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12V Accessory Battery Replacement on 2018 NX 300h

Discussion in 'Lexus Hybrids and EVs' started by drash, Apr 6, 2023.

  1. drash

    drash Senior Member

    Jan 5, 2005
    Upstate NY
    Other Hybrid
    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.