90-120 watt constant power draw with nothing on?

[birty]

When I'm out and about in my Elddis Crusader Zephyr and staying off-grid, I use a Bluetti power station along with an extra battery to keep things ticking over. I plug it into the caravan's mains using the 3-pin adapter into the power station—pretty much like you'd do at home to a standard plug.

I've noticed something odd though: even with the caravan's mains power switched off, the Bluetti still seems to be drawing around 90–120 watts constantly. 🤔

Does anyone know what might be causing that, or if there's a way to stop it? I could just switch the power station off, but ideally I'd like to keep my 5G router running, which only uses about 10–20 watts.

Any thoughts or advice would be much appreciated—thanks in advance!

 

[littlebasher]

The fridge will work independently to the 12V system when running on mains, probably that

 

[birty]

Hi, thank you for replying, I can confirm that the lights on the fridge are also off, it also does the same when the fridge running on gas overnight and all electric items are off, someone suggested that when on mains it may be trickle charging the leisure battery? Does this sound feasible? I would have thought once a battery was full it would stop charging?

 

[birdman101]

Would say it is the Battery main reason. If the Battery shows 12.6 volts fully charged,switch the charger off and see if the current draw stops.

 

[birty]

I just asked AI the question and got this might have answered my own question.! Same answer as you Birdman101 thank you! Presume to switch it off I just do at fuse board?

“That constant 90–120 W draw, even with everything in the caravan “off,” is almost certainly the built-in charger working to keep your leisure battery topped up — and those watts aren’t all going into the battery.

Here’s what’s likely happening:

1. The charger is always on when you’re on mains

• Many caravan power systems energise the charger automatically when hooked up to 230 V, even if you’ve turned off lights, sockets, and other appliances.
• The charger itself consumes power just to run — older or non-smart chargers can use 50–100 W even when the battery is full.

2. Float charging still draws a bit

• When your battery is full, a modern smart charger drops into a “float” mode at ~13.6 V, which should use only a handful of watts.
• If your system is older or basic, it may hold the battery at a higher voltage and waste power as heat.

3. Other always-on bits

Even with “everything off,” you’ll still have:

• Control panel electronics
• 12 V relays for fridge changeover
• Any fitted alarms or trackers
• Possibly a mains RCD/MCB board indicator light

If you want to prove it’s the charger:

1. Plug in the caravan to your portable power station as normal.
2. Switch off or unplug the charger at its breaker or fuse (often marked “Battery Charger” or “Converter”).
3. Watch the wattage — if it drops massively, you’ve found the culprit.

If that’s the case and you want to save your portable power station capacity, you can:

• Only charge the leisure battery periodically instead of continuously.
• Replace the charger with a modern multi-stage smart charger, which may idle at <5 W when not actively charging.