Technical Alternator / Battery issue?

[d4zzl3r]

Hello all, is it possible for an alternator's charging performance to degrade? I mean it is a case of it either works or it doesn't.

2014 TA 105 had since new, 55000 miles. Never before had a battery or charging issue, never not started.

During the recent cold weather it failed to start. I charged the battery and its been fine since.

When it didn't start it was strange, not a slow cranking which slowed as the battery charge got less and less (like i have experienced with older cars). It was turning over as if it was going to start but just cut out. Tried three or four times, same result. So i charged it up and its been fine since.

Thinking about it afterwards it felt like it does when the stop/start is activated. So now i'm thinking the non-starting was related to the stop/start system? I think a weak battery (or one with a low charge) can affect a stop/start system?

The charging light goes out as it should so i presume the alternator is OK. I'm thinking that battery is not holding a charge.
The pictures below tell a different story?

Picture 1 shows the battery after i had charged it at 100 SoC (battery charger was still attached).
Picture 2 shows alternator charging test.

 

[bugsymike]

Others may give more specific advice, but over the years I have tested the charging rate ideally around 14.2 volts when lightly revved but with a load on such as headlights and fan etc. to check if it copes OK.
Ideally a good battery when resting should show around 12.5 volts. Remember when ignition key first removed there is a load /drain from the battery as the ECU shuts down the system.
I also have a batter tester that you put in the cranking capacity EN, SAE etc. say 740 amps or so on a van battery, then the meter runs the test and will tell the capacity of the battery in % compared with what it states on the label. It can also say if just needs charging or is scrap. I have taken the battery from my 2.8 Ivecos showing only 65% and they have still been quite good for several years on a smaller engine.
Another thing on modern vehicles is the output is controlled via the ECU so it may be worth checking with a good diagnostic tool to see if any recorded errors.

 

[Mike1alike]

Others may give more specific advice, but over the years I have tested the charging rate ideally around 14.2 volts when lightly revved but with a load on such as headlights and fan etc. to check if it copes OK.

I think the OP has the Smart / ECU-Controlled Alternator, that's why voltage is lower than what we know as normal.

 

[Mike1alike]

On a 2014 TwinAir with Stop/Start, the charging system is ECU-controlled (smart charging), so voltage does not always sit at 14V constantly like older cars.
However, readings of 12.3–12.4V at both idle and higher RPM suggest that the alternator is not actively charging, that is essentially battery voltage.
Even with smart charging, you should normally see voltage rise above 13.5V during driving.
The low ripple voltage (8mV) suggests the diode pack is healthy, so this is unlikely to be an internal short.
Given the age of the car and Stop/Start system sensitivity, the most likely cause is a weak or aging battery. A battery can show 100% SoC on a charger but still collapse under load.
Next steps:
• Measure voltage while driving — does it ever exceed 13.5V?
• Perform a proper battery load test
• Confirm correct EFB/AGM battery type is fitted
• Check if battery has been replaced without system reset
If charging voltage never rises above battery voltage during driving, then alternator control or regulator fault becomes more likely.

 

[jackwhoo]

You have driven about 4000 miles over last 3 years and 7 months. It is very likely battery condition / state of charge was affected. Particularly if it's daily drive is still 7miles in two halves.

 

[Mike1alike]

You have driven about 4000 miles over last 3 years and 7 months. It is very likely battery condition / state of charge was affected. Particularly if it's daily drive is still 7miles in two halves.

How did you come to those numbers...?!

 

[jackwhoo]

How did you come to those numbers...?!

OP has made other threads containing the info

 

[Mike1alike]

Yes, not driving enough does discharge the battery. But still... those voltages say something is not quite alright.

 

[jackwhoo]

Depends on driving conditions when measured , state of charge of battery, charging protocol

 

[jrkitching]

014 TA 105 had since new, 55000 miles. Never before had a battery or charging issue, never not started.

If this is the original battery that was on the car when supplied new, then just replace it.

 

[varesecrazy]

My punto TA got 12 years from the factory battery,
but most trips were 2 hours

 

[jrkitching]

My punto TA got 12 years from the factory battery

The OP's car will be 12 years old this year...

The most I've ever managed is a shade under 10 years.

 

[varesecrazy]

The OP's car will be 12 years old this year...

The most I've ever managed is a shade under 10 years.

Don't rule out Just through age,

But long periods of Low charge will damage it internally..


Well worth spending £80 at Tayna batteries, delivered to your door

 

[d4zzl3r]

WOW, thank you all, very helpful and great advice/information. I had a feeling it might be the battery caused maybe by age or more likely the short commute (daughter uses the car as her daily) or by both. Maybe the short commute as done for the ageing battery which otherwise might have lasted a bit longer. I’ll do a bit more testing but I think my next stop is Tayna.

 

[GettinBetter]

is it possible for an alternator's charging performance to degrade?

IMO, yes it is. But taking your question literally, if the brushes deteriorate, then yes. An intelligent Alternator still has brushes and still has a voltage regulator, but the voltage regulator is controlled by the engine ECU.

I can't believe the previous posters never mentioned it, but ...
Your first test should be to put a quality jump lead from the negative terminal to a nice clean part of the engine (ideally the alternator, but it's a pain to get to), and recheck that charge rate.
Then:

• If there is no change, and the battery is over 5 yrs old, and Start/Stop doesn't work, then go for a new battery.
• If there is a noticeable increase:

1. Give the battery a bloody good trickle (4A or under) charge for about a week.
2. Inspect/replace the earth cables, A.) Battery negative terminal to chassis, and B.) Chassis to gearbox.

I have a current & voltage controlled DC power supply (an absolute life saver), and I stick my spare on 14V @ 500mA for a week, or untill the charge meter drops to around 50mA. Always gives my batteries a new lease of life.

My intelligent alternator charge voltage (measured at the battery), is rarely above 12.8V, but never drops below 12.7, no matter what load I put on it.

That's my tuppence worth

 

[bugsymike]

, but the voltage regulator is controlled by the engine ECU.

I can't believe the previous posters never mentioned it, but ...

#2 "Another thing on modern vehicles is the output is controlled via the ECU so it may be worth checking with a good diagnostic tool to see if any recorded errors."

 

[d4zzl3r]

I remember in the old days before all this electronic malarky we tested the alternator by putting the headlights on and revving the engine. If the headlights went brighter we were charging.

 

[The Panda Nut]

I remember in the old days before all this electronic malarky we tested the alternator by putting the headlights on and revving the engine. If the headlights went brighter we were charging.

Now because of progress you need MONEY to spend on test rquipment you will rarley use. And MONEY to buy new test gear because you cant remember where you put the first one... That is REAL improvement. Great when it all works, but mind numbingly dumb when it doesnt.

 

[Mike1alike]

Plus... Planned obsolescence!!!

 

[steveras57]

id prefer a starting handle!