redundant satnav / cd changer causing flat battery?

[exbonneville]

Hi, not posted for a while but my X5 E53 2006 3.0d LeMansBlue has started to flatten the battery and I was wondering if the CD changer and satnav units in the nearside boot cubby are the cause. Couple of years ago had the Dynavin N6 unit professionally installed incorporating its own satnav and audio options. Works perfectly. But the old units in the boot are still in situ and removing the panel reveals lights still working as if it is searching for a disc.

Should I remove the units or just remove their fuses? If fuses, how can I be sure I don't disable other car functions sharing the same fuse? Sorry, I'm old and not that smart with car electronics.

The battery was replaced in Dec 18 when it had a major service/MOT by my local Indy, Rutland Prestige. Would be grateful for advice before going back to them (for another large bill!).

Thank you

[Alan Gunn]

Can you just unplug the cables at the back of the units.

[exbonneville]

Thank you. Hadn't thought of that! I assumed I would need to remove them to get to the cables, so I'd probably not bother replacing them.

I'm going to contact the Indy first thing tomorrow (Monday) since they had the car for a flat battery in the first place and replaced it as it was due a full service anyway. Looks like the new battery hasn't cured the problem of a power drain somewhere.

[henrym3]

I have the N6 fitted as is all the other gear you mentioned, my CD/ SAT and HU that I have in that cubby hole all work and flash and don’t drain my battery, you must have something else that is causing the drain like the FSU perhaps. You maybe will have to connect a multi meter and start taking fuses out. A complete PITA.

[exbonneville]

@henrym3 Thank you. I had an inkling that might be the case as for almost 2 years I haven't had a problem. Oh well The task will be for the Indy mechanic to find, the PITA will end up in my wallet no doubt.

30 years of BMW and they have been a loyal friend. Guess I'll have to take this one on the chin. <BG>

[X5Sport]

How old is your battery? This cold weather is very good at finding dying cells. Unless you are doing a lot of miles on a regular basis your battery will fade. These cars need a run of twenty miles to recover each engine start given that heater, glow plugs, heated screens etc are in use it will mean more miles are needed.

My X6 battery has lasted over 8 years but only because I keep the car on a conditioner/charger when it isn't being used. Even that is no longer keeping the charge state up and after two weeks the battery is not good. Any battery over 4-6 years is doing well. I’m going to have to buy a new one shortly

E53s are also known for starter failures where excess current is pulled. This gives the symptoms of a flat battery but it is the starter that is the issue. Replacement is the only cure. It is a diy if you have the correct ETorx sockets.

[henrym3]

Good point on the battery X5Sport, since I retired I seem to do lots of short journeys and I’m following your advice without even thinking about it. The CTEK is now getting some proper use on a regular basis

[exbonneville]

OK, getting somewhere now. My Indy garage mechanic has identified the drain (0.3 amps) from a component in the tow-bar electrics. Now that is starting to make sense as last year I had a local tow-bar fitting company "upgrade" my tow-bar electrics to add the fridge and leisure battery charging when coupled to the caravan with the engine running. I used the car almost daily so there hasn't been enough drain to flatten it but lately, since my wife retired, I haven't used anything like as much.

I remember the tech who fitted the electrics upgrade saying that rather than adapt the existing BMW wiring he replaced it with a separate loom. In that loom are a couple of "boxes" and it seems one of them is not going to sleep!

Right now my car mechanic is having a phone conversation with the tow-bar mechanic to discuss it and I may end up taking the car back to tow-bar man. Either way I am relieved I now know what the probably cause is and it should be a simple fix.

I'll come back with the final word when it is done and I hope this may be of some help to anyone else having a similar issue.

[Alan Gunn]

Nice when you find the drain as it's not so easy to do a lot of the time.

[exbonneville]

Update: mechanic working on my car spoke to tow-bar mechanic on phone who talked him through some "adjustments" that seem to have done the trick! Who would have thought? The plan now is to leave it overnight to confirm one way or the other in the morning. Fingers crossed.

[exbonneville]

To bring this thread to a close I have my car back and the battery drain issue has been solved.

It seems that when the additional caravan leisure battery charge and fridge power lines were put in they each have a relay (located in the offside cubby) in the loom. Their purpose is to detect the extra load and allow power to those bits when coupled up with the engine running. When not plugged in they close and, which was a surprise to the tow-bar fitter, they have an adjustment facility to vary the sensitivity. All it took was a quarter of a turn with a watchmakers screwdriver and problem solved.

Tow-bar fitter was very helpful and said he had never adjusted one before as they are supplied factory set. He had heard they might need adjustment but had never come across it himself. So everyone involved learnt something and I am a happy X5 owner again.

If it is okay I'd like to give a big shout out for Rutland Prestige in Oakham, specialists in German made cars, and UK Tow-bars Ltd in March, Cambridgeshire who couldn't have been more helpful.

Thanks

[Alan Gunn]

Nice one