DC Electrical System – 2021

Home RefitRefit 2021 – DC Electrical System 2021

Like I have stated before, this boat has already circumnavigated. Over the course of those 10+ years, the previous owner worked hard to improve and repair the boat with what he had in some pretty remote places. Additionally, once he found a workable solution, he seldom went back and made it “right”. As such, when it came to the DC system on the boat, as he was presented with the need to power a new thing, he often reached for the closest wire that was hot and had capacity to power that new thing. Additionally the original DC panel was full. He’d long since used the remaining spaces for spare breakers. Finally, when this boat was made, even though he had it built with the express purpose of going cruising, Beneteau was building these boats primarily for RACING. As such the factory electrical systems were not designed to support a cruising boat’s electrical needs. He had to make do with what was there.

Original Nav Station configuration w DC (Above) AC (Below) and radios (VHF and HF) and the RayMarine MFD

So what we found that created cause for concern was a significant amount of power being consumed on the boat that was not controllable by the DC switch/ breaker panel.

We also knew the 6 circa 2006 solar panels on the back of the boat were just crying to be updated.

We also inherited a KISS wind generator. On a good day this could produce about 400W.

Original Wind Generator installed on Stern of the Boat

What we learned was that the compressors for both the refrigerator and the freezer had low voltage protects – in other words they would shut down if the voltage feeding them dropped too low. We lost 2 freezers full of food to this.

The original battery configuration for the boat was 8 -6VDC golf cart lead acid batteries arranged in a 12VDC configuration. While this was OK to hold things overnight, it was really too limited for the boat and required help from the GenSet or the main engine almost daily – especially being fed by the old 6x80W panels.

NOTE: Golf Cart batteries with heavy discharge/ charge cycling in warmer weather boil off water much more rapidly than regular car starter batteries. I highly recommend something like “Water my Battery” as a means of being able to easily keep up with the demand. Otherwise you may find yourself putting it off due to the difficulty of reaching all your batteries depending on how they are configured.

So it turns out golf cart batteries are great for slow discharge, they can not handle the needs of galley AC appliances. Also when we are underway, with the autopilot running, we discovered that the overall power draw really exceeded what they could sustainably do leading to the freezer defrosting.


  1. All DC power controlled by the main electrical panel
  2. Improve solar to sustainably replenish the batteries
  3. Accommodate the new electronics we wanted to install on the boat

Later we learned about the low voltage cut-off issues which was the final straw that pushed us to the Lithium upgrade in 2022.

The first step was to try to identify everything on the boat consuming DC power and where that power was being sourced.

NOTE: in Oct of 2022 when this is being drafted, I am still not sure we know everything. We certainly still don’t have a great idea of power consumption by load.

We then started to create a new circuit diagram for the boat. We quickly decided that sub-panels (a combination of switch panels and fuse blocks) were going to be required to include everything that wasn’t wired through the main panel.

Logical AC & DC Electrical Diagram including new Solar Panels.

NOTE: pulling new wire to the main panel area is very challenging as the routes through that part of the boat are basically full.

We then started to install the new subpanels and fuse blocks and lay in the new circuits to feed all the new electronics and some new lighting. The new solar arch was going to get a bunch of new lights, a camera etc. The ship’s electronics were getting several new devices. See the Electronics 2021 page.

We also did some homework on how to power the new consumer type electronics we wanted to install around a new Internet accessible ship’s network (both wired and WiFi). In that process we found that most of the devices were actually running off of either 5 or 12VDC and that the “wall worts” were just transformers to get back to that type of power. By cutting those AC devices off and using step down or step up transformers we were able to provide DC voltage at the right power level to power most of the consumer electronics. This allows us not to need the inverter to power most of those devices to include the ship’s PC, router and other supporting elements. We also acquired a bunch of 12VDC USB charging stations that are installed all over the boat to keep portable devices charged.

Finally we did acquire a new main DC panel that includes a master 100A breaker. It is large enough to accommodate future DC needs.

This is the panel type and size, but our labels are different

Continue reading here for what we did in 2022.