Battery Discharge

[Aquasurfer]

My lexus would not start the other day so checked it with Battery charger and was very low. I went to a garage and they tested it - said it had been discharged. I got a new Battery and put on car. Car came to life and had a few journeys. However this morning when went to use it was exactly the same scenario again.

What could be doing this and why? How do I sort out...

Any help appreciated.

Thanks

[peter026]

There could be a number of reasons for this so here goes the ones I can remember

1) side/headlight left on

2) Reading/courtesy light left on

3) A corroded or loose connection between the Battery and cable attached to it

4) The boot courtesy light not turning off, a defective switch..........this is one of the common faults for Battery discharge

5) A defective charging system

Hope this is some help

[Mr Morse]

4) The boot courtesy light not turning off, a defective switch..........this is one of the common faults for battery discharge

I had this very same problem on the Tubby, the boot light staying on.

[Aquasurfer]

There could be a number of reasons for this so here goes the ones I can remember

1) side/headlight left on

2) Reading/courtesy light left on

3) A corroded or loose connection between the battery and cable attached to it

4) The boot courtesy light not turning off, a defective switch..........this is one of the common faults for battery discharge

5) A defective charging system

Hope this is some help

No lights left on

Wires to Battery all look okay

How will I know about the boot courtesy light ???

Charging system = Alternator ?? how will I know...

[Chris Skelton]

There could be a number of reasons for this so here goes the ones I can remember

1) side/headlight left on

2) Reading/courtesy light left on

3) A corroded or loose connection between the battery and cable attached to it

4) The boot courtesy light not turning off, a defective switch..........this is one of the common faults for battery discharge

5) A defective charging system

Hope this is some help

No lights left on

Wires to Battery all look okay

How will I know about the boot courtesy light ???

Charging system = Alternator ?? how will I know...

Garagecan put a tester on it andtell you if something is using power. Then you isolate by pulling fuses......

[adz]

Charging system = Alternator ?? how will I know...

Check your Battery across the terminals with a DVM ( multimeter) It should be at least 12 Volts

Start the car and do the same test (with engine revs about 1000-1500RPM) , the voltage should rise to at least 13.5V, more like 14V.

It's a 5 minute job which any garage could do if you haven't got a meter.

If the Volts stay at 12V (or even drop) your charging circuit or associated wiring/ fuse is at fault.

Good luck and post back when you get a result

[eXOBeX]

Adz's example above is a good one. Locating a fault is slightly fiddlier. Put a multimeter to the 10A range. Disconnect the Battery (either cable, negative probably safer), put one meter probe (red in this case) to the disconnected Battery cable and the other to the disconnected Battery post.

DO NOT START THE CAR OR YOU'LL BLOW THE METER!

You'll now be showing a current draw, probably 100 milliamps or more, which is not good.

Pull one of the fuses. If the meter drops significantly, there's your problem circuit. If not, put it back in and move to the next one. The ECTS and EFI fuses will show some change when pulled, this is normal as they're always running.

Found your problem circuit? Now you can narrow the fault down as you know where to start looking.

One method that's just come to mind for testing the boot light: set a camcorder (or camera phone with video record facility) recording, pop it in the boot and shut the lid. Now open it, stop the recording and play it back to see if the light went out.

Oh, once you've finished with the meter, don't forget to unplug the red lead from the 10A socket and plug it back into the normal one, or you'll short out the next thing you try to read the voltage of!

[Aquasurfer]

Adz's example above is a good one. Locating a fault is slightly fiddlier. Put a multimeter to the 10A range. Disconnect the battery (either cable, negative probably safer), put one meter probe (red in this case) to the disconnected battery cable and the other to the disconnected battery post.

DO NOT START THE CAR OR YOU'LL BLOW THE METER!

You'll now be showing a current draw, probably 100 milliamps or more, which is not good.

Pull one of the fuses. If the meter drops significantly, there's your problem circuit. If not, put it back in and move to the next one. The ECTS and EFI fuses will show some change when pulled, this is normal as they're always running.

Found your problem circuit? Now you can narrow the fault down as you know where to start looking.

One method that's just come to mind for testing the boot light: set a camcorder (or camera phone with video record facility) recording, pop it in the boot and shut the lid. Now open it, stop the recording and play it back to see if the light went out.

Oh, once you've finished with the meter, don't forget to unplug the red lead from the 10A socket and plug it back into the normal one, or you'll short out the next thing you try to read the voltage of!

Mate has agreed to go in boot and see if light comes on when i close lid as long as i let him back out after - lol

Oh yeah where are fuses etc as not got manual with me ... which ones pull etc...

Thanks

[Aquasurfer]

Adz's example above is a good one. Locating a fault is slightly fiddlier. Put a multimeter to the 10A range. Disconnect the battery (either cable, negative probably safer), put one meter probe (red in this case) to the disconnected battery cable and the other to the disconnected battery post.

DO NOT START THE CAR OR YOU'LL BLOW THE METER!

You'll now be showing a current draw, probably 100 milliamps or more, which is not good.

Pull one of the fuses. If the meter drops significantly, there's your problem circuit. If not, put it back in and move to the next one. The ECTS and EFI fuses will show some change when pulled, this is normal as they're always running.

Found your problem circuit? Now you can narrow the fault down as you know where to start looking.

One method that's just come to mind for testing the boot light: set a camcorder (or camera phone with video record facility) recording, pop it in the boot and shut the lid. Now open it, stop the recording and play it back to see if the light went out.

Oh, once you've finished with the meter, don't forget to unplug the red lead from the 10A socket and plug it back into the normal one, or you'll short out the next thing you try to read the voltage of!

[maneesh]

I had the same problem as you. After 1.5 hrs at Lexus, they came back and said it was the CD changer that was draining the Battery (weird I know). They disconnected the CD changer, and I didn't have a problem after that.

[Nitmoi]

I had Battery loss through a CD changer on my VW Camper same, took it out and flogged it - end of problem.