RRRAAAYYY2
Bronco Guru
That's a common misconception. If you had 100 batteries, the starter & winch would get the same amount of current they did with 1 good, charged battery & good wiring. But if you run the winch continuously long enough to need 2 batteries, you're probably overheating the winch motor.
If you want something cheap, simple, safe, & effective, use the Ford system. It works. And you can add a switch to control the relay if you want (say, for jump-starting without opening the hood), but it'll do fine wired directly into any fused key-on circuit (like the gauges).
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Note that there's a fusible link wire between the batteries, but I'd use a ~150A circuit breaker.
Actually if you wire the batteries together properly, there would be almost zero resistance in the 100 batteries, vs a lot of resistance in the single battery. So instead of a slow discharge of 600amps from the single battery, you would have instant amperage and no voltage sag in the 100 batteries. In a starter circuit the single battery would drop to 9.5volts, while the 100 batteries would likely stay well above 12volts. (That is 26% more voltage, which is 100% more power) So there would be tremendous difference between the performance of the two systems.
Again, the Ford system is designed to be cost effective, not the best way to do something. When it cuts the battery life in half, it is not "effective".