Distribution, Connectors, and Keeping It Away From the CAN Bus

Introduction

🔴 THIS VOLUME DESCRIBES AN ARCHITECTURE THAT WAS NOT BUILT. Corrected 2026-08-30. There is no house battery, no DC-DC charger and no fused distribution block. Loads plug into an EcoFlow River 3 Max Plus directly. 🔴 The one thing that carries over and matters most: the CPAP runs on the pack’s 12 V DC port, NEVER through the inverter — overnight inverter idle would cost a meaningful share of an 858 Wh pack. ⚠ Also gone with the fridge: the constant-power circuit this volume calls the reason a house battery is necessary. → Vehicle Power vol 1.

With a house battery charged properly, the remaining question is how power reaches the fifteen or so things that want it. The equipment list already names the right instincts — a fused distribution system, possibly a RigRunner, and Anderson Powerpole connectors as the standard — and this volume works out what that means in practice and where a modern truck adds a constraint that older vehicles did not.

3.1 One distribution point, not a nest of adapters

The default answer to “this needs 12 V” is a plug in the accessory socket, and after four devices that answer becomes a heat problem, a reliability problem, and an undiagnosable mess.

The correct arrangement is a single fused distribution block fed by one adequately-sized cable from the house battery, with every load on its own labelled, correctly-rated fuse. That gives four things at once: a fault takes out one device rather than everything, the fuse rating can match the wire rather than the largest device on a shared circuit, faults are traceable, and adding a load later is a five-minute job rather than a re-wire.

A RigRunner-style block is exactly the right product, and it is popular in amateur radio for precisely this reason — it combines the fuse block and the Powerpole standard in one unit.

Switched versus constant is a per-device decision and worth making deliberately:

Table 1 — Switched versus constant is a per-device decision and worth making deliberately

Load	Supply	Why
Fridge	Constant	Must run overnight; that is the entire point
House battery monitor	Constant	Must count amp-hours continuously
Radios	Switched or manually switched	No value drawing when nobody is aboard
Cellular gateway	Switched, or its own switch	Under 14 W is small but continuous
Cockpit charging	Switched	Nothing should charge a flat tablet all week
Camp lighting	Switched, at the load	Wants a local switch, not a key

⚠ The fridge is out of the build, so this reason no longer applies. The fridge on constant power is the load that makes a house battery necessary — it is the one thing that must survive the truck being switched off, and it is the reason none of this can hang off an ignition-switched accessory circuit.

3.2 Powerpoles, and why the standard is the point

Anderson Powerpole is the right choice, and the reasoning is worth recording because it is not primarily about the connector’s electrical merits.

• It is genderless. Every connector is the same part, which eliminates an entire category of “wrong end” errors.
• It is the de facto amateur radio standard. Every piece of ham gear, every field station, and every emergency-communications kit uses it. Equipment moves between the truck, the shack, and a portable setup without adapters, which matters for a build that includes an X6100 go-box.
• It is genuinely high-current and low-resistance, in a form small enough for a distribution block.
• Contacts are field-replaceable with a crimp tool, so a damaged connector is repaired at camp rather than being a dead load.

Two cautions that cost people afternoons:

Assemble to a consistent polarity convention and never deviate. The ARES/RACES convention — red on the left, tongue down, hood away — is worth adopting simply because it is the one everyone else uses, so borrowed or shared equipment mates correctly.

Crimp, do not solder. Powerpole contacts are designed for crimping; solder wicks up the strands and creates a rigid point that fatigues and breaks under vibration. This is a vehicle. Buy the proper crimp tool.

Powerpole is not the right connector for everything. The high-current run between the battery, the DC-DC charger, and the distribution block is beyond a standard 30 A Powerpole and wants a heavier connector or a direct lugged termination. Powerpoles are for the distribution side.

3.3 The constraint a modern truck adds

This is the part that differs from a build on an older vehicle, and it is worth taking seriously.

A 2026 truck is a network of computers. CAN bus modules manage the engine, transmission, stability control, driver assistance, airbags, and the battery-monitoring sensor that the smart charging system depends on. These modules communicate over low-voltage differential signalling and they reference chassis ground.

