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Matt, Mechanical Engineer
Category: UK Car
Satisfied Customers: 20396
Experience:  BEng hons Mech engineering, in auto industry 22 years
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I have a 56 plate renault megan 1.5 dci dynamiqe its

Customer Question

hi i have a 56 plate renault megan 1.5 dci dynamiqe its recently been a problem starting the battery draining i tried starting it yesterday all i got was a clicking noise which i thinkb was from cellanoid then nothing i jump started it drove aroundfor couple of hours every thing was normal with the car apart from using electric windows no other elec were usedgot home turn car off waited 30 seconds then tried to start it there was absolutley nothing no clicking no ignition lights can only describe it as a black out then red light centre of clocks started to flash i did eventually get ignition lights but wouldnt start
Submitted: 3 months ago.
Category: UK Car
Expert:  Matt replied 3 months ago.


I'd first check the easy things like is the boot light or any other interior light staying on then check that the main battery connections are tight and in good condition also check the earth strap to the engine / gearbox.Next I'd check the current drain aspect, the best way to find what circuit is causing the excessive currant drain is to fit a current sensing multimeter in series with the positive battery lead on the car and the battery, or use a current clamp meter on the battery positive cable.

A typical current drain with everything off and un-alarmed should be around 0.05Amp and if its higher than this remove a fuse and re-measure, if measurement doesn't change then replace the fuse and remove the next.

Once you've isolated the circuit with the excessive drain check the wiring connections and plugs to components and the wiring harness that runs by the engine bay fuse box - the wiring harness chaffs / rubs through and gets damaged - but its not always easy to see so be careful when checking..

Also check that the alternator is actually charging the battery in the car by taking a battery voltage reading with the engine off then another with the engine running. The 2nd reading should be higher than the 1st and climbing steadily. And also check that the alternator is secure to the engine as this provides the ground for the charging circuit and make sure that the engine / gearbox earth strap is secure and the contacts are clean and bright.

if the alternator appears not to be working - take it to a electrical specialist and ask them to test it as sometimes you can replace just the diode pack and this will repair the alternator without requiring replacement

And one last thing is – how old is the battery? – As even good quality ones need replacing every 5 years and faulty battery just won’t hold a charge

Expert:  Matt replied 3 months ago.


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