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

34 comments:

  1. Hi Jack, I must say having lived through a controller failure that resulted in a full on condition, where the contactor also welded on, is an experience that I do not want to relive. I thought with three levels of safety, fuses, contactor and controller relay I thought I was safe. I later put a red handled disconnect cable attached to a properly rated Anderson plug. Fortunately it has never happened again, but if it does I hope we are ready for it.

    You are right with the current you are talking about in the Escalade you have serious power that can weld or cut any steel.

    ReplyDelete
    Replies
    1. I like to refer to what you are talking about as 'vaporizing' the bus, wire or whatever else you are dealing with...lol

      Delete
    2. David:

      Out of the pot and into the fire. I know of four fires directly attributable to Anderson plugs. One happened in front of me. And Ron Erb of St. Louis handled the graphics at the trial for the one here in Cape that burned down an entire factory.

      Good luck with THAT. I've been noodling some sort of old fashioned knife switch, but nothing promising yet.


      Jack Rickard

      Delete
    3. Hopefully you can still kick it into neutral if the power is on?

      This idea is well out of the loop but if you can weld any metal.... Consider an explosive cutter or bolt. Sounds mad but maybe have a chat with a manufacturer?

      I'm feeling lucky building for 250A which is double of the grenade current.

      Delete
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  3. Many thanks for the show again this week guys.

    ReplyDelete
  4. Hi Jack,
    Have you mounted any of the batteries like the Calb 180s sideways in any of the cars or done any testing where they were laying on their sides during the testing? What is your opinion on cell orientation other than standard vertical installation?

    ReplyDelete
    Replies
    1. We have 17 CA:B 180's in Speedster Redux that are laying flat on their sides, jiggling and vibrating and heating and cooling down the road. No anomalies after 1 year.

      I do not think it matters.

      I would not hang them upside down as the liquid would block the vent hole.

      Jack Rickard

      Delete
  5. Yes!
    The old music is back!

    Good show guys!

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    1. This comment has been removed by the author.

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  7. How valuable would a dual stator brushless motor be for EV land?

    custom made motor with dual stator:

    http://www.sineton.com/web/images/sdg%20slow%20transparent.gif

    Harkening back to an earlier discussion, an interesting tidbit on the Model S:
    http://www.treehugger.com/cars/tesla-model-s-electric-sedan-has-greater-driving-range-expected-320-miles.html
    "...the Model S having the best aerodynamics of any sedan in its class with a Cd of approximately 0.24. Model S aerodynamics are so optimized that the total aerodynamic drag force experienced by the car – which is significantly larger in frontal area – is almost the same as a Roadster for a given speed."

    ReplyDelete
  8. Are you going to energize the low fan on the climate control with the charging system so that it warms up the cabin and not just the dashboard?

    ReplyDelete
  9. Recent F1 GP Spain had a surprising winner. Even more shocking was the following incident in Williams' garage. I first suspected KERS and its BMS had something to do with it, only to find out not being alone in those fears: BBC Sport

    ReplyDelete
    Replies
    1. Andy. I think you are getting confused between the Williams KERS system and their flywheel business.

      Flywheels are (or were) allowed in the F1 rules when KERS came in in 2009. In 2009 several teams developed KERS systems, but very few of them actually ran them during the season because they were costly and were one more thing to package. In fact they compromised the aerodynamics of the cars. That season no team that ran KERS did very well until later in the season.

      Williams developed a flywheel KERS system for 2009 but didn't race with it in the season. This was refined, became a business and later ended up in Porsche's 911's GT3R which I believe was raced in Le Mans. Certainly it did several endurance events.

      http://www.popularmechanics.com/cars/alternative-fuel/hybrids/porsche-911-gt3r-hybrid-flywheel

      This year the same flywheel (or something similar) is in Audi's LMP1 car. It will race at Le Mans later this year.

      http://www.autoblog.com/2012/02/29/audi-unleashes-hybrid-awd-powertrain-on-le-mans-with-new-r18-e/

      All but 2 teams in F1 now race with KERS, and they are all battery based. I don't know what type of battery chemistry Williams uses. I know that Mclaren uses A123 batteries.

      If your interested in the Williams flywheel business then you can find out about it here:

      http://www.williamshybridpower.com/technology/whps-flywheel-technology

      On the fire, I think it's probably a bit early to assign blame. It happened when a mechanic was emptying fuel bowsers. KERS could well be the cause, but who knows at this stage.

      -Nick :-)

      Delete
    2. Thanks Nick for useful links! I simply had a hunch, being a F1 fan, following it for decades without recalling any similar incident.

      Knowing KERS were back, I googled Spanish GP 2012 and KERS, yielding in reports indicating possible cause of the fire.

