More Swallow. More Elescalade. We’ve decided to abandon the electric powered ELEScalade concept and go with a new rocket powered package from EEPYBIRD that uses Mentos and Coca Cola.
The Elescalade we begin populating the large battery box in the back with 57 cells of 400 AH. These 400 Ah cells weigh 29 lbs each for 1653 lbs. With straps and cables and box, probably more like 1725 lbs. It does squat the ELEscalade down on its haunches.
But that also gives us 76380 watt-Hours of power.
The Elescalade has a curb weight of 5800 lbs and a gross of 7200 lbs. We’re going to be over gross at 7550lbs and with an additional 1000 lbs of people meat, QUITE over gross.
Our 10:1 rule normally serves us very well and that would seem to indicate 750 to 850 watt-Hours per mile or a little under 100 miles range.
But we think we will do both MUCH better than that, and much worse than that, with this vehicle.
We haven’t done much with this, as we have little to test with and some problems. The Rhinehart Motion Systems Controller has never achieved sufficiently consistent operation to offer any useful testing on the 2009 Mini Cooper Clubman. We have another vehicle, a 2007 Ford Edge in the 5000 lbs class offering perhaps more direct experience with an automatic. BUt this conversion was so badly done from the beginning – we kind of inherited it from Arnulf Larsgard when he folded his Iowa plans, that we’ve barely been able to get it into operation.
But we have noticed and more or less confirmed anecdotally a remarkable inversion in these higher weight vehicles. The Mini Cooper is 3550 lbs while the Ford Edge is over 5000. And accelerating that mass turns out to be hard work. In town, the Edge can use as much as a kilowatt hour per mile. The MiniCooper is more like 400 wH per mile.
But on the freeway, where wind resistance always cuts down our mileage on the light cars, things take a dramatic turn. The Mini Cooper drops from about 1.15 Ah per mile (420 watt hours) to 0.85 Ah per mile (310 watt hours/mile) at 70 mph on the freeway. Similarly, the Edge with the automatic transmission drops down to about 400 watt hours per mile.
This is a little counterintuitive. I don’t think it is because they are so very efficient on the freeway. I think it is because they are so very INeffecient in town. Accelerating that much mass is just expensive. When you quit doing it, mere air resistance can’t by comparison compete.
So we think we’ll have something like 70 mile range in town. But will probably be able to drive the 120 miles to St. Louis rather easily in the ELEscalade. And it’s six speed 6L80E transmission with a pretty serious overdrive in sixth gear could in fact extend that phenomenon quite all out of bounds.
The truck will no doubt be heavy.
There is a subtle point of temperature that might be worth stressing at this point. It was observed by the official BMW Mini Cooper electric program which I find interesting.
The presumption on battery cells is that they must be thermally controlled for safety and to avoid thermal runaway somehow and a fire. Our experience is that cell heat just has NOT been an issue and when we do make provisions for it, they are largely wasted.
That view is largely shared by BMW – with the corollary that we’ve also noticed – a decrease in performance in the cold. We’ve done little to quantify this. The listed 10-15% is so much smaller than the penalty with Pb chemistry cells that we almost celebrate it. But it is very real.
Then too, the LiFePo4 cells we use all seem to indicate NOT to charge below freezing – 32F or 0C. Truthfully, I thought this was a typo when I first saw it and although I’ve requested additional information on this perhaps a dozen times from various vendors, nobody has any specifics as to why this is or even whether it is.
But the Mini Cooper guys noticed that on some days of chill, their range fell below what was comfortable for their use. That’s pretty serious. And they are talking about what they HOPE to see in the new electrics from BMW.
Mostly this revolves around battery thermal management but really HEAT. They want heated batteries.
And with batteries representing quite a mass, it is really better to START warm than to GET warm. So we’re doing something really quite similar in the ELEscalade.
