# Nissan Sunny Battery Keeps Going Flat



## pacuk01 (Jan 2, 2009)

Hi,

My mother has got an aging Nissan Sunny. Been a very good car. But over last couple of years it has had a problem where battery seems to go flat in cold weather, and the car wont start. Replacing the battery has usually seemed to cure this until this year.

I have put on a new battery. Car goes flat after 4 days if damp and cold. I replace this new battery as it might have been faulty. Still have same problem. I test the drain on battery when car is engine and ignition is of and decided that the small drain on the battery might be caused by a faulty alternator. I fit a new alternator, the small drain on the battery now goes away, but after four days of non use the car still goes flat. I am running out of ideas. I understand there might be an intermittent power drain on the battery which is enough to make the car fail to start. How will I find the fault. or will it just be easier to fit an isolator to the battery to stop the drain. It is obviously an electrical drain - All doors are shut and the lights are out. I was trying to think of which circuits have power even though the igntion is off. There must be power to internal lights, Central Locking, Clock...anything else??

I am at the end of my tether on this one, and so is my mother.


Any help please?


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## rogoman (Dec 16, 2004)

Check to see if any of the interior lights or brake lights or tail lights stay on.


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## ziggatron (Feb 6, 2014)

Radio always has power along with any security and on star type of systems. Check battery terminals for corrosion and that they are tight. Battery cables can take on corrosion and move down the cable under the coating.


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## pacuk01 (Jan 2, 2009)

The battery is brand new, took back the old one in case it was faulty. The terminals and cables are clean, and there is a good contact. Radio is switched off, no interior or boot light left on. Battery barely registers when I put a voltmeter on it.


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## ziggatron (Feb 6, 2014)

No radio has a switched power wire and constant power wire. If it didn't have power 24/7 it would loose time and all the programmed stations so forth


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## pacuk01 (Jan 2, 2009)

*Car Battery Keeps going flat*

That could apply to any of the internal lights, central locking pos windows, not sure if they have power with keys out..how on earth will I trace the fault though. Even the clock must have a live feed and a switched feed


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## smj999smj (Jan 1, 2006)

A parasitic draw of over 50-miliamps is considered excessive. You'll need to do a parasitic draw test. This is best done with a parasitic draw tester or an ampmeter with a 2-amp shunt placed inline between the negative battery post and the end of the negative battery cable. If you don't have either of them, you can disconnect the negative battery cable and install a 12v test light between the cable and the battery post. If there is a considerable draw, the test light will light up. Make sure you turn off all of the accessories and disable the front door switch (when the door is open) when testing for parasitic draw. Give a minute or two if you have a security system. Then, remove the fuses one-by-one until the draw is eliminated; this will help you isolate the circuit that the draw is on. Get a wiring diagram for that particular circuit and locate all that is powered on it. With the fuse installed, disconnect those items one by one until the excessive draw is eliminated; this will tell you what component is source of the draw.


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