I have 3 batteries, 2- 1.5 V batteries, and a 9V battery. I need 12V to run a DC motor connected on the circuit. Hoh should I connect the batteries? In series or in parallel?


closed as off-topic by stafusa, Kyle Oman, Emilio Pisanty, Kyle Kanos, By Symmetry Feb 23 '18 at 14:54

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If this is for physics class, the answer is "in series". 2 batteries of 1.5V and one of 9V will give exactly 9+2*1.5 = 12V.

If this is a practical question, you shouldn't be connecting different batteries together. For example, if one of the 1.5V batteries runs out of juice first, the 9V battery will apply reverse voltage to it, causing leaks, gassing and possibly fire.


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