Battery going flat

[JWvrs25]

My battery appears to be quite weak in that I was fixing my car radio whilst sat in the car and the only thing switched on was the interior light

Went to start car and it just turns over once then gets stuck. Clocks on radio and dashboard reset as well

Charged it using a battery charger and after about 15 mins i tried it and it turned over slowly but managed to start.

This is the 3rd time this scenario has happened.

1st time i was using the radio whilst vacumming the car, the second I had the headlights on whilst setting beam up for about 10 mins.

If the car has been driven and is warm then you can leave lights and radio and wipers on for half an hour at least and it starts no trouble.

Issue is when its stone cold and any electrics are used for a bit.

Battery is 3 years old and is a 'Unipart'

Sometimes ive had it where on a cold morning the car starts ok but the dashboard clocks reset as if there's not enough power to keep them alive.

Battery was tested about a month ago by halfords who said it was fine.

Anyone know what i can check?

[sepulchrave]

Try charging it fully using the battery charger rather than just for 15 minutes!

 

Also check that the battery light on the dash comes on with the ignition before you start it.

[JWvrs25]

Battery light comes on and goes off when started

Will try a charge overnight - I did take the car for a hard drive after it had started which i would have though to charge the battery up properly

[Billc104]

I'm probably too late to tell you, but I think overnight is too long unless you have a clever charger that will stop itself.  I've read you should stop charging when you reach 14.1 to 14.4  volts to avoid gassing which is a problem with sealed batteries because you can't replace the water.  It depends on your charger of course but I suspect that whilst 15 mins was too short, overnight is far too long.  Also, I would suggest no need to drive hard to charge battery, just long enough.  

[VWD]

With this apparent lack of capacity in battery, I'd be concerned that either battery is on last legs or it's not getting charged properly. Might be worth a trip to one of the fastfit places for a battery & charge analysis. One trick to waken up an ailing battery used to be to give it a long slow charge. And if charger has not got a slow/trickle charge setting, then I'd try something like a brake light lamp in series with the charger, to reduce /limit the current, as most ailing batteries can start gassing prematurely with a full charge. If your battery is one where you can check the level in the cells ( DO NOT USE NAKED LIGHT OR LOOK IN ON CHARGE WITHOUT EYE PROTECTION) , you could check the individual cells for level, and top up where necessary. But in my experience of lead acid cells in other situations, when trickle charged, if a cell starts to loose liquid, then that cell is failing.

[KenONeill]

Further to that, one of my grandfather's neighbours had a battery with an actually clear case. When one of the cells in it failed, even a trickle charge made it look like that cell was boiling!!

[JWvrs25]

Charged the battery over night using a charger which cuts off once charged to about 13.2v.

Tried starting car and it turned over quite slowly but did start

Seems like the battery is definitely weak

[rum4mo]

One answer could be "buy a multi meter" they can be got cheaply enough, then you can start investigating what is going on, ie after taking charger leads off is the battery voltage >12.65V  keep meter on battery, what is the voltage when cranking the engine over (second person probably needed) etc etc.

 

Edit:- for instance, if the battery voltage holds up well when cranking the engine, the fault is elsewhere.

Edited 6 February, 2017 by rum4mo

[JWvrs25]

I have a multimeter

Battery seems to be at around 12.6 volts with engine off

Engine running its 14.2 volts

Will try and see what happens when cranking

[sepulchrave]

I suspect it's the starter motor which is weak, 12.6V is OK, 14.2V is also OK.

[JWvrs25]

and that would cause the battery to go flat when ive got the interior lights on for a bit then would it??

[sepulchrave]

16 minutes ago, clarendon462 said:

and that would cause the battery to go flat when ive got the interior lights on for a bit then would it??

 

No.

 

Use your multimeter, turn on the ignition, put all the lights on and the heater blower, rear demister etc. and see how fast the voltage drops and what it drops to.

[JWvrs25]

thats next on my list of things to try then

 

[kaspar]

Please can someone confirm what size the nut is on the battery retainer plate? 

 

I don't have tools and need the battery out to charge it properly so will need to buy or borrow something. 

 

Its a 2005 vrs and the version that is easier to get the battery out. 

 

Many thanks 

 

 

[JWvrs25]

1 hour ago, kaspar said:

Please can someone confirm what size the nut is on the battery retainer plate? 

 

I don't have tools and need the battery out to charge it properly so will need to buy or borrow something. 

 

Its a 2005 vrs and the version that is easier to get the battery out. 

 

Many thanks 

 

 

mine was a 13mm on a 2006 fabia but i would have thought they would be the same

[coiner]

40 minutes ago, clarendon462 said:

mine was a 13mm on a 2006 fabia but i would have thought they would be the same

 

thanks a lot Clarendon462