Is my battery coming to the end of its life?

[stani540]

hoping some of yo guys can shed some light on my battery problem.

what happens is basically i leave the car for the night or a few days and when i go to start it the battery is obviously flat or atleast doesn't have enough power to get the car going.

It happened a while back and i got it going and didn happen again for a while until christmas, i was working on the car, no interior lights on or radio no keys in the ignition even and went to start it and the battery was gone again.

since then i have fitted an amp and it seems to be getting worse it does it everytime i want to go out now, for example tonight got it going and drove to the cinema turned the car off watched a film at came out to find it dead again, however on saturday i went to the cinema also and when came out it started fine but hadn't when i started at home before the trip to the cinema.

My cupra is a 51 plate so going on 8 yrs old so is my 8 yr old battery on the out? or is it my amp system thats draining the power, it powers on and off fine and the rem cable is fine, all i can think it might be is the ground, but i rubbed it down to bare metal before attaching the ground to the locator nut in the spare wheel well so surely it cant be this.

if anybody could help me itd be great this is driving me insane!

cheers

 

[Salt]

It might be that the battery is fine, but the alternator doesn't always charge it up properly. The symptoms sound too inconsistent for it to be a steady decline in battery performance.

 

[wisejason]

get a multi meter on the battery and see what it reads. Then get someone to turn the car over and it the voltage drops off by more than a 203 volts then the battery is knackered. A good battery should harldy drop off when the car is turned over/started.

 

[Daymo]

get a power cap as well for your amp, it stops the sound system draining loads from your battery IIRC

 

[stani540]

do you recon i need a power cap? past few times i have been out the amp hasn even been on so i dont see how the amp is draining the battery.

so do you recon it could be the alternator on its way out?

 

[andycupra]

the battery was struggling before you fitted the stereo amp. So i think the amp is not so much causing this, but aggrivating it. Are you driving round with the stereo up all the time? if so then there is more demand on the battery. Add this to the fact its cold, you may have heaters on and demisters etc the battery has to supply more power.

In my mind its clearly a battery issue, or that the battery is not being charged correctly by the alternator. GIven the age etc id say it 90% certain to be the battery.
Have you tried puttnig it on charge? if you charge it and then it goes flat again very quickly then this would point to the battery as its clearly not taking a proper charge.

 

[DPJ]

the battery was struggling before you fitted the stereo amp. So i think the amp is not so much causing this, but aggrivating it. Are you driving round with the stereo up all the time? if so then there is more demand on the battery. Add this to the fact its cold, you may have heaters on and demisters etc the battery has to supply more power.

In my mind its clearly a battery issue, or that the battery is not being charged correctly by the alternator. GIven the age etc id say it 90% certain to be the battery.
Have you tried puttnig it on charge? if you charge it and then it goes flat again very quickly then this would point to the battery as its clearly not taking a proper charge.

I'd be inclined to agree with Andy.

 

[stani540]

get a multi meter on the battery and see what it reads. Then get someone to turn the car over and it the voltage drops off by more than a 203 volts then the battery is knackered. A good battery should harldy drop off when the car is turned over/started.

i take it the battery has to be fully charged for this or does it not as its pretty difficult to get mine charged at the moment

 

[stani540]

I'd be inclined to agree with Andy.

This is what i'm sort of leaning towards, but as i live in city centre flats i dont really have any real way of charging it as its in the basement with no available power outlets.

however at christmas when i went to visit my parents i charged it there and since then it hasn't rellay held a charge. im goin on a motorway journey at the weekend, i will take the fuse out of the amp and see what happens hopefully it will hold some charge! but if not i think i have an issue with the battery or alternator.

Do you definitely recon its more likely to be the battery?

After charging it at christmas. i drove back from hull to leeds, and then left it overnight, went to it the next day and it started fine. but then i left it a couple of days and nothing.

 

[stani540]

im starting to think my positive terminal is a bit corroded so may give that a clean tonight

 

[kyle'87]

Most likely to be the battery mate, If your getting a replacement the bosch silver tops is a very good battery.

Can always take it to a garage if you think its the alternator and they have a tester that they put on the terminals that checks the alternator charging.

Also be adivised not to get a powercap, the amp will be draining the battery when its on and how much so depends on the amp rating.

 

[wisejason]

im starting to think my positive terminal is a bit corroded so may give that a clean tonight

once you have given it a good clean, put a little grease over it to keep the moisture out.

 

[stani540]

just thought that so may leave it until the weekend! as i have no grease

 

[stani540]

how do i tell whether it is the alternator or the battery thats gone?

 

[Danjw]

I would say that its most likely to be the battery as i was having the same problems as you with my car before christmas with it sometimes starting and then decideing not to!!
Bought a new battery problem solved!!

 

[andycupra]

This is what i'm sort of leaning towards, but as i live in city centre flats i dont really have any real way of charging it as its in the basement with no available power outlets.

however at christmas when i went to visit my parents i charged it there and since then it hasn't rellay held a charge. im goin on a motorway journey at the weekend, i will take the fuse out of the amp and see what happens hopefully it will hold some charge! but if not i think i have an issue with the battery or alternator.

Do you definitely recon its more likely to be the battery?

After charging it at christmas. i drove back from hull to leeds, and then left it overnight, went to it the next day and it started fine. but then i left it a couple of days and nothing.

if the alternator was not charging the battery you would most likely have seen issues while driving after you fitted the amp. (was not holding charge before, then you have incrased the demand on it.
But seeing you have had this issue for some time? and only seen issues when its sitting overnight for 48 hours or so it would support the theory that the alternator is charging the battery, but that the battery is only holding a little power.

There is no way we can say 100% battery on a forum. But it would appear there is a fair few on here of the same opinion. Ie its 95% likely to be the battery.

It you want to be sure, then go to a garage and get them to test it. however some may charge, do you know a friendly garage? - a nice dealer may do this for free if you ring up and agree a convenient time to pop by.

Im sure its the battery. you only other thing is whether there is a draw of power when the car is sitting. eg light in boot being on all the time.
has the amp been fitted correctly with a remote wire so its not on all the time.
However i still think this is unlikely as you had issues before the amp was fitted.

Change the battery, then come on here and let us know if its fixed it.

 

[stani540]

i suppose there is evidence to show the alternator is working as if you turn the ignition off and turn it back on it starts fine, but leave it and its bad times!!!

so the battery must just be a goner!

Im going to disconnect the amp ebfore my motorway journey. then see what happens then over the weekend i will clean the positive terminal an grease it up before the return journey and see what happens!

 

[Mat]

halfords do a free battery check

 

[stani540]

is that aslogn as you buy one of there batteries?

may go down hlafords and get it looked at then


another question has anyone made or got a battery case like the one that originally came on the cupra as mine doesn have one, jsut to give the battery a bit more protection from the elements.

 

[Mat]

nope.

i had mine checked on my old car a few years ago. and they just came out and tested it. said it was fine so i drove off. guess if they say it's knackered, you could tell them you're off to a bank and be back later

Mine turned out to be a faulty earth