Hi all,

I have a Skoda Octavia 2017 2.0 TDI DSG and I think alternator is paying up. Sometimes the voltage is showing 14.4V but sadly sometimes doesn't work and it's showing 11.3V. What's the best solution to it because I know the price for the new one is quite high. Thanks for your help. 

4 hours ago, kamilm594 said:

Sometimes the voltage is showing 14.4V but sadly sometimes doesn't work and it's showing 11.3V.

With these recent cars the alternator is apt to be disabled unless the car thinks the battery needs more charge. If you also have Stop/Start, and you have a new(ish) to you battery, has it been mapped in to your car?

I assume it does not always charge the battery with 14.4v, it should be an adaptive charging I think. But, then the 11.3v is a bit weird!

Edited 5 December, 20223 yr by Vahids

11.3 V is too low with the engine running and suggests the battery is being discharged - that's lower than the voltage you'll get with the engine stopped, after all.

When the battery is not charging with the engine running the voltage should float at about 13 and a bit volts. Unfortunately I can't help you with what the fault might be.

28 minutes ago, Rodge said:

11.3 V is too low with the engine running and suggests the battery is being discharged - that's lower than the voltage you'll get with the engine stopped, after all.

 

There is a greater discharge & hence voltage drop with the engine running especially when you turn the steering wheel (if the battery is not being charged).

 

I am not sure about the OP's vehicle but if it has the battery management system for the later emissions standard then it effectively charges on the over-run as a sort of regenerative braking, most of the time driving on the throttle the alternator is not charging and 11.3 volts sounds about right, it only maintains something like 80% charge to allow for the regenerative charging.

On 04/12/2022 at 23:06, kamilm594 said:

Hi all,

I have a Skoda Octavia 2017 2.0 TDI DSG and I think alternator is paying up. Sometimes the voltage is showing 14.4V but sadly sometimes doesn't work and it's showing 11.3V. What's the best solution to it because I know the price for the new one is quite high. Thanks for your help. 

Are you experiencing starting problems, warning lights etc?   What made you check for voltages?

22 hours ago, J.R. said:

I am not sure about the OP's vehicle but if it has the battery management system for the later emissions standard then it effectively charges on the over-run as a sort of regenerative braking, most of the time driving on the throttle the alternator is not charging and 11.3 volts sounds about right, it only maintains something like 80% charge to allow for the regenerative charging.

11.3 volts is way too low, that will result in a dead battery. As I said, it should be about 13.5 V when it's not charging and 14.5 V when it is. I get 13.3 V and 14.8 V on my car. Others may vary, but anything below 12 V is too low.

I dont think that you have followed or understood what I was trying to explain, that the OP's vehicle probably has a battery management system whose aim is to not use fuel to charge the battery but instead use the alternator during braking and decelleration phases.

 

Your figures are incorrect, no 12v vehicle battery will have 13.5v when not charging and with the engine running, it will be around 11.3v allowing for a partial charge leaving capacity for over-run charging and the voltage drop from the ECU and all the other active systems, significantly less as soon as the electric power steering is used although I expect the battery management system allows the alternator to charge under that condition.

 

On a normal vehicle with a traditional charging system you may read 13.5v immediately after engine shutdown on a new battery but this will quickly drop to 12.7v as the battery cools and continue to drop slowly with the parasitic current draw. Unless you take the battery voltage after about 20 minutes and without waking up the canbus system (by shunting the bonnet closed contact) then you wont even see 12.7v, whenever I am doing a VCDS scan the terminal 30 voltage is under 12v.

 

11.3 volts is undercharged, or a partial charge for a battery management system vehicle, it will not result in a dead battery, it needs to drop below 10.5v for a long period for damage to occur, not transient volt drop like when cranking, the battery management system will not allow this to occur.

 

In any case the 11.3 volts is a transient reading of the battery under a discharge load, the actual open circuit cell voltage measured without load (following the procedure) say 20 minutes after shut down I would expect to be between 12.3 and 12.7 volts, possibly slightly less.

Edited 7 December, 20223 yr by J.R.

Can confirm I used to see a range of 11.x - 13.x (tipping into low 14) on my 2.0tdi.

On 06/12/2022 at 21:18, Rodge said:

11.3 volts is way too low, that will result in a dead battery. As I said, it should be about 13.5 V when it's not charging and 14.5 V when it is. I get 13.3 V and 14.8 V on my car. Others may vary, but anything below 12 V is too low.

On my 1.4TSI the battery voltage would be around 14.4V for a few minutes after charging, then drop to around 12.5V for most of the time driving except when braking when the regenerative braking would increase the voltage during braking.

