2001 740i Automatic

Depending on treatment batteries can last 3 to 5 years.

Lots of cold starts, short trips and never getting fully charged up will shorten the life.

7 series draw residual current with no key to keep electronics in standby.

Even a small fault / error (e.g. glove box left open) will flatten the battery.

Adapter sounds like a good idea.

If that was indeed the first replacement battery, it's not unusual. My original failed just outside the warranty period, but the replacement is still fine at over 6 years old.

I'm not sure BMW use the very best batteries.

When I'm working my usual journey is very much shorter than that - only about 3 miles each way and in the winter in the dark in both directions. However it does get used most days - and rarely stands unused for more than 2.

It really depends on how long it is unused for. On a fully charged battery

2-3 weeks is the limit. If a fully charged battery is going flat in a few days it needs investigating.

Pull a battery terminal and read the current draw with the key out and all the doors closed. Is it within the specs in the book? If not, find the leak and fix it.

You should know that because of all the accessories that are running when the car is shut off that the idle current draw on these cars is pretty damn high. It might possibly be a problem if he is driving the car very infrequently and for only short distances; the battery is discharging when not in use, may get discharged too far down, and might not get enough chance to get charged back up.

Replacing the battery with a larger deep-cycle battery will mean he'll be able to leave the thing idle for longer and that the battery won't be damage if it's discharged too far.

BUT, it's quite possible that he has a leak. The ammeter will tell you.

--scott

A friend with a Peugeot only drive about ten miles a day, he went through about a battery a year.

My mate has a Toyota Prius, it seems it has a battery for the starter motor in addition to the main drive batteries. It goes flat about once a week, dealer says he needs to take it for a 20 miles drive at least once a week!

In the UK they used to use Bosch, not sure about modern ones.

I heard that US BMWs (even those made in Germany) had US Interstate(?) batteries at one point to avoid some US import charge on foreign batteries.

The replacement Bosch I bought for my E39 was identical to the original apart from name. But has lasted much longer - and still going strong.

Perhaps like the GM autos too? Never did suss out why they fitted an inferior 'box.

My E38 Battery lasted 12 years before it needed replacing but I really don't believe it needed it then - However, the new one is still going strong and it's

3 years old - new owner is very happy with it.

Hope my E65 battery lasts as long

How do you find the E65?

I got an E38 a few years ago but have been let down by the build quality a few times.

I open the garage door, and there it is!

(sorry.)

Sorry John but I've just got back from a 10 day trip from UK to Alicante in Spain. 2600 miles average fuel @ 37.8mpg (diesel) car will easily hit 150mph although road test states 147 I feel 155 is easy to hit. Cruised most of the time at 130kph (80mph) with bursts to 160kph (100).

Very nice car - better than the E38. Easier to handle, lighter steering but more positive, sticks to the road like shit to a blanket. TV option is total crap. Radio is Ok but I think I should have got the digital receiver (one on eBay for £70?). Boot or Trunk seems a lot smaller then the E38 - not enough height - probably due to the enormously fat spare wheel.

Sat nav is good but only if you play with the DVD and add things like speed camera data for UK & Euroland and of course full UK postcode search - all this should be standard from VDO/Navteq/Falk.

As I have contacts** I can add this important stuff to the vastly overpriced DVD from BMW/Navteq. So if anyone has the 2008-01 (or 2007-01/02) DVDs and would like a modded backup DVD with all the goodies then email me off list and as long as you confirm you own an original BMW DVD then I'll add the goodies to it.