On Thu, 18 Dec 2003 21:53:30 -0500, "Marty S."
wrote:
I'm looking for information about electric motors and the most efficient
battery combinations in terms of weight of adding a battery vs. the power
that going to 24volt might give me. I live in an area that doesn't allow
gas motors on its reservoirs; only electric motors, so I could only power my
12' jon boat with electric. I'd like to match up the most efficient
combination of motor size, battery, and weight. I would like to know if I
get longer run time and/or more power with a 50lb 12volt motor or a similar
sized 24volt motor? Or, would I get a better weight-power-endurance
combination getting a 36volt, 100+ lb motor??

Also, would I get more run time from 2 batteries (1 to run, and one as a
spare, i.e., "refuel") with a 12volt motor, or 2 batteries running
simultaneously on a 24volt motor?
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All other things being equal, a 24 volt system should be more
efficient. The reason is less voltage drop in the cables (assuming
equal size). When it comes to batteries, there is no substitute for
weight. More lead equals more power. Regarding the question of
running from two batteries at the same time, or from one then the
other, I'd vote for both batteries at once. You should get longer
battery life that way since you'd be less likely to discharge below
the 50% level. The advantage of course to first one battery, then the
other, is the ability to get home after you draw down the first.
Drawing down the batteries to zero is a recipe for short life however.