Re: Batteries in parallel or not?
No. Not unless you use a dual battery switch, isolator, or ACR and make very long high speed runs. Chances are the alternator on the engine does not have enough output to significantly charge the deep cycle battery in a short run back to the dock or ramp. What you are doing is best for both batteries. Even with a switch, the alternator issue is still an issue. Look at it this way. Your trolling motor probably draws about 40+ amps so if you ran it for only one hour, and your engine alternator had a 20 amp alternator, you would need to run the engine wide open for two hours to replace the current you used. If you simply hardwired the two batteries in parallel you create another problem. When using the trolling motor you also draw off the starting battery. So although time on the water may be extended drawing from both batteries, you also increase the possibility that the engine won't start because you drew down the starting battery too far.
