So, I’ve still got to think about how to do the connectors, but so far, this is what the module looks like.
I’ve spaced the MOSFETs apart in case I decide to use physically bigger parts. The schematic looks like this.
Experimenting with the orientation of the PowerPole connectors, yes, you can mount a pair with one rotated 90°, but then it is impossible to configure the mating pair to match that 90° orientation, the rotated connector will always be 180° out.
So there goes that idea. However, I can use a 2D plywood “funnel” to make it impossible to misalign the connectors. The following not-to-scale diagram shows the gist of what I’m thinking of.
Effectively, I have 3 connectors: White represents Source, Green represents the Gate and Yellow represents the Drain of a typical MOSFET. There’s a pull-up to ensure the MOSFET stays OFF unless explicitly pulled low to turn it ON. The three pins wire directly up to where Q2 and Q4 are located.
In the event of magic smoke escape, I can grab a pair of oven mitts (the heat-sink will be hot, right?), grab the heat-sink and pull upwards to release it and disconnect it from the circuit. The process should be idiot proof enough that I should be able to leave instructions for anyone to follow.
Re-installing a module is the reverse process, just align the module and pull down. It’ll click into place and should start operating straight away.
I’m toying with the idea of including a small thermal fuse on the heat-sink to remove the MOSFETs from circuit should they get too hot. Reason being, someone might not be around if the magic smoke does escape, although provided the heat-sink does the job in the load test next weekend, this should be unlikely.
These look like they’ll do what they want. Okay, means I have to settle for 25A instead of 30A… but the charger is only 20A right now anyway. The 30A max rating was chosen based on the capability of the connectors. 25A is “good enough”.
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