I have a 12v trolling motor (55 lb) that is rated for 50 amps. At speed I only pull < 30 amps in my inflatable boat. I know that increasing the voltage will make the prop spin faster, which will draw more amps, but also make me go faster, which is the goal.
Is it possible/safe/feasible to connect my 12v lead-acid battery in series with a 3.7v Lithium-Ion bundle (of reasonably similar C) for a 15.7 (nominal) volt setup? I have already done some hand-wavy calculations and think I will hit my amp limit (though I should probably stay around 45 to be safe) at ~14.5v, so I will use a PWM (which I already have installed) to limit my amperage... I.E., dont worry about the other factors involved;
I just want to know, is there some fundamental reason such a setup would not work?
I have already considered using step-up/boost converters to increase the voltage, but with the amperage required I would need either an expensive one or many less expensive ones, and I rather spend that money/use that space on more battery power because of the added Watt-hrs they bring onboard.