Tuesday, February 28, 2012

Flatenem Series A123 Module

This week we heard from John Hardy of the Midlands in the UK. John is about to publish a new book titled ICE FREE specifically on the topic of converting your car to electric drive.

He suggested a flat pack design and while a little rough and perhaps a little obvious, we pretty much liked the idea.

We've been talking about a flat pack for a few weeks to put under a Smart Car build or to test an A123 pack under a Speedster. This concept does well enough.

I suppose we jumped the gun describing the book, but I wanted a little context for the conversation, like who he was and where he was from. The book came up. The problem is it isn't precisely released yet, so you can't have one. But it should be on Amazon soon.

The other aspect we went on with in this video at some length and probably at some tedium was the JLD404AH Intelligent AH Meter. We actually found this meter BY ACCIDENT in a box of stuff we had ordered a year ago. We more recently found this DC Voltmeter that allowed you to set relays based on voltage and we kind of designed a bottom balancing circuit out of this very simply by connecting that control relay to a contactor and a 0.1 ohm 250watt power resistor. This little "bleeder" would bleed a cell at about 30 amps until it gets down to 2.50 volts, or really whatever value you set, and then disconnect the load.

But while rooting through a box of similar meters, we found this Intelligent AH Meter version. We had never hooked it up. And it was no longer available, and worse the documentation was no longer available.

But it was a pretty similar meter and we gradually were able to piece together how to work it. incredibly, the relays could be activated by Voltage on those as well. In fact, you could tie the relays to voltage, current, ampere-hours, or time in a way that is so flexible, you really can't quite work it all out mentally. It actually lets you set TWO levels an activation threshold and a deactivation threshold kind of like a thermostat.

A thermostat? Well yee. THis is the easiest example, which is unfortunate because this device does NOT measure temperature. But let's say you wanted to turn on a heater to bring a pot of water to a certain temperate and hold it there. Wouldn't it be nice to have a relay that would run the heater. IF the water is below 100 degrees for example, it energizes, turning on the heater. When it reaches 140 degrees it reenergizes, allowing the temperature to fall. But at 100 degrees, it comes on again. In this way, it cycles but without hystereses. It has a band gap.

That's how these relays work. And you can set them on an ascending curve or descending curve. And they can work on voltage, current, amp hours, or time.

The flexibility of all this hurts the head, so I won't pursue it. But it makes it a very handy little device.

We went back to the guy we bought this from and had a couple of weeks of discussion to get him to reprise it. We ordered a dozen, and put it in the video which we released Sunday noonish.

We also put a description and a way to order on our web site online store. By Monday morning, we had sold twelve. Of course, I already had two of our dozen on the lab bench. So we're not only sold out, but scrambling to get enough to fill the current orders.

This basically illustrates the ongoing need for instrumentation. We recently reviewed Valery Mitzikhov's EMW Dashboard. It turns out this hardware isn't done by EMW at all, but rather by Dmitri Butvinik, an online impresario we've crossed swords with before. The hardware literally came apart in our hands. And now that we know where its from, the odds of fixing the 5% accuracy problem are essentially none. I played with some GOOD hall effect sensor s a year ago and found accuracy to be a devilish problem. I assumed Valery, with a Phd in Physics, had some magic sauce on this topic since they used a hall effect sensor. As it turns out, no. He has simply bitten on a Dmitri device assuming it would report accurate current. It doesn't. And it can't. In fact it's a very cheap hall effect sensor to begin with. Dmitri and his followers are big fans of cheap.

In any event, we're going to piece together this AH meter, a 12v DC-DC converter to power it with full isolation from your pack voltage, a shunt that COULD be mounted with a bit of additional work, and a Operations Manual that yours truly has cobbled together to serve as some DOCUMENTATION for this device.

The device uses a shunt. We get rather inexpensive shunts from China that are 75 mv. Let's talk a little about current measurement. Everyone KNOWS all this, and in most cases know at least part of it wrong.

Basically to measure current, the most accurate and temperature stable way to do this is with a known small value of resistance. According to George Ohm, the amount of current through a given resistance is a function of the voltage you apply. Conversely, if you measure the voltage across a known resistance, you can calculate the current flow.

To measure high current levels, you want a very LOW resistance value so you dissipate a minimum of current as heat. The power dissipated will be a function of current level, times resistance, squared. So if you have a high level of current, you must have a very low value of resistance.

