[bigevent]

Hi all,

I am trying to buy a battery for my 2003 Passat wagon V6. I am wondering if anyone recommend any battery brand/type. The autozone says the group size is 98R/H6 and the CCA is 540 for my car. I am thinking about getting one of these below. Do you have any recommendation? the bottom one is a little cheaper.

Thank you for checking.

bigevent

 

[VAGguy]

Either one is fine. They sized the battery depending on trim level and accessories it was built with, along with the alternator amperage. I believe i have a 730CCA in my 1.8T GLS, but only because I wanted it. I have stereo equipment and added things like power seats. Can't hurt anything more than your wallet. I also swapped in a 120a alternator.

 

[ylwagon]

For reference, Wal-Mart has an AGM battery for your car @ $170.

 

[VAGguy]

After reading about AGMs lately, I would be more inclined to get a regular old lead plate battery for our low tech charging system, instead.

 

[AndreasPassat]

Huh? What have you read?

 

[ylwagon]

I have only limited knowledge about the AGM (Absorbent Glass Mat) battery characteristics, but VAGguy might not be incorrect. Regulating the charge current, rather than charge Voltage, seems to be the thing.

 

[AndreasPassat]

Admittingly the AGM's are more suited to the later model vehicles due to their insane amount of electrical gadgets and countless current loads when the vehicle is not running.
The AGM's are constructed in a way that can handle harsh abuse. The lead plates are basically sandwiched in a pillow of glass fibers and that protects the plates from touching each other.
Basically keeps all the plates separated and prevents buckling from harsh vibrations and high charging rates.

 

[bigevent]

Either one is fine. They sized the battery depending on trim level and accessories it was built with, along with the alternator amperage. I believe i have a 730CCA in my 1.8T GLS, but only because I wanted it. I have stereo equipment and added things like power seats. Can't hurt anything more than your wallet. I also swapped in a 120a alternator.

Thank you VAGguy and all, I will consider getting the Duralast Gold with the 730 CCA since I use the heated seat. Today it took me for a while to start the engine in the morning. I had to step on the accelerator a lot to make it work. It did not even make a vroom sound when it finally started so I was not sure if the engine is running or not. I hope I did not break anything while trying to start the engine. I hope I can start the engine tomorrow morning to get the Duralast Gold Battery from Autozone. I like that they install without extra charge when I purchase from them.

Thank you for all your comments and advice.

bigevent

 

[Tomvw]

After reading about AGMs lately, I would be more inclined to get a regular old lead plate battery for our low tech charging system, instead.

I agree with VAGguy.

AGM batteries require 2 stage charging, a standard old alternator such as on the B5/5.5 Passat cannot properly charge an AGM battery.
Here is a link with a lot of good info.

https://workshoppist.com/car-alternator-charge-agm-battery/

 

[VAGguy]

I agree with VAGguy.

AGM batteries require 2 stage charging, a standard old alternator such as on the B5/5.5 Passat cannot properly charge an AGM battery.
Here is a link with a lot of good info.

https://workshoppist.com/car-alternator-charge-agm-battery/

Agreed.

In my Audis, you have to code the battery to the car, I believe for this purpose. It is like hitting the reset button on the charging system to recognize it's a new battery which takes a slightly different charging profile. The car will adjust as the battery ages to ensure optimal charging.

 

[DeliveryValve]

I too is skeptical of the AGM in our Passats. But alas I just installed one from Costco as they only offered the H7 size in an AGM. I originally wanted to get an OE VW battery as my old one lasted 4 1/2 years. But my dealership doesn't stock the 80 ah (H7) battery my car needs. I have PTSD from leaking batteries on my other vehicles, and causing corrosion and rust through. Another reason I consider using an AGM. I've purchased several Duralast, Walmart and other flooded lead batteries in the past in my other vehicles, but they all leaked fumes and caused corrosion. I don't know how today's Duralast are built, but I would check your dealership for an OE battery.

And for my car, we'll see how this AGM holds up in my car.

 

[PZ]

The Passat can charge the AGM battery. Not sure if it's optimal charging, but I ran one for 4yrs and 4 months. The other 3 batteries I ran in the car died right at 4 yrs, same as my other cars.
The only reason I bought the AGM was that I wanted to move the battery to the hatch of the wagon for better balance.

 

[Tomvw]

In a B5/5.5 Passat, an AGM battery will never be fully charged in typical use, and in most cases it will be over-charged on long drives.

"Some claim that AGM batteries actually are a drop-in replacement for flooded lead-acid units in car applications, because the optimal charging voltages for the two battery types are not all that different.

There is some truth to this claim: the optimal absorption and float voltages of flooded lead-acid and AGM batteries are indeed within 0.2V or so: typical values are 14.7V/13.6V for AGM and 14.5V/13.4V for flooded.

However, this claim misses an important point: an AGM battery is much more prone to both under- and overcharging than a regular flooded lead-acid battery. Specifically:

AGMs suffer much more from insufficient absorption charge
AGMs are more sensitive to overcharging
So while the crude charging profile of a car alternator & regulator combination is not really optimal for either battery type, AGMs suffer much more from the deficiencies."

 

[passat03wagon]

I have an AGM since 2013 in my 1.8T Passat. I hooked a multimeter to it just now and it shows 12.2v with the power off, 14.5v with the engine running.

 

[Tomvw]

I have an AGM since 2013 in my 1.8T Passat. I hooked a multimeter to it just now and it shows 12.2v with the power off, 14.5v with the engine running.

That battery is only about half charged.