Well I have had a few low battery warnings in the last couple of weeks so I had the battery tested thinkings it’s 5 years old probably needs changing.

Took it in to my local battery specialist who checked battery and said it was good, bit low on charge though.

Because of the warnings and the fact I had just done a 200 mile round trip they checked the alternator for me and found on full load, lights on rear heater, radio and car in defrost the alternator was only giving out 13.3v and advised alternator was on its way out.

 

Heres the scary bit, new alternator fitted by Skoda is £968.00!! An aftermarket Lucas alternator is £588.00 fitted.

When did alternators get so expensive?

 

Going on holiday soon so getting a new Lucas one fitted, can’t believe a genuine one will be worth the extra £400.00, any thoughts?

New style charging systems for AGM and EFB batteries don't necessarily put out the (constant) voltages that old style ones do.

 

I would say at 5 years old the battery is much more likely to be the problem, and at the prices you're talking for the alt replacement, imagine how gutted you'd be if you changed that and found no change to the situation. 

 

 

On my previous 1.4TSI I used to monitor the battery voltage on occasions and it would be 14.x volts after starting but when driving would drop as low as 12.x volts as the battery management tried to keep the battery state of charge no more than 80% to allow headroom for some micro regnerative braking (when the voltage again increased to 14.x volts).

My viewpoint. You've done that trip with no heavy consumers running, apart from maybe headlights and a/c. If the alternator gives you that reading under heavy load I'd expect it to be more than capable of charging the battery under a light load. As mentioned above the battery is probably on its way out.

Thanks for the feed back.

The issue is after a 200m round trip the battery should have charged more than 80%.

With engine on lights on rear heated screen, mirrors and working the steering wheel the alternator should have been kicking out 14.4v ish, not 13v.

The battery load tested okay but the alternator gear reported Output too low. Spoke to the stealers and an indie specialist who both agreed alternator.

No, both of your first two statements are quite wrong.

3 hours ago, Leodis41 said:

low battery warnings

Charge the battery first using a smart main charger.

 

Thanks. AG Falco

3 hours ago, Leodis41 said:

Spoke to the stealers and an indie specialist who both agreed alternator.

 

They are both incorrect, either ignorant and ill informed which is perhaps understandable hence acceptable or looking to milk you which is not.

Edited 24 July, 20232 yr by J.R.

5 hours ago, PetrolDave said:

On my previous 1.4TSI I used to monitor the battery voltage on occasions and it would be 14.x volts after starting but when driving would drop as low as 12.x volts as the battery management tried to keep the battery state of charge no more than 80% to allow headroom for some micro regnerative braking (when the voltage again increased to 14.x volts).

The odd times I've checked the SOC using the trip set button, I've never seen more than about 70%.  I'll check it in a few days time before starting the engine (not used for about 2 wks) and again after a 250 mile trip I'm planning.

17 hours ago, Leodis41 said:

The issue is after a 200m round trip the battery should have charged more than 80%.

Wrong, the Battery Management System aims to charge the battery to no more than 80%, as I explained in my previous post

 

19 hours ago, PetrolDave said:

the battery management tried to keep the battery state of charge no more than 80% to allow headroom for some micro regnerative braking

 

19 hours ago, ords said:

The odd times I've checked the SOC using the trip set button, I've never seen more than about 70%.  I'll check it in a few days time before starting the engine (not used for about 2 wks) and again after a 250 mile trip I'm planning.

The SOC function appears to have been deleted around MY16 (I wonder why?). My 2015 Octavia does not have it.

1 hour ago, Warrior193 said:

The SOC function appears to have been deleted around MY16 (I wonder why?). My 2015 Octavia does not have it.

Neither my 2015 nor 2016 Octavias have had the SoC function working.

1 hour ago, Warrior193 said:

The SOC function appears to have been deleted around MY16

Because present batteries will not be at 100% ( by design ) and if the customer could see this they would get worried that the battery ( even when new ) is faulty.

 

Thanks. AG Falco

10 minutes ago, AGFalco said:

if the customer could see this they would get worried that the battery ( even when new ) is faulty.

 

And end up being taken for £588 or £968 for a new alternator!

 

The OP is making the sounds of a willing victim.

40 minutes ago, AGFalco said:

Because present batteries will not be at 100% ( by design ) and if the customer could see this they would get worried that the battery ( even when new ) is faulty.

 

Thanks. AG Falco

Call me cynical, but that's what I suspected.

On 24/07/2023 at 20:09, AGFalco said:

Charge the battery first using a smart main charger.

 

Thanks. AG Falco

Out of interest, would a smart charger only charge to around 80%?

1 hour ago, ords said:

Out of interest, would a smart charger only charge to around 80%?

No.

 

I charge my EFB battery regularly with a smart charger, especially during the winter.

At 7 years and 73 K miles from new my battery is still showing good when tested.

 

Thanks. AG Falco

^^^ What AG says, I do this every month or two, due to my running low annual miles - mostly 18 mile round trip work commute.

A likely drawback to 'smart' alternators is possible long-term battery damage caused by persistent low charge state when running relatively low mileage - I would have thought that it would be possible for VAG to build an algorithm into the charging system, to allow it to act more like a conventional alternator during frequent short runs - although this might change the test emission figures.    

9 hours ago, Warrior193 said:

I would have thought that it would be possible for VAG to build an algorithm into the charging system, to allow it to act more like a conventional alternator during frequent short runs

Or just remove the small wire to the Negative connection on the battery.

 

Thanks. AG Falco

The two things that concern me about that are -

1; That disables auto idle stop (which, personally I find useful, but disable when anticipating a very short stop) 

2; Does that not raise the possibility of overcharging the battery when driving conditions change and more regenerative charging becomes available? 

1 hour ago, Warrior193 said:

The two things that concern me about that are -

I have not disconnected that wire.

 

1. I will always turn off the stop/start when first starting the car and only put it back on when I think it is required.

2. No, as this makes the alternator behave like a older/ normal one.

 

Thanks. AG Falco

2. That's too high a voltage for an AGM/EFB battery that's fully charged.

That's why everything had to change for these types.

I believe it does do what he says if the shunt resistor cable is disconnected, but probably with a lower charging voltage, something like 13.7v max and not 14.4v.

 

Charging voltage reduces when the battery approaches full charge anyway, if it mimics the operation of the normal alternator regulator it will do the same.

Edited 26 July, 20232 yr by J.R.

On 24/07/2023 at 22:39, ords said:

The odd times I've checked the SOC using the trip set button, I've never seen more than about 70%.  I'll check it in a few days time before starting the engine (not used for about 2 wks) and again after a 250 mile trip I'm planning.

Well, it wouldn't work at all first thing but at the end of my trip it did work and read 80%

23 hours ago, AGFalco said:

I have not disconnected that wire.

 

1. I will always turn off the stop/start when first starting the car and only put it back on when I think it is required.

2. No, as this makes the alternator behave like a older/ normal one.

 

Thanks. AG Falco

But vehicles with the 'older/normal type' of charging systems did not have regenerative charging - I have seen nothing to suggest that disconnection of the sensing tag on the battery disables regenerative charging - it simply disables the idle stop function by simulating a battery voltage that is too low to allow it.