Starter battery drained on a T5

[jliungman]

Hi!

I have now had to get new, hideously expensive Bosch batteries twice since I bought my 2004 California last summer. Now, the second new battery is drained beyond salvage. Trying to figure out what is going on.
1. We don´t drive the car a lot. A couple of times a week at most. Rarely more than 25 minutes drive.
2. With the most recent battery, I have charged it every 1 or 2 weeks with a CTEK charger.
3. When I drive, the voltage in the system looks as it should. (So I don´t think it is the alternator malfunctioning.)

Hypotheses:
1. That big diesel takes a lot of juice to crank. It takes some mileage to replace the amps you use to start the engine. Repeated short hops lead to a progressively drained battery.
2. Something is leaking power. I just can´t seem to figure out what. I was suspecting the cruise control, but I have recently been careful to turn that off after use. Is there an easy way to check if power is flowing from the battery when every is (seemingly) turned off?
3. The alternator is not charging properly. I don´t think this is it, because the voltage looks ok.
4. The system for charging the service batteries is somehow not working as it should. Could it be that the service system is low and the alternator is struggling to charge this AND the starter battery. (I charge the service batteries fairly regularly, so I doubt this is the explanation. The service batteries are also brand new and I don´t use them in the winter.)

Does anyone have experience of this problem? Is there a "check this first because it´s a known issue" kind of answer out there?

Many thanks

John

 

[AlisonF]

There are quite a few threads about battery drainage. If you use the search function you may find something there which could help identify your issue.

 

[jliungman]

There are quite a few threads about battery drainage. If you use the search function you may find something there which could help identify your issue.

Thanks, but what I have seen seems to be about the service battery. This is the starter battery!

 

[AlisonF]

Thanks, but what I have seen seems to be about the service battery. This is the starter battery!

Sorry if I got that wrong.
Some of the 12v sockets in an Ocean run off the engine battery.
It sounds like the engine battery is being drained from something whilst not being used.

 

[Adam Jenkins]

It sounds as if you have a parasitic amperage draw if you have drained two new Bosch batteries to incapacity. There are several u-tube videos which show you how to determine if this is the case. You need a multimeter which is relatively cheap to buy and very useful. Any amperage draw from the battery above >100 mamps once you have switched off the engine and waited for about 30 mins will determine that some component is draining your battery.