Guys,

I sat in my focus (MK4 1.5, 134kw, Petrol) after a week of no use and nothing. The battery is dead. I measured around 3V. The car is ~3.5 year old. I am going to replace the battery myself. A couple of questions:

• Is there something I should know before replacing the battery? Is there any special procedure or commissioning needed? This is not an old corolla I used to have 🙂
• Shall I go for the original battery (Varta JX6T-10655-FA , D3V5A ESP, EFB 70Ah) or any quality replacement does the job?

Note: The battery may have been "weak" since the day 1. My start-stop system kicked-in only few times in last couple years. The repair shop told me that the car reports slightly lower battery voltage but they recommended not doing anything about it.

Thank you and have a great day everyone.

Warhawk

 

 

You might get away with jump starting it.  My Mk4 battery dropped to about 2V but jump started fine and charged up quickly after being run for a bit.

 

1 hour ago, TomsFocus said:

You might get away with jump starting it.  My Mk4 battery dropped to about 2V but jump started fine and charged up quickly after being run for a bit.

I've just connected it to a laboratory power supply (I am an electronics engineer) and charging it. Still, I do not want to have a car that dies after a week with no use.

Exce

3 minutes ago, unofix said:

Excellent link, thank you. I swear I googled before 🙂

 

3 hours ago, WarhawkCZ said:

I've just connected it to a laboratory power supply (I am an electronics engineer) and charging it. Still, I do not want to have a car that dies after a week with no use.

The fact that it dropped so low suggests there was likely to have been a battery drain (module not shut down properly) instead of 'normal sleep' over that week.  After mine was recharged once, it never went flat again.

On 5/30/2023 at 2:06 PM, TomsFocus said:

The fact that it dropped so low suggests there was likely to have been a battery drain (module not shut down properly) instead of 'normal sleep' over that week.  After mine was recharged once, it never went flat again.

This is a fair point. Normally, I would also get a notification to my cellphone that the vehicle entered deep sleep to avoid battery drainage. Additionally, batteries die often in winter and not in this lovely summer weather we have now in Germany. I give it some time before pulling the trigger on a new battery.

If search brings you here, here's an update.

After recharging the completely depleted battery, and resetting the BMS system, the vehicle operates normally. I did about four short drives after the "incident" and then the car unfortunately stayed in the garage for ~6days again. No signs of any problems. I could turn the engine on straight away.

@TomsFocuswas probably right. Maybe some module /electronics did not turn-off properly that caused the battery drainage. I'll keep an eye on this.

@unofixMay I ask you what kind of the software did you use for monitoring the battery? I assume you have one of these OBD to Bluetooth boxes. Am I right?

FORScan Lite Android. £7

vLinker FD dongle £29 for the android version.

Example below from my battery, which at the time was only 18 days old