A8 Parts Forum - Brake light warning came on after brief spirited driving

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- - Brake light warning came on after brief spirited driving (https://forum.a8parts.co.uk/showthread.php?t=10919)

Quote:

Originally Posted by Johnmed (Post 103657)

The same error code for the battery regulation module was there before I bought the car mate. So I'm guessing it's not because I tried to jump start two cars.

Fair enough, was just a thought +++

Quote:

Originally Posted by Mechcanico Lee (Post 103658)

Yes good point Paul with regards to Johnmeds car , with mine (your old un ) battery was brand new and was only getting the 60% SOC .

There was nothing wrong with orginal battery by the way........ just upgraded for the aux heater job .

Power upgraded and dpfs gutted now on the old girl ........ goes like the frekkin wind 42 mpg steady 70 mph ish now

Glad all is well mate, bet the Aux Heater comes in handy on the cold mornings! +++

Did another scan of the battery regulation module today, not having used the car since Friday. The battery voltage being so low suggests I should replace it, right?

Monday,14,December,2015,10:51:19:32264
VCDS Version: Release 11.11.3
Data version: 20120401

--------------------------------------------------------------------------------
--------------------------------------------------------------------------------

10:50:43
11.85 V Battery Voltage (actual)
StatCurStg 0 Static-Current Shut-Off Stage
-19.6 A Current Value from Battery
0.00 Static-Current Mean Value
10006 Ah Total Energy Balance
10000 Ah Total Energy Throuput
56.0 Duration last Standing Time
0.00 Duration last Driving Cycle
70.0 % Battery State of Charge (SOC)

Little update, I replaced the battery with a Bosch S5 110Ah and 5 year guarantee for peace of mind. All coded in. Easiest job I've done on the D3 yet.

Let it stand for a couple of days then scan battery regulation again and see what SOC is and battery voltage is .

I assume when you scanned ignition was on and maybe other consumers as you can see the -19 .6 amp draw from the battery so batt volts will drop somewhat .

If you wanted to check true batt volts , latch boot lock over ,stick volt meter on batt and lock car and let it go to sleep ..... 10 mins or so let's say , then see what volts are , you could do same test after a day or so and see if battery is staying good

Will do another scan after a few long drives.

Thanks again Lee.

Some comments about D3s and the Battery stuff ...

Quote:

Originally Posted by Mechcanico Lee (Post 103646)

See on the coding at the end the 105A im assuming that means 105 amp hour because thats what was on the orginal battery

1. Easy to see why you thought this Lee but actually the 105 A is the last two parts of the part number. The original Audi battery just happened to have a part code that matched its 'Amp Hour' value. :)

VAG parts are xxx yyy zzz nn = vehicle subsystem part version

2. The Battery Meter % and its associated SOC values in the ECU that you read out with VCDS is one of the mysteries of life. The ECU calculates it and its value is shown in the MMI display but no-one knows what formula is used to determine it. I think Audi gave up on it, which is why it was removed at one of the MMI updates. After problems, I've seen the number 'stuck' at 10% on my car for three days before it magically returns to 100%, so don't trust it. :(

3. Best bet for working out the battery SOC is to use a volt meter across the battery. :) - 100% is 12.6V, 75& is 12.4V, 50% is 12.1V, 25% is 11.9V - all approximate values for 'normal' temperatures - Spring in the UK!

Quote:

Originally Posted by JulianHicks (Post 105996)

1. Easy to see why you thought this Lee but actually the 150 A is the last two parts of the part number. The original Audi battery just happened to have a part code that matched its 'Amp Hour' value. :)

VAG parts are xxx yyy zzz nn = vehicle subsystem part version

2. The Battery Meter % and its associated SOC values in the ECU that you read out with VCDS is one of the mysteries of life. The ECU calculates it and its value is shown in the MMI display but no-one knows what formula is used to determine it. I think Audi gave up on it, which is why it was removed at one of the MMI updates. After problems, I've seen the number 'stuck' at 10% on my car for three days before it magically returns to 100%, so don't trust it. :(

3. Best bet for working out the battery SOC is to use a volt meter across the battery. :) - 100% is 12.6V, 75& is 12.4V, 50% is 12.1V, 25% is 11.9V - all approximate values for 'normal' temperatures - Spring in the UK!

Thanks for the clarification Julian.

Right you are ....so just coincidence then the end part number being the same .

Regards to the state of charge ,you would have to test it with no load at all I assume because if there was some load on it the state of charge could be 100% but a slight load would pull the volts down somewhat