We’re finally making a bit of progress on the Cadillac Elescalade Project.
Lucien completed our auxiliary adapter plate for the 11 inch motors. This is our enormous polish friend from Cape Precision Machine. They have taken a good bit of time with this project, but it’s true I had told them there was no rush as we are waiting on batteries. In any event, the final product seems worth the wait.
This is a 7/8 inch adapter plate of 6061 aluminum. It is recessed both to accept the boss on the face of the motor, and the motor itself and so you can tap it on with a hammer and it probably wouldn’t even need screws. We do have eight flathead allen screws that secure it.
This plate provides mounting for our Air Conditioning Compressor and the Power Steering Pump. We put in an idler from the Cadllac, a tensioner from the Cadlilac and in fact used a Cadlllac Power Steering Pump pulley as the drive pulley.
The drive pulley was the key. They had to hog out the existing diameter on this and put in a new bushing, properly centered, to fit the 7/8 inch auxilliary shaft of the motor. But wait! There’s more!
We want to use the Engine Control Unit (ECU) on the vehicle. This little computer gets inputs from all over the car, but by far and away the most important is engine RPM. Without the RPM signal, it thinks the engine is stopped.
Acutally it is GONE entirely but we want it to think our electric motor is somehow an ICE engine.
So we were able to order what is termed a RELUCTOR RING from GM that normally resides on the crankshaft of the L2 engine. A small pickup unit then is threaded into the block to pick up a series of pulses from the teeth of this ring.
We dont’ have a block. We don’t have a crankshaft. So we mounted this ring on the drive pulley. We’ll then mount the pickup on the adapter plate and hopefully provide the ECU with accurate RPM information in a format it likes.
The plate also provides mounting for a couple of aluminum billet brackets to properly locate the air conditioning compressor and power steering pump. To change these, we’ll simply unbolt the normal mounting bolts and pull straight up. They come right out.
The Power Steering pump is actually part of a larger project. We are going to replace the vacuum assited brakes with brakes using a unit GM calls “hydroboost”. These are often used on diesels who do not generate sufficient vacuuum pressure. They work off hydraulic pressure from the power steering pump, which then powers both steering and brakes.
One of the hangups was using a stock belt. I kind of insisted on this. Lay it out however you want, but use a stock 6 rib serpentine belt I can buy at NAPA. This way, if we lose a belt, we can obtain a normal NAPA part number belt off the rack. The result was 71 1/8 inches of belt. We had them scribe the part number INTO the adapter plate. 12 years from now when this is an issue, I can write down this number, go to NAPA, and hopefully they can make me well.
The unit ran totally silently, with no wobbles or vibrations at all. This is the kind of thing where you can save a few bucks on a conversion by doing it yourself, and most people doing a car will do this. I can’t fault it, but for me, it’s kind of important to get this part right. And we’ve had some adventures with the mechanix of these things anyway on the Mini Cooper.
In this episode, we also tackle the battery box. We’ve centered on a main pack of 57 Winston Battery COmpany 400 AH LiFeYPo4 cells. I started with Thunderskys’s, went to Sky Energy, and now back to the yellow batteries. Why? I like the flatter discharge curve of the CALBs. But I had not had cells from TS since the addition of the Yttrium to the cathode material. This appears to lengthen the life and in fact, they are claiming 5000 cycles at 70% discharge.
Ultimately, beyond power, beyond energy density, I am about cell life. I actually think we may have accidentally stumbled onto something with the Chinese battery suppliers putting us at an advantage over the Panasonic’s and LG Chems favored by the OEM auto makers. Yes, we forfeit a bit of energy density, though precious little. In return we get a hardy package, and cell life. The Panasonics used by Tesla appear to be rated for 300 cycles. We have a “secrete” internal memorandum with page after page of concerns over this, so I’m not alone in this, plenty within Tesla are concerned as well. We actually picked up an interesting thing from this document. Apparently, the Panasonics lose 20% of their capacity per year just sitting – if fully charged. If discharged to 50% SOC, this deterioration drops to 4%.
This is in line with our belief system about keeping the cells as close to 50% as possible for long life. But how do you keep a cell at 50% when you’re driving the car. The natural propensity is to fully charge it. That way its ready if you need it. But apparently the batteries would last longer if you would NOT park it for days on end at full charge.
I dont’ think we have a 20% capacity decrease per year. But we probably have some, and this more or less holds true four our cells as well, just probably to a much lesser degree, and perhaps to a degree where it doesn’t really matter.
In any event, the 3000/5000 cycles in the Winston Battery Company cells appear to be the top of the mark. And up from the 2000/3000 cycles prior to the Yttrium rare earth additive. So we wanted to try them.
400 AH cells will be the largest we’ve done and in fact the largest we’ve seen done in a passenger vehicle. These cells are fully 18 inches wide, though their height and thickness are quite familiar from the 160 AH models.
We think we can do three rows of 19 cells in a package 50×56 inches. That’s 1696 lbs of cells in a 3/4 ton pickup truck. And it will give us 191 volts at 400 AH for 76380 watt-hours of energy. I’m looking for the truck to come in about 7500 lbs in the end, which should indicate about 750 wH per mile. I don’t know if we will gain efficiency or lose it in going to this size, but I would be willing to guess that the wH/mile could be almost anything BUT 750wH/m therefore.
In any event, that sounds like 100 mile max range, 80 mile safe range. Familiar. No matter what size vehicle we do, that’s about what it comes out to.
I actually have 70 cells coming. We may do some further packs under neath the frame. That would take us to 93800 or about 115 miles perhaps max range.
We have two Soliton 1 controllers each capable of 1000 Amps and we want none less from this pair. 2000 amperes of power. But in truth, this would normally be for a second or two. That would be 5C for these cells. well within their capability. Recall that we did simliar testing in REDUX Speedster at about 5.5C and the CALB cells worked marvelously. So despite two eleven inch motors and two Soliton controllers, I expect these much larger 400Ah cells to be loafing most of the time.
We have noticed sluggish batteries in the dead cold of winter – easily 15% degradation. Given the expense of this pack and it’s size, we’ve decided to make provisions to heat them.
And so a special battery box with a false floor and PEX 180degree Fahrenheit tubing in the bottom. We’ll heat glycol and water and use it to heat ourselves first, and our batteries in the rear. We’re also going to add an AC pump and block heater to gently heat them while charging overnight.
Enjoy the video.