Discussion
Hurrah for the sun, thought I this morning. Roof off, went for a blast. Got back, stopped for three minutes (I was outside the house luckily enough) and blow me if the car wouldn't start again. It showed every sign of a discharged battery -- very little energy going into the starter motor.
Some may remember I bought a spare battery a couple of weeks or so ago so I connect it up, and the car starts on the button.
Now what could have gone wrong? The battery is barely a year old so it's not past its sell-by date yet. There are no warning lights on the dash to say that ther's no juice coming out of the alternator. So what's likely to be the problem?
I speculate that either the battery HAS gone u/s (do batteries die this early?) or that somehow the alternator is dead -- but in that case wouldn't I get a red ignition warning light?
Puzzled...
Some may remember I bought a spare battery a couple of weeks or so ago so I connect it up, and the car starts on the button.
Now what could have gone wrong? The battery is barely a year old so it's not past its sell-by date yet. There are no warning lights on the dash to say that ther's no juice coming out of the alternator. So what's likely to be the problem?
I speculate that either the battery HAS gone u/s (do batteries die this early?) or that somehow the alternator is dead -- but in that case wouldn't I get a red ignition warning light?
Puzzled...
My alternator went and I got no red warning light.. 
When you charge it up just enough to start it (if you have a trickle charger) then it dies after ignition, your alter is donald ducked..
Otherwise does the car get regular use ? Or long distances or many short distances
All in all my car had crap wiring and the interior light was draining 5amps or so. So it could be worth getting a trusted auto elec to take a peek to find where the drain is coming from.(apart from the alarm of course)
>> Edited by Jason F on Saturday 23 February 15:58
When you charge it up just enough to start it (if you have a trickle charger) then it dies after ignition, your alter is donald ducked..
Otherwise does the car get regular use ? Or long distances or many short distances
All in all my car had crap wiring and the interior light was draining 5amps or so. So it could be worth getting a trusted auto elec to take a peek to find where the drain is coming from.(apart from the alarm of course)
>> Edited by Jason F on Saturday 23 February 15:58
I used to be a spert.
I had a battery die after 12 months, not sure why it died. The AA man who came out tested the alternator for me and comfirmed it was functioning correctly - cheaper and easier than an autoelectrician. The new one I put in has not been a problem since. Only time my TVR has let me down too ...
T/.
I had a battery die after 12 months, not sure why it died. The AA man who came out tested the alternator for me and comfirmed it was functioning correctly - cheaper and easier than an autoelectrician. The new one I put in has not been a problem since. Only time my TVR has let me down too ...
T/.
quote:
Hurrah for the sun, thought I this morning. Roof off, went for a blast. Got back, stopped for three minutes (I was outside the house luckily enough) and blow me if the car wouldn't start again. It showed every sign of a discharged battery -- very little energy going into the starter motor.
Some may remember I bought a spare battery a couple of weeks or so ago so I connect it up, and the car starts on the button.
Now what could have gone wrong? The battery is barely a year old so it's not past its sell-by date yet. There are no warning lights on the dash to say that ther's no juice coming out of the alternator. So what's likely to be the problem?
I speculate that either the battery HAS gone u/s (do batteries die this early?) or that somehow the alternator is dead -- but in that case wouldn't I get a red ignition warning light?
Puzzled...
Suggest you start by looking for any other symptoms. Does the no-charge warning come on when you switch on? If this isn't working that kind of explains why you didn't get any warning! If the warning light *has* failed, it's conceivable that this is the whole problem, because the current through this light is used to 'boot strap' the alternator at startup. The aternator should self-energize on its own without it, but it will take much higher revs for it to kick in, and depending on the alternator, what gearing it is driven at and your driving habits this may just not be happening.
Also keep an eye on the voltage. The voltage should pick up by a volt or so as the alternator kicks in, and should not drop significantly when you switch on like lights and so on.
Hope this helps,
Peter Humphries (and a green V8S)
The no-charge warning light's behaviour was totally normal: on when ignition-only on, off as soon as engine starts. What's more, it was a blast -- the whole of the useful rev range was explored...
And being a Chimaera, it doesn't have a built-in voltage meter -- but I'll check that idea out. Time to stick an AVO meter across the jump leads.
And being a Chimaera, it doesn't have a built-in voltage meter -- but I'll check that idea out. Time to stick an AVO meter across the jump leads.
2 thoughts:
Are you sure that this is not the hot starter motor problem we are all too familiar with? By the time you had connected the spare battery maybe the motor had cooled enough and started as normal. The symptoms you describe are exactly what happens and you just have to wait. Have you suffered this problem before? Has the car got a bit hot in traffic in the past to cause the onset of the problem? When you were trying to start, did you see if any of the other cars electrics were working indicating that the battery was ok? Suggest next time it happens you turn on lots of accessories that will put a decent load on the battery (for a short while) and check that they work ok - such as headlights, heater fan, etc.
Batteries can fail not only because they have aged and won't hold a charge. They can suffer from bad inter-cell connections internally that can appear to be ok (hence no ignition warning light) until a heavy current drain is applied. At that point the battery volts will collapse to near enough zero. Best test is to take it along to a garage and ask them to do a discharge test on the battery - measures volts while connecting a heavy load across the terminals with the battery in a charged state. The problem could also be just a poor / corroded connection on one or other of the battery terminals. If you can't get to do a discharge test you could look to see what happens to the brightness of your interior light when it next fails to start (while you are trying to start it). If it virtually goes out that is similar to failing the discharge test but this result could also be caused by a flat battery.
