Overall first impression and taking it apart.


The car on my driveway as arrived


As mentioned, since in Australia they drive on the wrong side of the road, here is what the interior looks like. The 12V auxiliary battery was disconnected for the long journey. I charged it up, connected it back, and turned on the key. The dash lit up, radio showed some Hebrew characters on its display, SOC meter showed about 15% of the traction battery capacity, but the main contactors did not engage. A bit disappointing, but not very surprising. The only inconvenience this had caused was that I can't roll it in and out of garage under its own power. I could take apart charging inlet and attempt to charge traction pack with onboard NLG513 (this was trivial for me to figure out), but with no traction there was no point.


Closer inspection revealed "usual suspects" as main components: - UQM 450 AC drive, BRUSA NLG513-SA charger, MES 400-1000 DC/DC converter, MES 70/6E vacuum pump, MES RM4 water heater and Bosch water pump. Interestingly - except for the AC drive, my business sells all these components to the conversion market. Which reinforced my sense that these components used by OEM are the most sensible selection for well engineered for mass production EV. But the battery swapping mechanism was new to me and it is unique to this vehicle. So I raised it to find out how exactly battery swapping system was designed.


I must say this is quite amazing piece of engineering. From what it looks like, it was quite an expensive system. No wonder that this vehicle turn out cost far more than it was anticipated.


Basically a cam system around the car, activated from single location on the left side, is linked using shafts and U-joints to four large claws that grab the pack by its corners and hold it underneath the car. The pack is guided in and out by two large alignment pins sliding into a mating tubes mounted up front to the body.


Here is close up photo of one of the claws open. The battery can be unsnapped in about 15-20 seconds with this ingenious mechanism. All I had to do is to crank the actuator (worm drive) head, seen on the photo above this one.


Guiding alignment pins welded to the the machined aluminum battery tray. Entire tray has grooves and battery modules attachment features CNC milled in it. Quite a work of art. Massive steel claw on top is also visible.


Close up of the battery tray. The alignment guide and the bracket with retaining pin.


The battery is shaped after the standard cavity in Nissan's underbody.


The battery consists of 8 modules manufactured by A123 Systems. There are 3 module sizes used in this vehicle, but its clever packaging allows to stack any number of cells using standard heat sink plates, plastic covers and the BMS components. The long modules have 3P16S arrangement, the medium ones are 3P11S and the short ones are 3P6S.


The cell type A123 uses here is LiIon AMP20M1HD-A pouch cells produced in South Korea. Cell's nominal voltage is 3.3V, nominal capacity is 19.5Ah. A I mentioned, there are three sizes of battery modules used in Qashqai - 16 cells (3 modules), 11 cells (2 modules) and 6 cells (3 modules). A "cell" here actually consists of three 19.5Ah cells in parallel. Quick calculation on the back of a napkin reveals that this entire battery then has got a total of 3*3*16+2*3*11+3*3*6=264 cells. With 3P arrangement in all modules this means 264/3=88 cells in series. At 3.3V nominal voltage that's 290.4V pack and at 19.5*3=58.5 Ah nominal capacity it's got 290.4 V * 58.5 Ah = ~17 kWh energy contents. That's about 71% of Nissan Leaf's battery. Assuming same 240Wh/mile consumption as Leaf claims (at 35mph speeds), that translates to 70.8 miles range, or ~56 miles at freeway speeds. Not spectacular, but keep in mind that the battery is designed to be swappable and perhaps it was calculated that a customer can always get to the nearest swapping station with this kind of range. Anyway, this was interesting to find out, but it was not the point of disassembly...

The power cables snake around the tray and connect the modules in series. The pack has emergency disconnect in about [electrical] middle, so the cabling appears more complicated than plain series connection of all the modules. The BMS network (black looms) is routed separately from power cables to reduce interference. Naturally, all the comms are implemented via CAN.


Main contactors and A123's current sensor module. Everything is standard as expected. You can see precharge resistor above smaller precharge contactor. (There are actually two resistors in parallel, one below the other). Granted, I reconstructed the schematic of this block, but did not discover anything surprising or unusual - if I were to design this circuit, that's exactly how I would wire it all as well. The only component on the left (partially visible on the photo) is current measurement module - you can see that the pack negative cable connected to a bus bar fed through a Hall effect current sensor is entering this box. I'll take the box apart, but since I have designed EVision system that required accurate current sensing, I already have pretty clear idea what's inside this module.


Connections to the UQM power inverter. Hi quality metal feed through glands and solid aluminum blocks in the enclosed compartment - again solid engineering at its core.


Zoomed in detail of the photo above.


Fragment of the contactor box - a bus bar fed feed through the Hall sensor into the A123 precision current measurement block.


All battery modules are attached to the fiberglass tray through this stainless steel hardware. Apparent simplicity of appearance is a result of great experience in engineering such things - these parts of the battery design are often overlooked.

 


Sanden integrated A/C compressor+motor+inverter - self contained unit specifically designed for use in an EV. I might take advantage of it in my conversion project, but first I have to determine its DC voltage operating limits. I must say I was lucky that this vehicle was an engineering prototype, there are labels, arrows, notes and clues written with a marker on many components, cables, blocks, connectors etc., which helped to identify what I'm looking at. If the car was a production model, deciphering which cable goes to what module would be far more difficult. In the case of this unit it is very clear though: HV orange cables (+ and - were marked by somebody at assembly, thank you...), and 4 signal wires two of which are twisted, so 12V aux power and CAN bus.


After all the modules were taken off the tray, each was perked up with external power supply to about 60% SOC for long storage. It is unlikely I can get hold of more of these modules, so it is not enough for my conversion progress in progress, and I'm not sure I'd se this type of battery anyway but these packs may be useful for the BMS tests and as something as a range extender trailer. The BMS PCBs would be replaced with my own, but it is hardly worth the effort to design them from scratch to fit in place of stock PCBs for just one off battery system. For now will wait and see what kind of use these modules can be put in.

 
Power distribution box. Everything is heavy duty there.


Back cover of the PDU laid on top of BRUSA NLG513 battery charger - thanks for sharing the wiring!