Just a heads up to all don't take for granted if your battery light on the dash comes on that it is the battery I did and it nearly cost me my car had put a smart charge connection on the battery a few weeks ago and it indicated it need edge charging so checked voltage and was only reading 11.5v so assumed I would soon need a new battery .battery light lit up a week or so back so ordered a new battery which duly arrived put it on that evening and was sat in the car removing the fault code with the engine running when I noticed smoke pouring from under the bonnet it was the alternator absolutely fried .

I think if I had taken the car for a run it would of burst into flame .weeks prior to this I have had a strange noise every now and again hard to describe but it would come and go had it down to my mates garage and he was convinced it was the turbo vanes had a bit of cack on them so gave mea tin of fortie turbo clean over a day or two after putting in noise goes so me thinking its cured the prob carries on .

Now weekend of all the trouble starting battery light had come on and whilst driving home had trouble with the power steering esp and abs lights where coming on left it till Monday morning and no start battery hadn't arrived by then so had to wait a day or two .

So in hind sight should of checked the alternator output as well and not assumed it was just the battery so if anyone else has similar symptoms check both .

my alternator went few weeks ago, first symtoms was light on the went of periodically then stayed on permanently, they were getting droannig noise on acceleration and when slowing via engine breaking they hell brook loose and car lost the plot mainly power steering went. Had mine change and totally different car, runs quicker, no turbo lag, start quicker and much smoother, have you got obd2 and forscan will bring up code or try the in car code check ot sure how to doit but google will tell you i imagine

i take that on board when checking glad you did not have a fire not nice

When investigating a flat battery or other potential issue you should always check the voltage with the engine running to make sure the alternator output is charging the battery sufficiently otherwise your only guessing the battery is at fault - as you found out the fault was elsewhere.

Glad you got it before you potentially ended up with a fire though.

Hi. I have ford focus 2012, about a year ago battery light started to show up. took it to a garage tested battery was fine so I was told need to change the alternator, Changed the alternator but light stills shows up randomly and sometimes disappear itself. the alternator was brand new. car runs fine as it has been ever since. a couple of times whilst driving the car jammed for a second and then back to normal but that happened only twice in last two years. What could be the problem here? Thanks