In the U.S., most shunts are machined to have a resistance where the full current level will cause a voltage drop of 50mv. For example, you might have a shunt that is rated at 100Amps/50mv. That means that if you run 100 amps through it, you would read 0.050 volts or 50 millivolts across the terminals as the voltage drop across that resistance. If we take that voltage and divide it by the current 0.050/500 we get the resistance of the shunt resistor - in this case 0.0001 ohms or 0.1 milliohms. Indeed a very small value. But if accurate enough, very useful.

Chinese meters almost always specify 75mv shunts. And so we are coupling this meter with a 1000A/75mv shunt. In the meter, there is a APuH value where you enter the full scale value of current - 1000 amps. And of course it has a fixed 75 mv input.

Because of this full scale variable, we can actually use ANY shunt with this menu. What you are setting is the number of amperes to display and to count in the AH calculation when the meter measures 75 millivolts. If we had a 500A/50mv shunt for example, it would never exhibit a voltage drop of 75mv until it carried 750 Amperes. No problem. Hook it up to the meter and enter 750 as the full scale current value.

Similarly, if you had a 100A/100mv shunt you wanted to use. How many amperes should you enter for 75 mv? Well, how about 75 amperes?

There are a couple of things to keep in mind here. First, it is just a fixed value of resistance. The maximum current that can be measured is a function of the METER primarily. In other words, we don't know what this meter does with inputs above 75 mv. So you want more or less to size your shunt so you never exceed the 75 mv.

The other criteria is that the power dissipated DOES heat the shunt slightly. If you run 1000 amps through a 100 A shunt, not good. It will heat it and that will affect accuracy and too much heating and the accuracy goes off permanently. But it is NOT precisely a problem to run 2000 amps through a 1000 amp shunt, or 1000 amps through a 500 amp shunt briefly. We just don't' know exactly what the meter is going to do with the information.

The other proviso is that the LOWER you go the more accurate you become. There is no point using a 1000 amp shunt in a buggy that will never do more than 200 amps. The scale is 75 mv to 1000 amps and so 1 mov of change in voltage represents 13.33 amperes. At a 300 amp shunt, each millivolt represents 4 amperes so you have a much more accurate scale, and you're not going over 300 amperes anyway.

Similarly, the 75 mv shunts are more accurate, all other things being equal, than the 50 mv shunts. You are simply using a wider voltage drop to represent the same change in current.

The EV community has faced a real challenge in finding current measurement and particularly kWh or AH accumulator/counters sized for our use. The only other market for such devices, aside from nuclear power plants, are solar power systems. ANd they tend to be 50 amp and 48v scale items. Similarly, some attention is paid by large boat and recreational vehicle owners. BUt again, 48v and 50amp or 100amp is pretty much the game there.

And so if you want to accurately measure 500 or 1000 amps and you have a pack voltage of 150 or 250 volts, there is really not much out there to find in the way of generic measurement devices.

The ability to measure 50 mv or 75 mv is actually chip based. There are some phenomenal operational amplifier chips out there to do this and have been for many years. The problem is that they are now ENTIRELY surface mount devices. I cannot find one that will measure both directions and provide a useful output in a larger chip format. And I cannot SEE much less solder SMT devices.

Hall effect devices CAN output higher values such as 0-5v or 4-20ma or even 0-10v that can be read with standard A/D circuits in multicrontroller devices such as Arduinos. But they become quite nonlinear outside of their defined range, and it is quite hard to find the zero point, even with temperature compensation. And so at these scales where we are charging at 25 amps and driving at 1300 amps and need to be able to measure both accurately, that can be difficult to do with hall effect devices. And not possible at all with undersized inexpensive ones.

We have used the Xantrex device for several years. It is kind of pricey at $250-$275. I cannot SEE the display in any lighting conditions. And the little terminal board in the back is very difficult to poke a wire into and get it to stay put. But we've lived with it. THe JLD404AH is the first meter I've found that does what I want, allows control based on AH, and that I can read.

But given the immediate dozen sales, I'm guessing we need to keep looking. Apparently, we are NOT the only people looking for instrumentation.

We'll try to expedite all current orders and get new stock in soonest.

Jack Rickard

Wednesday, February 22, 2012

The Cape Girardeau ENDURO.

Of batteries and range and endurance and costs and complexities and batteries....

