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Derek Werner
Derek Werner, ASE Certified Technician
Category: Toyota
Satisfied Customers: 137
Experience:  ASE Master Technician, L1 Advanced level specialist
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My 2009 prius starts when jumped. The battery is 29 month

Customer Question

Hi. My 2009 prius starts when jumped. The battery is 29 month old and, when taken out of the car, checks at 12.9v. When put back it, it drains down to 3.9.
Submitted: 2 years ago.
Category: Toyota
Expert:  Derek Werner replied 2 years ago.

Hello and welcome!

It sounds like there is a bad cell in the battery.

I would recommend getting it tested or replaced.

How long does it take for the voltage to drop down to 3.9volts?