Let's say we have a battery of with a given electrical capacity and we are trying to maximize the work being done with it. Then let's say we use the battery and some length of wire to generate a magnetic field which we will use to rotate a magnet. The total magnetic field generated for a given amount of current is determined by how long the wire is. However, the longer our wire, the greater the resistance is, so the more voltage we would need to maintain the same current. Is it true that if we increase the length of the wire in proportion to the voltage, that we can keep the same current but create more magnetic field as a result? Is our ability to convert milliamp hours into work limited only by voltage and the length of wire we choose? Is there a theoretical limit to milliamp hour to work conversion that can't be breached regardless of the technology?