This week we continue A123 module obsession AND we do some minor work on the Cadillac Elescalade.

Apparently the A123 cell thing is of intense interest to at least some segment of our viewership. If developed, it would appear to offer some alternative cell strategies. However, these are not entirely without difficulties.

A couple of items. We continue to have lab anomalies I'm hesitant to report in detail. The reason I can't share these with you guys is you guys. You shred me every time I do with a laundry list of how I SHOULD have done the test.

We are accustomed to testing large format cells - 160 Ah and 180 Ah units with the odd 400 Ah cell thrown in. It's true I've done quite a bit of work in the last year in pairing two 90Ah cells for 180 Ah.

Suddenly dealing with 20Ah cells is just a different world. 1/2Ah or even 1 Ah isn't anything on a 180Ah cell. It's not really much of anything on a 100 Ah cell. It's a LOT on a 20 Ah cell. And so our procedures and test equipment, which I am ALSO always testing, gets a little bollixed up on what I'm doing at any given moment.

IS the decrease in capacity from 19Ah to 17.8 Ah due to test equipment or have I damaged the cell? Or not fully charged it in the first place?

As everyone who has gone into real cell testing has discovered, defining fully discharged OR defining fully charged is actually a little squishy. You can fully charge the cell using anything you want. Let it rest a couple of hours, and it will take more using the same metric. Similarly on discharge. A "bit more" starts to get hard to define at 20 Ah.

But we have had some mysteries. Like bottom balancing four cells to exactly 2.50 volts and then charging the pack. When we discharge it, they are all out of b a lance again. So we repeat the process and they are BACK in balance again?

How about draining a cell to 2.50v and then leaving it overnight with NOTHING connected to it. To find the next day it is ruined at 0.85v. Wait a minute. Recharged it works fine again????

We do not see these sorts of things with the larger prismatic cells. I would characterize these A123 cells as about as stable as a burlap sack full of cats. But I don't know if that's a good thing or a bad thing.

More reality. Yes, I know you all are all packaging engineering experts and I was made to WATCH the other kids during art class in the second grade. But whatever I do adds 1/3 to the weight and volume of A123 cells. You can pretty much figure that if it takes 10 cells and they weigh .496grams each that will be 4.96 kg. My package will be 4.96 x 1.33 or 6.6kg. So any increase in energy density you "imagine" from these cells is not only not possible, but if I'm doing the packaging there is a penalty here. A half sized pack doesn't get you half the range. It probably gets you 1/3 the range. So your 100 mile car with a pack that costs slightly MORE than half a pack probably actually delivers 1/3 the range or 35 miles or so.

Similarly the costs. Yes, it's $100 for resin. Let's try polycarbonate at $150. Or straw, at $90. Whatever I do, at least in prototype, dramatically increases the cost of these cells which STARTED OUT very pricey themselves. As their price has fallen, the percentage devoted to connectors and resin and molds and so forth has risen as a percentage.

So despite my obsession with these cells and posing them as a low cost alternative because of their high power output, reality keeps intervening to make it clear to me that this will NEVER be my choice for cells in a car. The large format leggo block 180Ah CALB is the battery of choice for me in designing a car at the moment. And I would list A123's as "problematical".

But that's not to say some effort making them LESS problematical isn't in order.

On the good side, despite my totally ruined mold, the 13.2v 120 Ah battery is testing well at about 113 Ah without any real overcharging or over discharging. I have mentioned some oddities but the cells seem to still be ticking along. But from what I am seeing I can see new insight into why some are so focused on top balancing BMS systems. They are a brute force way of making these cells do your bidding or appear to. I suspect there is another better way, but I'm still looking for it.

And the 13.3v package is looking pretty good to me in camp green and black. It is a little heavy at 36 lbs was it? But obviously durable. All cells are available at the top, perhaps too much so. A dropped wrench on this one would be fireworks. I might put some effort into a soft rubber "cap" made out of the silicon rubber mold material. Pour it on, let it cure, and pull it off. Then you make your connections and mash it back on to secure the terminals. Kind of a soft rubber hoodie for a battery.

All this is kind of stalling out our larger projects. But I confess I am having some fun. ANd it feels like we are just doing some things very differently from the OEM's and the very elegant high tech style so in vogue. But I kind of think "car stuff" out to be a little more rough and tumble along the lines of the SLI battery, which has evolved over 100 years - in fact we missed the anniversary of Kettering's electric start automobile 100th anniversary this week.

