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Steve
Steve, BMW Expert
Category: BMW
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Experience:  BMW Expert
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2008 BMW 118 diesel, which I drive mainly around London on

Resolved Question:

2008 BMW 118 diesel, which I drive mainly around London on short journeys, suffers from low battery problems. A heavy duty battery was fitted on the advice of Hexagon, from whom I bought it new, in 2010. Today I've had the battery charged by a local garage, who had it on charge for 7 hours, but was still drawing 4 amps, which they think is higher than they would expect. With everything switched off, it draws about 0.1 amps but it fluctuates. I've had it recharged before, but, especially in the winter, it runs down. Is there anything I can do about this?
Submitted: 3 years ago.
Category: BMW
Expert:  Steve replied 3 years ago.

hello

 

there are a few options

 

1) you should have a full current draw test or power diagnosis test carried out to verify if there is a faulty component that is drawing more power than it should when the car is off and "asleep". 0.1 amps is a little high, so there may be an issue.

 

if the current draw test comes back all okay, then you have two more options

 

2) change driving behavior since repeated short trips places a heavy burden on the battery and charging system

 

3) put the car on trickle charge each night to ensure the battery never gets too low

 

I know these last two options are somewhat unsatisfying, but repeated short trips are a legitimate concern on new BMWs given the heavy amount of electronics they have - if there is no undue current draw and the alternator is working properly, then the driving habits are to blame and these are the only options.

 

 

Sorry if you were hoping for a different answer, please don't shoot the messenger - I can only give the honest answer, which I have. Please remember that a low rating PUNISHES me for my honest and prompt response, and I receive nothing for my time and answer until a positive rating is clicked.

Please let me know if you have further questions. Please do not forget to click a positive rating as this is the only way I receive credit for my answer, thank you. Best wishes with your vehicle.

Customer: replied 3 years ago.

Your reply is helpful, but can you desccribe what a current draw rest is? Also I only have street parking available, so cannot trickel charge overnight. Any other ideas?

Expert:  Steve replied 3 years ago.

a current draw test involves monitoring amperage draw with the car in sleep mode, then pulling fuses on by one to see when the draw stops or drops off. this will thus identify the problem circuit that is draining the battery. Also, if you have anything aftermarket installed, that should be removed

 

if there is no undue draw, the alternator is working properly, and the battery is correct and not faulty, then there are no other reasonable ways to address this, besides what I have stated.

 

Please let me know if you have further questions. Please do not forget to click a positive rating as this is the only way I receive credit for my answer, thank you.

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