Battery drain

[cheeseandbeans]

Afternoon all. Well the last couple of weeks have been the first time I've been able to use my Z in anger and I've discovered something is draining the battery.

If I charge the battery fully and use it every day it's pretty much flat again by day 3.

Any ideas? I've read on another thread about pulling fuses until you find the culprit. Does anyone know how easy it would be to identify a faulty alternator?

Cheers

 

[GazHyde]

Commonly tends to be interior lights particularly the boot (because you can't tell if it's on still when it's shut!) and occasionally the bonnet alarm switch. Easy way to test for the boot light staying on is to put your smartphone in the boot recording video and close the lid!

 

[cheeseandbeans]

Commonly tends to be interior lights particularly the boot (because you can't tell if it's on still when it's shut!) and occasionally the bonnet alarm switch. Easy way to test for the boot light staying on is to put your smartphone in the boot recording video and close the lid!

Great shout that mate. Will do that later.

 

[jonco]

.......Does anyone know how easy it would be to identify a faulty alternator?......

Just read in another thread that you have diagnostics package - if you can get INPA working you can check battery voltage/charge rate through Status (I think option it's option 5 analog values 3?ish)

Edit :You may be able to check through other modules but I have not used them - sure somebody else will know.

 

[Tracy Dee]

Try a isolator on the battery.

 

[littlefeller]

dont the boot light time out?

 

[jonco]

dont the boot light time out?

Nope - with the boot open and light on, you can test the `off' contact by pushing a screw driver or bar into the slot. Straight on/off on mine.

 

[littlefeller]

is the boot light on a different circuit to the other interior lights?

 

[Brian H]

is the boot light on a different circuit to the other interior lights?

Yes it is a single light with a single switch which is located in the boot latch.

 

[littlefeller]

i dont know why (brain getting older now) but for some reason i thought the interior lights including the boot light circuits all lead back to the ZKE control unit, am i wrong here? i do know the interior lights (not boot light) will time out after about 15 min, as dictated by the ZKE unit.

 

[Brian H]

i dont know why (brain getting older now) but for some reason i thought the interior lights including the boot light circuits all lead back to the ZKE control unit, am i wrong here? i do know the interior lights (not boot light) will time out after about 15 min, as dictated by the ZKE unit.

It would be nice if the boot light timed out, I know from previous experience that it just stays on, surprisingly it does not take too long to flatten your battery.

 

[Redline]

It would be nice if the boot light timed out, I know from previous experience that it just stays on, surprisingly it does not take too long to flatten your battery.

We've gotten so used to all these little gizmos on cars.
Would be a great option for a replacement LED bulb to have it time out. A good little option for these problem scenarios. I claim all design property rights

 

[Alan W]

How old is the battery? 5 years or more (or approaching 5 years) then I'd replace it. I had a similar issue and was convinced I had a drain somewhere and thought the battery looked newish (clearly because it sits in the boot as not exposed to the elements) and then I spoke to the previous owner who had the car for 8 years and had never replaced it! New battery fitted and never had any more problems..

 

[jonco]

i dont know why (brain getting older now) but for some reason i thought the interior lights including the boot light circuits all lead back to the ZKE control unit, am i wrong here? i do know the interior lights (not boot light) will time out after about 15 min, as dictated by the ZKE unit.

Interesting point - this is the ETM for the '98 http://www.hc.lv/inc/Upload/news_290/File/e36z3_98.pdf. Check 6320.0 and 6330.3. Never noticed any timeout and when I have been working it the boot but I usually take bulb out.

Easy way to check I suppose is to deliberately leave boot open and see what happens - may try that later

 

[colb]

I had a duff alternator discovered it was at fault after using the car at night with headlights on, next day battery flat.
On checking alternator it was only putting out 12v not the 14v it should have been with engine running. Easy to check with a voltmeter on the battery terminals with engine running. Now have a small voltmeter that plugs in the cig lighter socket to keep an eye on charging state. Replacing alternator put it right.

 

[littlefeller]

Interesting point - this is the ETM for the '98 http://www.hc.lv/inc/Upload/news_290/File/e36z3_98.pdf. Check 6320.0 and 6330.3. Never noticed any timeout and when I have been working it the boot but I usually take bulb out.

Easy way to check I suppose is to deliberately leave boot open and see what happens - may try that later

i will give it a go lunchtime, it wont drain mine as it is led.

 

[littlefeller]

We've gotten so used to all these little gizmos on cars.
Would be a great option for a replacement LED bulb to have it time out. A good little option for these problem scenarios. I claim all design property rights

umm interesting idea, if mine does not time out i may try this idea

 

[littlefeller]

interestingly, in the diagrams listed above the boot light is powered by the ZKE unit, i will give it a try at lunch time.

 

[littlefeller]

i can now confirm the boot light does NOT time out like the other lights.

 

[mrscalex]

I was suffering from battery drain. The boot light was turning off so I was getting ready for some more involved diagnostics. I took it out and it fixed the problem anyway!