i just put a 36 volt TM on my 24 volt system...
how do i hook up an extra battery to get 36 volts without re-wiring my whole boat? 1 battery stays like it is, and the other 2 pos to pos, or pos to neg? i know absolutle zero anout electrical junk, so any help will be appreciated.... and legend rick will buy you a beer..

The batteries have to be put in series. Your two that you have now should already be in series. What you have to do is go from battery 1+ to battery 2- to battery 3+ Then from battery 3- to battery 2+ to battery 1- The wire coming from your trolling motor + should be run through a breaker and then to battery 1+ The - wire from the trolling motor will hook up to battery 1-