Alternator issue ?

F

ferrelscent

Active member
 South East London
My E85 Z4 (03) was in the garage for a new oxygen sensor recently.

While there the mechanic told me the battery warning light had been on while driving. So he said he had checked the alternator and reckoned insufficient power was getting back to the battery. I did not see this check being done myself.

The problem is that I have not observed this battery warning light before, during or after this visit to his garage and I've had no flat battery issues. In fact I didn't drive it for 3 weeks recently and it started for me after that with no issues, in freezing weather.

I'd rather not fork out for a new alternator if there is nothing wrong with it.

If I leave it what's the worst that can happen ?...will it just not start one day, or will I actually get some warning from a battery warning light before that happens ?

Is there any way I can check this myself ?

PS - The battery is only a year or two old so in good shape
 
Put a Voltmeter on the + and - battery terminals without the engine running looking for a minimum of about 12.4 ish Volts for a good battery.

Then with the Voltmeter on the + and - battery terminals, but this time with the engine running test the alternator, a healthy unit should be giving around 13.7v at idle and not much over about 14.5v (too much higher is bad). Then stick on lights, fans, rear window etc and see if the volts hold up to those levels. If the numbers are good then your battery and alternator probably are Ok.

With regards to the dash light it's worth getting a cheap code reader like the Torque pro app on your mobile which is used with an OBD2 bluetooth dongle (again cheap on the web) and this can check and clear many fault codes giving you some clues as to what has been going on. https://youtu.be/Nv13Nc4FXQY

My guess is your mechanic has triggered the light when monkeying around with his repair and its not an issue.
 
Was ur mechanic angling at supplying a new battery or replacing the alternator when he advised you about this? If so, he could be trying to drum up business with unecessary repairs.

If not, I would suggest as above with a vm test. If that works out ok it might just be that your battery needs a recondition.
How old is the battery?
 
Battery is only a year or two old.

Mechanic quoted me several hundred pounds for altenator and belt.

As I say, I've suffered no battery issues or warning lights myself. I had taken the car in for other issues nothing to do with the battery or altenator and which have been resolved.

Will need to see if i can find a cheap volt meter somewhere.

I was thinking about Halfords...don't they do a free test to see if you need a new battery etc ?

Thanks for advice.
 
It's terrible to cast aspersions on your mechanic but trust and honesty are elusive commodities these days unfortunately.

I would certainly invest the tenner for a multimeter and if the battery is knackered replace that first as it can actually have a detrimental effect on your alternator.

If the vm test points towards an alternator issue get a second opinion at a reputable garage.

Good luck.
 
Normally the red ignition/battery light will flicker or light up if there's an issue with the alternator. That's how it used to work on old skool cars.
If you haven't noticed any thing, more while driving at night, then it sounds like he's taking the Pee :|
 
Ok thanks.

If its only a tenner I might as well invest in the meter and use it again in future.

But how about the Halfords free battery check idea ?

To me the fact I rarely drive the car, its dark and cold all day so the lights and blowers are on all the time and I'm suffering no issues whatsoever and no warning lights suggests to me there is no actual problem.
 
ferrelscent said:
Ok thanks.

If its only a tenner I might as well invest in the meter and use it again in future.

But how about the Halfords free battery check idea ?

To me the fact I rarely drive the car, its dark and cold all day so the lights and blowers are on all the time and I'm suffering no issues whatsoever and no warning lights suggests to me there is no actual problem.
Click to expand...
I find places like Halfords like to sell you things, their "free" checks are normally a way to your wallet, so be aware.
If you have no issues, don't worry about it :thumbsup:
 
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