Battery or alternator?

conorkeating

Hey guys, just looking for a quick bit of advice about my car (99 Mondeo Saloon 1.6 petrol). Driving home a couple of days ago the battery dash light started coming on and off with no obvious pattern. FYI the battery is the original so 15 years old by now and the car has gone through around 110,000 miles. Today I got out my voltmeter and took the following readings:
Engine off = 11.9
Minimum electrics, engine idling 1k rpm = 11.3
Minimum electrics, engine revving 2k rpm = 13.8
Full electrics on, engine idling 1k rpm = 13.4
Full electrics on, engine revving 2k rpm = 10.6

What would these figures indicate, replace battery or get the alternator repaired? I'd appreciate the help from any mechanic, electrician or know-it-all who can solve the problem.

Cheers in advance.

Avns1s

conorkeating wrote: »

Hey guys, just looking for a quick bit of advice about my car (99 Mondeo Saloon 1.6 petrol). Driving home a couple of days ago the battery dash light started coming on and off with no obvious pattern. FYI the battery is the original so 15 years old by now and the car has gone through around 110,000 miles. Today I got out my voltmeter and took the following readings:
Engine off = 11.9
Minimum electrics, engine idling 1k rpm = 11.3
Minimum electrics, engine revving 2k rpm = 13.8
Full electrics on, engine idling 1k rpm = 13.4
Full electrics on, engine revving 2k rpm = 10.6

What would these figures indicate, replace battery or get the alternator repaired? I'd appreciate the help from any mechanic, electrician or know-it-all who can solve the problem.

Cheers in advance.

The one in bold is strange in the context of the others. Not a typo?

On the face of all you said, it's an alternator problem. Having said that, I don't think I have ever seen a battery still in use after 15 years.

pablo128

A simple rule, is around 13.5v at tickover, and 14.5v at a high idle. Alternator so.

conorkeating

I thought the same about the battery, but I did have the AA out after the engine flooded or something and the car wouldn't start. He was surprised that the battery had lasted this long but said to hold on to that particular battery as long as I can - something about them not making replacements anywhere near as good as the original.

So that's 1 vote for alternator I guess. Was kind of hoping you wouldn't say that.

conorkeating

Forgot to answer your original question Avns1s, not a typo.

greasepalm

i would advise doing both as old battery would have more resistance making altenator work harder,15 years best life or is that doggy years.

CJhaughey

If its any use to you, there is a lad on Ebay based in Mayo selling Alternator rebuild kits for small money.
I rebuilt my Avensis one recently for less than €25.
The hardest part was removing the Alternator, the actual rebuild took only about 1 hr.
He has a load of videos on youtube under the name of Westronicsirl which give handy tips on dissassembling and renovating Alternators and rebuilding them.
I have no connection to him apart from being a very happy customer who saved a lot of money by diy-ing it.

greasepalm

i would be wary of cheap fixes and no way will i see that altenator last,overhauls can mean bearing change and rectifier or other bits on a unit of 15 years or 100,000 miles

CJhaughey

greasepalm wrote: »

i would be wary of cheap fixes and no way will i see that altenator last,overhauls can mean bearing change and rectifier or other bits on a unit of 15 years or 100,000 miles

And what do you think the fix I did involved?
Slip ring, 2 x NTN bearings, new brushbox and rectifier,
No reason to think that it won't last given that its all new componentry.
You don't have to pay a fortune to rebuild an alternator, its not rocket science.
When you buy a rebuilt one, thats all that has been done to it.
Buying new is OK but you are looking at least 250+
Up to you what you want to spend your money on I guess.

guil

CJhaughey wrote: »

If its any use to you, there is a lad on Ebay based in Mayo selling Alternator rebuild kits for small money.
I rebuilt my Avensis one recently for less than €25.
The hardest part was removing the Alternator, the actual rebuild took only about 1 hr.
He has a load of videos on youtube under the name of Westronicsirl which give handy tips on dissassembling and renovating Alternators and rebuilding them.
I have no connection to him apart from being a very happy customer who saved a lot of money by diy-ing it.

Dont suppose you have a link?

pablo128

I agree about changing the battery when getting the alternator done. A bad battery can cause the alternator to go, as the alternator has to work harder. It can also cause the starting motor to go too.

Regarding rebuilding the alternator, I put a set of brushes into my dads Toyota Picnic alternator a few years back. The car now has over 250k miles and still going strong. The brushes cost me 7 euro from Toyota. I just had to solder them into the brush pack.

greasepalm

CJhaughey wrote: »

And what do you think the fix I did involved?
Slip ring, 2 x NTN bearings, new brushbox and rectifier,
No reason to think that it won't last given that its all new componentry.
You don't have to pay a fortune to rebuild an alternator, its not rocket science.
When you buy a rebuilt one, thats all that has been done to it.
Buying new is OK but you are looking at least 250+
Up to you what you want to spend your money on I guess.

more than i thought for that price:D

CJhaughey

guil wrote: »

Dont suppose you have a link?

http://www.ebay.co.uk/usr/goldlion_autoelectrics