Battery discharge

[Paul Philpot]

I have a Banner battery (2 years old) fitted to my 1.4 Supersport.

If I don't use the car for about a week the battery drops from 13.5v to 11.4v. 

Is this an issue or normal?

Thanks

[garybee]

What does the battery do if you disconnect it from the car?  It is possible that the car has a fault that is causing a parasitic draw.

The best way to tell if the car is causing the issue is with a 'low amp' clamp meter but if you're not into this kind of thing it's probably not something you own.  2nd best way is to use an ammeter in series but you need to connect this very carefully so as not to break the connection from the batteryto the car.  If you just remove the terminal then connect the ammeter it can cause a fault to disappear and everything appear to be ok when it isn't.

Chances are it's the battery but I don't like buying expensive parts on a guess so always test to make sure.

[SM25T]

Immobiliser will drain a Banner to unusable voltage within 2 weeks. Battery master switch is the answer.