In a past show we detailed our electric “heater”. This is made from a home tankless water heater of some 24 kW capacity. With our 190v DC pack, we’re probably looking at 14 kW with TWO tanks and heaters really. So we will be able to warm our water using a pair of heaters in small tanks, and at some temperature cut out one of the heaters and at a second temperature cut out the other. As temp falls, the “other” would cycle back on. And so we can heat quickly, and then drop our energy use to “maintain” temperature.
This is part of a glycol water system that will be pumped through our cabin heat exchanger so WE can be toasty warm first. But then it will go through our battery box which would represent a pretty deep heat sink if it were cold soaked.
So we’re going to make sure it isn’t. We’re going to have a second system that is made of small rubber flexible heating pads that will attach to the tanks. They operate on 240 vac and are a couple hundred watts each.
These “gentle” heaters will be fed the same 240 as the battery charger, and at the same time. Additionally, we will switch the 12v pumps on when charging. We’ll qualify that with a “season” switch so it only happens in winter, not in summer. Or perhaps automatically with a thermostat.
In this way, when you plug your car in at the end of the day to charge it, the warmth will be maintained all night. Because of the continuous or lengthy nature of this, we want a fairly small and gentle heat in this case. The urgency is not so much to save power as we are on our wall AC, but recall that we only have to maintain it above freezing for the batteries and then of course for our comfort in the morning. A couple of hundred watts should do it if it is on all night.
Again, the mission of the ELEscalade is to be warm and toasty in the winter and cool in the summer. Actual motion is a secondary criteria on this build. And performance and range almost not even a consideration.
Oh, I suppose it’s always a consideration, but secondary for this build.
In any event, it’s a bit of fun to be underway and putting together the battery pack. The large terminals and M14 bolts and Nordlocks are interesting. MANLY battery connections. Speaking of which. EVWorks in Australia had these 55 mm braided copper straps listed for 400Ah Thundersky cells and we bought a bunch of them. We’ve had them sitting around for eight or nine months. They have a much larger terminal bolt hole of course to accommodate the much larger M14 cap screw, as compared to the M8 or 8 mm diameter terminal screw we normally use on the smaller cells.
Unfortunately, they don’t work. These cells are not on 55 mm centers, but rather 67.5 mm centers. So they are too short. Incredibly, EVWorks threw us TOTALLY under the bus. While acknowledging the mistake, their solution is to remove the 400AH reference from the web site and thank you very much for the field report. They have NO straps suitable for 400Ah cells and no intention of getting us any. Sorry…..
Of course, their suppliers, whom they refuse to reveal but whom we of course found anyway, want a kind of a hugish 3000 straps minimum to build them. And we need about 70.
I’m so incensed by this cavalier attitude, as well as the truly egregious shipping charges EVworks has started charging, that we’re going to look at just buying the 3000 straps, along with 3000 of all the other sizes, the bolts, the Nordlocks, and just going into the battery terminal connection business. That way I’ll have them and you can get them without having to go to Australia for them. Ridiculous situation.
But truly, we love these copper braided straps. They are flexible and do NOT put pressure on the terminals when flexing. They work well with the Nordlocks which have become a central element of our terminal connection strategy. We simply do not use the copper bent straps sent by the manufacturers any longer.
For the moment, we’ve cut the end out of the straps so they are long enough to fit. They don’t REALLY fit and we have kind of not quite enough surface area here for 3000 amps of current. But it will let us wire up the pack until we can get proper 67.5 mm straps in from China.
We got some 1/4 x 3/4 aluminum bar and some 1/2 x 3/4 aluminum bar in from McMaster Carr and we are starting our new strategy of clamping tabs together with 1/4 inch 20 thread screws for the A123 cells. There is nothing really innovative here. Numerous people do this more or less this way and describe it online and a number of different viewers have suggested this, albeit in one screw and two screw and plastic screw variants. Hopefully we’ll have something to show this week or next. I’ve ordered 300 of the cells and once they are in, we can show several approaches at once.
Back to my Mentos and Coca Cola….