leischvost wrote:
When I bought my boat last year, it already had the actuator set up. It seems that the downriggers were running on one battery and the rest of my electrical/main motor sits on the other battery. I typically just leave mine on both... that way it can be charged while running the big motor. If it hasn't been used for a month, I do like you suggested and trickle charge both batteries.... just to be sure

The most charge you can be putting to the batteries is 17 amps, while trolling with your main and depending on the alternator 40/45 amps while running approximately 3000 rpms. If you are trolling with a 9.9 kicker, it produces 6 amps? If you have Scotty downriggers, they draw 8 amps, each?
If you have access to a charger, you will probably never have a problem! In fact, if you go to Cannon's website and download their manual, you will see Cannon recommend NOT running more than 2 downriggers off of one battery. Running off 2 batteries creates less drain on the one and is better for the batteries.
If you plan to fish the WCVI, without shore power available you will probably have a dead batteries within 4 days of trolling with the downriggers? I have a friend that has his wired the same way and "just like clockwork", it takes him 3 ½ days to call and tell me he is dead in the water! I have a tow rope I bought... just for him, as I found towing him is easier than try to either jump or pass a batteries from one boat, to the other.
Oh BTW, there is nothing worse than having a USCG certified Captain setting at a dock, in his band new 42 ft power yacht, with no shore power and dead batteries, because the "factory" wired the batteries wrong? And, he didn't even think about checking that, but boy that electric blender sure did work good, for a long time!
Good luck!