It has the start/stop. It's a very large battery for a 4 cyl engine. I think you're correct and it's not AGM.
No more AGM batteries for me
- Thread starter stanlee
- Start date
Lots of short tripping or highway cruising? I just ran my son 220 miles round trip to Detroit airport. Minus the first 10 miles and idling at the drop off site, my volts stayed @ 12.8-12.9. No stop starts, thank goodness.
We live outside of a small town in southern Delaware. So no city traffic traffic with lots of stoplights. A mix of 25 MPH and 40 MPH roads. If we try and drive on RT 1 on a summer Saturday with the summer.beach traffic we might hit some stop and go traffic. But we try and avoid that.
I have an AGM like that. It may have been discharged during a winter 3 years ago and might have froze. The tech at the store noticed a slight bulge in the casing when he placed a straight edge against it. He did a test on it and it checked out.
The battery went dead twice, once each in two different Chevy trucks. Once charged up, it sits fine with very little voltage loss over time. Both those trucks now have new batteries and they work fine. There is nothing wrong with the trucks and in both circumstances the terminals were clean and tight and the alternator voltages were correct. Both dead instances occurred after shutting the truck off after a highway run. We suspected the grounds but like I mentioned, the trucks are running fine with new batteries.
I’m giving the battery a complete Hail Mary smart charge right now and we’ll see. I hate to throw out a battery that seems to hold a charge but might have to. It’s like there is something shorting out inside the case periodically.
Once you have to begin putting a charger on an agm, its on its way out the door.
Toyota doesn't use AGM.
https://www.toyotapartsandservice.com/wp-content/uploads/2024/10/03_Batteries2025_hi.pdf
Lots of older Toyota hybrids all had AGM. I think they were all AGM until 2015 or so. Your chart even says so in there. Look up the part numbers and they are AGM.
The only ones showing AGM are the H8 and H9 for the Supra. The older Prius 12V batteries you're referring to have been suspected to be AGM, but I have never seen any official Toyota documentation indicating so.
They probably realized they weren’t a good fit for their charging systems. My wife and I are experiencing different drops in battery health with identical cars. Her efb was replaced with an agm while I used a flooded battery. Both replaced 12/24. My battery still test perfect but hers is decreasing.
I had a 2010 Prius and replaced the original AGM battery at age... wait for it. 14 YEARS OLD (in 2024!).
They have vent hoses for the AGM batteries. Not sure if that helps or not but the S46B24R is an AGM battery that was in a ton of different hybrids. I guess stranger things have happened and Toyota could possibly have made this a non-AGM part in later production or something.
I recently had to top off my 3 year old AGM battery as the plates were totally dry and when it got down to the freezing temps, I could hear the car was cranking slower.
They are harder to top off though.
They are harder to top off though.
AGM's are valve regulated batteries. They shouldn't vent and lose electrolyte unless they are overcharged to the extent that pressure builds up enough to pop the safety valve.
