XSeries-forum

Twice in the last two weeks, the car has totally died as a result of relatively small loads with the engine not running eg. radio and interior lights on ~ 10 minutes whilst vacuuming out - after jump starting, the car seems OK again and will readily start in the mornings. Car is Jan 2006 - does this sound like worn-out battery?

Yes I would say so, but Do you need to drive it for a bit before it restarts off the key or will it start straight after a jump?

If the 06 battery has never been replaced from new that puts it at 6 years old and due for renewal.

What you say does sound like a battery issue (but 10 mins can kill most batteries on the X5's)!

I had the pleasure of helping Jeegnesh replace his Bosch S3 battery which he bought on the 28th of November 2011 - making that battery a failure at less than 3 months! But he does like using his remote heater a bit!

That's why he should fit a better one - S5 or S6. If you go cheap, you get cheap....

Even so, the Aux heater system should cut off if it senses a low battery state.

Engineering Tip - Do not 'Deep Discharge' a modern car battery. It will shorten the life of the battery considerably as they are not designed for it and it causes irreversible damage. There are specific 'deep discharge' batteries but these are special use and not for use in normal cars as the main battery. I used to be the Fleet Technical Manager for a fleet of highly specialised radio vehicles with dual charging systems which used deep discharge batteries to run the hardware we installed, and normal car batteries for the engines. Battery conditioners were used should any of the SVs not be used for a while. If you are doing infrequent or short journeys then invest in a CTEK Battery conditioner, or similar. It will save your battery and in the long term you wallet too.

Thanks for the replies- I have had the car for 12 months and talking to the previous owner who had the car for three years and did not change the unit, I guess it is the original battery at 6 years old - so i will take the plunge and buy a new Bosch S5 - BTW where abouts in the back is the battery?

Under the spare wheel, then under the rear air suspension gubbins. Not difficult to change, just takes a bit of time and faffing about. Oh, and it's big and heavy!! You will need a 10, 12, 15 and 17mm (I think) sockets and a 10mm spanner. I think those are the only sizes. May not need the 17mm.

To remove it, first remove the spare wheel
That will expose a domed device (rear air suspension pump assembly) held on a triangular frame.
Under and remove the nuts and bolts at each point of the triangle and lift the assembly to lean it against the back seat. You should be able to prop it in place vertically
The battery is right at the rear of the vehicle in a plastic bucket.
Disconnect the -ve wire first, next the vent pipe (you need to reconnect this to the replacement)
Disconnect te +ve lead - handle this lead with a bit of care as it has an explosive charge in it. It won't fire, just be aware of it for static discharge precautions. No nylons!!
Undo the hold down clamp.
Carefully lift out the battery - heavy!!

Refit by reversing the process - don't forget the vent pipe.
If you get a DSC warning light, simply (and whilst moving very slowly forward so as not to strain the steering components) move the steering from full lock to full lock. That should clear the light.

So you need to take the spare wheel out and there's some sort of compartment under that?

Edited my post to help

Thanks very much!