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'Well partly I agree. However If the Car control unit believes ... will only charge up to X. So it is a good idea to inform the control "
Exactly. IF the BMS really is following the coulomb counter, it will cut back before the battery is fully charged. Unless it is smart enough to continue charging until the current acceptance rate falls, which tells it to change from bulk to absorption mode. And we just don't know.
This evening I threw a voltmeter on the car after a short run and a good reason to expect it is fully charged. Battery came down quickly to 12.7 as the float charge went off, and then with the car shut down it stayed steady at 12.70. So whatever the car is up to, it appears to have fully charged the battery, which is at 12.70 when full now.
[Much later]
BTW, I've had an inquiry into AoA for a while now. It took them over a week to say "We've been terribly busy, sorry about that, but we have resources..." and I'm patiently waiting to see what or if they can actually tell me about the inner workings of the charge system.
Research information and Solution:
Here are the battery codes if you want to test a bigger capacity battery or correct your existing one (as I just did). Now it is 11 PN code not 10. My Spec PR code is J0R which means 80AH/380A (and battery PN 000915105DH). I should try the following: 000915105DK instead because I have a bigger capacity 100Ah battery. Hope this helps. 4F0 and 8k0 were superseded. I recommend that you try to use the following latest battery Part number information relevant to your battery capacity(prefacelift and facelift are the same). These codes are relevant to Q5 only (I did not check if other B8 have the same PN).
It works . I first changed to 000915105CE and then to 000915105DK (because DK was not accepted at the beginning).
Here is my revised battery information:
For 92Amps battery code: 000915105CE (replaced part number 4F0915105E)
Battery mystery hopefully solved. 2 alternator types exist 140A and 150A so hopefully battery can now fully charge even with the 140A one (not sure which I have).
Thanks for questioning this, otherwise I would never find out my battery coding mistake (of the previous owner).
Now it shows that I have a 100Ah battery (not sure if that figure will change in a few days). Hope my increased capacity will now be fully utilized. Let me know your opinion on this. Try the new PN code (for 92Ah 000915105CE) depending on your battery capacity and type.
Note info from internet:
On sealed batteries which do not have a built-in charge indicator, the status of charge can be determined by checking the battery's open circuit voltage with a voltmeter. A reading of 12.70 volts indicates a fully charged battery; 12.40 volts is 75% charged, 12.20 volts is 50% charged, and 12.00 volts is 25% charged.
My battery tester has lights on alternator and battery condition (alternator charge 15.5V overload 14.5V charge at max 13.2V charge ok, battery state: 12.6 fully, 12V half, 11,5 low).
Charge indicator in order to choose your battery PN correctly:
Some information corrected in the 2 last posts.
8K0915105D became 000915105DH
8K0915105H became 000915105DE
4F0915105E became 000915105CE
000915105AH became 000915105DK
000915105AK became 000915105DL
In case the proper PN fails (11 digit code) try a different one (see revised PN above) as intermediate until accepted and then try the proper one. Note battery specs have to match PN (or choose the one below the battery specs if similar)
Thanks... i had to use the " OLD " coding. I suppose if your vehicle comes with the old coding,, you have to use the old codes.
I replaced the battery in a 2014 Q5 2.0 TFSI flex with a generic energizer 80 amp hour battery from Costco.
On battery voltage as a measure of capacity:
A rough guide is that a fully charged and rested battery will be 12.6-12.8 volts, depending on the specific battery chemistry, which varies with location, brand, and type. When a battery is being charged by an alternator, typically it is charged to 13.8 volts and that extra volt is called a "surface charge". If the battery is measure immediately at shut down, it may read that high.
In order to burn off the surface charge, you can put on the headlights or another high load for 2-5 minutes, then shut them and see what the battery covers to. Or, get a more correct figure by simply walking away for 8 hours or overnight and measuring the real charge after that. (Yes, the Audi will be sucking some power during that time, but there's no quick easy way to do this without expensive test equipment and/or experience.)
The rule of thumb is that each tenth of a volt reflects 10% of the charge capacity, so if the battery spec was 12.6 volts when new, it would be 50% used up at 12.1 volts, etc. Audi seems to think the car will go berserk at 12.2 volts, as best I can tell that just FUD, it should crank over just fine even at 12.0 and continue to run.
There's one other BIG thing to consider if you are doing it yourself. That's the calibration and accuracy of your voltmeter. Remember, 1/10 of a volt is 10% of your battery. Well, I took a cheap Horror Fright meter and it was 4/10ths of a volt OFF, fresh out of the box. My better older better was still 0.2v off, so I broke down and got a calibrator for the meters. I now know to the hundredth of a volt that my meters are on spec, and of they say the battery is 12.4 volts, that's what it really is. If you're not into soldering, you cvan buy a calibrated meter from Fluke and a few other name brands. Expensive, yes, but most top-tier lifetime quality tools are.
04-18-2018, 04:18 PM
. I first changed to 000915105CE and then to 000915105DK (because DK was not accepted at the beginning).
