Dreaded battery drain issue 2011 V70 D3

[cheshired5]

Originally Posted by nelpiece

The latest reading from the Car Scanner app is Quiescent current average of -32mA. The days since the last reset are around 3589 (the car is 10 years old so this means it's never been reset)

The average taken over 10 years will be burying your recent problem so reset the count cycle if you can to begin with.
Regardless, you will need a multimeter as the drain showed by the BMS is a system total and not specific enough for accurate troubleshooting.

Ignore suggestions to pull fuses.
As the video shows, active fuses/circuits can be measured with a multimeter with the fuse in place.

Don't discount a failure in the rectifier/diode pack on the alternator which can cause a parasitic drain not discovered by monitoring fuses.
The alternator DC output measured directly from the alternator and a diode test on the alternator will confirm or eliminate that.
There's a strong argument to eliminate the alternator first as it's faster and often less fiddly.

Whilst you may see a parasitic drain with diagnostics, you will not accurately diagnose the cause or fix so at some point, you have to put down the gadgets and do some old school testing.

It's like how tyre pressure monitors will show you have an air loss but at some point, you need a physical person with physical tools to diagnose and correct the root cause.

If you don't have a multimeter, buy one, buy two, in fact you could buy 10 perfectly decent ones for the cost of replacing the car battery.

[nelpiece]

Hi cheshired5,

Thanks for your input. I have bought a multimeter and used it to measure the battery voltage this week.

We've just taken the car on an hour's round trip and I've measured the battery voltage with the multimeter and it's 12.6v. However, the Low Battery warning is still showing on the dash and the Car Scanner app says the battery charge level is 40% which doesn't seem right.

Could it be that it's just a BMS reset which is required? I have tried to do this myself using the 3 methods;

Disconnecting the BMS module for 10 seconds whilst the ignition is on, as explained here:
https://www.youtube.com/watch?app=desktop&v=uH9TmL5mHOs

I've also tried disconnecting the BMS module for 10 seconds whilst the engine is running
as explained here:
https://www.youtube.com/watch?v=ul8QOfdn_94

And I've tried doing the manual reset of BMS here: https://www.youtube.com/watch?app=desktop&v=iu9z5m78Szw

None of these have worked (Car Scanner app showing last battery reset was 3500+ days ago).

Do I need a Volvo garage to reset the BMS?

[piotrek]

24% to 40% SOC after 1 hour drive seems correct.

The BMS uses coulomb counting - not only voltage - to estimate the SOC.

[nelpiece]

So resetting the BMS wouldn’t change the SOC reading in the Car Scanner app?

[cheshired5]

Measure battery voltage with engine idling and minimal electrical load then turn on every electrical drain you can think of and measure again.
Do both above measurements with engine at 2000 rpm and report back the 4 readings.

[nelpiece]

Originally Posted by cheshired5

Measure battery voltage with engine idling and minimal electrical load then turn on every electrical drain you can think of and measure again.
Do both above measurements with engine at 2000 rpm and report back the 4 readings.

Hi cheshired5,

Here are the readings from the 4 tests:

Engine idling, minimal electrical load: 14.77v
Engine idling, all electrical systems running: 14.75v
2000 rpm, minimal electrical load: 14.75v
2000 rpm, all electrical systems running: 14.77v

Thanks for your help with this.

[cheshired5]

Thanks for the extra information.
The alternator is fine so you now need to connect the multimeter in series between the battery negative lead and negative post to read the standby current drain as shown in the previously mentioned video.

This will confirm the maximum drain when the car is shutdown then do the voltage drop test shown across every available fuse to find the active circuits.

[nelpiece]

Thank you, I will try and give that a go.

Interestingly, the latest Quiescent Current Average on the Car Scanner app is -12mA with a battery charge level of 53%. The reading of -32mA on Friday morning was after I’d left the OBD module plugged in overnight.

I will connect the multimeter in series and measure the drain. Hoping the parasitic drain has been resolved after all.

[cheshired5]

If I've understood correctly, the drain which saw off two batteries happened before the OBD scanner was bought.
If so, whatever that drain was has never been identified.

If the drain is now within spec and stays that way then sure, there's nothing more that can be done.

[nelpiece]

Hi everyone,

I just wanted to come back to this thread and let you know that the parasitic drain issue appears to have been resolved. I took the car on a trip to Cornwall and did 1200 miles in a week. The Start/Stop came back and when I plugged the module in it read a battery charge of 78% and a Quiescent Current Average on the Car Scanner app of -12mA.

So changing the left hand drivers stalk did in fact fix the issue. Go figure!

Thanks to everyone for their help, in particular cheshired5 and piotrek.