Think of your DC motor as the marathon runner of your energy storage system—it needs a steady pace (current) to go the distance without burning out. The rated working current is its "sweet spot": the maximum continuous current it can handle while maintaining optimal performance and longevity.
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[pdf] If you are hooking batteries up in series, connect the positive terminal of one to the negative of the next, and so on. The following formula applies to series circuits: (V total = V 1 +V 2 etc.). This will provide you with extra voltage for the load, but no extra current (I total = I 1 = I 2 etc.).
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