Three rules follow:

Never take a ground from a convenient body bolt near a control module. A high-current accessory ground sharing a path with a module’s reference creates a voltage offset across that path when current flows, and the module sees a shifted ground. The symptoms are intermittent, weather-dependent, and extremely hard to trace — spurious warnings, phantom faults, occasional shutdowns. Run accessory grounds back to the house battery’s negative, or to one properly established, heavy, dedicated ground point.

Do not tap into vehicle circuits for signals or power. The switched ignition signal the DC-DC charger needs should come from an add-a-circuit at the fuse panel, drawing negligible current, not from splicing into an existing wire. Modern body control modules monitor circuits and object to unexpected loads.

Keep high-current runs physically away from CAN bus harnesses where routing allows. A 30 A charging cable running parallel to a data harness for several feet is an inductive coupling opportunity. Cross at right angles rather than running alongside.

The battery-monitoring sensor on the starting battery’s negative terminal is the one to know about specifically. Vehicles with smart charging measure current in and out of the starting battery through a shunt at that terminal. Anything connected to the battery’s negative post before that sensor is invisible to the vehicle, so the charging system mis-estimates state of charge and mis-manages the alternator. Accessory negatives belong on the chassis side of the sensor, or on the house battery entirely — never on the starting battery post itself.

3.4 Grounding, bonding, and RF

The Antennas and Mounting dive raises common-mode current on coax braid as the usual cause of the radio interfering with the truck and the truck interfering with the radio. The power side has the same problem from the other direction.

• A single-point ground for the accessory system avoids ground loops. Multiple grounds at different chassis points create current paths through the body, and those paths radiate.
• Ferrite chokes on the DC feeds to the radios cost a few dollars and are the standard remedy for alternator whine.
• Route power away from coax where practical, and cross at right angles where routing forces a meeting.
• A switching DC-DC charger is a source of RF noise. It is a high-frequency converter, and mounting it close to a receiver’s antenna feedline or the cellular gateway is asking for a raised noise floor. Distance is the cheap fix, and it should be part of the mounting decision rather than discovered later.

That last point deserves emphasis because it connects two dives: the Cellular Gateway dive is entirely about recovering signals at the edge of detectability, and a noisy charger a few feet away raises the noise floor the gateway is fighting. Mount them apart.

3.5 Monitoring, because a system you cannot see is a system you cannot trust

A shunt-based battery monitor is not optional. Voltage alone is a poor indicator on lead-acid and a nearly useless one on lithium, whose discharge curve is almost flat from 90% down to 20%. A shunt counts amp-hours in and out and reports actual state of charge.

Its practical value on a trip is deciding whether to run the fridge harder, whether the panel is doing anything under canopy, and — the real one — whether there is enough left for another night without moving the truck. That is a question with a number as its answer, and without a shunt there is no number.

It is also what turns the estimates in the first volume into measurements. The single most valuable thing this project can record about its electrical system is a real amp-hour count after a real night at camp.

3.6 Installation practice worth adopting

• Label both ends of every wire. At installation this costs minutes; in two years it saves hours.
• Draw the schematic as built, not as planned, and keep it in this dive.
• Leave a service loop at every termination.
• Grommet every bulkhead pass-through, sleeve every run along a frame rail, secure every few feet.
• Fuse at every source, within inches of the terminal, sized to the cable.
• Anti-seize on ring terminals — Michigan road salt is a corrosion problem, and a corroded high-current connection is a heat problem.
• Carry spare fuses of every value used, in the drawer, with the spare Powerpole contacts and a crimp tool.

References

• Anderson Powerpole: genderless design, amateur-radio de facto standard, field-replaceable crimp contacts; ARES/RACES polarity convention.
• Battery monitoring: shunt-based amp-hour counting required for LiFePO4 because of its flat discharge curve.
• DC-DC charger engine-detect behaviour on smart-alternator vehicles, per the previous volume.
• Vehicle CAN bus grounding practice: accessory grounds returned to a dedicated point rather than shared with module reference grounds; battery-monitoring sensors on the starting battery negative terminal.