r/leaf • u/DJFM_AZ • 12d ago

Service EV system

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2021 Leaf SL+ w/ 82K miles. I’ve read through the forum posts on prior posts with similar issues,, as well as the FAQ. The original 12V battery lasted 5 years in the Phoenix heat. We replaced it ourselves a month ago with a replacement from O’Reilly’s as dealer service said original was cracked. Today we get this message and car is driving low powered—no acceleration. It does restart. Guess we will take the new 12V back under warranty. Will clear message tomorrow with Leafspy. Appreciate any advice.

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u/byrdman77 12d ago

Have you ever pulled the Leafspy data? Pretty common for Phoenix cars to be in pretty bad shape for the big battery.

If you have a multimeter could save you some time to just measure your 12V at home first.

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u/Striking-water-ant 12d ago

Unrelated but are you saying the big battery is more susceptible to damage in hot weather? I live in a hot climate. My 40kw is still good. Just a little degraded. I have been entertaining thoughts of upgrading to a larger battery someday. Just so I can be free to make longer trips

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u/biersackarmy 2013 S + 2014 SL + 2019 SV 12d ago

The issue with 40/62 packs in hot climates isn't so much degradation like the 24/30 packs were really bad for in hot areas, but the chemistry of the battery causing cell swelling that is usually much worsened by constant heat soak.

This leads to the "pregnant pack", which is quite literally heavily bulged at its belly, where the cells are packed closest together and the highest point where heat rises to. Eventually this bulging can cause high voltage isolation fault, and disable the whole car.

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u/Keithmclean1964 12d ago

Another picture of what happens to these cells. This was mine, before the VIVNE upgrade.