      Let's wait and read the official findings. It wouldn't make me any prouder if having guessed right. KERS proven guilty would be a hard blow for electrification of cars. Lots of eyes are focusing everything around F1.

      Car fires are very bad publicity.

      Delete
    3. Apologies, I know nothing of F1.
      Never occurred to me they would use batteries as a third party on what is basically a "super capacitor". Still doesn't.

      That WHP flywheel motor looks cool as a weight saver and it rotates fast!

      I worked with bowser's and can testify fuel flowing under pressure through a non conductive pipe will create scary voltages if not properly Earthed across.

      Delete
  10. Pretty clever terminal cover idea:

    http://thsev.blogspot.com/2012/04/vacuum-forming-terminal-covers.html

    Would make a nice a nice little garage-based business, opportunity, too.

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    Replies
    1. The first generation of the Enginer Plugin Hybrid Conversion kit had 40ah Thundersky batteries. They came pre-assembled with jumper straps and BMS wiring in a wooden crate. They also had a gray soft vinyl insulating cover that snapped on top of the straps. I just wish I could find them for the bigger cells.

      Covers like these are an absolute necessity. 99.9% of the time they are a pain in the butt and just plain in the way. But that 0.1% when a tool or other piece of metal came to close makes them pay for themselves in about 0.05 seconds.

      Delete
  11. Hey Jack, un-related question, what beer were you drinking? I didn't recognize what part of the label I could see.

    David

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    Replies
    1. Nice one David,

      JACK!
      Don't say a word until they sponsor you.

      Delete
    2. Fritz Root Beer believe it or not. A microbrewery soda company in St. Louis has revived a brand with a recipe going back to 1947. I've become addicted to it.

      Jack Rickard

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    3. Good for you for supporting not only an American company, but a local one as well!

      Delete
    4. Got me!
      I'd same with Allgates brewery.

      Delete
  12. somewhat interesting video about the powerelectronics in a prius
    http://www.youtube.com/watch?v=UxuqHcUbSQ0
    including 3 phase controller for aircon pump

    get it before Jack deletes it

    ReplyDelete
    Replies
    1. Jack deletes video's?

      An old Prius could make a worthy scrapheap challenge car into electric but I very much doubt it's easy. The last version is a mains plug in like the GM Volt.. All the toys are there possibly at a knock down price..

      Prius's have terribly thin bodywork to keep the weight down so they don't weld well. Garages are quick to scrap these after any bump concerning body structure.

      Now I wonder what is the power output of the motor unit?

      Delete
    2. Of course its not interesting to you with your purely voyeuristic tendencies. I have no idea why you bother on here at all!

      This system is down to good and reliable engineering. Understand that.

      And no, it's a great format for a light weight EV who's sum of parts could be obtained very cheaply.
      Thanks for the heads up.

      Delete
  13. How many charging points here?:-
    http://ow.ly/i/DiXX
    Effectively knocking 10% off the hotel bill.

    I nicked this "heads up" humour from Kevin Sharpe of the UK who's doing a great job as a Tesla driving converted electristian with 30k miles under his bonnet.
    http://zerocarbonworld.org/
    http://openchargemap.org/

    He's already installed 174 of 1k (13A+32A) free charge points in the UK. Obviously making a case for more ;)

    Money talks.
    Here in the EU its $9/Gallon. A free recharge at a pub equals spending nothing for cooked food, wine, entertainment and beer. That's a better quality of life for less money.

    Politico's read this.
    The international balance of payments gained by NOT exporting our money for liquid fuels and the oil wars means the so-called EV rebate is not sufficient. Do the maths, the monetary savings are a profit against EV users.

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    Replies
    1. I so wish blogger had a like button as fabebook does; I would definitely be liking your post Andyj!

      Delete
    2. (****)
      Thanks Cory.
      Sorry but Dad told me not to send any more checks in the post because Santander Bank will topple if I keep it up.

      Hey, maybe all those recently millionaire'd ex-CIA people who run spyface.inc can help while hiding their offshore drug running accounts, along with Willard Romney/Obamas bottomless access to the $tolen stuff. ;)

      Others must be getting sick of my almost constant posting. Stop encouraging me, haha.

      Delete
  14. Jack you have commented about A123 being in business with SAIC, I came across: this:

    http://www.activistpost.com/2012/05/is-gm-becoming-china-motors.html


    regarding SAIC and their GM partnership.

    ReplyDelete
  15. Excellent show this week. Once again, batteries and brushes top the list. 13% Gain on the ground real world is very nice. And just by adding brushes.

    Pete :)

    ReplyDelete
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    ReplyDelete