Hi I was just woundering if someone could help me out my car keeps needing a jump not every day but every now and then…I took it to halfords which told me my battery was ok I got told it was alternator but I have tried Googling how I would know but nothing is indicating it’s the the alternator it’s a 1.6 litre stop start 15 plate if anyone could help me out it be much appreciated as times are hard and would appreciate if I could get some advice before I spend on it and still have the same problem.

Just search this forum for the subject "State Of Charge"

You need to buy a battery charger and use it once a month.

2 hours ago, Jod123 said:

I took it to halfords which told me my battery was ok I got told it was alternator

A lot depends on how the car is used. Short journeys may not recharge the battery fully. I would ignore Halfords, their "magic" battery tester boxes are not reliable.

But like Unofix says, the first step is to use a charger, left on for several hours. If the battery is flat (fails to start the engine), but the charger indicates fully charged too soon (within about 5 hours for a 10A charger, longer for a lower current charger), then the battery is in a poor state. It should take at least 5 hours to recharge a flat but good 50AH battery with a 10A charger, 10 hours with a 5A charger, etc. Amps times Hours = AH, plus a couple of hours for "saturation", where charge continues at a lower current.) 

If it has been flattened several times already, then it is likely to be duff anyway, they do not like being flat.

If you fit a new battery, you ideally need to keep it charged using the charger until you have confirmed why it failed, or it may go flat and be degraded permanently. With an electronic charger, the time needed to indicate fully charged is a good test. If it takes a long time, even though the car is being used normally (at least one longish run a week), then an alternator fault is very possible. A parasitic current draw is another possibility. To diagnose an alternator, especially on a start-stop car, takes good test equipment being used by someone who understands what they are doing. Or a lot of tests and measurements over quite a long time for a DIY method. It is not easy, sadly.

So a charger is the best option, not easy if the car is parked on the road, I know. A solar charger might help, and a plug-in voltmeter (cheap off Ebay or Amazon) might help with diagnosis. I, or others here, might be able to tell if readings taken after periods of non-use and taken during driving look sensible or seem completely stupid.

 

 

6 hours ago, Tdci-Peter said:

A lot depends on how the car is used. Short journeys may not recharge the battery fully. I would ignore Halfords, their "magic" battery tester boxes are not reliable.

But like Unofix says, the first step is to use a charger, left on for several hours. If the battery is flat (fails to start the engine), but the charger indicates fully charged too soon (within about 5 hours for a 10A charger, longer for a lower current charger), then the battery is in a poor state. It should take at least 5 hours to recharge a flat but good 50AH battery with a 10A charger, 10 hours with a 5A charger, etc. Amps times Hours = AH, plus a couple of hours for "saturation", where charge continues at a lower current.) 

If it has been flattened several times already, then it is likely to be duff anyway, they do not like being flat.

If you fit a new battery, you ideally need to keep it charged using the charger until you have confirmed why it failed, or it may go flat and be degraded permanently. With an electronic charger, the time needed to indicate fully charged is a good test. If it takes a long time, even though the car is being used normally (at least one longish run a week), then an alternator fault is very possible. A parasitic current draw is another possibility. To diagnose an alternator, especially on a start-stop car, takes good test equipment being used by someone who understands what they are doing. Or a lot of tests and measurements over quite a long time for a DIY method. It is not easy, sadly.

So a charger is the best option, not easy if the car is parked on the road, I know. A solar charger might help, and a plug-in voltmeter (cheap off Ebay or Amazon) might help with diagnosis. I, or others here, might be able to tell if readings taken after periods of non-use and taken during driving look sensible or seem completely stupid.

 

 

Thanks for all ur help I got told to buy a battery tester which I did and got told when I put it on the battery when it was off it’s giving good reading then got told start it but it seems to b jumping up n down only between 1-3 up or down.i don’t do long drives I just do usual driving schools shops ect I jumped it about 4 weeks ago it had been sat for 4 days while I was away n then my daughter was sat in car while I ran in shop n she turned ignition off but left radio on I wasent long in shop about 5-10 mins max n I came out n it was dead…then 2 days ago I went out the day b4 it was fine started fine and then that day i went to go out and again it wasent starting n had to jump it again.

First I knew of my alternator failing was power steering cut out while driving followed by the car cutting out soon after. Best guess is your battery but should be checked properly.

To be fair, it's a 2015, 7 years old, it's probably still on it's original, now knackered battery.

Stick a new one on before it dies all together and catches you out

1 hour ago, Jod123 said:

while I ran in shop n she turned ignition off but left radio on I wasent long in shop about 5-10 mins max n I came out n it was dead…then 2 days ago I went out the day b4 it was fine started fine and then that day i went to go out and again it wasent starting n had to jump it again.

It does sound to me that there may be a problem with the charging, or just a connection problem with one of the heavy cables from battery to engine. To start ok, run to the shop, then fail to start after 10 minutes of waiting (radio power consumption is negligible over that time) means either a bad connection or it is failing to charge. I would guess the battery is also on its last legs, but, as I said above, if you fit a new one, I would get the wiring and charging system properly tested, or it could be money down the drain if it keeps going flat.

If most of the time you do very short stop-start journeys, it may be worth getting a solar charger if you can't regularly use a proper charger. When my car goes through a period of little or no use over more than 2 weeks, I ensure it gets a proper charge. One decent long run (an hour or so of driving) or a proper charge, every fortnight, should be enough to keep a battery in good condition, but frequent very short trips are not good for it. My battery is now 10 years old and starts the car every time, though I am suspecting it may show up a bit of weakness this winter!

Thank you all for ur help yeah it’s odd why it does it as I knock my lights off there’s nothing on n it’s been fine and the last time I used it which was Friday  it started fine and then on the Saturday I went to go out in it n it just wouldent start.

Got a new battery fitted so hopefully it will sort the problem if not then I will know it’s the alternator thanks again everyone for all your help and advice 👍🏻

🤞hopefully all good now. Worth checking the plug/wiring at alternator if problem persists.👍