Battery being drained with key on

I replaced my battery with a genuine Honda one about 3 years ago and its working fine and shows the green indicator in the peep hole

When Im parked up in my car and leave the car key on the final setting with the engine stopped it seems to drain the battery down in about 10 minutes or so. I've removed the HFT unit which sometimes can cause drain issues so its not that. If I then get the car started and drive for a while it works as normal again. So alternator/battery etc seem fine, but there is something running it down quickly with the key in... any ideas??

Could just be a failing battery, I replaced mine this week, 4 years old this month.
Quality Yuasa 5000 series as well.
Check the battery resting voltage in the morning, it might be on the way out.
Mine was giving strange symptoms before xmas and it just died over the break.

Could be your alarm battery draining the main battery.
There are a few topics on this

brett said:

Could be your alarm battery draining the main battery.
There are a few topics on this

Click to expand...

It's unlikely that the small alarm battery could drain the relatively huge car battery (~1AHr capacity Vs ~50AHr capacity)

It could be that the 3-year old battery has failed early (although this life is consistent with most warranties).

Bear in mind that the glowplugs actually operate for an extended period of several minutes (the light that comes on for a few seconds is merely a warning not to start the cold engine immediately on switch-on). And they'll consume a very high amount of power from the battery if the engine is not running.

Why are you leaving the ignition key in the 'on' position without the engine running?

The last time it happened I was waiting in a queue for a car wash and it was raining so I wanted to keep the fan on to keep the windows from steaming up. The radio was also on but nothing else, no lights etc. I was quite surprised at how quickly it drained as I would do this from time to time for longer over the years without any issue