12V Accessory Battery Replacement on 2018 NX 300h

I needed a 12V battery because the I was getting some troubling signs from the current one. For instance when my wife drove out of the garage, she said her analog clock reset itself. I had noticed it also wasn't keeping track of last setting and would reset them at random. Time to check the battery.

Pulled out my battery tester, not a top-of-the-line one but a Topdon one I purchased for about $34. Anyways the battery tester didn't like using the under hood connection, so I cleared out the cargo area to access the battery directly (right behind the driver's side rear fender). Found out the battery tester said it fine but was at 41% and needed charging. This was after being driven for about 35 miles that day too. Not exactly a good sign. I could have charged it and this would have extended the battery a bit more but decided to replace it before it died hard. FWI: the battery Lexus requires is a 460 CCA group size 47, and every place I looked said it requires an AGM.

The best price was Rock Auto at about $152 for an AC Delco AGM - 3 year warranty, $205 for a Bosch AGM - 4 year warranty. Wasn't too crazy about how I was going to get the core back to them since they wanted $18 for the core.

Long story short decided to check out a local place that specializes in automotive batteries (the 12V variety). I pulled the battery and found out it was a Panasonic flooded lead-acid battery.


Anyways the local place wanted $169 for an Exide AGM replacement and they would test the old one and replace it while I waited. Reinstalled the original battery and brought the car down there. They tested it and found the same thing I did, 40% and needed charging but overall it was in good shape. Since lead acid batteries, even deep discharge ones, should never go below 50%, I decided to replace the now 5 year old battery with the Exide AGM. They replaced it and reprogrammed the car. The Exide battery part number is MX-H5/L2/47.



They did offer to put in a cheaper flooded lead-acid but I went ahead with the AGM. So supported a local business and walked in and out in one day. Bottom line - wife happy.