RNS510/Columbus causing overnight battery drain

**Poltroon** · 05-06-2017, 04:30 PM

My MY11 Octavia suffers from an occasional overnight battery drain problem. After parking overnight, next day the battery is flat or close to it, with no obvious things like lights turned on or whatever.

I have finally narrowed the problem down to the (factory fitted) Columbus which (I'm told) is a re-badged RNS510.

I have a DC clamp meter and can measure the battery drain. Normally after a drive if I park the car, turn everything off, exit the vehicle and remote-lock the doors then then after a few moments the current flow starts at 2-3A and drops steadily to an idle current of about 40mA. This typically takes 20 mins or so as various things turn themselves off. The 40-50mA drain is normal and is no issue.

However ... just occasionally the drain does not drop down. Today I managed to catch it and saw that the current was stuck on approx 2.3A. This went on for hours and would certainly drain the battery overnight. I stuck a voltmeter across each of the fuses in turn and noted that there was about 8.8mV drop across F8 (15A fuse) which supplies the Columbus. Pull the fuse and the battery drain stops instantly which pretty conclusively points at the Columbus being guilty. Replace the fuse and everything behaves normally again.

(Incidentally there is a useful guide here that suggests my measured 8.8mV corresponds to a 2A flow which is pretty close Tech Tip: Volkswagen Diagnosis for Excessive Static Current Draw )

I can't see anything odd about the Columbus, it seems to work normally except that once in a while it does not shut down.

So, the questions are: Has anyone else seen this behaviour ? Anyone got any suggestions as to what might be wrong, or what I might be able to do about it?

**kamold** · 05-06-2017, 06:15 PM

Is your Columbus running the original firmware (likely 2760)?
If so try upgrading to 5238 (you'll need to reload your map data and music) using this guide:
Firmware updates for RNS510 units in Australia/NZ

It's possible the unit might be hanging on shutdown (it stays powered for 30mins after shutdown of terminal 15 so that if you start the car again (ie if you just went to get fuel etc) the unit is already booted and running.