Battery

Micky 32 said:

Thought i’d update this thread. Nearly 3 years later. I’m still on the original battery lol. Coming up on 6 years 160,000 miles. It’s done approx 45,000 starts (according to vcds) . It’s one tough AGM battery hanging in there.

---

Click to expand...

I had the original (factory installed) Varta AGM in my B7 Passat replaced two years ago. At that time it had been working flawlessly for 8 years and some 110.000 miles but I felt I was driving on borrowed time ever since the 5-year mark (due to past experience with traditional flooded batteries). Also, I had had a few hesitant starts on cold mornings, and some "friendly persuasion" from the dealer, so I decided not to risk it.

Long story short:
- hesitant starts were caused by 1 dead and 1 dying glow plug, not the battery,
- 1 year after the new battery had been installed I removed the battery cover only to discover an EFB battery not an AGM (I had ordered and payed for an AGM, with a service bill to prove it).

Needless to say, I haven't seen that dealer ever since.

Quintus Rotam said:

I had the original (factory installed) Varta AGM in my B7 Passat replaced two years ago. At that time it had been working flawlessly for 8 years and some 110.000 miles but I felt I was driving on borrowed time ever since the 5-year mark (due to past experience with traditional flooded batteries). Also, I had had a few hesitant starts on cold mornings, and some "friendly persuasion" from the dealer, so I decided not to risk it.

Long story short:
- hesitant starts were caused by 1 dead and 1 dying glow plug, not the battery,
- 1 year after the new battery had been installed I removed the battery cover only to discover an EFB battery not an AGM (I had ordered and payed for an AGM, with a service bill to prove it).

Needless to say, I haven't seen that dealer ever since.

Click to expand...

My battery is a strange one. It seems to have good and bad days. Sometimes it sounds full of life but the odd crank might sound low. From 3 years it definitely showed some signs of wear hence my original post but hasn’t deteriorated much since i first posted. Cranking would sound a little low sometimes. When temperatures were low you might get an error or two flash up on the dash ( brake error etc) . My ac conductance tester over the last 2/3 years tells me to replace the battery (sometimes)

The other day i was in very heavy traffic. The stop start system activated numerous times and the battery never faltered. Also if the fans are running when you turn off the car during a regen they could run nearly 10 mins full on but the battery will never flatten. I suspect the battery has lots of capacity but it’s resistance maybe a little high for some reason. My experience with dying batteries is that if you left your radio or parking lights on for about 15 mins the car won’t start. Mine isn’t doing that.

Speaking of dealers, a friend got his battery replaced in his B7 and they put a normal flooded battery in!

Micky 32 said:

Speaking of dealers, a friend got his battery replaced in his B7 and they put a normal flooded battery in!

Click to expand...

If it's a B7 A4/S4/RS4 then that's OK as they don't have start/stop - I ran them for 13 years with 'normal' batteries.

PetrolDave said:

If it's a B7 A4/S4/RS4 then that's OK as they don't have start/stop - I ran them for 13 years with 'normal' batteries.

Click to expand...

Sorry i meant to say B7 Passat with stop/start. The original was an AGM 10 years old.

I forgot to add. Last week my car was at the dealers for a week getting the flywheel and DSG clutch pack replaced. When they phoned me to say the car was ready he said to me “ oh your battery failed a test”. I’m not sure why they felt they needed to test it. It was at the airport for a week a few weeks back and started no problem. It was 0 degrees C the other night and it still started flawlessly the next morning.

Micky 32 said:

When they phoned me to say the car was ready he said to me “ oh your battery failed a test”.

Click to expand...

You need to ask them what SoC their battery tester showed.

I guess they test the battery because the car had been basically standing for a week while they repaired it.

I thought i’d update this thread coming up on 4 years. The car is still on it’s original AGM battery. It will be 7 years old next Feb. Despite showing a few weaknesses in 2020 it never deteriorated much since. I’m sure it’s no where near as good as a new battery at this stage but the car never fails to start. After 300,000 km and 60k starter counts ( according to vcds) Varta AGM batteries are one tough suckers.