LCR New battery dying fast

[ySoCereal]

Hey there,

For a little while I've had some issues with my battery dying really quick. A month ago I put a brand new one in as the old one was dying after 3 days. I dropped the car off at the garage for mot before I went offshore and left it with them. They had it for 2.5 weeks and reported no issues.

Got home and it had been sat for 1.5 weeks at this point, was completely dead, no lights on dash etc. Jump started it, drove off and battery light came on followed by all other lights, then loss of engine power etc.. the same garage came out, said the alternator was knackered.

Bought a new alternator, fit it and they tried to charge the battery overnight but said it wasn't taking a charge. Was a new battery so the shop exchanged it yesterday for a brand new fully charged one.

Drove 50miles home with it, parked the car for the night. Went to start it just now and again it's completely dead, no lights on dash. It jump started instantly and drove fine.

Can anyone help shed some light on this? What is killing my battery charge so quick? No lights etc are left on, just the alarm system..

Thanks

 

[verbal_kint]

Have you got a multimeter to read the charge? If not get one, they are not expensive and a great tool to have.

Read the battery and repeat at regular intervals to see if it really is losing charge. You could then try the same exercise with the battery not connected to the car system.

If the charge is dropping significantly, it should hold 12v + with no problem, a drop to say 10v over a day of sitting around could mean an unusual drain, Stereo left on? Interior light (in boot even) could have been left on. You might have corroded wire that is allowing a drain to happen.

If it drops charge easily when not connected then that's a faulty battery, you could give it a good recharge and then re test.

 

[Stuart09]

Also worth a mention when you do get it running put the multimeter across the battery to test the alternator.
Put lights on and Rear window demister and should be showing between 13.5v and 14.5v for a healthy alternator.
I would also make sure you rule out the obvious by checking you haven't left an interior light on or something . Not sure if a blown bulb can still cause a draw when switched on. It was like that in a mitsibishi galant I had.

mk1 Leon cupra 1.8T 20v.

 

[andycupra]

remove bulb from boot light. just in case its that