Low 12-Volt Battery Apply Parking Brake Securely...

Is that what is in your Gen3 now? So, it is not OEM 12V? The last use of my Schumacher charger was on HCH for a dead battery last year. After charging it, it did start fine. This happened when the IMA battery was failing but before its replacement, so I did replace the 12V battery a few days later. It was an original 9 years old OEM FURUKAWA 12V battery. That's without any battery tending until I replaced it with NAPA battery. So, had I done daily battery tending, would it have lasted another 9 years? I think the car will be a rust bucket way before that, LOL.

 

Hey I know I'm OCD.

 

Hey guys,

I just had my 2018 Prius Prime battery go dead since I've been working from home during COVID-19.

Funny story is that after I jumped it, I was trying to drive it on the gas engine so it would charge the battery and come to find out that it doesn't charge the battery that way and in fact, doesn't even have an alternator which makes sense since it would make it harder to start on demand with the extra load of an alternator.

Anyways, I bought this charger off of Amazon and charged the battery.. It seemed like reasonably good quality and not too expensive.

I read the whole thread and just wanted to add some info.
I just verified that at least with my car, it does charge the 12v battery off of the big hybrid battery if the READY light is on (i.e. not in Accessory mode).

My battery was at 12.25v but then went up to 14.10v while in READY mode.
I'll have to see what it charges up to after sitting in that mode for a few hours.

Before
While in READY mode

Thanks everyone for all the info in this thread.

 

Welcome to PC. Yes, you are correct that all you need is to put the car in READY, you do not need to drive the car (or run engine) to charge the 12v battery that is if you have enough charge in the traction battery. With car in READY and run for a few hours, the 12v battery will charge-up to 12.7-12.8v. However, it is still not the full capacity of the 12v battery and over time (weeks) repeated infrequent use of traction battery alone to charge the 12v battery will start to lower the resting state voltage on the 12v battery.

If you are interested, here is a thread that discusses the subject deeper.
12v Battery Is Discharging, Re-Charge Now ! | Page 11 | PriusChat