conductor_hibrido
Problems with the auxiliary battery of my hybrid Toyota Prius
(Translated from Spanish)
Summary of the thread
A 2008 Toyota Prius hybrid with 390,000 km is experiencing issues with its auxiliary battery, which was installed new in October 2023 but discharged by July 2025. A Toyota workshop diagnosed the battery as needing replacement due to a low CCA measurement, while another workshop found it to be in good condition despite a decrease in CCA and an increase in IR values. Possible causes include a parasitic drain, loose connections, or a faulty alternator. Suggested solutions involve checking for parasitic drain, inspecting battery terminals, and verifying the alternator's performance, with a recommendation to consider warranty rights if the battery continues to underperform.
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3 comment(s)
conductor_hibrido (community.author)
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It sounds like there might be an issue with the battery or the charging system. First, check for any parasitic drain by ensuring all lights and electronics are off when the car is not in use. Also, inspect the battery terminals for corrosion or loose connections, as these can affect performance. If everything seems fine, it might be worth having the alternator checked to ensure it's charging the battery properly. If the problem persists, consider exercising your warranty rights, especially if the battery continues to underperform. Let me know how it goes or if you have any further questions.
Thank you for your response. The first workshop verified that there were no parasitic downloads, as they proposed replacing the battery with a new one, and so it was done. I have been driving for a few days with the new battery without any problems, so I understand that it is not a problem with the alternator either.
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CarlyMechanic
community_quotation:
community_author_wrote_on
Thank you for your response. The first workshop verified that there were no parasitic downloads, as they proposed replacing the battery with a new one, and so it was done. I have been driving for a few days with the new battery without any problems, so I understand that it is not a problem with the alternator either.
It's good to hear that the new battery is working well so far. Keep an eye on its performance over the next few weeks to ensure everything remains stable. If you notice any issues again, it might be worth revisiting the workshop for further inspection. If you have any more questions or need further assistance, feel free to ask.
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TOYOTA
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PRIUS
CarlyMechanic
It sounds like there might be an issue with the battery or the charging system. First, check for any parasitic drain by ensuring all lights and electronics are off when the car is not in use. Also, inspect the battery terminals for corrosion or loose connections, as these can affect performance. If everything seems fine, it might be worth having the alternator checked to ensure it's charging the battery properly. If the problem persists, consider exercising your warranty rights, especially if the battery continues to underperform. Let me know how it goes or if you have any further questions.