Well, since its “burn your soul” hot outside, I decided NOT to venture out of the condo today. My plan had been to go back aboard and take out the anchor rode to photograph the chafe marks and also measure the exact amount of rode we had out, which I have marked. I’d been wanting to regal my readers with the harrowing tale of anchoring on the high seas in a gale. But you know… That’s way too interesting for a 150 degree day. Instead you’ll all have to settle for boring wiring diagrams. Yeah. And while I’m at it I’ll talk about wires and electrons. That should dull down all of Dani’s recent interesting posts sufficiently to return this blog to its technically monotonous roots!

I’ve read and learned more than I ever wanted to about 12v electrical systems in the last year. In my extensive searching I picked up on many different points of view that resonated with me and fit in with our specific plans. Our situation is that of shoestring budget circumnavigation attempters. What does that mean for the electrical system? Well the first and key point which seems to shock everyone is that it means we have no shore power. That is right. When we got Sundowner she didn’t have a working shore power connection and despite the “weirdness” of it, we decided to keep it that way. She is purely a 12v boat.

This fits in with two very important facts about shoestring circumnavigators. 1) We have no money. Where do you find shore power? At the shore where it costs a lot of money to keep a boat. Why not just build a boat that is so self sufficient that you don’t EVER need to go to dock for power? Sounds better to us. The second reason is that we avoid a TON of complexity and equipment by forgoing the 110 or 220 volt systems. No need for other breaker panels, grounding systems, galvanic isolators and whatever else goes along with it to have that electric coffee pot.

Instead of all that high voltage, we wanted to make Sundowner as power efficient as possible. Our first move was to switch to LEDs. We installed a sophisticated battery monitor. I put in a nice MPPT controller to give those batteries what they need. Despite all this we haven’t touched the solar panels. I only hooked up the two 55 watt cockpit solars (wired in parallel). So we went on our little trip with a grand total of 110 watts of solar power hooked up and planned NOT to run the engine for battery charging. Since this was really our first go of it all, we didn’t know what to expect.

Well, every day we woke up and the battery bank was down couple of percent on the state of charge. Usually we ran 2 x 12v fans (el cheapos), 2 x lights, and had both the VHF and stereo on for periods of time. Altogether this did almost nothing to our state of charge. We basically max out at 2amp draw running almost everything. So over the 8 hours we might sleep (haha, yeah right! ) we depleted around 14 amps maximum. A drop in the bucket for our battery bank to cope with. And of course the solar kept up with that no problem. Generally by 10 or 11 am we’re at 100% SOC even in cloudy weather.

I know that when we add refrigeration that our power demands will at the very least double. I know power hungry laptops will increase the toll as well. But honestly, right now we’re even considering not install a wind generator at all unless we get to the point we need it. Another couple hundred watts of solar would be very cheap, easy to mount, and probably keep us up. The more power efficient we become, the easier it is to build a charging system that will keep up. So far we’ve been doing great.

Of particular note, the LED lights. We turn everything on and literally laugh as we TRY and cannot get the amp draw over 1 amp/hour. The Fusion stereo also sips power for the loud output we’re getting out of it. At near max volume it pulls around .5 amp/hour. The little wally world fans we got seem to pull around .3 – .5 amps/hour. This isn’t bad but my God are they loud! I can see why everyone talks about the “quietness” of fans in those sorts of discussions. I spent one night wondering if our neighbors could hear our fans. Anyway, that is our short term gear report.

I know long ago I promised a wiring diagram. This is obviously an interim diagram as I’m sure much more will change between now and our leave date but I will submit it in its current form for all of your viewing pleasure:
Wiring Diagrams 2

Of note here… I’m still shocked that I was able to find a 4 GC2 battery box and fit it on one side of the engine room. I had thought for sure I was going to have to split the bank up on two sides of the boat. The big nylon trucking strap we used to secure the box did a good job on our trip. The wild hobby horsing and rolling in the gulf islands didn’t budge it. I checked the bulk head as well several times and everything looks alright.

Note the bilge pumps are on separate banks. The little 500gph pump that is in the bottom of the bilge is hooked up to the starter bank. It was first wired to the starting bank and I’ve just left it there. I felt it good to have two different pumps on two different banks. The big pump has a switch mounted high in the bilge so it will cut on if the water goes over the little pumps head. Its wired to a separate panel so we can switch it on and off manually.

One thing we really like is the ON/OFF switch mounted where we can just “turn the boat off” without turning off the bilge pumps, etc.  We just have a really easy way to shut it all down.  At night though when I cut the main power I notice that we’re still at -.15 amp(ish) amps.  Now I believe this is from a combination of factors.  I haven’t investigated fully yet but it could be.

  • Those old school solar panels don’t have blocking diodes
  • The Echo Charge is using a bit of power
  • The battery monitor itself is using some power

In any event, it isn’t much.

The panel wiring has also come a long way.  I don’t have all the final breaker sizes sorted out quite yet but I’m getting pretty close to laying down the final design.

Wiring Diagrams 2

Of note is that I’ve individually run each “powered accessory” its own wires from a block. I’ve been good about not splicing into existing lines. The wire from the panel to the blocks is 12g and from the blocks to the devices is generally 18g duplex. All oversized for our application. The 12g is probably a bit overkill, but hey, might as well go big. Some of the wires to the mast block are bigger, notably the common ground wire.

Anyway, hopefully you’re not drooling out the side of your face yet. I know this stuff seems arcane, but really, its fun. Trust me. I haven’t led you astray yet have I?