So in my quest to build an E bike, I have run across quite a few electrical devices such as mosfet drivers and op amps that need dual power supplies, is there anyway to create a "center tap" effect like that of a transformer, or a ground wire like that of two batteries hooked in series with only ONE battery?

 

Yes, but it depends upon the exact configuration.

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Well if one could gain access to the individual battery cell terminals one could use the center terminal of a single 12 volt battery (the connection between the 3rd and 4th cells) and therefore have a +6.3 and a -6.3 value relative to this center tapped common. However most modern lead acid batteries don't allow easy access to the cell interconnects and one would be left with drilling and tapping to try and reach the interconnection. Even if you could arrange such a arrangement you would then have to deal with then how to recharge such an systerm.

Circuit common or just common is a better term to use then ground which can be a misunderstood to mean an external earth ground wired to the circuit common. A moving vehicle cannot really have a ground as long as tires are rubber

A more practical solution when needing dual polarity in a DC powered system is to utilize an isolated DC to DC converter which allows the converter's output positive terminal to be wired to the existing DC common and using the converter's output negative terminal as a negative polarity output.


Lefty