Looking at pack disconnect relays/contactors. I think the Gigavac GX12S or Blue Sea 7713 are good options.
THe GX12S is a dual power coil, which only uses 1W once closed. Low enough power for my application. It can handle several hundred amps continuous.
www.gigavac.com
The 7713 uses only 13mA when closed, and has its own control circuitry, so it can be controlled without a separate driver circuit. It is rated for ~500A continuous, and has a manual override.
500 Amp magnetic latching (bi-stable) switch provides high-amp switching under load, manually or from remote locations
www.bluesea.com
I have seen some 300A solid state BMS units for Ebikes and similar. I honestly don't think they would handle more than 150A. Though If I wanted to go all hardware hacking on them, I could replaces the FETS and heatsinks.
For reliability reasons, i prefer a mechanical contactor over the integrated solid state switches. I will give the external solid state switches a look later to see what the cost/packaging looks like. At least with the external/standalone contactor/switch units, I can bypass if a component fails. With the all-in-one designs, a single component failure may take the whole system down. I try to avoid this if possible, as failure for a full timer is a serious deal. No heat, no light, no food, no cooking. No Bueno.
Part of the reason the DIY BMS appeals to me, is that I can modify the code to control pack heater/cooler. I also would like an audible alarm/light during a caution event, to provide warning before the pack disconnects. This gives the operator (if present) some time to correct the issue before disconnect occurs.
