Subject: Flat Battery/IBS Author: krisbiker2 : member since August, 2007 : 4 posts Posted on: 2009-03-13 06:33:28

Heres some info people may find useful, I apologise if its been posted before. The E60 has a sensor fitted to the negative lead that effects sleep mode. Normally when you park up, the car enters sleep mode approx 20 mins later. If the Intelligent Battery Sensor goes wrong this does not happen- the car can stay in standby mode, flattening the battery after several hours, depending on charge state and battery condition when parking up. The load on the battery in parked condition in sleep mode is approx 1A, in standby it can be in excess of 7A. I have found with a 200aHr battery, fully charged, the car can withstand this load and still start for about 10 hours. If you find your battery goes flat overnight, the IBS could be the problem- it can be overcome for testing purposes by disconnecting the red lead from the sensor at a plug near the battery, (which is in the boot on the R/H side) If the problem disappears, the IBS is at fault. Leaving the IBS red lead disconnected, on full charge with a good batt, the car will still start after 1 week and does not flag any faults on the check control. BMW charge £130 approx for a new sensor- breakers yards around £20, it takes under half hour to fit if you want to replace, -disconnect two leads, plus the battery neg lead has to be removed as the sensor is integral to it.

• Flat Battery/IBS - krisbiker2 2009-03-13 06:33:28 (284 views)