 

So based on my experience 13.5V when driving seems high and could suggest a battery that isn't in top condition.

 

Totally agree that 11.3V while driving is too low.

On 05/12/2022 at 12:30, Vahids said:

I assume it does not always charge the battery with 14.4v, it should be an adaptive charging I think. But, then the 11.3v is a bit weird!

It is weird, it looks like sometimes its working fine and sometimes it doesn't.

On 05/12/2022 at 23:21, ords said:

Are you experiencing starting problems, warning lights etc?   What made you check for voltages?

Yeah so first of all my rear window heating stopped working and than dash cam which is connected to rear wiper stopped charging, that made me thinking what was happening but there was no problem with starting the car. And than this message came up so I knew the battery is dead and when I checked the voltage it was 11.3 so it means the alternator wasn't working. And now the alternator is working only sometimes so I'm thinking of a repair if it would be possible because the new one is quite expensive. 

How can I find out the model of the alternator I need before actually taking it out so I could check how much would it be, maybe some serial number??

On 10/12/2022 at 00:06, kamilm594 said:

How can I find out the model of the alternator I need before actually taking it out so I could check how much would it be, maybe some serial number??

Few options. Check a part listing like 7zap, although if there have been superseding part numbers, being free it doesn't usually show the latest part.

 

Accross mqb cars, alternators are pretty standard and usually 140a or 180a depending on options. The higher output for options like heated seats..

 

Put your reg in eurocarparts or gsf. Or call the.. their online parts checker are usually OK but can fail to pin point exact variations based on car spec.

 

How many miles has car done? 2017 model right? 

 

Edit: On the full list of vehicle option pr codes. 8GU is 140a

Edited 12 December, 20223 yr by TheClient

52 minutes ago, TheClient said:

Few options. Check a part listing like 7zap, although if there have been superseding part numbers, being free it doesn't usually show the latest part.

 

Accross mqb cars, alternators are pretty standard and usually 140a or 180a depending on options. The higher output for options like heated seats..

 

Put your reg in eurocarparts or gsf. Or call the.. their online parts checker are usually OK but can fail to pin point exact variations based on car spec.

 

How many miles has car done? 2017 model right? 

 

Edit: On the full list of vehicle option pr codes. 8GU is 140a

Yeah 2017 model around 82000 miles. 

1 hour ago, kamilm594 said:

Yeah 2017 model around 82000 miles. 

Seems a little early. But could be just brushes or the freewheel hub.

 

A replacement aftermarket is going to be circa £250 minimum possibly with requirement of your unit back.

 

Eurocarparts gsf have elstock, lucas. I'd rather a hella unit myself. 

 

If you can diagnose yours, it can be better to repair than get reco exchange units.  

Agree with the above. I just looked up the relevant ETKA page via LLL parts and the (genuine, new) prices of the alternators had me gasping a bit! There's one or two part numbers that go into 4 figures.  😲

LLLParts

 

 

11 minutes ago, Breezy_Pete said:

Agree with the above. I just looked up the relevant ETKA page via LLL parts and the (genuine, new) prices of the alternators had me gasping a bit! There's one or two part numbers that go into 4 figures.  😲

LLLParts

I did the same for my own car, made me gulp!

the genuine prices look very pricey. And not sure why some alternative with same output but different manufacturer are like £400 more than the other one.

 

Even on autodoc the hellas are about £450....

 

But I did find opie oils listing this hella at £240, seems very reasonable.

 

https://www.opieoils.co.uk/p-217059-hella-alternator-14v-140a-8el-015-630-041.aspx

 

HX - valeo equiv.

 

 

 

Even armed with my VIN decoded, I still get 5x listed alternators.  So the only real way to be sure is to take it out, or get a good look at the parts number on the Alt, if they haven't been destroyed by weather.

 

Apart from using a multimeter, what have you done for diagnostic?

Did you check Earth strap etc?

Wiring checked?

 

Odds are you will need a new battery also now to add insult to injury, deep discharge will have made battery struggle to hold future charges (if it takes one at all)

There's a pretty good field for compatible engine codes in the listings though.  The bosch v valeo will just be alternate OEMs. So either will work.  OP: Armed with your engine code it should narrow the OPs options .  You could use an inspection mirror on the back side of the alternator to try to get a photo of the original sticker.  Unless there are heated seats or some other high current option, it will likely be the std 140A PR-8GU units. once youve got the oem code then there will be a proliferation of aftermarkets that will work.... Like for my car, Lucas LRA03658, cross references HX (along with others).