The 1912 Cadillac Touring Edition was first to eliminate the hand crank and opened up driving to everyone. Cadillac founder Henry M. Leland, who had already pioneered electric lights and electric ignition on his cars, worked closely with Charles F. Kettering, the inventor of the electric starter, to incorporate the device into his cars. The electric starter also was GM’s first electric motor – a core business today anticipating the growth in the electrification of the automobile.

Point is, that battery has been "evolving" for a century now. It looks the way it does for a reason, or a million reasons. It arrived in Darwinian fashion to be exactly what it is. And so using that as a starting point is not a bad, if slightly blind, strategy.

But new ideas are good too. And so we are casting about. We have used several. We used the alternating cells on the nylon threaded rod. I liked that, but it buried our terminals. We kind of stress tested it, which on reflection may not have been good medicine. But it got us to a pretty gruesome failure quickly which prevents spending more time on such a thing and then having it blow later.

We then mimicked the individual cell thing we already get from China. A word about that. I've heard a lot about just using similar boxes and similar terminals from China. Well, I've looked for them on Alibaba and I can't find them. If you can find who makes those, yes, I wold prefer to just buy the existing hardware and plastic extruded boxes, even if I had to cut them down a bit. Haven't found a source.

And this to the concept of ideas. An idea is not a general piece of shit on a napkin. They work better with measurements, specific product recommendations, and sources. "Expanding foam" is fine. But there are a brazillian. Similarly urethane resins, polycarbonate, silicon rubber, etc. ALl have different cure times, shore hardness, tensile strength, exothermic reaction, temperature tolerance, etc etc. ad nauseum.g

This is why I can be a little short with some of the arm chair theorists. If you've really thought this through by looking up at the ceiling, you're not in the same category as someone like Nabil or Peter who have hooked some of this up and then had an idea they don't have the resource to implement. And then if you're a Damien Maguire or Paul Holmes are someone in that category, just send me a list of parts you need and a delivery address and we'll wait for YOUR video.

I did include a segment of Damien Maguire's in this episode. If you were looking for someone to liven up the pace of conversation, Damien is more in my camp than out of it. But he does some interesting and of course tedious work on bottom balancing and shows you the ugly end of it on his BMW and so I included the entire video he uploaded to YouTube. I think he will find bottom balancing surprisingly effective in a lot of ways, and no easier than he thought.

I was reminded by the head of REAP systems, a leading BMS developer at the EVCCON that while bottom balancing might be more effective than top balancing, at least arguably, it was not very convenient. My response to him, and to Damien, is that in all the battery testing we've done, across several years and now locations, I've never once had a SINGLE LiFePo4 cell express ANY interest at all in my convenience. They are just curiously agnostic and apparently have no feelings for MY feelings whatsoever. But on the other hand, if I ask one to do the dive for the cause at my behest, they will head toward zero volts so fast you think they actually LIKE to give their lives in order to save mine. Valient. Just valiant. Splendid behavior.

This week I'm working on a new supur sekert module project. We are code naming this one the FLATENUM SERIES. It will be a flat pack designed to slide under Speedster Duh and ultimately get hooked up to it to provide 120v of juice at 60Ah. I have kind of a theory that this small Ah pack will act as a pack stiffener - holding the voltage up on acceleration. After acceleration, it would be restored by the larger prismatic pack to an identical state. This appears obvious. But it either may or may not be TRUE. We haven't really done such a thing. I would THINK it will work and instead of plunging to 106v on a hard acceleration we should maintain up at about 114 or even 116volts. This means more power through the controller to the wheels.

it should add about 200 lbs to the car, but in theory another 25 miles as well.

To make all things fair, i'll just quietly mention in passing that we are considering an addition to the Drag Race and Autocross at EVCCON this year. It will be a two hour race we will call the EVTV ELECTRIC ENDURO. It will run through a very SCENIC fall drive from Cape Girardeau up the hilly twisty U.S. 61 to Perrryville Missouri, thence across highway 51 to Illinois, where it will pick up Illinois highway 3 down the banks of the Mississippie before recrossing at the Cape Girardeau Bill Emerson Bridge back into town. And it looks like 127 miles on the map.

