Is my battery needing replaced

[Aakayamy]

Hi guys. I’ve got a Skoda Octavia 2019 mk3 1.6 tdi DSG

 

my car battery has been going down lately and I’ve checked the car this morning with a multimeter. Without car started and with car started. 
can someone tell me if I need to replace my battery and also can someone tell me which battery is best to get. Thanks

 

 

This is my current battery. 

[Phoenixboy]

That's low. prior to starting my battery was at 12.6v, tick over 15v. Although I've had my battery replaced 6 months ago now. 

[Aakayamy]

So should be over 14/15v after starting? 
would you happen to recommend which brand I should get? My current one is exide 

[indars]

With idling engine, turn on lights, heater, window heating...what are readings then? Don't know about Octy execution but some voltage regulators are clever these days. My father's '2015 Subary reacts to high energy consumption and only in this moment multimeter shows high charging voltage 13...14 volts (don't remember exact value). But it was Std battery since this car have no StartStop system. But anyway...

As for good brends (if old battery is dead indeed): Exide, Varta, Bosch, Yuasa for example. If money allows, take AGM instead of EFB. In simple/funny words, EFB is just cheap version of AGM.

Best tool for battery is not multimeter but battery load fork. Every +/- normal workshop should have it. Multimeter is more useful to find parasitic battery drain.

P.S.

My 2L diesel Octy still have original Varta AGM battery for 6.5 years and 155k km. But I cheated StartStop and it's not working no more (everybody is allowed to ruin private car as she/he likes).

[J.R.]

That is a normal reading of your vehicle has start/stop and the battery management system that charges on the over-run, I think your model year will have that but others will confirm.

 

Basically it never fully charges your battery so that it can recover the kinetic energy when braking or slowing down through the alternator.

 

Also when you took your before start reading you will have woken up all the canbus modules after opening the car door and bonnet, these draw a lot of current, enough to give a 0.5 volt drop to your meter reading.

[Warrior193]

Hello @Aakayamy are you able to get a load or condition test on your battery? 12.22 VDC reading under your assumed mustimeter test conditions is probably ok - just a little undercharged, do you do a lot of relatively short runs? Do you know if the battery is the original one fitted?

Be aware that a battery adaptation should be done if the battery is replaced. 

[J.R.]

Short runs no longer discharge the batteries of modern vehicles with a minimum of 90 ampere alternators often much much more than that, they can recharge a battery from a cold start in seconds even with the maximum electrical load being used.

 

I am sure the voltage he is seeing is correct for a vehicle with a battery mismanagement system and allowing for the volt drop from the canbus modules woken up.

 

He has not reported any difficulty in starting, but hey, plenty of places will take his money to replace a perfectly servicable battery if it makes him happy.

[Warrior193]

1 hour ago, J.R. said:

Short runs no longer discharge the batteries of modern vehicles with a minimum of 90 ampere alternators often much much more than that, they can recharge a battery from a cold start in seconds even with the maximum electrical load being used.

 

I am sure the voltage he is seeing is correct for a vehicle with a battery mismanagement system and allowing for the volt drop from the canbus modules woken up.

 

He has not reported any difficulty in starting, but hey, plenty of places will take his money to replace a perfectly servicable battery if it makes him happy.

I'm afraid that I have to disagree with you regarding 'smart' alternators and short runs @J.R. - I do mostly short runs for my commute to work and the battery regularly displays low voltages on test before I recharge it - yes the battery is 7 years old, but it consistently tests as 'good battery' after charging - and holds charge over static periods. Alternator output tests OK. Battery SOC recovers to normal levels when I do longer runs.  

 Original alternator and battery were replaced under warranty in first year.

[Aakayamy]

I am a taxi driver so most of my runs are short but I do big runs too. I’m going to hook up vcds and check what voltage I’m getting. I will report back shortly. 

[Warrior193]

7 minutes ago, Aakayamy said:

I am a taxi driver so most of my runs are short but I do big runs too. I’m going to hook up vcds and check what voltage I’m getting. I will report back shortly. 

I believe that you will need to monitor alternator output over a reasonable period of running, under varying driving conditions. There may be an app available for this - I recall seeing a previous poster who did this. 

[TheClient]

14 minutes ago, Aakayamy said:

I am a taxi driver so most of my runs are short but I do big runs too. I’m going to hook up vcds and check what voltage I’m getting. I will report back shortly. 

Vcds will just report the same voltages as you’ve measured. 

[Aakayamy]

Oh ok. 
I will take it down to a local garage to inspect the battery and alternator on Monday and see what they say. 

I have noticed that every morning when car had been left overnight on driveway they it cranks first time. 
But if I’m parked up and car is switched off but radio running for like 5 minutes is when the car won’t crank up and I have to jumpstart it. 
I would have thought the battery would be the culprit but then again could be the alternator too. 
 

