I spent the afternoon in West Marine; I made some decisions about the electrical and needed to execute my plan.
First, I ordered the well recommended Casey book on Sailboat Electrics. That won't be here until Tuesday, but not actually having knowledge hasn't stopped me before.
First, I gathered what I knew:
- I needed to physically fit the battery through a hatch opening 20" x 9". It could be no taller than about 8 1/2".
- The 12V trolling motor that I ordered uses 50 amps when full open. I'd like to have around 2 hours at full open. That means 100AmpHour battery.
- I have no idea how to mount the battery so it doesn't move.
- I want a 12v system to run a GPS chart plotter and maybe a VHF radio. These have to be removable so that I can stow them safely.
- I want LED navigation lights on a switch.
- I want cabin lights (this is easy, LED strip lights).
I can't believe that it took me over an hour, but I had a lot of decisions to make. In the store, I could design all the details in my head.
I had a simple wiring diagram drawn in pencil. Once I had everything purchased, I enhanced it (thanks to Digikey):
For inside the well, I bought:
- 79AH AGM battery (group 24) and a housing for it. This has a little less capacity than I wanted, but should still have plenty of juice. And it will definitely fit in the well and I know I can mount the housing inside the well.
- a 350 amp battery main switch. They didn't have anything smaller that I could mount easily.
- some 6 AWG red & black wire from the battery terminals to a 100A dual bus. This can carry 50A to the trolling motor without burning up.
- A 10AWG lead with connectors from the trolling motor section. Half will be connected directly to the battery. (The version I bought had round lugs on it, the one on the link doesn't.)
- A 15A offboard charger. I'll cut off the clamps and add the other 1/2 of the connector from #4. Then I can just drop the charger in the boat, connect it and 6 hours later have a fully charged battery.
- A fuse holder and a 30A fuse. This will go from the bus bar up front to the switch panel. I used a 30A fuse so that I could use 10AWG wire to the switch panel.
- All the crimp connectors I needed.
To mount on B3:
- A 4 circuit breaker/switch panel with 2x 12v cigarette adapters. Unfortunately, one of the switches controls the two 12v adapters, so that leaves me with only 3 switches. Which is just enough, but I may regret no more space later. The panel has 15A circuit breaker switches. I think this means it could handle up to 60A, but that would have been #6 wire all the way to the panel and that seemed ridiculous, so I fused it at 30A so I could use 10AWG.
I even bought some accessories, like cable clips, screws and velcro.
I don't know where the nav lights will live, so I didn't buy any.
And I don't want to invest in a GPS or VHF quite yet.
It was an expensive trip, but I know what I can do this week.
What's really weird: I wanted to ground everything to the chassis. Duh, you can't do that on a wooden boat. And when I work with the FIRST robotics program, they won't let you do it for the robot either. At least FIRST supplies you with a ground bus.
I have an idea on how to mount the GPS and radio on B4 so that it is easily visible, although I may do like Noddy and put it inside on B3.
Now, I need to start laying out components and crimping connectors onto wires. I'll mount the battery box down, but I'll probably have to cut it up a bit to get it to fit correctly. Then I can finish priming and painting behind B3 so that I can get everything permanently mounted.
I do still need some strain relief and preferably a waterproof (yeah right) grommet for when I run though the bulkheads. I know bcbimmer is using PEX as a conduit. That seems like a good idea.
I'll also need to figure out how the motor will be wired. Hopefully that will arrive this week.