Low battery voltage

[MariusLM]

Hello all,

 

I have a strange situation with my Skoda 2017 2.0 DSG combi. I bought my car at 104.000 Km, 8 month ago.

 

This situation begun when after a 90 Km travel somewhere at country the car starts very hard. I put a voltmeter and I saw I have a low voltage. I charged my battery with a charger and next week at the next travel the situation reapear. Than I have replaced my car's battery because I tought was broken. With the new battery the situation is the same.

 

I was to the local Skoda in town, and after test the car said all are working fine.

 

I have bought a Cigarette Lighter Socket Voltmeter and I saw that the voltage when the car is running is low (12.1 -12.3 V). I think this is the reason the car battery is always low after I travel with the car. When the throttle pedal is not pressed the voltage is good (about 14.8V), but when I press the throttle pedal the voltaje is 12.1V. I have also saw that when the seat heating is enabled there is always a charging voltage (14.6 - 4.8 V). Below are two video whith this behavior:

 

- with the seat heating enabled: 

https://youtu.be/stcIQYdV_F0

 

- in driving mode and when I relesed the throttle pedal:

 

https://youtu.be/HmJ3hlHQXDg

 

 

Can anyoane help me to figure out why this is happening and how can I fix this? I always drive with the battery as low voltage and I am expecting the battery wil crash.

 

Thank you!

[Q102]

They battery or alternator voltage will be higher with more load on the engine ie heated seats/ lights on etc. The maximum it should go to is about 14.8V. In normal driving, with a fully charged battery, the output will be about 12-13V

A good garage should be able to check the alternator output. One thing to mention is that these cars will disable the charging during driving with a good battery voltage to save a bit of fuel, it can be alarming to watch the voltage drop!

If the battery reads about 12V when engine not running, I'd say that's about right.

 

 

[MariusLM]

Thank you Q102 for your message! When I start the travel the battery show 12V. So it is uncharged. The car start with a battery with a low voltage. And I go 90 Km and the volmeter show 12.1-12.3 V all this time. How will be the battery charged when the alternator will charge with 12.1V all that 90Km?

[J.R.]

The OP has the later charging system that ony charges the battery to something like 60% but will use the full alternator output when braking or coasting, the behaviour that he has described is completely normal. Well what someone unfortunate to be saddled with one of the later technological disasters will have no choice but to accept as normal in any case.

[patrolman]

Did you tell the battery system you fitted a new battery ?

[MariusLM]

14 minutes ago, patrolman said:

Did you tell the battery system you fitted a new battery ?

yes. with VCDS

[Breezy_Pete]

An Australian Briskoda member made some logs of charging voltage and current, which may be of interest. The only such work I've come across.  These were done on a car with start/stop switched off.

https://www.briskoda.net/forums/topic/488268-brake-energy-recovery-how-does-it-work/?do=findComment&comment=5483973

 

[Johngerard]

1 hour ago, MariusLM said:

yes. with VCDS

 

If you sill have access to VCDS, go to advanced values (can't think of proper name) and get the following data, below. The usable battery charge, IDE01842 , and the battery voltage at rest, IDE01843, will tell a lot, take these values with engine OFF. You can do it with engine running afterwards for more info.

 

You can also add Alternator output or generator output from the menu which you can monitor at the same time.

 

 IDE01834   Battery voltage 12.166 V

  IDE01836   Battery current -4.386 A

  IDE01837   Temperature of battery sensor 12 °C

  IDE01839   Battery charge level 79 %

  IDE01841   Battery internal resistance 7.8 mOhm

  IDE01842   Usable battery charge 28 Ah

  IDE01843   Battery voltage at rest 12.5 V

  IDE07681-MAS06086   Battery total charging throughput-Total re-charge 1354.8 Ah

  IDE07681-MAS06087   Battery total charging throughput-Entire energy throughput 1478.3 Ah

Edited 6 April, 2022 by Johngerard