New Battery for 2001 S4

[Wheel366]

My 2001 S4 has been just sitting since Covid. I would take it out or start it once in a while but there was a time where it sat for 6 months. So, obviously the battery died. It is an Interstate H6 with a date sticker from 2015. Got a Schumacher battery maintainer and it worked for a time. Recently, the Schumacher would show a bad battery. Not really sure if it was the device or battery, I got a CTEK MXS 5.0. This one didn't show any error but after about 2 weeks I went to start the battery and the car wouldn't start. This led me to needing a new battery.

I have been going back and forth about what to get since I'm not driving the car. I settled on a Walmart EverStart Platinum AGM, Group Size H7 / LN4 / 94R. The S4s had a battery size change for the 2001.5 and 2002 model years. I decided to get the larger battery since both were the same price. My options were limited as to where to get it. The closest Walmarts were out of stock. There are others but further away. I ended up going to one about 12 miles away. Most stores that were further only showed 1 in stock as did this store. So, I ordered online and picked up. The battery they brought out had a date sticker of 11/23. Knowing it was the only battery in the store and not wanting to drive to other stores I took it. Brought it home hooked up to the CTEK and charged it. Not sure how long it took but Stage 3 took ~4-5 hours. Looking at the terminals, they didn't look perfect. Had some scratch marks on them. I installed the battery this morning and it started fine. At this point it has a 4 year warranty so if I have any issues, I'll just warranty and get a new one and if I can't get that size, I'll get the smaller H6 which always worked fine in the past. The serial # starts with an EP though the documentation on the website points to Clarios. I don't real care at this point if it works and lasts. It was the same price as a Costco Interstate with a better warranty, so I can't complain. If I were driving it more, I would think about an Odyssey.

 

[Wheel366]

So, now I have a question. After installing the battery yesterday, I waited until today to hook the CTEK back up to go through the full 8 stages. After hooking up, it took ~10 minutes for stage 3 and then a few hours ~3-4 for stage 4 which is what is supposed to take the battery from 80% to 100%, which I already had done the day before. I then changed the setting on the CTEK to do a recon and it quickly went through stage 3 again and took a little while to go through stage 4; not exactly sure how long. After it got to stage 7, I changed the CTEK again to remove the recon setting going through stages 1-3 quickly. It is back to stage 4 and it has been about an hour.

Is this normal? My guess is probably not. This is the first new battery in my Audi since 2015 and I never used a maintainer until after covid. I'm thinking I will let all stages complete, disconnect and wait a few weeks before trying to start the car. I do have a tester on the way.

Also, is it normal for an electronic buzzing sound to come from the CTEK?

 

[JHZR2]

First, reconditioning to equalize the cells takes the voltage up to 16 or higher. You shouldn’t do this connected to the vehicle, IMO. You also shouldn’t do it on an AGM necessarily.

What’s done is done.

If stage 4 is the constant voltage stage, the drop in accepting current is logarithmic. So it takes a long time to hit some preconceived amount. If the battery was older and say, it could have had some sulfation and capacity loss. The chargers also tend to be very careful with their stages, so that can take time too.

Buzzing doesn’t sound good, but it may make noise due to switching and fans in some units.

Not sure of your logic in waiting a few weeks.

If you want to observe the battery, charge it to full, remove the charger. Take a voltage reading 15 mins later. Then a day later, then a week. You want to see how fast it self discharges.

After that just put it into use, and keep a small maintenance charger on it when it’s sitting.

 

[Wheel366]

First, reconditioning to equalize the cells takes the voltage up to 16 or higher. You shouldn’t do this connected to the vehicle, IMO. You also shouldn’t do it on an AGM necessarily.

What’s done is done.

If stage 4 is the constant voltage stage, the drop in accepting current is logarithmic. So it takes a long time to hit some preconceived amount. If the battery was older and say, it could have had some sulfation and capacity loss. The chargers also tend to be very careful with their stages, so that can take time too.

Buzzing doesn’t sound good, but it may make noise due to switching and fans in some units.

Not sure of your logic in waiting a few weeks.

If you want to observe the battery, charge it to full, remove the charger. Take a voltage reading 15 mins later. Then a day later, then a week. You want to see how fast it self discharges.

After that just put it into use, and keep a small maintenance charger on it when it’s sitting.

Appreciate the response. Even though I have changed batteries in the past, a lot of this is new to me and I am NOT an electronics genius. I'm hoping sometime this year to re-register the car and try to get historic plates so I don't have to do emissions testing anymore and then go from there and start fixing it up slowly. The car needs a lot of work but if I drop the coin needed to fix everything at once, my wife will divorce me! So, little bits at a time.