salimshah

Gents, lets give this issue some rest time.

We are all entitled to have our opinion and let others form their own. Share your opinions freely, but please do not belittle each other.

Salim

iolmaster

iTrader: (1)

Not belittling. My dad has a masters from Pitt in EE and worked for GE for 40 years. His specialty was, guess what, motors. He designed transport systems for steel mills. Mostly in Japan. He has confirmed that it would not be a good idea to run a motor in a car at a higher RPM than is designed. Likely would cause premature failure. He can't imagine how one 12 volt battery could run a motor faster than another 12 volt battery. Especially with a voltage regulator built into the system. Just sayin!

ColAngus

LoL! There is no engineering-level explanation required, here. What a silly thing to argue about. You don't think he can actually notice the windows winding up faster??!

RX in NC

And to make the argument even more interesting, replacing the standard wet-cell battery in my wife's XK8 with an AGM battery in July 2018 did NOT cause any noticeable difference in window operation speed, HVAC blower operation speed, or any other onboard system in that vehicle. What it DID do was to stop the random spurious OBDII codes and dashboard warning lights from occasionally being triggered, so it was certainly worth the effort.

Why the AGM battery in my 3.6R caused these peculiar changes in that vehicle remains a mystery. But the fact of the matter remains that it indeed did.

iolmaster

iTrader: (1)

You are missing the point. It is not that I do not accept the observation. I do not accept the conclusion that the AGM battery chemistry is the reason for the change. Apparently this was a replacement in a Subaru. Could it be that the original battery in the Subaru was getting weak and needed to be replaced? That would account for the change in speed of the window. Putting any new battery in would bring the voltage up to the design spec. There are a number of reasons that could have this effect with an older battery. My position is, if you take two new batteries one AGM the other wet cell and have them both checked t make sure they are functioning properly, fully charge them. You will not see a difference in the speed of any of the motors in the car. I am not saying there are not benefits to the AGM. I bought one. They may be able to run accessories longer than a standard wet cell. But it certainly is not to be able to run any motor in the car faster. In fact, that would not be good for the motor. If someone has an explanation as to why an AGM battery would run a motor at a higher RPM compared to an exact speced wet cell. I would love to be able to say I learned something today.

RX in NC

The problem with your theory regarding my factory 3.6R battery getting too weak to properly power the windows is simply that the window speed operation from the factory battery never slowed down from the time I purchased the vehicle (November 2015) until the day the factory battery was replaced with the AGM battery (August 2019). That is why I was so startled when I had to reset the automatic window operation procedure after I installed the AGM battery and experienced for the first time just how fast the windows were now moving. Having installed an AGM battery in the XK8 in July 2018 with no noticeable routine systems operational changes, the 3.6R's new behavior was completely unexpected.

Would a new wet-cell battery have created this same new behavior? That is certainly possible but we will never know for sure.

Buzzer777

This entire thing made me feel sorry that I posted my battery replacement experience and final choice.