DC System – 2022

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Diversified Marine Electronics – Annapolis, MD

PKYS – Annapolis, MD

Power on a boat that has as much electronics and supporting our Scuba diving is a different beast than the normal cruising boat. We started out with 800Ah of lead acid batteries as the house bank. They were not up to the task of even 1 day of reliable power while underway. This has led to our refrigeration/freezer compressors shutting down and frozen food defrosting. We had also had difficulties operating the kitchen AC appliances that involved heating elements. The Lead Acid batteries simply weren’t able to keep up with high loads over short periods of time.

We were told by many that the answer was Lithium batteries. The Victron Ecosystem is highly integrated, smart and provided everything we needed so we worked with David at Diversified Marine Services in Annapolis to design our system.

Lithium is really dangerous if it is not installed properly. If you are considering upgrading to Lithium, PLEASE, PLEASE work with someone actually trained in its use and by the OEM for the products you decide you want to use. DO NOT RELY solely on the work and design we have here. Please get a real trained Electrical Engineer to help you and the University of You Tube is not the answer.

The below diagram is the logical diagram of the electrical system on SV Unladen Swallow.

Logical Configuration
Wiring for the BMS

The above graphic shows the wiring we used for the BMS. Note: if we had not configured the batteries as one group of parallel batteries with a single Pos/Neg lead, we would have brought the battery leads into a Lynx distributer on these posts. The circuits coming off the green terminals on the side are the control circuits for OK to charge and OK to discharge. The lines marked Cerbo provide the power to run the cerbo control unit. There is also an electronic switch that can be used to start a GenSet or something similar.

This diagram was provided by Victron as a reference system. It’s a bit dated as some of the parts and pieces have been upgraded by Victron. Specifically, it does not include any of the Lynx technology so the BMS shown has been replaced and the primary bussing was replaced by Lynx.

Balmar external Regulator – Model# 618 wiring

This diagram is how the upgraded Balmar Alternator is wired. This is still a bit of a work in progress. The external regulator is a bit dated, but the engineers swear by it. There is a 3 char LCD that provides the internal interface. There is also a PC interface that may be worth purchasing because you will want to be able to see the display while the alternator is running to diagnose and monitor it. We are going to install one and see how things go.

Reference Configuration from Victron

The power requirements to run the scuba compressor are significant. 30-32Amps running on 110VAC. That’s over 300 amps in 12VDC. In order to support this kind of load, we had to go to a 5KVW Inverter Charger and the primary wiring is 04 gauge. This is wire as thick as my thumb. It is very difficult to work with given its bend radius. It is also very expensive – we paid $500 for 25′ of Red and 25′ of Black colored wire.

The system is designed so all of the loads are now controlled on a single circuit. All of the charging inputs are also taken in on the Lynx via fused circuits.

The electric winches have given us some issues which led us to discover that the primary electric winch was eating itself leading to much higher power draw. More to follow as we have purchased a new winch that is a very different technology and we have high hopes for it once, we get it installed.

This the main DC busing wiring and associated devices

The above picture is definitely not the work of a trained electrical installer but it did take me the better part of a full week of uninstalling and then re-installing the new Victron based bus. The plywood provides a fixed mounting surface above the Port diesel tank for everything on the main bus.

In this picture, the BMS is the small box at the top, the 2 boxes in the middle are the primary bus – each of the lines has a mega fuse sized to the power expected to traverse that line. The big switch in the middle is used to isolate the Inverter/Charger. The small box at the bottom of the Lynx is the DC-to-DC charger to keep the starter battery charged. The other blue box is the battery protect. All of the DC load – other than the Inverter/Charger – goes through this box.

What’s not shown at the far left of this picture are the original battery cut off switches. The switch for the house battery needed to be completely cleaned off of all of the extra circuits that bypassed the main panel and now actually does control every load on the boat. The starter battery switch is also now clean, with the piggy back loads re-homed to where they belonged in the overall power architecture.

The other part of the upgrade is new switch panel at the helm to control a couple of new or re-homed devices.

2024 Update

The Cerbo GX has taken on a much greater role in the overall system. Check Out the dedicated Cerbo GX page for a detailed explanation of its function and how it’s wired into the larger Victron ecosystem and other functions on the boat.