The INEOS Grenadier is purpose-built for overlanding — which means sooner or later, a fridge ends up in the cargo area. The Dometic is the most common choice. Getting power to it is straightforward if you understand what circuits are available and how they're fused.

Three options work reliably. Each has real-world trade-offs. This guide covers the factory 12V socket, the roof DTP ports, and the direct aux battery path — with actual amperage numbers from the forum and the connectors you need for each.

The Three Power Routes

The Grenadier gives you multiple ways to power a 12V fridge. Which one makes sense depends on whether you want ignition-switched or always-on power, how you want to route the cable, and whether you have the dual battery option.

Power Source	Circuit Rating	Always-On?	Connector Type	Verdict
Rear 12V socket	15A fused	No (ignition + PWR switch)	12V barrel / Anderson adapter	Simple, limited
DTP roof port (EXT2/EXT3)	25A per port	No (switch-controlled)	DTP-06-2S → Anderson SB50	Best routed install
Direct aux battery	Battery capacity (fuse your own)	Yes	Anderson SB50 with inline MIDI fuse	Best for overnight use

Option 1: Factory Rear 12V Socket

The simplest approach. The Grenadier has a 12V socket in the rear cargo area. It's ignition-switched — it only has power when the vehicle is running, or when the PWR switch on the overhead panel is engaged.

The rear socket is fused at 15A. Per the Dometic CD30 spec, the compressor draws approximately 3A at 12V DC running — well within the socket's rated capacity. Forum member Glen, who tracked down the actual Dometic load figure, noted:

The limitation is the connector itself. A standard 12V barrel plug is prone to working loose under off-road vibration, and it provides no positive retention. Glen's recommendation from the same thread: use a positive-lock connector (like a Deutsch or Anderson) between the socket wiring and the fridge lead, rather than relying on a friction-fit plug.

Option 2: DTP Roof Port via DVA DTP-to-Anderson Cable

The Grenadier's rooftop DTP (Deutsch DTP) ports are the factory-designed accessory power outlets. On vehicles with the High Load Auxiliary Switch Panel, the roof has four DTP ports:

• EXT2 — single port, right-front (above driver door), 25A, independent switch
• EXT3 — three ports (left-front, left-rear, right-rear door areas), 25A shared circuit, single switch

Each DTP port is rated 25A continuous — more than enough for a Dometic fridge. The DTP connector body itself is a Deutsch DTP series, environmentally sealed with a positive latch, rated for -55°C to +125°C and 100+ mating cycles. This is a significant upgrade over the rear 12V socket for any permanent or semi-permanent fridge installation.

The challenge: Dometic fridges typically use an Anderson SB50 connector (or a proprietary Dometic barrel plug), not a DTP plug. DVA makes a pre-terminated cable that bridges this gap directly:

This approach lets you control fridge power with the EXT2 or EXT3 overhead switch. Run the 3-meter cable from the roof port, route it along the headliner or D-pillar trim, and terminate at an Anderson socket in the cargo area. If your Dometic came with an Anderson-terminated lead, it plugs directly. If not, a field-fit Anderson SB50 connector on the fridge cable takes about 10 minutes.

Routing the DTP Cable Indoors

To reach the cargo area from a roof port, the cable typically runs:

1. From the DTP roof port through the roof channel or along the headliner edge
2. Down the D-pillar trim (driver or passenger side) using the existing factory trim gaps
3. Through the cargo area to the fridge mounting location

Most D-pillar runs require a 3-meter cable. The 1-meter version works if you're routing to a roof-mounted accessory (like a fridge in a rooftop tent or cargo rack) rather than an interior cargo area.

If you're powering multiple accessories from a single DTP port, the DVA DTP power splitter adds a second outlet from one port — useful if the fridge shares a DTP port with another 12V device.

Option 3: Direct Auxiliary Battery Wiring

Grenadiers equipped with the dual battery option have a second battery in the engine bay. This is the preferred source for fridges that need to run overnight with the engine off — the factory EXT/INT circuits cut power when the vehicle is off (or require the PWR switch to be manually engaged).

The direct battery path bypasses the overhead switch panel entirely. This means the fridge runs whenever it wants to — the Dometic's internal thermostat and battery protection circuit manage the power. The trade-off: you lose the overhead switch as a kill switch, so you rely on the fridge's own low-voltage disconnect to protect the aux battery.

Fusing for Direct Battery Wiring

If you go the direct battery route, fuse the positive cable as close to the battery terminal as possible — within 18 inches ideally. For a single Dometic fridge at 3–6A peak draw, a 40A MIDI fuse on the battery-side lead is standard practice. This protects against a short in the long run to the cargo area, not just the fridge's internal fuse.

