I'm trying to come up with some form of precise overvoltage protection between battery chargers and batteries between 12V and 48V batteries. I have 12 and 24 sorted using different methods: crowbar circuit, voltage monitoring relay, even Arduino and some voltage monitoring devices off of Adafruit.
However, 48V overvoltage protection is giving me a lot of grief. My crowbar circuit is way too imprecise and has too much tolerance... for VRLA batteries, the charging voltage is around 53.6V and I need the protection to trigger at 56.4V. Unfortunately, I cannot find a Zener diode with the required ratings, nor do voltage comparators like TL431 go up to that value. Industrial voltage monitoring relays are way too expensive. And I cannot find a solution using an Arduino because of the ratings. Keeping in mind, 48V battery charger supplies up to 250A (2500AH capacity batteries).
I'm having a bit of a mental block here. I am really hoping someone can point me to a standard configurable overvoltage protection device for the required rating.