I think Speedster Redux can make it now and Speedster Duh likely will make it after the A123 addition if it works. But if you're working on an extender pack, battery trailer, etc there may well be a showcase for it in the EVTV Enduro. Probably a timed race rather than a true road race. Time and the ability to complete being the issue.

View Larger Map

I may try to arrange some charging in Perryville for those who want to try half of it, and still get back to the festivities without a flatbed. Yes, the entire concept is for this very beautiful scenic country drive to be just beyond your reach. An electric road race no one can finish. That's just the way my mind works. I would have been different had I been born a TALL instead of a ROUND. But I'm still around.

One other element that will apply to drag race, autocross, and endure - anti homolugation. If you have produced over 100 of these vehicles, you cannot compete other than exhibition only. It must be a custom conversion or VERY small run OEM with less than a hundred instances on the road. We remain TEsla Fanboyz too, but that's not really what EVCCON is about.

Jack Rickard

Monday, February 13, 2012


What do you mean obsessive/compulsive?

This week we continue our obsession on A123 cells. I fear this obsession on developing a mechanical package for these cells to use in a car is going to cost me my entire viewership of our EVTV weekly show.

But we continue to pursue it for a number of reasons.

FIRST. We think this higher power cell opens the door to a different kind of power pack for electric vehicles. Not dramatically different, but just conceptually different. Our DIY crowd lives in a strange space of time, space, and money restrictions that VW and BMW simply do not face.

As a result, EVTV has lived in a strange grey zone of tension between those who want to build excellent electric vehicles and those who want to do it inexpensively. There is a little army of guys out there still building lead acid vehicles because they perceive the $3000 of lead cost as workable and $10,000 for Lithium as not. They desperately want to be perceived as "pioneers" in the electric vehicle movement. When I tell them they are not only NOT pioneers, but actually damaging to the cause, it drives them into a frenzy of hostility and abuse mostly directed at the messenger ME.

Let me repeat: lead is dead. IT is at this point a NOT very interesting science project. It is not a car. ANd it reenforces false stereotypes about electric cars among the public. If you have a lead powered electric car, please hide it from view.

But the desire for a lesser cost battery, and the willingness to settle for less range, just might be an itch we can scratch with the A123 MD1HD-A 20Ah pouch cell.

Here's why. This cell only has 20Ah of energy in it and in testing, really more like 19 Ah. But it can put out 20C of POWER and so it's POWER density is quite high. To drive a 1000Amp controller and motor, would only require three of these cells in parallel. A 60Ah pack would cover up to 1350 amps actually which encompasses the power requirements of every single vehicle we've done at EVTV including the eCobra.

And so a 100 Ah pack is actually overkill for a normal car with regards to power or instantaneous current requirements. But it is a smaller pack than we normally use.

As an exercise, let's redesign our pack for Speedster Part Duh. This vehicle is limited to 120v by the controller. If we did a 100Ah version of this at 5 cells in parallel, we would actually be a little less than that, probably 90-95Ah. At let's say at 120v, such a pack would of course have 10,800 kWh. But the weight of the cells, not counting any modules, would be more like 180 lbs instead of our current 450 lbs and could conceivably bring our wH per mile down to 200. That's a 54 mile range to 100% DOD and of course 43.2 miles to 80%.

The national average for a daily drive is 39.4 miles and 78% of the population can deal with a car that does 40 miles or less.

The car would be lighter. And the cost of the cells based on our last purchase would be $4770. The cost of the cells we HAVE in it now for an 80 mile safe range is a bit over $8000 with shipping.

And so we have lead acid, with 1200 lbs of cells and about a 30 mile range at $3000, the CALB 180's with an 80 mile range at 450 lbs of cells at $8000, and the A123 at 180 lbs and 43 mile range at $4800.

The A123 fills in nicely and the CAR actually PERFORMS better than either of the other options because of lower cell weight and so lower vehicle weight.

But perhaps most importantly, the initial cost is closer to the lead $3000 cost than it is to the CALB 180's $8000 cost. And the car is not only fully functional, but probably super functional as it will drive better at a light weight than it will with the CALB 180 cells.

IF you then like the car, and need more range, ADDING cells to the system is almost a trivial exercise.

And so we see these cells as allowing a whole new group of our viewers who mostly view, finally get started to build. That's a big play for us and a big play toward the adoption of electric drive for personal mobility worldwide.

