I replaced my E53's battery in July last year and had intermittent problems with the alarm going off without reason, the 4x4 light coming up on occasion and the tyre pressure indicator alarm coming on intermittently. Had all alarm sensors replaced under warranty.... no fault found on the rest. 2 months later (all problems still intermittent) it went in for a routine service and one of the things they did was replace the battery under warranty. (the first time I replaced it was not at an agent) Problems solved. Replace your battery, new ones are not always good ones.