The PCU combines what would otherwise be distributed across several devices: battery monitor, tank gauge, energy overview, and device control on a single touch display. All interfaces are already built into the device — no additional modules are needed. This article shows what it replaces, how it is wired, and where its limits lie compared to a modular bus system.
What it replaces
In a conventionally structured onboard electrical system, three to four individual devices sit side-by-side on the switch panel: a battery monitor, one or more tank gauges, possibly a temperature instrument, plus a switch panel. Each has its own power supply, its own cutout, and its own operating logic.
The PCU replaces this array with a single display. This not only saves space on the panel but, more importantly, wiring — and with the wiring, the most common source of errors during installation.
| Function | What the PCU provides |
|---|---|
| Battery monitoring | State of charge, voltage, current, temperature in real time, also for the starter battery |
| Tanks | Fresh, grey, and black water, compatible with common sensor types |
| Energy flow | Diagram of all sources and consumers in real time |
| Device control | Refrigerator, heating, air conditioning via CI and CAN bus |
| Temperature | Indoor and outdoor temperature |
Designed for 12- and 24-volt electrical systems and all common battery types. The installation cutout is 120 x 70 millimeters, the display area 144 x 90.
The distributor halves the wiring
The second component is the Connect Hub. Without it, each sensor cable would run individually to the display; with it, tank sensors, shunts, and batteries converge tool-free at a central point, and a single cable runs from there.
The practical benefit lies less in the amount of cabling than in the installation location. The hub sits where the sensors are — typically in the utility room — the display where it is operated. There is a distance of up to ten meters between the two, and only this one cable needs to be routed through the vehicle or boat.
NoteThe hub is also the right answer for later expansions. If a tank or a second shunt is added, it is connected to the hub — not to the display, which may be behind a panel.
Expansion: from displaying to switching
Up to this point, the PCU is a monitoring device with limited control. It only becomes a full-fledged load management system with a switching unit, and this fundamentally changes the design of the electrical system.
Such a unit replaces relays, fuses, and distribution blocks with a programmable device. Eight inputs, eight outputs, 90 amps total current, up to 25 amps per channel — and the current limit is not set by a fuse, but adjusted in five-amp increments. If you change a circuit, you no longer replace a fuse, but change a value.
In addition, there are functions that would be complex with relays: dimming, flashing, time control, rule-based logic, battery protection per output, and direct control of motors, valves, or an electric step via an H-bridge. Multiple units can be linked.
WarningElectronic protection applies to the circuits running through the module. It does not replace the main fuse at the battery or the fuse for the module's supply line itself. This line carries the full current and must be fused close to the battery.
When PCU, when bus system
Both approaches lead to a common display. The difference lies in where the intelligence resides.
The PCU excels when the scope is manageable and installation needs to be quick: one battery bank, two to four tanks, a handful of consumers, plus devices with CI or CAN connectivity. Fewer parts, less wiring, one operating logic.
A modular bus system is worthwhile as soon as the system needs to grow beyond this scope: multiple battery groups with their own shunts, individual charging sources and large consumers to be measured separately, AC side, connection to chartplotters, displays in multiple locations. There, each device is an individual participant, and the system grows by adding a module.
The honest rule of thumb: If you count more than about eight measurement points during planning or want to integrate third-party systems with their own bus, it's better to plan modularly from the start. If you stay below that, the integrated unit saves time and parts.
What should be decided before installation
- Number and type of tank sensors. These determine which signal types are needed.
- Number of battery groups. One measuring point per group — consumer and starter batteries are counted separately.
- Which devices are to be controlled via bus. Refrigerator, heating, and air conditioning must have the appropriate interface.
- Whether switching is to be implemented. This decides on the switching unit — and that on the structure of the entire distribution.
- Installation location of the distributor. Close to the sensors, dry, accessible.
Typical errors
- Sensor cables routed individually to the display. This is exactly what the distributor avoids — if you omit it, you lay multiple times the cable.
- Distributor installed in an inaccessible location. It is the point where later expansions connect.
- Switching unit without its own fuse. The supply line carries the full current.
- Device control without checking the interface. Not every refrigerator speaks CI or CAN bus.
- Planned too small. If you foresee modular growth, it's better to start modularly.
- Everything routed through the display. Safety-relevant consumers need a path that works without electronics.