REASON TWO. I'm just incensed at the hubris of Miet Ming Chang and the A123 group in accepting $249 million dollars and publicly dissing ANYONE not an OEM qualified in their mind to be an OEM right on their web site WITH my tax dollars in their jeans. I'm further incensed that they would lay off 125 hapless yucks the first time Fisker hits a glitch, saving themselves what $7 million a year in payroll while lunching at the Fish on their $249 million dollar grant.

I'm THEN incensed that they actually make the cells in Korea, and have MADE IN USA printed on them there.

And then I'm enormously entertained that FISKER has now missed the milestones on THEIR Department of Energy LOANS and have shut down their production and layed off 65 workers. This is a company A123 invested $30 million dollars in, and lo Fisker announced A123's cells to be the very highest quality available.

Now A123 has a rather diminished need for cells.

And so it APPEARS that the Asian factories, facing plummeting demand from A123, are actually selling the cells out the back door to Chinese traders. And there we purchase them.

Several people have alluded to the fact that these may be "reject" cells from QA or "seconds" or otherwise undesirable cells. I would note that EVERY person I have heard this from also sells competing batteries. It is just dehumanizing to watch the "who's ox got gored" scenario play out EVERY TIME in EXACTLY the same way.

Our examination and testing would tend to indicate that the cells we are receiving are brand new and of acceptable quality per the published specification. At some price, the performance is what the performance is and we find 18.5 to 19.5 Ah of energy density and a full 23C tested current capacity very persuasive at these prices.

So reason two is simply that it tickles my fancy to buy cells from China purportedly made in the USA from a US manufacturer who's head is so far rammed up their own ass you would have to e-mail them JPEGS of sunlight if you ever want them to know what it looks like.

REASON THREE has to do with establishing the ongoing market price of these cells. The factory and traders have to make some level of profit to continue making the cells at all. I don't know where the floor is. Our first purchase was a little over 2 months ago at $36 per cell I think. Our latest purchase in December was at $20 per cell plus shipping and paypal charges. Nathan Knoppenberg reported this week a quote of $17.40 FOB china. I asked my guy and he quoted $19.20. As these two quotes were from the same company and our viewers have already purchased several thousand cells from this guy, I kind of went ballistic on him. His response is that I can have them at whatever price I want to pay.

Lower pricing is good. You want to squeeze. But when you squeeze all the oxygen out of the room, understand that the supply might just disappear.. In infant industries such as this, while you are seeking the lowest price, understand that it is generally in your interest for these people who make motors, controllers, batteries, et al to remain in business and for it to actually be an attractive business for others as well.

In any event, CALB cells are at $1.20 per amp hour and TS/Winston/Sinopoly somewhere around $1 to $1.05. At anything like $19 and below, these A123 cells suddenly make sense in a lot of ways. At $15 they pretty much kill off the larger prismatics.

REASON FOUR - it may just be a better battery. A little over a year ago, in our December 6, 2010 blog entry "What heSaid, What I said" a professor Jay Whitacre of Carnegie Mellon University did a video addressing the Carnegie Mellon EV club and talking about batteries, battery management systems, chemistry, etc. This guy has had quite a career specifically with Lithium batteries going back to the NASA/Jet Propulsion Lab and a decade of it. In this video, he several times held up the A123 cell as the "gold standard" by which LiFePo4 cells should be compared. Since then, A123 has done several presentations to DOE as to how they have improved their cells, and mostly this 20 Ah cell. It is a LONG way from the little can cells used in the deWalt power tools.
(Incidentially deWalt as it turns out has a patent on a little BOTTOM BALANCING battery charger).

Now Daniel A Cogswell and Martin Z. Bazant of MIT have published a paper, Coherency strain and the kinetics of phase separation in LiFePO4 that would appear to imply that fracturing of the crystalline matrix in LiFePo4 cells may be DIMINISHED by the use of HIGHER current levels during charge and discharge. In other words, the harder you work em, the longer they last. I have for about a year now thought that the disconnect in the broad electric vehicle community that I feel is about really smart people NOT looking hard enough at these LiFePo4 cells because of their lowish energy density. They don't REALLY know why these cells work, and yet they are moving on to others that have none of the same advantages, for a few ma of energy. How about driving THIS chemistry to its limits first.

