Intermittent death - lots of potential causes checked

[griston64]

Your battery is charging ok when running ( should be between 13.7 to 14.7 ) but it's dropping too quickly and not holding the charge.

I'd be wondering what's making the car splutter and cut out after running ok for 5 mins ?? Surely thats still going to happen even with a brand new battery ?

[Foeux]

Originally Posted by Ian21401

Foeux,
I’ve been following this thread and it has me intrigued.
Just a few thoughts from an outsider. Feel free to ignore them if you wish.

Post #26, When you first tried the engine would not turn over. Did you check the battery voltage before you tried to start the engine? To try to establish whether the battery voltage was already too low, or 1) it suddenly dropped once the ignition was switched to position 1, or 2) it suddenly dropped when the switch was in position 2, or 3) it suddenly dropped when the starter motor was trying to turn?

Once started using a jumper battery the alternator is charging.
I understand that you then disconnected the jumper battery?
and then after a few minutes of running on it’s own battery the engine dies?

You mention that the charge rate was dropping after the engine stopped.
As the engine was now stopped there would be no charge from the alternator so, do you mean the battery voltage was dropping?

Is it possible to state what the battery voltage dropped to before you switched off the ignition?
Yet, when you switched off the ignition the battery voltage returned to 12.24 volts.
Given that the engine would not turn over when first tried this morning. Is it possible once the engine has been running then died to check the battery voltage periodically to establish at what rate the battery voltage drops?

I am very pleased for your input. To clarify, the battery 'heals' itself back to 12.32v if left long enough. With key in position 2, the voltage drops rapidly to 9.2v which happens over the course of 2 mins. I know this as I was testing earlier to see if I could make the voltage drop slow or stop by pulling fuses to identify the bad circuit. Alas I could not but interestingly it seems to stabilise at about 9.2v in pos 2. As soon as you try to start it, the voltage drops madly to 3v ish as you turn the starter. The car is then 'dead' or at least in a condition that might start with a jump. The most recent serious stop, it wouldn't even start with a jump UNTIL it had been towed and waited a while, whereupon it started - could this be a loose wire thing?

Now that I have left the car from its original state of unwellness, it has 'healed' the battery back to 12.29/12.32v. Turn the key to pos2, it will do it again.

Originally Posted by griston64

Your battery is charging ok when running ( should be between 13.7 to 14.7 ) but it's dropping too quickly and not holding the charge.

I'd be wondering what's making the car splutter and cut out after running ok for 5 mins ?? Surely thats still going to happen even with a brand new battery ?

This is what I wonder and why I am so keen to diagnose instead of fire the parts gun at the car: New battery, alternator and starter and cables might not fix it and I have then chucked out good volvo parts, only to replace them with inferior newer ones that will wear out quicker.


As for the battery calcium/silver thing, surely the car is dumb as bricks?

If there were a small nuclear reactor generating the correct voltage, would it 'know'?

PS I have just been and started car, helped it get through rough running phase and wanting to die by keeping revs up. Seems ok now and will restart under own battery power. Am I stupid to think that water could be in somewhere and evaporating to the point where the car shows no fault once the heat of the engine drives moisture out?

[griston64]

It could be a combination of a slightly failing battery and poss moisture somewhere. Your battery is still too low at 12.3 as it should be 12.6 when car is off

[Foeux]

Originally Posted by griston64

It could be a combination of a slightly failing battery and poss moisture somewhere. Your battery is still too low at 12.3 as it should be 12.6 when car is off

Batt voltage with car off now that it has run and charged battery is 12.58v, pretty well the 12.6v you are hoping for.

[Laird Scooby]

Originally Posted by Foeux

What checks could I do with a multimeter to see what's happening?



Thanks for the tip.

The Italian battery was just one a chum had laying around that got me out of a pinch.

Before I do battery, what checks could I do with a multimeter to see what's going awry?

