Trolling Motor powered by lithium ion 18650's?

[johnrobholmes]

Discharging the cells to 3.3v each isn't too bad of an idea really. It would increase the cycle life significantly, and if I have learned anything about large packs it is that the last 20% of the capacity is where you get the most pack imbalance.

You would certainly lose some pep once the cells fall to 3.7v each, but do you run at full throttle with the lead acid often? Have you ever measured the lead acid voltage under load to know what the performance is? I do like the idea of using the converter for smoothing out the voltage during your run, but I guess the final question is how your priorities stack up. It would be a good idea to construct the pack so that switching to 3sXXp construction could happen in an emergency if the DC regulators failed.