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Twin engine, dual battery hookup on F 36

Posted: Mon Sep 16, 2019 1:33 pm
by Footeloose
Hi there all you Trojan guys, & gals. It's been a while, but since chatting I have finished the valve jobs on both 440's, they're running well. Today's issue is that I don't understand how the solenoid & cables should be connected to have the starboard battery used as the start battery, & the port battery used as the accessory battery. I have all the original manuals, & have yet to find a wiring diagram describing this hookup. I does make sense to use that setup, so would like the system. Right now I have it setup with each battery starting & controlling each engine, but neither alternator seems to be charging, at least not registering on the volt meters. Wonder if not having the batteries set up as discussed, is not allowing charging. When I got the boat, all of that was disconnected, so not sure of the proper hookup. I would certainly appreciate some help with this, maybe even a diagram if any are available. Also, any pics of the F36 hanging in lifting straps, or description of the strap location for haulout would be helpful, even though it's pretty straight forward. Thanks again for being there, Dave.

Re: Twin engine, dual battery hookup on F 36

Posted: Mon Sep 16, 2019 7:38 pm
by captainmaniac
I have a F32 not a 36, but expect setup to be similar. Each battery should be a start battery for its own engine, and the solenoid puts them in parallel (when you flip the switch) to help boost if one is too weak to start it's engine. It's not really set up for 'start' and 'accessory', though you will find Trojan originally wired things up to probably default to port battery for most lower station and cabin 12V accessories, starboard for bridge accessories and blower (at least that's what the F32 is like). Often there is a 3rd (or more) battery for 'House', to power accessory type things when needed that won't drain your starting batteries.

Take a look at the info in this post re the crossover box wiring viewtopic.php?f=1&t=9114&p=91527&hilit= ... 77e#p91527

Re: Twin engine, dual battery hookup on F 36

Posted: Tue Sep 17, 2019 8:31 am
by Footeloose
Good morning Captain, thanks for your answer. I'm leaning toward keeping it simple, & leaving mine setup as I mentioned. Years back I had a 1967 36' Trojan, with the emergency start system setup, but don't honestly remember ever using it. As for the alternator/charging issue, I will use a meter to check for output. I'm still "learning" the boat, so am sure things will get easier as I learn more myself, & from all you generous contributors. It is tough plowing through some of these things, since given the age of the boat, I have no idea what other owners have done along the way. Thanks again, have a great day. Dave.

Re: Twin engine, dual battery hookup on F 36

Posted: Tue Sep 17, 2019 9:05 pm
by WayWeGo
I believe the batteries are always put in parallel when starting the engines and the emergency start switch is actually a backup system in case the rectifier that parallels the batteries fails.

Here is a picture of our boat on a travel lift with the factory specified locations circled in red. The travel lift operator was not comfortable with the specified rear location and I couldn't get him to use it.
Sling Locations.jpg
Sling Locations.jpg (75.44 KiB) Viewed 1297 times

Re: Twin engine, dual battery hookup on F 36

Posted: Thu Sep 19, 2019 7:20 am
by P-Dogg
WayWeGo wrote:
Tue Sep 17, 2019 9:05 pm
I believe the batteries are always put in parallel when starting the engines and the emergency start switch is actually a backup system in case the rectifier that parallels the batteries fails.
Or when youre in a bad way and you need to combine the batts to transmit a mayday. IIRC, my manual indicates what WWG said about always starting in parallel is correct.

Re: Twin engine, dual battery hookup on F 36

Posted: Thu Sep 26, 2019 8:16 pm
by Footeloose
Hi guys, thanks for the mail. The picture of your boat in the travel lift is perfect! Pretty much what I'd have guessed, but always nice to get it straight. I appreciate it. Have a good nite, Dave