Do alternators fail when replacing the battery...??

[JConnors]

Hi there,

Am in the middle of an ongoing issue with the RAC. My girlfriend is an RAC member. Here is the background to the matter, wich was e-mailed to the RAC Customer Service depatment...

"On Tuesday 21st September 2010 I had to called out the RAC to come fix a problem with my partners car, FL03 BWV. Someone came to our address and replaced the battery in the car, saying it was flat. We bought a new battery there and then. Today (24th Sept), my partner was on his way to collect his daughter from school when his car broke down. His electrics had all stopped functioning and the power steering stopped. He managed to get the car to somewhere safe and had to call someone else to go and collect his daughter from the school gates and have her brought to him, while he waited for his own recovery service (Mondial). His recovery guy found out that the fault was with a dead alternator and the brand new RAC battery was completely flat. The car, my partners daughter and my partner had to be followed the the recovery man back to their home address, after having to have the new RAC battery removed and replaced with a spare battery from the recovery man. During the trip back home the spare battery had to be swapped out for yet another spare battery from the recovery man's limited selection, as it was drained flat. This shows that the initial diagnostic check was not done correctly as the fault is with the alternator (this dashboard light was on when the RAC came out and has been ever since). The RAC man didn't even look for the alternator, he just based his work on the battery. My partners recovery man had to jack the car up to look at the alternator and wiring loom to find the fault. This wasn't done by the RAC man, he only look in the battery box. So, we have paid for a battery that is more than likely not needed, and we still have a car that is not working. More importantly, we have had a 8yr old girl stood at school gates waiting for someone who had put faith in the RAC. Can someone please contact me to explain and resolve this issue."

This is their reply....http://www.jamieconnors.me.uk/RAC/Letter.jpg.

Is it "not uncommon for an alternator to fail after a battery has been replaced"? I have had many car batteries swapped out and never experienced an alternator to die!?!?! Anyone agree with the RAC?

Am looking to take this matter further as the car is still sat on the driveway with a dead new RAC battery. Oh, I have been to two garages and got quotes (as requested by the RAC people before the letter was sent to us) for the work to be carried out - now they are saying we need to provide quotes and evidence to support our complaint. What is going on?

Anyone with any advice/suggestions/thoughts?

[Darren]

It is possible the battery was faulty (not holding its charge) - however, in my experience (not that much mind and I'm not a car mechanic but have had a few of these go) is that if a battery dies, its a good sign there might be a problem with the alternator and this should always be checked.

The alternator is there to charge the battery while the car is moving and converts mechanical energy from the engine to electrical to recharge the battery. Batteries are only really used to give the current to start the car up in the first place, from there in power is supplied by the running engine.

In every case where I've had a flat battery, it was the alternator that was the problem and not the battery. Normally though, I've had the battery replaced as well as the alternator. Maybe it's just my bad luck.

[Gareth]

In every case where I've had a flat battery, it was the alternator that was the problem and not the battery.

My experience is slightly wider in two ways.

First is that I reckon batteries appear to have a 'life' - it used to be that a battery would last 4-5 years, failing in the colder weather leading up to winter - but these days I've sometimes heard of people having the same battery for a few years more. Our 6 year old car is on it's 2nd battery, replaced before we bought it.

Second, flat batteries have two causes; either a current drain when the car isn't in use, or they're not being properly charged. Current drains can have a variety of causes, and sometimes tracking them down can be difficult. A lack of charging might not always be caused by the alternator; sometimes it can be that an earth strap is loose or contacts are dirty.

[morsing]

The first call-out guy should have investigated why the batery was flat. Properly. And checked the alternator with all appliances running.

I'd guess the alternator had died but it's easier for them to replace the battery and now they won't take the blame.

[Zipper]

I didn't know that it is common for an alternator to die after replacing the battery, but it is possible.
"Possible" isn't the same as "common", of course - I don't really know what to make of the RAC claim.

Down here batteries last anything from 6 months (taxis) to a year or two (taxis & driver training cars) to 3 or 4 years if you have a premium battery and keep it clean, and have a smidgin of luck to boot.
My manual Swift's battery died after one year almost to the day, it happened without warning as is so often the case with modern cars, my older Corolla's battery rarely lasted more than 14 months and like the Swift gave little or no warning of impending failure.
This year I replaced my auto's battery after 12 months "just in case".
Our tropical weather is not kind to batteries and to electrical equipment in general.

Being an ex-technical officer and after watching several AANT (our equivalent of RAC) people and two battery specialists do roadside battery replacements, I would think it would be extremely unusual for the alternator not to be checked, even when the battery itself is tested as faulty.
If the person who replaced the battery didn't check the alternator he would have been very remiss indeed.

