Hi guys,

 

Could you please tell me which would be the default voltage output of a standard alternator for a 1.4 mpi (8v) Skoda Fabia? Mine has an output of 13.6-13.8, but a local battery dealer told me that he couldn't apply warranty for a battery if voltage isn't between 14.2 - 14.8. Have you ever encountered this kind of issue or he's just trying to sell me nuts ?

Sounds like bulls hit but it should hit 14v with most of the power consumers off

I'd expect a healthy alternator to supply 14.4v.

 

I can't comment on "I can't apply warranty" without more information to know if the issue is "not of merchantable quality" or "insured against failure of part for $period".

He tells me that an alternator with an output of less than 14V is the cause if my faulty battery, quoting his words 'those things are killing good batteries'. IIRC, with full beam, fog lights, AC, mirror and back window heaters and the fan blower at full speed, a multimeter connected to the battery shows 12.8V and 13.6-13.8 with all consumers off.

 

Should I take my alternator to be serviced ? Is there a charge controller that can be replaced, configured or at least, checked ?

 

Later edit: I just wanted to claim warranty for my battery which after ~36h of stand still just didn't want to turn my engine, I had to get a donor car to start mine.  I usually drive my car daily, 1st drive in the morning is pretty short (less than 3 miles), but after leaving work it does at least 15 or 20 miles. All this time, I'm running with the main beam on all the time, the fan blower at 1st or 2nd stage, my radio on ... and maybe the door mirrors and the back window heaters on. Once or maybe twice / week I'm driving it a bit further, ~50 miles. IMHO, the battery should get a pretty good charge all this time. My car doesn't have an alarm system or any other consumer when the engine is turned off, only the dashboard and other builtin electrics stuff. After I jump started the car, I had to turn off the engine after ~ 5 or 10 minutes. I intentionally started it with the main beams on (and the radio) and it went perfect. 

Edited 27 December, 201510 yr by Alexandru

Are those voltages with the engine at idle?

Yes, that figures are at idle or increased idle when the AC compressor was running.

Try it with the engine revving as it would be when driving,2-4K rpm etc.

I think those figures you are quoting will be fine at idle,but you want to see them rise up above 14v with the engine revving.

Back in the day of my classic 1275GT mini if I turned on the Cibie Super Oscars at idle the voltage was below 12v at idle

Also check your boot light isn't stuck on

If battery is drained, it is the most bigger consumer and it's draining most of the current from alternator. Especially if battery is shorted. You will never had 14.4V with bad battery, no matter how good or bad is alternator and thats the catch they hook you on.

I think from memory that we've had this many times before with the 1.4 MPI engine, I seem to remember that this engines alternator only chucks out ~13.7V which is what all alternators used to produce before the modern era of ECU controlled charging systems.

So I should just live with it? Is there any actual issue with my alternator output ? What can I do to claim warranty for a future battery if these models only have an output of ~13.7V?

I don't thinks there's an issue, as to the warranty I have no idea what to suggest.

 

If you measure the output from an old mains charger you'll find it's also about 13.7V, it doesn't work as well because of the Calcium coating new batteries have on their plates to extend shelf life.

He tells me that an alternator with an output of less than 14V is the cause if my faulty battery, quoting his words 'those things are killing good batteries'. IIRC, with full beam, fog lights, AC, mirror and back window heaters and the fan blower at full speed, a multimeter connected to the battery shows 12.8V and 13.6-13.8 with all consumers off.

 

Should I take my alternator to be serviced ? Is there a charge controller that can be replaced, configured or at least, checked ?

 

Later edit: I just wanted to claim warranty for my battery which after ~36h of stand still just didn't want to turn my engine, I had to get a donor car to start mine.  I usually drive my car daily, 1st drive in the morning is pretty short (less than 3 miles), but after leaving work it does at least 15 or 20 miles. All this time, I'm running with the main beam on all the time, the fan blower at 1st or 2nd stage, my radio on ... and maybe the door mirrors and the back window heaters on. Once or maybe twice / week I'm driving it a bit further, ~50 miles. IMHO, the battery should get a pretty good charge all this time. My car doesn't have an alarm system or any other consumer when the engine is turned off, only the dashboard and other builtin electrics stuff. After I jump started the car, I had to turn off the engine after ~ 5 or 10 minutes. I intentionally started it with the main beams on (and the radio) and it went perfect. 

Well, if you're showing over 12v with that lot on, then the battery is being charged a bit at all times other than startup.

 

Ask the dealer to prove that the battery is not at fault by doing a discharge test, because I'm suspecting a weak cell.

I've found this. Maybe I should inspect and/or replace it ? I will ask him for a discharge test as well, that's a good idea. 

Edited 27 December, 201510 yr by Alexandru

I've found this. Maybe I should inspect and/or replace it ? I will ask him for a discharge test as well, that's a good idea.

You can get a complete alternator for not much more than that

I've found this. Maybe I should inspect and/or replace it ? I will ask him for a discharge test as well, that's a good idea. 

 

Why? A voltage reg. won't RAISE an alternators output to 14.4V, only limit it.

I know, I was thinking maybe if it's limiting more than it should be.

I've found this. Maybe I should inspect and/or replace it ? 

Pointless; the existing regulator is only a little outside normal limits.

If you have ac then you should have the 70a alternator at least which should be kicking 14.4 at 2000rpm really..

Where are you measuring the voltage at. Possibly the main lead has some resistance in it by now try measuring the voltage at the 15mm nut on the back of the alt and compare it with the battery and see if there any difference in the readings

And yes maybe the brush pack is worn in yours but I wouldn't think it would charge at all then

With engine running and a few power consumers on (say headlights and rear screen heater and fan on 4) measure the voltage between some clean metal on the engine (scrape a bit of oxide off the alternator body for example, and touch one probe there) and battery negative post.  I think it's quite common to lose some voltage in the return/earth/ground path, usually corroded connections.  This measures that loss, and will help you narrow down where the problem is, because you can move the probe that's on the engine metalwork in steps towards the other probe on the battery negative, following the earth leads, and when the voltage drop suddenly goes to a very low value, you've just stepped across the bad connection. 

Edited 27 December, 201510 yr by Wino

With engine running and a few power consumers on (say headlights and rear screen heater and fan on 4) measure the voltage between some clean metal on the engine (scrape a bit of oxide off the alternator body for example, and touch one probe there) and battery negative post.  I think it's quite common to lose some voltage in the return/earth/ground path, usually corroded connections.  This measures that loss, and will help you narrow down where the problem is, because you can move the probe that's on the engine metalwork in steps towards the other probe on the battery negative, following the earth leads, and when the voltage drop suddenly goes to a very low value, you've just stepped across the bad connection.

Battery positive post if you want to get any reading at all!

Nope. This is looking for voltage drop in the return path. It should be nearly zero; but if there are any bad connections, e.g main body earth wire onto starter stud, you'll see hundreds of millivolts of drop when you put your probes where I've suggested.

You may be overthinking this Wino, I don't think there's a problem, all the early 1.4 MPI engines seem to run 13.7V - 13.8V.

Let's let Alex decide whether he wants to follow my suggestion or not. I find it hard to believe that mpi engines are 'special' in respect of using a charge voltage that would barely work at all.

Perhaps one or two other owners could measure theirs? Voltage regulators often state their nominal voltage on the outside, what does yours say on it Alex? Anything visible?