12V battery and charging issues?

Hi everyone,

Long time viewer. First time poster. Please forgive me if I posted this in the wrong message group. I tried to post in the Gen 3 forum but it seems that I am not allowed to create a new thread as a new member unless I have made 4 posts. I thought I'd post it here as I am having the similar issue.

I bought a new 2016 Toyota Prius 3 Hybrid just over a month ago. I had it installed with a remote starter and a dashcam (Blackvue dr650gw-2ch with Power Magic Pro). The power magic pro is set to cut off once the battery reaches 11.8V. The dashcam runs when the car is turned on and goes into "parking mode" when the car is turned off (it periodically records when it detects motion e.g. when someone hits on car that is parked in a shopping center). When I come back home from work, my car's 12V battery is about 12.3V. I am unsure but this seems like a low voltage to me. In the mornings, the car voltage is about 12V or 11.8V.

My car has refused to start twice. When I checked, the battery voltage was about 9V when it refused to start (I checked it using the remote starter remote control). I took it to the Toyota service dealer and they blamed the dashcam and me driving short distances (my workplace is not far from my home), even though the camera is suppose to cut off at 11.8V.

I turned the "parking mode" off so that the camera is completely turned off when the car is turned off. I also bought a volt meter that plugs into the cigarette lighter socket to do some further testing (I am aware that its not the most accurate testing device). I found that the car voltage in the mornings is about 12.2V. I have tried leaving the car on about 40 - 50 minutes to charge the 12V battery. I have seen it as high as 12.5V after leaving the car on for 40 minutes. But in the morning, its still about 12.2 - 12.3V (this is with the dashcam's "parking mode" turned off). Again, to me, that seems low.

I left the volt meter in the car while driving and noticed something peculiar. I would see it at about 14.1V when the car is in "ready" mode. But after driving for a short while, I would see the voltage reading drop to about 12.5V. This is with the lights and AC turned off. When I put the car into neutral or park, the voltage will rise back to 14.1V. Only in drive or reverse will I see this voltage drop. Turning on the AC or lights makes no difference. I know the traction battery delivers about 14V to charge the 12V battery and I also understand (based on the info I found in this forum) that it drops the voltage after a while to prevent overcharging the 12V battery, but a drop to 12.5V is something I have not seen mentioned here.

I also noticed that when my battery's charge is low (e.g. 12V as opposed to 12.3V), the car takes noticeably longer to drop from 14.1V to 12.5V i.e. it stays longer at 14.1V.

Anybody have any ideas or any experience with this? Anybody tried checking their voltage of their 2016 Toyota Prius? Would love some feedback. Thanks.

 

Thanks a lot for the reply everyone. Really appreciate the great input. To answer some of the follow up queries in the replies:

alanclarkeau - I did turn off the "parking mode" for a few days to assess the battery drain (see paragraph 4 of my initial post). I should clarify that when I say leaving the car on, I mean leaving it on in "ready" mode.

IMkenNY - since I disabled the parking mode on my dashcam, I did not have the battery die on me. But I still have the battery giving me about 12.2 V in the morning before I go to work. And that's with me leaving the car on for 50 minutes in "ready" mode to charge the battery.

Mendel Leisk - is charging the 12 V battery with a smart charger better than leaving the car in "ready" mode and allowing the car itself to charge the battery? I thought that was the best way to get the 12 V battery charged. I am no expert on this topic though but appreciate your opinion or anyone else who is knowledgeable on the topic.

I am still interested to know about the voltage drop phenomenon i.e. from 14.1 V to 12.5 V. I looked around the forum and saw some posts about voltage drop but that's to about 13.5 to 13.8 V. Has anyone else seen a voltage drop that is that low?

Again, thanks to all that took the time to reply. Appreciate the opinions.

 

Thanks for the reply. I flipped through my manual and it says that 5A is the maximum. Thanks again for the input. Do you have an idea about the voltage drop? Does your car have the same thing?

 

Thanks for the reply. I understand that. The traction battery provides the 14.4V to the 12V battery when the car is in READY mode. My question is why is there a drop to about 12.5V when I have the car in N or D gear, but when I place the car back in P, it goes back up to 14.4V?

By the way, without the dashcam turned on, I am getting a parasitic draw of 250 mA. This is with all the doors closed, and waiting for about 5 minutes for all the computer / fuel pump stuff to turn off. My understanding is that it is too much of a draw.