Our latest module uses a mold we made from a CALB 180 prismatic cell using Mold Star 30 Platinum Silicone Rubber from a company titled SMOOTH-ON. This took about 16 hours to cure but gives me a very durable but flexible rubber mold to pour cast urethane in. The material needs no release agent when used with urethanes. So you just pour it in and in 10 minutes pull it out.

The urethan resin we used this week (resin du jour as we try a lot of different ones) is their SMOOTH CAST ONYX which has a deep glossy black finish. It takes about 40 ounces in our mold. The bad news there is there is this stuff is $94 per gallon meaning we could do three batteries per gallon or EACH cell would take about $31 plus shipping just of resin. We probably need to find something less expensive.

Assuming about $10 worth of hardware, $31 in resin, and six cells at $26.50 our little battery costs about $200 each for 115 Ah. And our 36 cells in Speedster Duh, instead of the theoretical $4800, is more like $7200. Of course, that is with 120 Ah instead of the 100Ah described at the beginning. But you can see that the form and the cost of the actual modularization of these pouch cells is what it is entirely about. You can wipe out the advantage of them if you have too high a costs in the module. And of course you wipe out the advantage if the modules can't handle the current or lead to early cell death.

So we are doing more work on a module. But we had kind of hoped our viewers would do some work in this area as well.

We also took a first look at Valery Mitzikhov's EMW Bluetooth Dashboard for Android in this episode. MORE ON THAT LATER. This is a fascinating device with a few early version problems.

Yes, the audio is wretched in the first part of the show. Brain forgot to change batteries in the Juiced Link. We would not have even HAD a show but for our new backup TASCAM DR-100 recorder. But even there, he had the microphone pointed at the wall instead of at us and so the sound is like being in a bathroom. We'll do better. I hope....


Tuesday, February 7, 2012

This week the Brain is off to see his parents in Southern California. They are not as young and pretty as they once were and indeed Lou is facing open heart surgery. If you are accustomed to prayer you might put in a word.

Leaving me loose in the shop by myself. Actually, I enjoy solitude and particularly in the shop. If I set something down, I can kind of count on it being there when I come back. With a single other soul in the building it is always remarkable to me. I could build a trick double throw me down quick disconnect air powered overspeed protected refrigistastitator flavis waven that no one on the planet but myself even knew what it was, much less have a use for it, and lay it down on a bench immediately on assembly.

If I turn and refill a tea glass, when I come back 12 seconds later, the damn thing will have disappeared completely. A search ensues. EVERYONE in the shop SWEARS they haven't touched a thing. 45 minutes later I find it on the SINK in the bathroom.

OH YEAH. Is THAT what that was? I was wondering? So I took it into the bathroom. NOW I know what you were talking about.

I actually had an incident this week, again with an object so nondescript NO ONE could have a use for it EVEN ME, in theory, but I did. It had been moved and when I complained I was told in no uncertain terms by the only other person in the shop that they hadn't done it. When I noted that there were only two of us, he became THOROUGHLY incensed that I would "call him a liar" and threw a total fit. Without missing a beat, he then noted that he had only moved it for "safety reasons" and because it was in his way. ???? So he was INCENSED that I would call him a liar, which I never did, and then confessed to lying about it, which he did.

I apologized profusely of course and noted that I wouldn't' for anything in the world have him offended in any way. And indeed to prevent any POSSIBILITY of a future occurrence, I invited him to leave the shop and our employ as quickly as he could assemble his train.

Alzheimer's is not precisely a disease in my family. Picture it more as a tradition. So I kind of feel like Helen Keller after her parents have rearranged the furniture for the twelfth time.

So I kind of had a good time this week, once Rod had been promoted to whatever he's doing now, and I'm rattling around the shop by myself. It has been wonderful. It's true I am not as good as those guys at fabrication and just being able physically to reach things and lift things and so forth. But I actually got quite a bit done, albeit in piddling ways.

Not really shown in this weeks' episode. I got some 4 AWG cables run from the Manzanita to some terminals under the truck tied in with the J1772 plug wires. This gives us much stronger cables to carry the current for our PFC-75. I'm so accustomed to chargers that put out 20 amps, that having a 75 amp monster is a constant reminder. The little 10 gage wires I had on it, normally overkill for charger duties, were getting very warm.

