The simple idea

12V (DC) = your off-grid lifeline

12V runs the essentials when you’re not plugged in:

• Lights
• Water pump
• USB ports (often)
• Fans
• Diesel heater (if fitted)
• Many fridges in caravans (12V compressor type)
• Most control panels / monitoring systems

12V power comes mainly from your battery system, which may be topped up by:

• Vehicle charging (while towing/driving)
• Solar (if fitted)
• 240V battery charger (when plugged in)

240V (AC) = “house power” when plugged in

240V typically powers:

• Wall power points (GPOs)
• Air conditioning (usually)
• Microwave (if fitted)
• 240V battery charger (which then charges your batteries)
• Some appliances that are strictly 240V only

240V usually comes from:

• Shore power (caravan park pedestal / home outlet via a proper lead)
• A generator (when used correctly and safely)

The “two power worlds” and how they interact

When you’re not plugged into 240V

• Your caravan is mostly running on 12V battery power.
• 240V outlets won’t work unless you have an inverter and your system is configured to supply them.
• High-draw appliances can drain batteries quickly.

When you’re plugged into 240V

• Your 240V outlets should work.
• Your battery charger should charge your batteries.
• Many 12V items still run on 12V, but the charger helps keep the batteries topped up.
• Appliances like air con and microwave (if fitted) should be available (assuming breakers are on).

What powers what in a typical Mars setup?

Usually 12V

• Internal/external LED lights
• Water pump
• Diesel heater + fan
• Control panel / tank monitors
• USB ports (often)
• 12V compressor fridge (common in modern vans)

Usually 240V

• Air conditioner
• Microwave
• General power points (GPOs)
• Battery charger (charges batteries when plugged in)

Tip: If you’re unsure whether your fridge is 12V or 240V, check the fridge label and your control panel. Many modern vans use 12V compressor fridges that run from battery/solar.

Common misunderstandings (that cause most headaches)

“If I’m plugged into 240V, everything should work.”

Not always. Being plugged in gives you 240V only if:

• The outlet/pedestal is live
• Your power lead is in good condition and seated properly
• Your RCD/safety switch and breakers are ON
• Nothing is tripping the system

“The inverter gives me unlimited 240V.”

An inverter makes 240V from your 12V battery — but high-draw appliances (kettles, heaters, hair dryers) can flatten batteries quickly and may trip the inverter.

• Inverters can trip from overload, low battery voltage, or heat.
• Some vans only power specific outlets via inverter (not the whole van).

“Solar will keep up no matter what.”

Solar output changes hugely with shade, cloud, panel angle, heat, and what you’re running.

Safety first (quick but important)

240V can seriously injure or kill. Please follow these rules:

• Never DIY 240V wiring — use a licensed electrician/approved service agent
• Test your RCD/safety switch regularly (use the “TEST” button)
• Use a proper caravan-rated power lead (avoid cheap indoor extension cords)
• Keep connections off the ground and away from water
• If you smell burning, see melting, or hear buzzing: disconnect power immediately and contact support

Quick troubleshooting (fast checks)

A) My 240V isn’t working (no power points / no air con / no microwave)

1. Check the power source
   • Is the caravan park pedestal switched ON?
   • If at home, is the outlet working (test with another device)?
2. Check your power lead
   • Firmly plugged in at both ends?
   • Any heat, scorch marks, or loose fit?
3. Check the van’s 240V switchboard
   • Find your internal 240V switchboard
   • Make sure the RCD/safety switch is ON
   • Make sure all breakers are ON
4. If it trips immediately
   • Unplug appliances
   • Reset RCD/breaker
   • Plug in ONE item at a time to identify the culprit

B) My 12V isn’t working (no lights / no pump / fridge dead)

1. Check battery isolation
   • Is the battery isolator ON?
   • Is there a master switch on the control panel?
2. Check battery level
   • Look at your monitor (voltage or %)
   • If it’s very low, some systems shut down to protect the battery
3. Check charging
   • If possible, plug into 240V and confirm charging
   • If solar is fitted, confirm solar input is present (daylight / no shade)
4. Check fuses
   • Water pump not working? Often a fuse
   • Lights out? Often a circuit fuse or master isolation

Helpful clue: If your 12V is dead even while plugged into 240V, it often points to the charger not charging, batteries isolated, or a fault in the 12V system.

Quick decision tree

• Only 240V is dead, 12V works fine → shore power / RCD / breaker / lead issue
• Only 12V is dead, 240V works fine → battery isolated, battery flat, charger not charging, or 12V fuse issue
• Both 12V and 240V are dead → no incoming 240V + batteries flat or isolated

What to include when lodging a support ticket (so we can help fast)

When you submit a ticket, include:

• Your model + year (and VIN/chassis number if available)
• Are you plugged into 240V, running on solar, or towing/vehicle charging?
• A photo of your 240V switchboard (RCD + breakers)
• A photo of your battery monitor showing voltage/%
• What exactly isn’t working (lights, pump, fridge, power points, etc.)
• If something is tripping, a short video of it happening