First, the car has been in Florida it's whole life, so hot humid, never cold. Second, I have not noticed any problems with the trunk battery, though I have not even looked at it yet. I know the Lexus battery may be overpriced at $400, but Lexus is offering $50 off of that right now, so some savings. I have never had a normal battery last more than 5 years down in Florida. Is this not a normal battery, and has superhuman life? How many of you have replaced your 12V battery on a 2013-15 model years? Did it die on you, or did you just feel like it was time? I usually wait until it dies off since I have two cars to drive, have never been stranded anywhere. Actually, I get the hard to turnover warning, then run to WalMart and replace it. Have learned not to tempt fate. Plus like old faithful, it seems to happen every five years. I know some others have replaced the battery with non-Lexus replacements. Thanks.

 

The 12V battery wears very little if you drive at least a couple times a week. All it has to do is flip a relay to connect the hybrid battery when you start the car as well as keep some electronics on when the car is turned off. It's not surprising it's still working to this day but if you let it sit several weeks, it may get drained.

I'm probably going to replace mine with a factory Lexus one next year assuming this Covid19 stuff is done and I can drive again. My original battery will drain so low that it can't connect up the hybrid battery to start the car in just a week of sitting there. I've already decided to just pay for the Lexus battery since it lasted so long anyway.

 

Measure the SoC using a basic voltmeter.

use this calculator. I would replace if less then 40%



https://www.random-science-tools.com...id-battery.htm

 

I have actually never checked the voltage on my battery. May be a nice little Mr. Science project. Thanks.

 

The trick is to wait for 6 hours after the battery is fully charged. To see how well it holds. I do this periodically for both of my cars to ensure I don’t run into unexpected issues and replace at the right time.

 

When my 450h 12v battery died it could barely hold a charge for a couple hours. I had to use a jumper pack to start the car every time. Even though the 12v does not power anything that turns over the motor it runs a bunch if of other systems, so the car won’t start if it’s dead. There was no warning just find yourself with a dead battery one day. There are hardly any aftermarket options that will fit without modifications, weird size. My advice is go oem.

I changed my battery last year, car had about 95k mikes on it. The battery I removed was original from the factory.

 

I have found the OEM AGM lasts about 6 years. OEM lead acid to about 8 years.