Sorry this is a bit long but hope it helps, personally I favour the starter motor as being the most likely.
Are you sure that this is not the hot starter motor problem we are all too familiar with? By the time you had connected the spare battery maybe the motor had cooled enough and started as normal. The symptoms you describe are exactly what happens and you just have to wait. Have you suffered this problem before? Has the car got a bit hot in traffic in the past to cause the onset of the problem? When you were trying to start, did you see if any of the other cars electrics were working indicating that the battery was ok? Suggest next time it happens you turn on lots of accessories that will put a decent load on the battery (for a short while) and check that they work ok - such as headlights, heater fan, etc.
Batteries can fail not only because they have aged and won't hold a charge. They can suffer from bad inter-cell connections internally that can appear to be ok (hence no ignition warning light) until a heavy current drain is applied. At that point the battery volts will collapse to near enough zero. Best test is to take it along to a garage and ask them to do a discharge test on the battery - measures volts while connecting a heavy load across the terminals with the battery in a charged state. The problem could also be just a poor / corroded connection on one or other of the battery terminals. If you can't get to do a discharge test you could look to see what happens to the brightness of your interior light when it next fails to start (while you are trying to start it). If it virtually goes out that is similar to failing the discharge test but this result could also be caused by a flat battery.
Sorry this is a bit long but hope it helps, personally I favour the starter motor as being the most likely.
Martin
Thanks for those thoughts but it's definitely not a starter motor problem. Firstly, it's a fairly new motor -- I had the hot starter motor problem and replaced the unit about 18 months ago. Secondly, I'd just been for an open road blast -- the motor wasn't that hot. And with the hot motor problem, you get a click but no sense that the motor is even considering doing some useful. That didn't apply in this case. What's more this problem has happened once before when the car was cold.
Also, you know how you recognise when things aren't quite right even if the clues are small? I'm thinking of the firmness of the solenoids clunking when you unlock the car or the pitch of the fuel pump priming at ignition-on? Neither, in retrospect, were quite right. Those were signs that the battery wasn't charged enough even before I fully turned the key because I normally wait for the fuel pump to finish priming before I go for engine start (dunno if that's what you're supposed to do but it keeps me happy).
Nope, it's a battery/charging problem. I will however, ring Fernies tomorrow and see what they suggest -- I just hope it's not going to be an expensive call...
>> Edited by manek on Sunday 24th February 22:58
Thanks for those thoughts but it's definitely not a starter motor problem. Firstly, it's a fairly new motor -- I had the hot starter motor problem and replaced the unit about 18 months ago. Secondly, I'd just been for an open road blast -- the motor wasn't that hot. And with the hot motor problem, you get a click but no sense that the motor is even considering doing some useful. That didn't apply in this case. What's more this problem has happened once before when the car was cold.
Also, you know how you recognise when things aren't quite right even if the clues are small? I'm thinking of the firmness of the solenoids clunking when you unlock the car or the pitch of the fuel pump priming at ignition-on? Neither, in retrospect, were quite right. Those were signs that the battery wasn't charged enough even before I fully turned the key because I normally wait for the fuel pump to finish priming before I go for engine start (dunno if that's what you're supposed to do but it keeps me happy).
Nope, it's a battery/charging problem. I will however, ring Fernies tomorrow and see what they suggest -- I just hope it's not going to be an expensive call...
>> Edited by manek on Sunday 24th February 22:58
I've had a similar experience to this when my Chimaera let us down on a french autoroute. 
Symtoms here were: no power above 3000rpm, reduced power under 3000rpm, engine running very cool (50C). After parking in a supermarket carpark for five minutes, there was barely any juice left in the battery. Just about enough to open the doors.
The dealer back home diagnosed a faulty/blown "100A shunt fuse", which I assume sits between the alternator and the battery. The alternator light was NOT on when the engine died.
Looks like I'd been driving down from Calais on the battery alone, and it took half an hour or so to flatten it enough to screw up the ECU.
If your battery wasn't flat enough to screw up your ECO, is it worth checking this too?
Symtoms here were: no power above 3000rpm, reduced power under 3000rpm, engine running very cool (50C). After parking in a supermarket carpark for five minutes, there was barely any juice left in the battery. Just about enough to open the doors.
The dealer back home diagnosed a faulty/blown "100A shunt fuse", which I assume sits between the alternator and the battery. The alternator light was NOT on when the engine died.
Looks like I'd been driving down from Calais on the battery alone, and it took half an hour or so to flatten it enough to screw up the ECU.
If your battery wasn't flat enough to screw up your ECO, is it worth checking this too?
I'm pretty certain it was the battery just getting a little too discharged. I connected a second, fully-charged battery in parallel for a couple o days (no garage so it would charge from that, and everything seems to be OK now.
I say this from Montreux without the car -- when I get back from this conference I'm at on Sunday, I'll see if it starts again but my experience of the trips I did during the week suggests that it's OK now.
The motor is turning over at the right speed and so on.
Fingers crossed - and thanks for asking!
>> Edited by manek on Friday 1st March 16:45
so it would charge from that, and everything seems to be OK now. I say this from Montreux without the car -- when I get back from this conference I'm at on Sunday, I'll see if it starts again but my experience of the trips I did during the week suggests that it's OK now.
The motor is turning over at the right speed and so on.
Fingers crossed - and thanks for asking!
>> Edited by manek on Friday 1st March 16:45
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