Battery Issues????

sblythman · 15-06-2012, 12:52 PM

Hey guys ive got an au xr8 that i supercharged the end of last year and it has been running fine since then but as of lately i have not been able to get out in it as often as i would like to (probably about once or twice a month).

The issue is the last two times i have taken it out for a drive i have turned the car off only to hop back in it and try and start it with absolutely nothing. Not even a flinch from the starter motor. i'll explain both times...

1st time - Got in the car started fine, drove about 6 minutes up to the shops and switched it off. Had the radio running for about 1-2 minutes not even loud and i went to turn it on and just nothing at all happened, no power to the starter at all but all the electrics where still working. Lucky i was on a hill and i was able to roll start it and took it home.

2nd time - Hopped in the car started fine even though the previous flat battery up at the shops?? drove it down to the golf course afterwards hopped back in it and again with just nothing from the starter motor and electrics were slow and so i had to get one of my mates to jump start it but it was reaaally flat, we had to run his car for 2-3 minutes before we could start mine. Drove it home and then i just went out to it then after a week of it sitting there and it started fine???!!!

So basically i only get a flat battery when i leave my house??? The battery has never been flat at my house (even after sitting for 1.5 months) but take it for a 25 minute drive and it wont start again?? Does anyone have any ideas??? is this just the basic symptoms of a dieing battery??

Road_Warrior · 15-06-2012, 01:05 PM

Could be, but do a check on how much volts is being delivered into your battery by your alternator. If it is between say 13.5 to 14.5 volts then you can rule out your charging system.

sblythman · 15-06-2012, 01:56 PM

Just checked the battery...
ignition off: 11.94 volts
Ignition on: 14.45 volts

So that sounds pretty much fine yes? Could it be possible that the alternator is intermittently not working? Even then it doesnt explain why it is ALWAYS at full charge when im at home?

4ford · 15-06-2012, 02:06 PM

Interesting comment, "...nothing at all happened, no power to the starter at all but all the electrics where still working."

I seem to recall that when the key is turned to START, most everything else is automatically selected OFF by the key (except for the lights), things like wipers, radio, aircon fan are temporarily OFF whilst the key is held in START.

Is there a problem there?

Bushbasher · 15-06-2012, 02:19 PM

Have you checked that it's not actually the starter motor dying. Sounds to me like the starter motor is happy to crank over the first time from dead cold but then won't play once a little warmth is added to the mix from heat soak from the block. There's another thread in the LPG forum where the guy had almost exactly the same symptoms and it turned out to be the starter. If you can get your hands on another one I'd be starting there and doing a swap because a dead battery would cause the starter solenoid to try to kick in when you turned the key and you'd get a tick-tick-tick-tick before everything stopped, a dead starter can/will give you nothing like someone has disconnected it.

Just a thought.

Bushbasher

Road_Warrior · 15-06-2012, 02:44 PM

That battery of yours is flat if that is the voltage it returned. Bung it on a charger.

sblythman · 15-06-2012, 02:47 PM

Quote:

Originally Posted by 4ford

Interesting comment, "...nothing at all happened, no power to the starter at all but all the electrics where still working."

I seem to recall that when the key is turned to START, most everything else is automatically selected OFF by the key (except for the lights), things like wipers, radio, aircon fan are temporarily OFF whilst the key is held in START.

Is there a problem there?

Oh sorry i meant like there was still enough power for the radio to turn on the sunroof to shut and for me to wind up the windows. On the 2nd occurence though the windows were very slow to go up so it was very flat.

Quote:

Originally Posted by Bushbasher

Have you checked that it's not actually the starter motor dying. Sounds to me like the starter motor is happy to crank over the first time from dead cold but then won't play once a little warmth is added to the mix from heat soak from the block. There's another thread in the LPG forum where the guy had almost exactly the same symptoms and it turned out to be the starter. If you can get your hands on another one I'd be starting there and doing a swap because a dead battery would cause the starter solenoid to try to kick in when you turned the key and you'd get a tick-tick-tick-tick before everything stopped, a dead starter can/will give you nothing like someone has disconnected it.

Just a thought.

Bushbasher

See i was just thinking this same thing as well that maybe the starter motor was playing up once it had some heat in it but then i realised that the 2nd time round at the golf course...

A) the car was cold, it had been sitting there for nearly 4 hours and

B) I jump started it with my friends car in the end anyway so the starter motor worked then. It would not even make the tick sound after a lot of trys and then we hooked it up to my friends car and then even after a few goes and holding the revs up on his car the starter motor ticked and started the car first go?? so obviously there was no charge in the battery.

sblythman · 15-06-2012, 02:50 PM

Quote:

Originally Posted by Road_Warrior

That battery of yours is flat if that is the voltage it returned. Bung it on a charger.

What should the voltage read for a charged one? i thought about 12 volts was normal?

Evgeni · 15-06-2012, 03:05 PM

Ideally 12.6v

Road_Warrior · 15-06-2012, 03:31 PM

Quote:

Originally Posted by sblythman

What should the voltage read for a charged one? i thought about 12 volts was normal?

Yes but you need in excess of 12 volts to make the whole shooting match work, anything less than that constitutes a flat battery and you clearly have less than 12 volts, I've had batteries returning 12.2v and refused to start the car, yours is as flat as a pancake at 11.94v

Get a battery charger if you don't already have one, they're very handy to have for any vehicle you own regardless of whether you need it now or not

I have three