emini

It seems improved Weight distribution can be had by putting the inverter in the boot and most of the battery in the front. This does introduce longer motor cable runs which will reduce efficiency but it is looking worth it -- with the inverter up front there isn't much room for cells and it's 70kg lighter on the front axle than when I started. I'll be mocking up the front to see exactly how many cells fit without the inverter before I commit to this move.

The contactors supplied with my Siemens electric drive system were large Schaltbau C160 series contactors with arc chutes and blowout magnets in an even larger box. This was quite inconvenient in the mini as the only place they would was in the boot. I'm planning on putting at least some cells in the front of the car, which would require some clever packaging to get the contactors to at the front. So I replaced them with two Gigavac GX14 sealed contactors. At the moment I've mounted them on a plastic base in same place the old contactor box lived. When I'm done, they will likely be split up, I'm expecting one in the boot at the negative end of the battery and and one at the front of the car at the positive end.

In the foreground you can see the precharge circuit, two small relays and 8 PTC resistors allow the controller's capacitors to charge in an orderly fashion before the main contactors close. If this isn't done the capacitors charge very suddenly. This huge inrush current is hard on the capacitors, battery and contactors. Such situations may even cause the contactors to weld closed. You can see this inrush on a small scale when you plug your laptop or cell phone charger into the mains. Sometimes there is a pop and (in a darkened room) quite a large flash as the circuit connects (it only happens sometimes because the AC might be in a low voltage part of the cycle when you connect, or it might be at a high voltage). Check out the ends of the pins, you'll see pitting and scorch marks on most laptop power cords. Charging an electric vehicle's capacitors involves perhaps 100 to 1000 times more energy than a laptop so there is a soft start circuit to avoid the bang and the flash.

I left the wires long and curly because I'll be moving the contactors. When they're in their final location, I'll cut the wires just right. Unless I keep them curly (never underestimate the aesthetics of curly wires).

I'll post a side-by-side comparison of the contactors some time. The GX14 appears to be safer in an accident.