Car battery question

randerson

As this is my go to forum  I thought I’d try my luck and post a completely unrelated question here –

I’ve just been informed that my car battery may need replacing as my car won’t start. However all the dashboard lights work fine as well as central locking et cetera. The car just struggles. Start for about 2/3 seconds and then cuts out. Could this still be battery related even if all the other electrics work fine? Just don’t waste money on a new battery it’s not the problem. Any help would be gratefully received!

Danny1969

Does the car start and run or just turn over slower and slower and then stop ?

Basically there's 3 components that fail battery wise ... the alternator, the rectifier \ regulator and  the battery. When the engines running there should be around 14V on the battery terminals ... if you got that then the first 2 are fine . 

If that car starts and then cuts out it could be anything ... insulation breaking down on HT .. fuel solenoid etc  

Revolting1

When you say start do you mean the engine is actually running or just turning over?

proggy

Could be a number of things.
Take the battery off the car and give it a full charge then see how you get on.

Blaendulais

A tiny tiny amount of battery will work your lights.  You need a massive % of it to start as danny said measure across the terminals - get the AA to do it

ICBM

Yes, this is a normal symptom of a failing battery. Under almost no load it will still put out the normal 12V, so the car's electronics will work, but when you try to use the starter motor it will pull a very large current and the voltage will drop right down if the battery's internal resistance has risen, which they do when they're old and close to dying.

But it could also be something else - a bad connection between the battery and the starter motor which is introducing high resistance - the most likely place is the bolt that connects the negative lead to the chassis, either of the battery or the motor. These can rust and do exactly what you're describing, my old Renault had precisely that problem once.

randerson

having just gone out there now after I  left it a couple of days, now the car does not start at all.
no response from the engine at all but all the electronics light up as normal. Don’t know
If that helps clarify anything?

ICBM

randerson said:

having just gone out there now and left it a couple of days, now the car does not start at all.
no response from the engine at all but all the electronics light up as normal. Don’t know
If that helps clarify anything?

Both of the above problems would still apply. When you try the starter, do the car electronics cut out? If they do, it's probably the battery. If they don't, it's probably the battery or starter motor chassis connections - although the car could be sensing the voltage drop and not operating the relay, so it's not conclusive.

randerson

IICBM said:

randerson said:

having just gone out there now and left it a couple of days, now the car does not start at all.
no response from the engine at all but all the electronics light up as normal. Don’t know
If that helps clarify anything?

Both of the above problems would still apply. When you try the starter, do the car electronics cut out? If they do, it's probably the battery. If they don't, it's probably the battery or starter motor chassis connections - although the car could be sensing the voltage drop and not operating the relay, so it's not conclusive.

Electronics don’t turn off however –i’ve  just discovered Skoda Fabio is notorious for immobiliser issues. Their description was exactly as I described – car starts turns over for 2 seconds and it cuts out. Obviously now this has changed and the car Engine won’t turn over at all now, however I I wonder if this could be linked? Appreciate all the help though!

ICBM

randerson said:

Electronics don’t turn off however –i’ve  just discovered Skoda Fabio is notorious for immobiliser issues. Their description was exactly as I described – car starts turns over for 2 seconds and it cuts out. Obviously now this has changed and the car Engine won’t turn over at all now, however I I wonder if this could be linked? Appreciate all the help though!

No problem. I know nothing about Skoda faults - only Renault ones . Although far less of those than popular wisdom would have you think...

Danny1969

mmmm with immobilizers it can be anything from the key \ fob it's self to the receiver electronics  which is in the dash normally or top of the screen somewhere. I used to get work from a garage resoldering boards and changing relays from Seat's to cure immobiliser faults. Not familiar with any Skoda ones though
Check battery in fob, try reprogramming sequence, check all push in connections on relays, fuses etc in electronics \ fuse box. Make sure connector on ECU is not corroded and on tight. 

I had a Jag that sometimes just wouldn't start and in the end I traced it to a bad joint on the bottom of the fusebox where a relay plugged in. Used to drive me mad 

John_P

Have you tried jump starting it or taking it off and using a charger?

if you have done either and it starts but doesn’t hold the charge then it could be the battery or alternator, if you have a meter check the alternator voltage - or pop it into a garage for a quick check.    

I’ve had exactly what you describe from both battery faults and an alternator problem.   

Phil_C

ICBM said:

randerson said:

Electronics don’t turn off however –i’ve  just discovered Skoda Fabio is notorious for immobiliser issues. Their description was exactly as I described – car starts turns over for 2 seconds and it cuts out. Obviously now this has changed and the car Engine won’t turn over at all now, however I I wonder if this could be linked? Appreciate all the help though!

No problem. I know nothing about Skoda faults - only Renault ones . Although far less of those than popular wisdom would have you think...

By any chance, do you go onto the Renault forums? I'm sure I've seen your username before


On topic, @randerson do you have access to a multimeter? A good battery will hold a 12.4v charge or higher and charge at 14+ v from the alternator when running.

As said, the starter demands the most power when initiated and a weak battery will cause problems.

ICBM

Phil_C said:

By any chance, do you go onto the Renault forums? I'm sure I've seen your username before

Only a couple of times I think - I can't even remember for sure, but I think I would have used a different name, I normally do. All my Renaults - I've owned four, one Clio and three varieties of Scenic - have actually been very reliable and hardly ever needed fault-finding. The annoying thing is that two of them were written off by other idiots driving into them...

Danny1969

If the battery can't provide enough current to turn the engines over then you will generally either hear the solenoid click on the starter motor OR you can test if it's sending current to the starting motor by turning on your radio first .... the impedance of the starting motor is so low everything else will be deprived of voltage while the keys turned and your hear the radio volume dip out, wipers slow to a crawl etc

If that doesn't happen when the key is turned to start position then no current is being sent to starter motor in which case your be investigating main cable to started, earth strap and immobilizer 

You can very often short the main cable from the battery  on the solenoid across to the starting motors +V terminal if you want to test the battery and starting motor independently of the immobiliser . Can be very hard to reach on some cars though  

nick79

Any idea how old the battery is? Has the car not been used much lately?
Chances are its just the battery. If you have a multi meter check the voltage, it should be about 12.4v - Much less than that means its probably knackered. Anything under 12 and it definitely is. 

As ICBM says, its got enough to power the dash up, central locking etc, but the big load required to turn the starter over is too much for it. 

Who has told you the battery needs replacing? What i would do is jump start it from another car and then check the voltage with the engine running to check the charging system, needs to be between 13.6v  to 14.6v-ish. 

randerson

Thanks everyone. Due to lockdown I can’t access a battery charger etc and can’t even ask for a jump start! I’ve opted for a mechanics visit later on today which should clarify things. Really  appreciate all your help though.

tone1

Put the ignition key in position 2 (all dash lights on) for 30 seconds, then back the key off to the 0 position (Ignition off) and then immediately try starting up again. If that doesn't work, try a terminal 30 battery reset (You will lose radio code). Make sure Key is out of ignition and wait 3 minutes. Disconnect negative terminal from battery and connect to the positive terminal for 30 seconds (But make sure you don't short the battery out) reconnect and try again...

randerson

Thanks for all the above guys. Turns out yes – battery. Got it replaced =  all good

nick79

Happy days

bazxkr

Glad you got sorted. Had to renew mine 4 weeks back. Totally died over 2 days of non use but only 2.5 years old. Multimeter read 2.6v when I checked it. That was deader than a really dead dead thing lol wouldn't even power the radio. 230 quid with the rac I won't see again. Used to have batteries last 5 to 7 years when I was a lad.