Electrical Wiring, battery questions

[RiggsWNC]

I’m drawing out the schematics for my 15 foot skiff build, and My lack of experience with marine electronics is showing. I have some questions.

My 12v loads are: motor starter, trolling motor, nav lights, interior light, VHF, fish finder, horn.

Should I have two batteries? One starting battery for the motor, and a separate deep cycle for the trolling motor and other loads? I think I would prefer this, it’s a river boat and I’ll use the trolling motor a lot. I would put both batteries inside my small center console, with my fuse block and switches.

Edit: just to be clear, I don’t intend on charging my deep cycle for the trolling motor and other loads from the motor alternator. I will charge this battery in my garage. I’d like to have some sort of easy charger hook up for this where I don’t have to remove the battery from the boat to charge.

Any suggestions or clarifications on that? I have other questions, but I’ll wait until I get some initial advice on this first. Thanks!

[Capt UB]

https://www.batterystuff.com/kb/article ... orial.html


If you can and like you said about not charging the deep cycles from the OB. Just make sure you fuse the trolling batteries.

Todays batteries are so much better, go with a dual purpose battery for starting and dash. Use LED lights and other low power toys. I use AGM batteries, cost more, but can take beating and no maintenance.

[RiggsWNC]

So, a deep cycle strictly for the trolling motor, and a dual purpose for starting and the other loads?

[cape man]

I installed a simple battery switch that allows you to use each individually or together. https://www.wholesalemarine.com/blue-se ... n0EALw_wcB
That way you can charge both, including the deep cycle whenever the engine is running. Switch to just the deep cycle while using the trolling motor, and just the starting battery when starting the engine. When it is parked or docked, you can turn the switch off to insure there is nothing draining either. If you use a bilge pump with an auto float, wire that lead directly to the deep cycle battery, bypassing the switch. Lots of different options for a simple plug in charger at home, including a solar trickle charger if the boat is anywhere near some sun.

[RiggsWNC]

this is my plan so far:

Two batteries.

First, A dedicated trolling motor deep cycle located in the bow. I will wire the battery to a fused disconnect/switch. Im not sure what the actual connection from the switch to the trolling motor leads will look like because I don’t have the motor yet. I will have a charging dongle connected to this battery.

Second, a dual purpose AGM located in the center console for motor starting and other 12V loads. Should I wire a main on/off switch for this? From there I intend to connect to a 6 circuit fuse block with a negative bus and from those fuse blocks to SPST switches for the lights and horn, and also to the VHF/fish Finder not through a switch. One switch for my underway nav lights, one for interior light, one push button for my horn. All lights are LED.

Should I have a main breaker before the fuse box? (Edit, fuse box manufacturer requires a 125A main upstream of the fuse box) Anyone have any other hardware suggestions?

[tcason]

Suggest adding a cigarette fused lighter outlet and a fused phone charger outlet.

I have used my phone charger outlet quite a bit.

[BarraMan]

I have a somewhat different approach!

If it were moi, I would:

1) connect the motor to one 120 Ah AGM battery via a switch panel that has two master switches and an interconnect switch
2) connect the trolling to another 120 Ah AGM battery via the other master switch and 50 amp circuit breaker

I like to keep my start battery dedicated to the o/b motor only, plus stuff like a bilge pump that you only run intermittently

3) my preference would be to run the “house” off the trolling motor battery, but if your running a fish finder you may get interference when the trolling motor is running. If that is the case then put the fish finder onto the “start” battery.

4) it’s not the end of the world if you run the trolling motor battery flat - the main thing is to be able to start your o/b. If it low hp I guess you can always pull start it, but if you have an interconnect you can use that to connect both batteries in parallel and get a start should your “start” battery fail.

5) I would put a 12v DC to 12v DC charger between the “start” and the trolling motor battery - that way you will top up you trolling motor battery while running around on the o/b. It will only kick in once your “start” battery is fully charged by either the o/b or an external mains charger.

For the record - I run 6x batteries: 1x start, 2x house in parallel, and 3x trolling motor batteries in series !!!

[OrangeQuest]

Here are a few articles that may help in how you could connect your battery and charging systems.

https://www.bluesea.com/support/articles

You may also want to pick up a few books on how to wire a new boat build. Here is a source I was able to pick up a few used books.
https://www.thriftbooks.com/b/boating-and-sailing/
A few of them have been very good reads.

[fallguy1000]

I have a two battery setup in my 16' boat.

The front battery supports a bow mounted trolling motor which I use now n then. It also provides power for the front nav light. I have a 2 amp trickle charger on it. I can plug it in overnite.

I did run a #6 wire from the back to the front in hopes of charging, but never used it and eventually took it out. I was planning to charge the trolling deep cell with the motor, but...

Instead, I found a location to mount a solar panel for the trolling battery. And that gives me a good edge on the trolling battery when I am away from power in the bush or at a dock that needs 150' of cord to get to my onboard charging.

I run all my other stuff off the start battery. I use an isolation switch because my fishfinder will on cycle itself and run my start battery down. I rarely leave the battery on. I did fish one evening with the electric and had my stern light on for two hours and killed my start. Had to run in on my kicker. Since then I put an LED in the stern light.

One time I wished for jumper cables as I got to the landing and was dead on arrival. Used a couple romex strands then; it was hack, but got us going. I paralleled the troll batt to the start..

[RiggsWNC]

The more I think about it, I’m going to put that fish finder circuit behind a SPST switch for that very reason. Same for the VHF. Also adding in a convenience 12v for phone charging and a spotlight. Thanks for the good ideas, a lot of talent on this website.