Need some help

J

jony9

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May 7, 2015
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Hi all. With the wife's car being in the garage she's been using mine, so that means I've had to use the z3 for the past week it normally stays in the garage thus time of year on a trickle charge,
I'm having to jump start it every morning now, I know the battery is good, what else should I be looking at? Cheers Jon
 
Check its actually charging when the engine is running, put a volt meter on the battery terminals with the engine running you should see around 14volts if the Alternator is producing a charge. No charge then alternator will need replacing or yours rebuilt if you have a local shop that refurbishes.
Other thing to check is a voltage drain with something staying live on the car when the ignition is off resulting in a flat battery. Again this can be checked using a volt meter and pulling fuses for the various circuits until you see the drain disappear and then check the identified component/wiring on the offending circuit. Some good videos on YouTube for checking voltage drain, worth looking at.
 
Battery terminals are a pain on the Z3.
Remove both terminals and give them a good clean, even then I find sometimes that I need to loosen them, give them a wiggle and then tighten them back up. If the connections are causing a problem you normally just get the "clicking" sound when trying to start the car.
 
How do you "know" the battery is good?

Tony.
 
Good question...
You can check the battery with this, especially CCA:

https://www.amazon.co.uk/KONNWEI-100-2000-Automotive-Alternator-Motorcycle/dp/B08MPXGSGN

Battery Checker.webp
 
t-tony said:
How do you "know" the battery is good?

Tony.
Click to expand...
I suppose I don't know but with it being a year old I would have thought it was ok. And when I'm connecting it to the trickle charge it checks the battery and I don't have any faults with that. I've noticed with this car we've had it from new. But now and again it does this alot I know something is definitely draining the battery its finding out what it is that's the big problem.
 
colb said:
Check its actually charging when the engine is running, put a volt meter on the battery terminals with the engine running you should see around 14volts if the Alternator is producing a charge. No charge then alternator will need replacing or yours rebuilt if you have a local shop that refurbishes.
Other thing to check is a voltage drain with something staying live on the car when the ignition is off resulting in a flat battery. Again this can be checked using a volt meter and pulling fuses for the various circuits until you see the drain disappear and then check the identified component/wiring on the offending circuit. Some good videos on YouTube for checking voltage drain, worth looking at.
Click to expand...


I'll go out and buy a voltage tester, it's done this for years there's something definitely draining the battery, I think I've probably gone through 7 batteries this last one I'm sure has a long guarantee on it so I'm not too worried about that if it is the battery then I'll get that swapped over, so next step it buy a voltage tester, in the summer maybe I'll change the starter and Alternator. Cheers Jon.
 
On a Z3 a common drain is the boot light not switching off when you close the boot. This is easy to check by putting your phone on video record and putting it into the boot when you close it.

Tony.
 
Also sticky switches on the door catches, leaves the interior light on with is hard to see in daylight.
 
Usually if the door switches do that the alarm goes off.

Tony.
 
If you are 100% sure that the battery is fine and that there is a battery drain
its pretty easy to find it using a multimeter and probing the fuse box.

Open the fuse box, close all other doors, lights, etc and lock the car.
Set your multimeter to the millivolts range.
Probe each fuse on its outer points like below:

fuse.webp


Wait for 3 seconds for the multimeter to stabilize.
If the reading does not drop to 0 mV, then you found the culprit.
By the looks of it you are having a large battery drain, so the
reading should be at least 2mV.

Check the fuse position on the following diagram to find the corresponding circuits.

Fuse Box Diagram BMW Z3 (E36; 1996-2002)

Fuse box diagrams (location and assignment of electrical fuses and relays) BMW Z3 (E36; 1996, 1997, 1998, 1999, 2000, 2001, 2002).
fuse-box.info fuse-box.info
Done.

Good luck.
 
For cars without a battery voltage gauge, you can purchase a USB charger/voltmeter from many stores or online.
I bought one for my 98 Z3 (2.8) and it works great because the cigarette lighter is always hot. It tells me battery voltage when the car is off and it tells me the system voltage when the car is running. The power draw is minimal so sometimes I don't turn it off or forget but easy enough to do by just withdrawing it slightly from the charging socket. Great peace of mind and fairly inexpensive.
51S-7GfKooL._AC_SX679_.jpg
 
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