I'm hoping somebody can advise as to my issue. I have a 53 plate streetka and for around 12 months it's never started first time but always second or third. Last week battery was flat. aa came out and Said alternator was faulty. Took it to my local garage who replaced it but alas problem still persists. The alternator gives of just 11v when started but once started and revved it goes up to 13v. All day it's ok starting just over night causes the issue. They have checked the plugs on the alternator including the blue and stripped them back but issues still there. Tends to be worse when the weather is cold. They are now suggesting it's the ecu.?
If anybody can help id be so great full

Regards Gary

 

Cold weather kills batteries, try a new battery if not done that already. Alternator sounds to be fine. It does sound like you have something draining the battery though. There is a product called a "dis carnect" that I used on a car that I didn't use that often, it goes on the battery and you remove a key to isolate the battery. You could try this to confirm something is draining.

 

It does sound like a parasitic drain which you will need to test fuses with a multi meter to identify what is draining the bat tery here. There's plenty videos on youtube and the likes explaining what you need to do.