As many know, the Manzanita is NOT my favorite charger. But this particular unit we spent about $4500 on several years ago when it first came out and it is capable of 75 amps at up to 400 volts. That's pretty stout.
Despite Manzanita's assurances that they are all fully capable of 75 amps, we get 68 amps or so into this one from the wall. That's still pretty stout. And with a 400Ah pack, we need all we can get. At that high current level, it will still take six hours to charge this 76 kWh pack.

I've done something kind of goofy here and may pay the price. We've mounted the charger, and a DC-DC converter, on TOP of the polycarbonate lid of the pack. So now to get to my pack, I have to remove a lid with a n ever increasing array of wires and stuff on top of it. I added the little voltmeter we talked about recently from LightObject to it for example, so I can see the pack voltage at a glance. Turns out this little 5740TV voltmeter is really pretty accurate. I just love these things. I found an older JLD404 AH counter from these guys and got it set up in the lab and working and it is pretty nice. Voltage, current, hours, and AH all in one little device. Problem is, they don't sell it anymore. They sell a JLD404, but it does something else and no longer does AH. But we're talking to them about getting them again.

I also tied the charger to the pack INSIDE the box. This poses a little problem I hadn't thought through. I need a hall effect device and a shunt device for current measurement and in order to work, it has to be inside the loop of both the controller AND the charger. In this case, that now means inside the battery box. So my electric car is moving one piece at a time into the battery box in back. And I'm not sure I can stem the flow of parts into the area.

We did bleed the pack down using our Aurora Inverter - basically running the shop off of the 76 kWh pack for two days until the pack was drained. Then I used an old Thundersky 30 A charger I have laying around with big jumper cable clips on it, to individually charge each cell up to about 2.80v - then letting them fall back to about 2.75. We did this to all 57 cells until they all read 2.75 +- 0.05v. At that point, we hooked our Manzanita back up and charged it to 205 volts. This will be about 3.6v per cell and is high enough for my purposes. Again, I like to undercharge a bit and we have a huge pack here.

As noted in the video, we did build a little heater for the Vantage GreenVan. Brain had reported in from California that he had visited HPEVS and they were working with Vantage GreenVan on a LiFePo4 version of the van. We've been enjoying one for some time. But it has a little diesel heater that I'm scared to death to even turn on. So I wired my daughter up a little electric heater using two of the by now familiar PTC heater elements and a Kilovac relay.

And as promised, I show the damage done to our A123 module attempts and even pry open one of the cells to look at the very different looking cathode on this cell and talk a little about the patent disputes over this cathode.

I'm still mystified by our losses there. This week I've made TWO little modules with 6 cells in parallel more like our prismatics. They are champions. About 117 Ah - full spec 19.6 Ah per cell.

I DID notice something that is a little problematical in an electric car and kind of hard to test. If I fully discharge a set, and then immediately full charge it, it looks like ti has lost capacity and reaches a high voltage quite prematurely. If I let it then set overnight, I can add another 10 or 15 Ah to the cell the next day with no harm at all. This is NOT like our existing cells. It is quite strange behavior. And it might explain some of our damages in the modules. I was running it HARD to discharge it and pretty hard to charge it and doing it quite back to back based pretty much on what it OUGHT to take.

Of course, I don't want to have to leave my car overnight before fully charging it? That makes no sense.

IN any event, this week I'm working on a rubber mold to make cells that look like CALB 180Ah cells but of smaller size and HIGHER power of course. A 120Ah cell would have a current capability from our tests of about
2750 amperes. Imagine driving the Elescalade on 57 of those. 57 x 6 x $26.60 = $9063. That might seem steep but it is some less than the $25,000 we have in the back now. Of course, again that would be a scant 23kWh pack and we would probably be limited to 25-30 miles on such a pack. But it drives home the point of those high power cells, we could still drive the two Soliton1's to their limit easily with such a pack or an even smaller one of 90Ah for example. And so we can use less expensive battery packs for shorter ranges. Not my style, but an option.

The problem of course is that it would take quite a bit of "sweat equity" to convert boxes of individual A123 cells to our prismatics - including hardware, resin, and so forth. So long run, I'm not sure what would be saved. But many of our viewers aren't concerned about the long run. They're concerned with limiting expense in the right now. If they'll settle for less range, these cells appear to be an option.

The cells from VictPower seem to be testing much better than the cells received from OSN power. We're clearly up over 19 Ah with these. We are charging to 3.65 volts and discharging to 2.50. There is indeed some power between 2.50 and 2.00. We're content to let it remain there.

Jack Rickard