1.9D alternator

P156KWJ · May 5th, 2020, 13:17

After suspecting a possible dip in charge, I dropped a multimeter on the battery of my 1.9 diesel last night. Whilst it isn't indicating anything catastrophic (tested after about an hours drive to work), with everything off the battery read 12.5 Volts. With the engine running it read between 13.5 and 13.9, but when RPMs were increased there was no change in this.

The belt was changed almost a year ago to today incidentally, but that is looking glazed already. No unusual sounds or squealing/whining with the exception of an annoying alternator whine that has appeared on the radio when using FM (consistent with engine speed).

Are these voltages normal or could the alt be on it's way out?

LTEcactus · May 5th, 2020, 16:42

Quote:

Originally Posted by P156KWJ

After suspecting a possible dip in charge, I dropped a multimeter on the battery of my 1.9 diesel last night. Whilst it isn't indicating anything catastrophic (tested after about an hours drive to work), with everything off the battery read 12.5 Volts. With the engine running it read between 13.5 and 13.9, but when RPMs were increased there was no change in this.

The belt was changed almost a year ago to today incidentally, but that is looking glazed already. No unusual sounds or squealing/whining with the exception of an annoying alternator whine that has appeared on the radio when using FM (consistent with engine speed).

Are these voltages normal or could the alt be on it's way out?

It could just be an old battery, when was yours changed?
Although the alternator whine does sound a bit worrying.

Darlo 1 · May 5th, 2020, 19:49

If i remember correctly an alternator should be showing 14.4 volts if its healthy, reckon yours is on its way out.

P156KWJ · May 6th, 2020, 01:52

Quote:

Originally Posted by LTEcactus

It could just be an old battery, when was yours changed?
Although the alternator whine does sound a bit worrying.

New battery when I bought it in March 2019 as it had been sat in the dealer's yard for a while in the cold. It's a Drivemaster so probably the cheapest one they could find

clarkey1984 · May 6th, 2020, 11:38

Anywhere between 13.5 and 14.5 alternator output is normal so far as I remember, I'd be suspect of the battery myself, although 12.4 from the battery isn't catastrophic, only about 0.5v down from what you'd expect from a brand new one.

canis · May 11th, 2020, 19:44

Sounds perfectly normal to me. Lots of people think "the engine should chagre more when revved up a bit". This was true with dynamos, about fifty years ago, but no longer the case. An alternator will charge as much at tick-over as it will any other time.

The radio interferance could be either the condensor capacitor (do they still have those) but more likely to be your aerial has made ground somewhere.

AndyV7o · May 11th, 2020, 21:17

As said, charging should be between 13.5-14.4v and stable at all rpm, but, put everything electrical on, heater, lights, stereo, etc, whilst running of course and re-check output. It should still be within range and maybe higher than at idle.
If it drops below 13.5v when under load, its on its way out..

May 5th, 2020, 13:17	#1
P156KWJ Senior Member Last Online: Nov 6th, 2022 16:57 Join Date: Mar 2019 Location: Nottingham	1.9D alternator After suspecting a possible dip in charge, I dropped a multimeter on the battery of my 1.9 diesel last night. Whilst it isn't indicating anything catastrophic (tested after about an hours drive to work), with everything off the battery read 12.5 Volts. With the engine running it read between 13.5 and 13.9, but when RPMs were increased there was no change in this. The belt was changed almost a year ago to today incidentally, but that is looking glazed already. No unusual sounds or squealing/whining with the exception of an annoying alternator whine that has appeared on the radio when using FM (consistent with engine speed). Are these voltages normal or could the alt be on it's way out? __________________ Present: 2002 C70 2.0T, 2003 Saab 9-5 3.0 V6 TiD Past: 2002 S40 1.9D, 2002 S40 2.0T, 2004 S40 1.8, 2002 & 2004 V40 1.9D, 2006 Saab 9-5 2.3t Various other French and Italian boxes

May 5th, 2020, 19:49	#3
Darlo 1 Lunatic. Last Online: Yesterday 22:56 Join Date: Dec 2006 Location: staffordshire	If i remember correctly an alternator should be showing 14.4 volts if its healthy, reckon yours is on its way out. __________________ V40 1.9D 2004 620 miles to the tankful. 235000 miles on clock. Now sold, S60 D5 2004. I vape therefore I am.

May 6th, 2020, 11:38	#5
clarkey1984 Premier Member Last Online: Apr 13th, 2022 09:41 Join Date: Jul 2014 Location: Beccles	Anywhere between 13.5 and 14.5 alternator output is normal so far as I remember, I'd be suspect of the battery myself, although 12.4 from the battery isn't catastrophic, only about 0.5v down from what you'd expect from a brand new one. __________________ 02 V40 T4 S, "Sargent silver" she's back!

May 11th, 2020, 19:44	#6
canis Non Fragile Last Online: Oct 13th, 2023 05:46 Join Date: Apr 2010 Location: Chadderton, Oldham	Sounds perfectly normal to me. Lots of people think "the engine should chagre more when revved up a bit". This was true with dynamos, about fifty years ago, but no longer the case. An alternator will charge as much at tick-over as it will any other time. The radio interferance could be either the condensor capacitor (do they still have those) but more likely to be your aerial has made ground somewhere.

May 11th, 2020, 21:17	#7
AndyV7o Premier Member Last Online: Jun 21st, 2021 20:47 Join Date: Jun 2018 Location: Creswell	As said, charging should be between 13.5-14.4v and stable at all rpm, but, put everything electrical on, heater, lights, stereo, etc, whilst running of course and re-check output. It should still be within range and maybe higher than at idle. If it drops below 13.5v when under load, its on its way out..

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