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Discussion Starter #1
Hi
I've had issues with starting my Laguna for a few months now. It turns over, but doesn't start. There is plenty on the forums about Top Dead Centre sensors but it doesn't seem to be the problem. When it does fail to start, I can generally get to start by disconnecting the battery for a few minutes.

However, after a couple of days not using the car, I came to it yesterday and it wouldn't even turn over, and the clock reset to 0:00. I managed to jump start from another car and it started OK. I left the engine running for 15 minutes or so and then tried to restart but it wouldn't. By this point it was getting dark, so sacked it in for the day. Tonight I gave it another try. I couldn't get into the car with the blipper and had to use the secret key. Once in there was a ticking from the dashboard and when I put the card in the slot all hell broke loose! The window motors juddered, all the dash lights flashed on and off and there was a funny ticking noise from the dash.

Now I replaced the battery about 2 months ago and I guess it could be a faulty battery, but I wonder if anyone has had similar electrical gremlins which may be prematurely draining the battery (by the way, I didn't leave my lights on and I've checked the battery terminal connections)

Any help much appreciated so that I can drive it down to the nearest Skoda garage and part ex it for the Driver Power Satisfaction Survey winner!

Cheers

Andy
 

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Looks like a job for the multi-tester. Check what voltage your alternator is putting out. Also test to see what current is being drawn when engine is off and car is locked - it shouldn't be more than a few milliamps otherwise it seems something is draining the battery.:)
 

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Discussion Starter #4
Hmm
So I disconnected the battery and reconnected it.
Battery voltage 10.2V - very low!
Battery current 20mA
Unlocked the doors and the current shot up to 3A and then settled at 1.7A!!!
Locked the doors again with the blipper. Current goes down to 150mA. It will only go back down to 20mA if I disconnect the battery and reconnect again.
Unlock the doors again with the blipper and current settles to 1.7A again. Lock the doors from the inside using button by gear stick, and current remains at 1.7A.
Suspect the immobiliser then? Any thoughts?
Battery is now disconnected and on charge overnight. Checked bootlight too (thanks for the tip off) but it was fine.
 

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Draing Battery

Hi Andylowe, Just a couple of points I think you should check out before blaming the immobiliser.
Have your battery tested after it has been fully charged - some companies (the likes of Quik-fit, etc) will do a load test free of charge. Reading with a multimeter only gives a passive read-out and does not give the potential voltage or current under load.
Have you checked the voltage across the battery when the engine is running – it should read 13.5 to 14.8 volts when engine running at 2000+ revs – this measures the out put voltage of the alternator.
When you checked residual voltage did you disconnect the battery – lock the car let it sit for 2-3 minutes – disconnect the battery positive lead and using the ampage setting on your multimeter measure the reading.
When locked the car should only be drawing enough current to maintain the memory in the ECU and the radio or Sat-nav if fitted. As a precaution I would disconnect the radio and see what happens. I had a similar problem some time ago where the radio was faulty and was drawing excess current even when switched off. Doing this would eliminate any radio problems and help narrow the search. The residual current reading of 1.7 amps is far too high and would drain even the best of batteries. Good luck in your search.:)
P.S. A duff alternator can also drain a battery!
 
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