 

[Aakayamy]

UPDATE

 

my father just came back from The local garage and got the battery and alternator checked and mechanic said the alternator is very weak. Battery is perfect.  
 

[Breezy_Pete]

Doesn't sound right to me.

Probably a mechanic unfamiliar with the variable output voltages of the alternator on these cars.

 

[J.R.]

10 hours ago, Warrior193 said:

I'm afraid that I have to disagree with you regarding 'smart' alternators and short runs @J.R. - I do mostly short runs for my commute to work and the battery regularly displays low voltages on test before I recharge it

 

But do you have a battery mismanagement system? 2015 I believe is the change point, thankfully I dont have one, if yours is then it will promptly discharge it again to 80% SOC so you can save the planet!

 

I understand where you are coming from, I would not be happy with a partially discharged battery and would disconnect the shunt resistor rather than keep charging the battery.

[Aakayamy]

My car is a 2019 Octavia 

[Warrior193]

6 minutes ago, J.R. said:

 

But do you have a battery mismanagement system? 2015 I believe is the change point, thankfully I dont have one, if yours is then it will promptly discharge it again to 80% SOC so you can save the planet!

 

I understand where you are coming from, I would not be happy with a partially discharged battery and would disconnect the shunt resistor rather than keep charging the battery.

My Octavia is MY16, yes, it has battery management and regenerative charging. I don't believe that it actually 'promptly discharges' the battery once it has been fully charged - I accept that the management system will hold off charging until there is reserve capacity for regenerative charging - in the interim, the battery has been cycled to full capacity, which is better for extending battery life.

This approach seems to work - I always use stop/start unless stop is estimated less than 5-10 seconds, generally run only short commute trips and Moll EFB battery is 7 years old. 

[J.R.]

No it does not have the means to promptly discharge the battery, it allows the vehicles systems to do that, I was over-egging it somewhat!

 

I can see and agree with your logic regarding extending the battery life, my choice would be to hobble the battery mismanagement system but I'm a Luddite.

 

I am assuming that your voltage measurements are taken with the battery disconnected and you are not being misled by the considerable volt drop from the woken up controllers.

 

I am having to do similar charging with my new to me electro-hydraulic tipping trailer, I can hear when it needs charging but the measured voltage looks reasonable, there really is a big difference for a few tenths of a volt and it doesn't help that the nominal voltage of 12v indicates a pretty much flat battery.

[Warrior193]

7 hours ago, J.R. said:

No it does not have the means to promptly discharge the battery, it allows the vehicles systems to do that, I was over-egging it somewhat!

 

I can see and agree with your logic regarding extending the battery life, my choice would be to hobble the battery mismanagement system but I'm a Luddite.

 

I am assuming that your voltage measurements are taken with the battery disconnected and you are not being misled by the considerable volt drop from the woken up controllers.

 

I am having to do similar charging with my new to me electro-hydraulic tipping trailer, I can hear when it needs charging but the measured voltage looks reasonable, there really is a big difference for a few tenths of a volt and it doesn't help that the nominal voltage of 12v indicates a pretty much flat battery.

I normally wait until ancillary circuits go back to sleep - although I have worked out a reasonable correlation between the two states over a series of tests. A little like understanding the difference in expected level when dipping oil hot or cold.

[Aakayamy]

This is my current battery state on vcds

kind of feel battery doesn’t look good. I’m certain the alternator is good so not sure why the local garage feels it’s needing replaced. I’ve ordered a varta e39 agm battery for £148 so will replace this tomorrow and check what voltage I’m getting. I will also program it with vcds.

[Warrior193]

@Aakayamy don't forget to get the battery adaptation done (change from EFB to AGM) you possibly will be changing other parameters too. Have you actually checked the maximum output of the alternator? 

[Aakayamy]

49 minutes ago, Warrior193 said:

@Aakayamy don't forget to get the battery adaptation done (change from EFB to AGM) you possibly will be changing other parameters too. Have you actually checked the maximum output of the alternator? 

How do I check that? 

If my car is left overnight and start first thing in the morning it starts fine and throughout the day too. It's only when I leave the radio on with engine off for 5/10 minutes I then have problems starting the car and have to jumpstart it. If my alternator was fault I would have had issues starting at all times no?

[Warrior193]

Load the battery up with headlights, screen heater etc. on - then test the battery voltage with the engine running. Most battery condition testers have an alternator and starter crank test function.

[Aakayamy]

Will get that checked thanks 

[Aakayamy]

Mechanic checked the alternator and said it was perfect. Not sure why the other place my dad went to said it was needing replaced. 
got the varta A7 (e39) agm battery today and installed it myself and did adaption with vcds. 
 

This is the voltage now I’m getting with and without started.