The panel has been delayed by a week, so we've made full use of the time to make many changes:
Some changes over the last week or so:
* We decided against the resistor arrays after all. They are so small that they are difficult to solder, plus they are actually difficult to source with 1% tolerance. It actually works out cheaper with individual resistors, anyway (neglecting assembly cost). It allows us greater flexibility with component values as well. It was a great design exercise, though.
* The board has been shrunk to the height (edit: as seen on the screen, really width in real life) of 4 5-watt resistors jammed against each other, and as small as possible to get the best tiling. The LEDs will be mounted above unplated slots in the PCB. They look so cute that way; the fibreglass is somewhat translucent.
* Many labels are in text on the blue layer now (will be on top). We won't bother with the expense of a second component overlay.
* We have several routed slots on the board for high voltage isolation.
* The external connections have been moved around to avoid being under the bypass resistors
* The bypass resistors will be on the other side of the board to the main components
* The large expensive FET is replaced with two smaller, much cheaper FETs
* LED resistors increased from 330R to 1K2 to reduce brightness and current draw (they were painfully bright up close)
* We are back to two monitor resistors again, but only one will be populated on most boards
* The expensive but cute push button has been removed altogether, replaced by a pair of pads designed to be shorted with a screwdriver. One of the pads will be a bypass resistor lead.
While we've won a few millimetres by turning the boards upside down, we will lost most of that because the resistors still need a few mm of air beneath them. Also, even with 1.09 A of bypass current, the heat eventually gets to the thermistor and the board gets an over temperature alarm just from the heat of the bypass resistors. That doesn't happen if the resistors are off the board by about 2 mm.
Separating the resistors by about 1.5 mm had little effect on the eventual temperature, whether the resistors were hard against the board or not. So that's one reason to squeeze the board size down.
Edit: uploaded image. Thanks, Andrew!
Nissan Leaf 2012 with new battery May 2019.
5650 W solar, PIP-4048MS inverter, 16 kWh battery.
1.4 kW solar with 1.2 kW Latronics inverter and FIT.
160 W solar, 2.5 kWh 24 V battery for lights.
Patching PIP-4048/5048 inverter-chargers.