12 volt battery failing to start the car

2024-03-22 1230 miles

New battery may have fixed the problem. Maybe? It’s hard to tell, since I haven’t had any issues in over a week. Except for a couple of longer drives, the car has been driven too regularly for it to drain. However, my first 12v battery was failing under fairly regular use, and plenty of battery maintenance precautions taken before failures even started, so I have some justified paranoia about the car.

I bought a Noco Genius 10 battery maintainer to check charge, and to save me from having to jump start my car. It’s something that will benefit me anyway since I can keep my battery in good health, but I had to rush getting one because I don’t want to be in the dark if the problem reoccurs. I am not exactly the target market for needing a battery maintainer since this household only has one car and it’s a near-daily driver, but it will be cheap insurance anyway.

 

That appears to be a 10A battery maintainer. Is the 10A rating the best size for maintining the 2024 PP battery ?

 

I don’t know for sure. My understanding is that the main difference between the Noco models is the amp rating, but it’s still only trickle-charging the 12v battery and not doing anything harmful to the battery. My reason for getting the 10 amp charger is to reduce charging time, should I actually need to recharge a battery from a low state. In maintenance mode, it should function the same as lower amp models, unless I am mistaken?

My thinking is that the 2 or 5 amp models will be less useful to me on a road trip (if I decide to take it with me), while the 10 amp model could be really helpful at a destination with AC power, and will avoid needing a jump start in some cases. An overnight charge is also extremely convenient for home use, since I don’t prefer to leave it plugged in all the time unless I am not using the car for an extended period.

If anyone wants to weigh in and let us know about appropriate specs for Noco chargers, feel free.

 

See https://priuschat.com/threads/third-day-with-new-car-dead-12v-battery-second-day-in-a-row.242574. I posted on page 7. The best thing you can do to charge the battery is put the car into READY but not drive it for 30 min. The worst thing you can do is actually drive the car... eventually it will charge it but only when it hits 60% and even then will only charge it to 85%.

 

I thought the battery warning light was for the traction battery?

 

I thought the battery warning light was for the traction battery?

 

Replace the Gen 4/Gen 5 OEM flooded-cell battery with an AGM battery, and it will solve most battery problems.

AGM battery for Gen 4/Gen 5 Prius/Prius Prime and observations on the 12-V charging system | PriusChat

 

Cars these days have protection circuits for the 12V with a warning light.
Problems with the traction battery would trigger the warnings for the hybrid system.

 

The low-battery warning, which is not a light but a written message on the display, is for the 3-V lithium-metal coin cell for the smart-key fob—not for the 12-V battery. There is no low-battery warning for the 12-V battery.

In conventional cars, the battery-warning lamp only lights when the alternator is broken. There is no alternator in Prius, and the battery is charged by the DC–DC converter. It turns out that there is a warning lamp for the DC–DC converter having been broken. It is accompanied by a message basically saying that the charging system has failed and the car should be towed to the dealer. This is apparently not what they saw.