C-Tek charging for E89
- Thread starter Papa P
- Start date
Hi, short and simple answer, no. Only charge from under bonnet points. Can screw around with electrical stuff beyond my knowledge charging directly to battery afaik 
Attleborough, Norfolk
There are myriad opinions at the touch of the Search button on here.
Some say it's ok, most don't.
You will be bypassing the IBS if you connect directly. To my mind, that must be there for a reason, so I always connect under the bonnet.
If you find that the leads are a little short to reach the earth bolt on the RH inner wing, then you can connect the earth clip to the earth stud about 6 inches down on the inside edge of the LH inner wing. It's easy to spot as it has several other earths terminating there.
Some say it's ok, most don't.
You will be bypassing the IBS if you connect directly. To my mind, that must be there for a reason, so I always connect under the bonnet.
If you find that the leads are a little short to reach the earth bolt on the RH inner wing, then you can connect the earth clip to the earth stud about 6 inches down on the inside edge of the LH inner wing. It's easy to spot as it has several other earths terminating there.
Scottish Borders
Scotland 🏴
Cheers Martin. I did see that but ruled it out as it is painted. I was also looking for green and yellow earth wires. Silly me forgetting that cars' wiring have absolutely no correlation to 'normal' wiring colours! 
What about one of the suspension top mount nuts/bolts? Easier to get to and are in contact with the chassis and not painted?
What about one of the suspension top mount nuts/bolts? Easier to get to and are in contact with the chassis and not painted?
Just to add my bit I've been using my C tek smart charger connected directly to my battery for the past 4 or 5 months with no issues at all so do what you wish with that info 
The last owner of my car also connected his charger straight to the battery terminals with no issues. I did the same for a few weeks then after reading about the IBS I started charging through the points in the engine bay but my negative connection is a bolt on the top strut thing
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Here’s BMW’s words on the matter from TIS….
Notice! Charging and trickle charging of the battery
The battery may only be recharged with a battery charger that has been approved by BMW and that has a constant charging voltage of 14.8V.
If possible, the battery temperature should be between 15 °C and 25 °C during charging. Under these preconditions, the battery is adequately charged when the charge current drops below 2.5 amps.
If the battery is recharged at low temperatures, the charging procedure should not be ended until the charge current drops below 1.5 A.
On vehicles with IBS, recharging the battery directly at the battery terminals could lead to a misinterpretation of the battery condition and even unwanted Check Control messages or fault entries.
If the battery is recharged while it is installed, it must be recharged using the jump start terminal points, whenever jump start terminal points are provided in the engine compartment. Only then can you be sure that charging is correctly recognised by the vehicle electronics on vehicles with an intelligent battery sensor (IBS).
Notice! Charging and trickle charging of the battery
The battery may only be recharged with a battery charger that has been approved by BMW and that has a constant charging voltage of 14.8V.
If possible, the battery temperature should be between 15 °C and 25 °C during charging. Under these preconditions, the battery is adequately charged when the charge current drops below 2.5 amps.
If the battery is recharged at low temperatures, the charging procedure should not be ended until the charge current drops below 1.5 A.
On vehicles with IBS, recharging the battery directly at the battery terminals could lead to a misinterpretation of the battery condition and even unwanted Check Control messages or fault entries.
If the battery is recharged while it is installed, it must be recharged using the jump start terminal points, whenever jump start terminal points are provided in the engine compartment. Only then can you be sure that charging is correctly recognised by the vehicle electronics on vehicles with an intelligent battery sensor (IBS).