Thanks both,

F

You've already done them, hence my conclusion you have the wrong type of battery. Regulator voltage should be 14.4-14.0V depending whether cold or hot, if your alternator voltage regulator is outputing 14,7V it's too much for what it was designed for. If it puts out less than 14.0V at idle with little or no load, there's again something wrong with it.

The problem is (as explained in the link i posted) that calcium/silver0calcium batteries need a minimum of 14.7V to overcome the initial charging resistance, normal lead-acid batteries with lead-antimony doping on the plates only need 13.8V to overcome this but to ensure good charge, reduce the risk of sulphation and several other reasons, this is normally 14.0V hot and running. In some extreme cases on very hot days, the alternator will reduce this a little but for general running these figures will be accurate.

That's why i'm saying you have the wrong type of battery (calcium) on there and need the old skool lead-acid battery without the so-called improvementrs of calcium/silver-calcium doping on the plates as THEY DON'T WORK on older cars that don't have smart alternators.
Yes, there are a few that prove to be the exception to the rule but it's been proven too many times now to be a coincidence.

[Laird Scooby]

Originally Posted by Foeux

Batt voltage with car off now that it has run and charged battery is 12.58v, pretty well the 12.6v you are hoping for.

That's about 90% fully charged - allegedly. However if it has sulphated through not being charged at the right voltage for a calcium battery, it's capacity will be heavily reduced so while it may appear near fully charged, it's capcity is only that of a battery about 1/4 the size for example.

You need a drop-tester to be certain of what it's doing now.

[Ian21401]

Dave,
I accept what you say about silver/calcium batteries and the fact that they may be sulphated and not holding charge, but, if the alternator is charging the battery whilst the engine is running then would there not be enough in the battery to keep the engine running until it was switched off? Is it possible that, once the engine is running and the alternator is spinning, at some stage a fault develops in the alternator so that the battery does not receive any charge and rapidly loses voltage to the point where there is insufficient voltage to power the ignition and hence the engine dies.
Foeux,
Another thought, has there been a fault code check done?
Following on from Dave’s advice that all three batteries you have tried are silver/calcium, are you able to fit a known/confirmed lead/acid battery to confirm (or not) that the battery is the cause.

[Laird Scooby]

Originally Posted by Ian21401

Dave,
I accept what you say about silver/calcium batteries and the fact that they may be sulphated and not holding charge, but, if the alternator is charging the battery whilst the engine is running then would there not be enough in the battery to keep the engine running until it was switched off? Is it possible that, once the engine is running and the alternator is spinning, at some stage a fault develops in the alternator so that the battery does not receive any charge and rapidly loses voltage to the point where there is insufficient voltage to power the ignition and hence the engine dies.
Foeux,
Another thought, has there been a fault code check done?
Following on from Dave’s advice that all three batteries you have tried are silver/calcium, are you able to fit a known/confirmed lead/acid battery to confirm (or not) that the battery is the cause.

I get what you're saying Ian but the answer to your question is no, probably not. If the battery wasn't taking any charge, the voltage would gradually reduce, the fuel ECU would recognise that and firstly go into Limp Mode and then cause all kinds of weird and wonderful running symptoms. Even with a battery good enough to start the car after charging independently, if the battery isn't capable of taking the charge from the alternator, the alternator won't put out so much and it becomes a vicious circle.

I have to say i wasn't surprised when the OP posted his recent problems after thinking it was fixed after what the guy did to the various connections, i had a sneaking suspicion about the battery but obviously with the potential prescence of other intermittent faults which have now been remdied, there wasn't enough evidence on the thread for me to suggest it.

[griston64]

If you know anyone with a smart charger you could run it through the cycle to see how it goes after desulphation

[Foeux]

Dear chums, thanks ever so much for sticking with me on this.

I can get hold of a drop tester and have drop tested the battery in there.

I have a smart charger and can run a desulphation cycle to see what happens.

Watch this space.

F