Battery behavior question - 2014 A4

[AOW162435]

We purchased our A4 new in July 2013. The car now has 54,000 miles and has been been flawless as a daily driver for my wife. I do all of the maintenance and have only visited the dealership for the occasional software update, etc.

I've noticed a few electrical quirks lately and am wondering if they are a sign of a battery on its last legs. On occasion the Homelink needs a few attempts to activate the garage door opener, the TPMS is grayed out when first driving (but becomes active after some driving), and my wife has noticed issues with phone calls.

If the battery is weak, I'm fine sourcing a replacement and installing, but thought I'd run it by the group first for some feedback. I have the VAGCOM cable and can check things out this weekend if that helps pinpoint the issue.

I've installed Interstate batteries in my other cars for years. Any reason to buy a battery from the Audi dealer vs. Interstate? The correct Interstate AGM battery I found is the MT5-49 H8, 900 CCA. One step down is the MTP-95R H9, 850 CCA.




Andreas

[mecg]

Weird electrical issues, like the time not being correct when I started my car, is what told me I needed to replace my battery in my 2013 A4. Now I have a great battery tester and rely on it to keep me ahead of the curve on battery failures for all my vehicles. https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1. I also keep my battery fully charged when I don't drive it much with this: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

BTW, I replaced my battery with an OEM from the dealer. That way I could use my VAGCOM and program the new battery into the computer, correctly.

[Spawne32]

If interstate is your brand then by all means use it, although admittedly im not sure how the coding works for the batteries without the use of a VAGCOM.

[AOW162435]

I have the cable and was under the impression one could code just about any appropriate battery?




Andreas

[Novarider]

You can use any battery. I recently replaced mine. You just have to change 1 number in the serial number (any number) with VCDS. That way the car knows it has a new battery

[greasykid]

You can use any battery. I recently replaced mine. You just have to change 1 number in the serial number (any number) with VCDS. That way the car knows it has a new battery

What is VCDS? Have 2014 A4 Quattro.

[AOW162435]

What is VCDS? Have 2014 A4 Quattro.

VCDS




Andreas

[plat]

You can use any battery. I recently replaced mine. You just have to change 1 number in the serial number (any number) with VCDS. That way the car knows it has a new battery

+1. Any battery brand will do. Just make sure you match or slightly exceed the performance ratings of the original battery including its size for proper fitment.

+1. On just changing the last one or two numbers of the battery serial number coded in your car. Very easy.

[Spawne32]

my battery has been around 50% after starting my car in the morning now in the cold weather -_-

[AOW162435]

I had some time this morning to access the battery and test it. At its resting state, I read 12.47v. Once the car was started, the readings went from an initial 13.65v to 14.35v a minute or so later.

Do these numbers point to a weak battery, or one that could be failing? They don't to me.

I hooked up VCDS, did the SRI reset while I was there, and scanned for any codes (none). I also tried to work my way through all of the menus in order to find a way to make the battery life info visible from the MMI. I gave up after 15 minutes of fiddling with it. Can someone let me know how to activate this feature in the MMI?









Andreas

[Spawne32]

It depends on how long the car has been sitting, after a charge, most batteries will be around 12.6-12.8, usually you dont want to see them go below that, but you have to load test them to determine how healthy they are. That gives the rating in CCA that they are still capable of producing.

[AOW162435]

It depends on how long the car has been sitting, after a charge, most batteries will be around 12.6-12.8, usually you dont want to see them go below that, but you have to load test them to determine how healthy they are. That gives the rating in CCA that they are still capable of producing.

Thank you. My wife came home with the car last night and I took my readings this morning.




Andreas

[greasykid]

as batteries are 12 volts I would be happy with any reading 12v or more.

[Spawne32]

as batteries are 12 volts I would be happy with any reading 12v or more.

12v batteries don't actually run at 12v, thats kind of poor wording on the part of the name. They use 6x 2.2v cells inside every 12v battery which accounts for 13.2 volts when fully charged. Age and state of charge wind up giving you a wider range of voltage however but the most you should see with a fully charged and healthy battery is 13.2, not actually 12v.

[Novarider]

Needs to be tested under a load. Once you start the engine you are getting alternator voltage readings. Mine tested fine with no load (12.6v) however once I turned on the ignition (not started) it dropped to 11.4v

[ELaw]

^^ What Novarider said!

I once had a battery fail very suddenly... the car started great until one day I went to the sub shop to grab lunch and when I came out absolutely nothing happened when I tried to start the car.

I put a voltmeter on the battery and measured just over 12 volts. Then I turned the parking lights on and measured... zero! Seriously, 0.0 volts on the meter. Something had happened inside the battery such that it could produce voltage when the load was extremely low, but as soon as you tried to draw any current at all, you'd get nothing.

Or to put it more succinctly, a "normal" voltage reading under no load does NOT mean your battery is good.

[AOW162435]

Thanks for the above. I will retest once we're home next week.




Andreas

[AOW162435]

Needs to be tested under a load. Once you start the engine you are getting alternator voltage readings. Mine tested fine with no load (12.6v) however once I turned on the ignition (not started) it dropped to 11.4v

We've been out of town for Christmas, so this morning I did one more check.

In its resting state, the battery measured 12.3v. With ignition on (engine not running), the battery measured 11.7v. With the engine started, the value went to 13.4v.

The car has never labored to start, but if the 11.7v reading points to a failing battery, I'll replace it next week.




Andreas

[ELaw]

Those numbers are a little hard to interpret.

The 12.3 resting number sounds okay, probably indicates the battery is fully charged or close to it, but as discussed earlier doesn't say much about the battery's ability to hold a charge.

The 11.7-volt reading is a little hard to comment on without knowing the outside temp and what loads were energized. In cold weather with the headlights and heater fan and maybe rear defroster going it might be sensible... in warmer weather with less load I'd say it was low. Oh and I should add I'm saying "cold" and "warm" by Massachusetts standards... it was 0 degrees outside when I got up this morning!

The 13.4 volt number seems a little low to me... was that at the moment the car was started? Usually right after starting it'll be a little over 14 volts, and drop slightly over a period of a few minutes. That number also can be affected by electrical load, but a 13.4 volt reading would be concerning to me unless just about everything electrical in the car was running at the time.

[Novarider]

You can take it to advance or autozone and have them test the battery and alternator.

[AOW162435]

Those numbers are a little hard to interpret.

The 12.3 resting number sounds okay, probably indicates the battery is fully charged or close to it, but as discussed earlier doesn't say much about the battery's ability to hold a charge.

The 11.7-volt reading is a little hard to comment on without knowing the outside temp and what loads were energized. In cold weather with the headlights and heater fan and maybe rear defroster going it might be sensible... in warmer weather with less load I'd say it was low. Oh and I should add I'm saying "cold" and "warm" by Massachusetts standards... it was 0 degrees outside when I got up this morning!

The 13.4 volt number seems a little low to me... was that at the moment the car was started? Usually right after starting it'll be a little over 14 volts, and drop slightly over a period of a few minutes. That number also can be affected by electrical load, but a 13.4 volt reading would be concerning to me unless just about everything electrical in the car was running at the time.

The 11.7 value was with the Engine Start button activated - so the dash, etc. wakes up. The car is in a heated garage (~66*).

You can take it to advance or autozone and have them test the battery and alternator.

Thanks but I decided to pick up a new battery from Audi this morning (Varta). Will install this evening (including VAG-COM coding) when my wife brings the car home. The latest oddity was that the volume control was grayed out early this morning when my wife was leaving...




Andreas