The DVA DTP Solution for Grenadier Fridge Power

For owners who want the cleanest install — no relay, no splice, no drilling — the DVA DTP-to-Anderson SB50 cable is the direct path from the factory roof port to an Anderson-terminated fridge. It's the only pre-made DTP-to-Anderson cable designed specifically for the Grenadier's Deutsch DTP06-2S plug spec.

Here's what the full wiring chain looks like with the DVA cable:

• Vehicle side: Grenadier EXT2 or EXT3 DTP04-2P roof receptacle → EXT overhead switch → factory fuse box
• DVA cable: DTP06-2S male plug into roof port → 3 meters of 12 AWG cable → Anderson SB50 female socket
• Fridge side: Anderson SB50 male plug on fridge lead (field-fit if not factory-terminated)

The overhead EXT switch gives you clean on/off without touching the fridge. The DTP connector's environmental seal keeps the roof penetration weatherproof at the port. No exposed terminals anywhere in the chain.

Browse the full DVA Grenadier Power & Connectivity collection for DTP cables, splitters, and mounting hardware — all designed to work within the Grenadier's factory DTP architecture without modifications to the vehicle harness.

Step-by-Step: DTP Roof Port to Anderson SB50 (Recommended Method)

1. Order the DVA DTP-to-Anderson SB50 cable

   Choose 1m if routing to a cargo rack or rooftop fridge. Choose 3m for an interior cargo area fridge run from the D-pillar. DVA DTP-to-Anderson SB50 →

2. Identify your DTP port (EXT2 or EXT3)

   EXT2 controls the single right-front port above the driver door independently. EXT3 controls three ports (left-front, left-rear, right-rear) on a shared circuit. If you want the fridge switch independent from other accessories, use EXT2.

3. Plug in the DVA cable at the roof port

   The DTP06-2S male end clicks into the DTP04-2P vehicle receptacle. You'll hear the latch seat. Give it a light tug to confirm engagement before routing.

4. Route cable to cargo area

   Run the cable along the headliner edge and down the D-pillar trim channel. Factory trim pieces have enough gap for a 12 AWG cable without cutting. Use adhesive cable clips at 12-inch intervals to prevent chafing.

5. Mount the Anderson SB50 socket in the cargo area

   Common placements: the removable side trim panel near the large door (where nadir5 mounted a similar outlet), or a small bracket on the cargo floor. The Anderson SB50 needs a 1-inch panel hole if panel-mounted.

6. Connect your fridge lead

   If your Dometic came with an Anderson SB50 lead, plug directly into the DVA cable's socket end. If not, crimp a field-fit Anderson SB50 male plug onto the fridge's power lead. The fridge's internal fuse is your downstream protection.

7. Test with the overhead EXT switch

   Toggle EXT2 or EXT3. Fridge should power on. Toggle off — fridge should stop. If the fridge doesn't respond, verify the wedgelock is fully seated in the DTP plug and the EXT circuit switch is not in the disabled/locked position.

Troubleshooting

No power at the DTP port

Check: Is the High Load Auxiliary Switch Panel option fitted to your vehicle? Not all Grenadiers ship with it. If so, is the correct EXT switch in the "on" position? The switches have three positions on some builds — verify the switch is actually active. Also confirm the fuse for that circuit hasn't blown (check the fuse box in the engine bay).

Intermittent power to the fridge

Usually a connector issue, not a wiring issue. The DTP plug must be fully latched — the locking tab must click. If using an Anderson SB50, ensure the shell housing is properly closed and the contacts are clean. Anderson connectors can develop a film of oxidation over time; a light pass with fine emery cloth restores contact quality.

Fridge powers on but runs warm

Check voltage at the fridge terminals under load. Dometic recommends a minimum 11.8V for the CD30 compressor to run efficiently. If you're running a long cable extension and seeing voltage drop below 12V, step up to 10 AWG for the run. Glen's analysis from the forum confirms 12 AWG handles the 3A load cleanly under 40 feet of total circuit length; beyond that, size up.

EXT3 switch turns off other accessories when fridge is plugged in

EXT3 is a shared circuit across three ports. If multiple accessories are on EXT3 and you're approaching 25A total draw, the fuse will blow. A Dometic fridge plus an LED light bar plus a compressor all on EXT3 simultaneously can exceed the shared 25A limit. Redistribute: move the fridge to EXT2 (independent circuit, 25A dedicated) and keep lights on EXT3.