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Either way we shouldn't discharge car batteries below 11 volts. How do we prevent that? What is the simples/cheapest low voltage cut-off circuit?  | Either way we shouldn't discharge car batteries below 11 volts. How do we prevent that? What is the simples/cheapest low voltage cut-off circuit?  | ||
Twisted_Haywire has some ideas for super simple circuits. Another option is to use a voltage comparator + divider + mosfet. You can get cheap comparators for $1 or less on ebay/aliexpress.  | |||
== PCB ==  | |||
If we end up wanting low voltage cut-off then if makes sense to put it on a PCB. [http://dirtypcbs.com/ Dirty PCBs] charge $14 for ten 5x5 cm PCBs, so $1.4 extra per unit, and it drops to $75 for 100 units.  | |||
== Higher voltage extended version ==  | == Higher voltage extended version ==  | ||