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Trouble tracing Battery Drainage


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HI all,

 

I hope I'm not the only person who has experienced this. My car (Octavia 1.9TDI 110PS) battery becomes flat after 4 days. The battery is healthy as it recharges well but the drainage is at 0.63amps on my multimeter. I have used the trial and error method of pulling out individual fuses in turn to see if there are drop in readings.

 

Whilst the reading does drop on some fuses the amount accumulate just over 0.1 of an amp. That is nowhere near the 0.3amps maximum as people say. Does anyone have any idea what to do before I give up and the let the garage do it? Is there something I have missed.

 

Also I noticed there are several electric features remain operational even after the key is out of the ignition with the car locked. The wind screen wiper, fuel filler cap, rear window heater and even the brakes lights come on if I press them. Obviously I don't leave them on but does it draw the battery quite a lot simply having those features on standby?

 

Any help and or advice would be appreciated.

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0.63 amps is quite a lot - .63amps X 24hrs = 15.12 amp hours/day - which is why your healthy battery is lasting about 4 days

 

Brake lights remain operational with the ignition off(normal)  BUT windscreen, fuel filler and rear window heater shouldn't. Has your ignition switch or an associated relay failed? Sounds like other systems still on!

 

Check earths - these can cause weird problems

 

Also try disconnecting the alternator. If the rectifier pack starts to fail this can cause a drain through the alternator

Edited by bigjohn
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I have unplugged the alternator and there is no drop in the amp reading. So I guess there is nothing to do with the rectifier or the alternator. I'm checking the relays but how can it tell if it's failed? Do I use the multimeter also? 

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I have unplugged the alternator and there is no drop in the amp reading. So I guess there is nothing to do with the rectifier or the alternator. I'm checking the relays but how can it tell if it's failed? Do I use the multimeter also? 

Yes,

 

Good point re brake light switch - common failure - unplug the connection block to see (This doesn't just feed brake lights there are multiple contacts) however this wouldn't leave wipers etc operational unless it's at the same time as a weird earthing problem

 

Need to use multimeter whilst removing (and replacing) each component (relay, switch etc..) to look for a reduction in the amp reading

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0.63 A -0.1A = 0.53A   | 0.53 X 12 = 6.37w

 

Suspiciously close to an interior type bulb wattage - presume boot light is not on! Drop a rear seat to check

 

However having wipers, rear window etc.. available with ignition off is not normal 

 

Brake lights working with ignition off IS normal 

 

If you remove the drivers side under dash cover and look under the door side of the steering wheel you will see two bus-bars (I think - its been a while) one should be only live when ignition on (I once wired this to the rear of my car to run an ignition on cool box). Get the multimeter onto these to check (voltage setting!)

Edited by bigjohn
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I have checked through the relays behind the dashboard facia and I have found relay 18 is drawing over 0.2A. As expected it is responsible for the wiper and the rear window heater BUT NOT the fuel filler cap. So I can definitely get this relay replaced but the reading is still between 0.37A-0.39A. 

I think I can look at the brake lights but where do I start?

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i to am having probs with battety drain on my mk 1 octavia im not clued up on cars these days . batt has gon flat about 4 times in 2 mnths if i sit with heatr on and ignition swtched 2 on but not engine running batt wil go flat in bout 10 mins

i have fittd aftr mrkt radio n subs but dnt thnk thts the prob any hlp or ideas plz

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One thing to remember guys and im not sure if it applies to the octavia but alot of cars will keep relays and modules running for a set time after ignition is off, I no when I worked at fiat and jeep we would leave the cars for half hour before checking individual items, we would however measure a drain straight away for a couple hours over the battery

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