My car battery is not holding its charge. It had this problem last summer and the garage I took it too initially said it was the battery so as this was over 3 years old I replaced it. However it was still losing its charge so I went back to where I got the battery (Halfords) and they tested it saying that the alternator was faulty because it said 'Ripple too big'. I then took it back to the garage and had a new alternator fitted. All was fine except for a mild electrical sounding whurring that would occasionally happen immediately on starting or turning off the engine (I don't know much about cars so didn't think much of this).
Over Christmas my alarm kept going off randomly and I was going to have it disconnected however the problem then stopped. However this week the battery has died 3 times and I have had to have it boost started each time. I took it to the garage and they tested it and said that the battery was not holding its charge. I then went back to Halfords where I bought the battery expecting to get a new one but it was tested and I was told the following;
start capacity: 80%
Ripple Too Big
They said that the problem was the alternator not providing enough power and was probably the wrong one for the car. I then went to Kwik Fit for a second opinion and the test was the same although they just told me it was because the alternator was faulty. I went back to the garage that fitted the alternator but they have said their tests say it was the battery. They say that they have tested the car with another battery which held its charge and also tested my battery seperately from the car and it lost its charge.
Is there anything else I can do? Or that it could be? I have a replacement battery I am borrowing from a friend at the moment and it while it seems better there is still a 'ripple too big' on tests and I am getting the whurring electricals and now dimming lights. I don't really want to buy a new battery only for it to last 6 months like the last one if the alternator is actually faulty and causing a problem with batteries after a few months? The warranty on the alternator only lasts until the summer.