[fungus]

My wifes 306 HDi is still on its original battery which is ten years old, and has covered 69K. The car does a mix of mainly short journeys with a longer one about once a week. I check the levels about every couple of months and only need to top up very occasionally. My Ibiza TDi is five and a half years old and has covered 94k. Thats still on the original battery. The sons 1.4 Ibiza is seven years old and only does short journeys. It's only done 33k and is still on the original battery. To be honest I can't remember the last time I replaced a battery, it was probably more than thirty years ago IIRC.

[JConnors]

UPDATE
*******

I have just sent an e-mail to the RAC Customer Care team with my thoughts on this issue. I will publish it here when I have a response back from them, as they have been informed of this (and my other post on another forum) posting telling you all about this matter.

Lets see what they say now. Not looking to hang someone out to dry, just looking to have the whole problem rectified. Have been without my car now for 10 days now!!!

[Octy_Ross]

Our Skoda ~114,000 miles on the clock. 4.5 years old. Original battery; shows no signs of problems.

Our MX-5 - ~38,000 miles on the clock 7 years old, original battery; shows no signs of problems.

[Gareth]

Our MX-5 - 7 years old, original battery

Out of curiosity, how do you know it's the original battery? I'd assumed one of our cars was on its original battery until I examined the battery closely and found a date on it.

[Mr Cholmondeley-Warner]

I chopped in my Skoda last year at 6 years of age with absolutely no sign of deterioration of the battery.

Wifey's car is 10 and a bit years old - original battery, no issues.

What knackers batteries is lack of use and charge. A battery left idle for a year may well die without any further intervention.

What can definitely knacker alternators is running with no load on them, so for example disconnecting the battery with the engine running.

[Octy_Ross]

Our MX-5 - 7 years old, original battery

Out of curiosity, how do you know it's the original battery? I'd assumed one of our cars was on its original battery until I examined the battery closely and found a date on it.

1st owner told me it was; I can see no evidence to not believe him.

[gfoot]

What can definitely knacker alternators is running with no load on them, so for example disconnecting the battery with the engine running.

Isn't there a similar problem then when the battery is fully charged? Or is the idea that the regulator on the alternator has been ramping down the output smoothly as the battery load reduced? I'd guess something like turning off a heated window would have a similar effect... it's worrying if it's damaging to the car.

I've been wondering how best to test the charge level of a car battery. From what I've read, you just do it with a voltmeter, but do you need something heavy duty or will a basic electronics-oriented one work? The probes are fiddly little things, I'd feel more comfortable with jump leads or something that clips on properly and looks sturdy! I guess there won't be any current flow though.

Is it also safe to test in this fashion with the engine running? I heard you can use the voltage provided by the alternator to judge whether the battery is charging or full. Again, doing this with a fiddly electronics voltmeter seems dangerous.

[michael769]

From what I've read, you just do it with a voltmeter, but do you need something heavy duty or will a basic electronics-oriented one work?

A standard volt meter will tell you if the battery is outputting the correct voltage, The voltage does decline as it discharges but does not do so in a linear way and the behavior of batteries varies a lot so it is difficult to get an accurate reading.

You do need to measure the charge with the engine off otherwise you will get the output from the alternator which is usually a bit higher than the battery. You can in theory detect full charge by measuring the current from the alternator, but in a car you will just end up measuring the cars power consumption rather than the charge current. This technique only really works reliably with an external charger where the only things in the circuit is the charger and the battery.

To accurately find out the actual level of charge ideally you need to measure the specific gravity of the batteries electrolyte. This involves taking a sample from the battery which means unsealing a modern sealed for life battery, which is not for the faint hearted. The testers are cheap and widely available and easy to use if you don't have a sealed battery.

Neither method gives a good indication of the health (its ability to hold a charge for any length of time) though. To best way properly test the health of a battery is to carry out what is known as a "drop test". A drop tester applies a large resistive load to the battery and then measures how it performs as it's charge is drained away. Again drop testers are easy to use but are quite expensive and require that the battery is completely disconnected from the vehicle.

[TripleS]

From what I've read, you just do it with a voltmeter, but do you need something heavy duty or will a basic electronics-oriented one work?

A standard volt meter will tell you if the battery is outputting the correct voltage, The voltage does decline as it discharges but does not do so in a linear way....

You can say that again!

The 12 volt figure is only nominal. According to my understanding a fully charged battery should show a voltage of about 13/13.5 volts and if it shows anything less than about 11/11.5 volts, it's dead; and if it is left like that for very long it may be impossible to revive it. A reading of 6 volts doesn't mean it's half charged.

Best wishes all,
Dave.

[JConnors]

UPDATE
*******

We have had nothing back from the RAC Customer Care team since my response to their letter....wonder what they are up to. Will chase them up on Monday by phone.