Hello,
I sold my 2002 GEM this year after owning it for 19 years. I am now the proud owner of a 2025 GEM e4 with a factory 8kW lithium battery, and I love it! I am a retired NASA mechanical design engineer, but have limited experience with Li-ion batteries. My current thinking is to treat the GEM car batteries like I treat my other Li-ion devices, such as cell phones, leaf blowers, and lawn mowers. I generally try to charge them only to 80%, and discharge them no further than 30%, in order to get maximum service life out of the batteries between replacement.
The GEM owner’s manual only speaks in generalities regarding best practices for batteries, while not specifying whether their advice refers to Lead Acid, AGM, or Lithium-ion. They do not address lithium batteries specifically, so I am reluctant to trust their advice.
Anyway, the owner’s manual says to always charge the battery to 100% after every use. They advise to avoid “short charging,” or disconnecting the charger prior to full charge. They say this will drastically reduce battery life. This advice is completely contrary to my understanding of how to maximize service life of lithium batteries.
My question for the forum experts on Lithium batteries, is how should I charge/discharge my GEM 8kW Li-ion battery to maximize service life in years?
