. That voltage is a little lower than we can deal with because as the batteries discharge, these Blue Sky's are innately lower voltage than the Thunderskays and you can take them down as low as 2.0 v which would be dramatically below the 180 volt minimum for our controller, and coincidentally, our DC-DC converter.

So the plan is to build a 29 inch by 30 inch box that will sit atop the back seat area across the support members. This baby will hold 55 cells for an additional 19,800 watt hours bringing our pack total to 42,400 wH and 424 volts. This is a little high on the voltage, but the Blue Skys come down to 3.4 volts essentially as soon as you remove the charger. That's more like 401.2 volts or 1.2 volts over our controller maximum. I think that dog will hunt, just barely.

Better, again assuming 300 wH per mile, that's a theoretical 140 mile range with an 80% DOD at 112 miles. I actually think we'll average somewhere between 250-280 wH per mile without air conditioning or heat on. So I think we're looking at 125-130 mile real range, dropping to 110 or so with air conditioning. This should be a serious upgrade from the BMW Mini-E with regards to REAL range (as opposed to press release range). And this makes sense. They have a 34 kWh pack and we're coming in at about 42.

As Ron Popeil says, but wait there's more.

I had planned the Porsche originally to use 160 Ah cells. But they were just too big. The car had so many compound curves that we kept getting beat out by a 32nd of an inche everywhere we looked. We dropped to the smaller 90 Ah cell and of course used more of them, but they fit better because of the smaller granularity.

So going to the Mini, I started with an order for 100 of the Blue Sky 100 Ah cells. You have to order these three months ahead of time.

Well, the Mini isn't a Porsche. In fact, once you get inside, it is a bit boxy in shape. And so we're winding up with these hugish rectangular boxes.

So while we COULD make our large box 10 inches high, I'm going to fabricate it to 13 inches.


This is cool. As it turns out, I can put 40 of the larger 180 Ah Blue Sky cells in the same space as the 55 100 Ah cells that way.

Additionally, I can put 20 of the 180 Ah cells in the back seat boxes in place of the 24 100 Ah cells. And indeed, it appears I can put 24 of the 180 Ah cells in place of the 39 100 Ah cells in the aft box - although they will stick up an inch above the box rim. The 180 Ah cells are 11 inches tall.

What this means is that we could ( or you could if you like) replace the 118 cells of 100 Ah each with a scant 84 of the 180 Ah cells. This results in a nearly perfect pack voltage of 285-302 vdc. But it gets better. Because of the much larger current capacity of the 180 Ah cell, our pack storage rises to a whopping 54 kWh and our range is starting to look like something around 180 miles. Yes, that's right, while BMW suffered some pretty serious embarassment about their puffed up range figures once the car hit the road, the Clubman we're doing would be able to do a smart 150 mile range WITH THE AIR CONDITIONER GOING FULL BLAST THE WHOLE WAY.

And with a little careful driving on a pretty day with the air con and heat off, I dare dream of a solid 200 mile run.

The only fly in the ointment, weight. Along with the additional power comes more weight. Our 750 lb pack will swell to about 1050 pounds using the larger cells. We should still be below gross, but not by much. The car won't accelerate as smartly, by about 300 lbs, and so there is a price to pay.

Speaking of prices, our Blue Skys at 100 Ah are justt a little under $14,000 with shipping. Going to the 180 Ah cells will run us up to about $16,500 with shipping. Neither count spares. You want to order spares because you need to have some cells on hand if some go bad, and ideally you want them from the same manufactured lot. A year later, your cells may not be available at all and three years later they probaby won't be. So we always order a few extra.

So our battery boxes are by design meaured out to accommodate either cell size. Your mileage may vary.

Finally, Brain has something special up his sleeve.

Recall that we are going to mount the largest battery box, 30 inches wide and 29 inches deep, on TOP of the back seat area. Of course, the two smaller boxes reside where the gas tank did, beneath the seats. What this means is that we'll have to remove ALL the batteries from the top box, all the straps and connections, and the box itself, to access the lower batteries.

As I HAVE been known to make changes after we have the car all put together, Brain has been grumbling about this for a month now. He found a set of rails used by railroads incidentally, to make battery boxes slide out affairs. These rails cost about $500 delivered, but they sport a 1000 lb rating. And he's dead set on designing a rail system for the upper box to allow it to SLIDE back into the cargo area, over the batteries THERE, revealing the lower battery boxes. Much like a kitchen drawer.

I think is going to be hard. I always think mechanical things are hard. That's why we mostly have Brain do such things. And he has that thin-lipped look over this one that means he's pretty set on it. Me? I'll watch that one on video, thanks.

Jack Rickard

Batteries and battery boxes

We've been working on battery boxes. I made two out of 0.63 diamond plate 18 x 13 inches and 13 inches deep. These will go in place of the gas tanks under the rear seat. We did two to retain the parking brake cables that run from the center console to the rear wheels.

These are very nice cables. To move them would require having new ones made. And these are just VERY nice with some sort of sheathing I really like and the parking brake works very well. So two boxes. This will allow us to stiffen a bit too.

Brain cut a single hole to accommodate the two boxes and installed a piece of 1x1 12 gage steel tube 20.5 inches long in the center. The boxes fit pretty well and we placed a piece of angle iron on the front edge to bolt it to the sheet just aft of the cross member.

These newer cars have a kind of unibody design and Europeans love to do this around a "pan". We have just cut a hole in the pan basically.

By sizing the boxes and using the piece of tubular steel between them, we basically fill the hole in the pan, and regain the stiffness it provided. Probably enhance it just a bit.

I lined one box with ABS and the other with bakelite. I don't really like either one. The bakelite cracks around the rivets. The ABS I suppose is alright but not overwhelming. The issue here is to insulate the boxes. Since our batteries are nominally 9 inches high, they will sit DOWN in the boxes a couple of inches. This gives us a good opportunity to get a wrench between a terminal and the inside wall of the box. That's not good. So we insulate them.

Each of the two boxes can hold 12 cells.