What it means
The control panel or battery monitor is reading low voltage or a low percentage on the leisure battery. Everything running off 12V — lights, water pump, fridge on 12V mode — will get weaker or start cutting out.
What to do
- Reduce non-essential loads (lights, fans, charging phones) straight away.
- Get the engine running, or connect to mains hook-up / solar if available, to start recharging.
- If it won't hold charge even after a full recharge, the battery itself may be at the end of its life.
Likely causes
- Battery genuinely near empty after a few days off-grid
- A parasitic drain — something left switched on
- Battery ageing and no longer holding its rated capacity
- Faulty charge relay or solar controller not topping it up while driving/parked
Rough UK cost
Diagnosis is often free at a habitation service; a replacement leisure battery runs £120 - £450 fitted.