Gen 4 12v battery status monitoring

[thud]

Is there any way to monitor the 12v Battery state of charge on the gen 4 Prius?  I have been having some problems with starting and getting the “12v Battery low” warning.  I have had the dealer check the car and they say there is nothing wrong but I would like to see for myself how well the 12v Battery is holding it’s charge.

so is there any way of monitoring this on the cars display? I can’t seem to find anything in the manual.  I don’t have any way of plugging into the diagnostic port and don’t want to buy anything to enable this.

 

thanks.

[PeteB]

I had a problem with my Gen 4 12V Battery too, and in the end the dealer replaced it.

I keep an eye on it with this:

https://www.ebay.co.uk/itm/12V-USB-Charger-Car-Cigarette-Lighter-Socket-Power-Digital-Voltmeter-Thermometer/282786775448?epid=791786015&hash=item41d767c198:g:1YAAAOSwSQFaQ2d6

If I put it in the rear cigar lighter socket and put the car in ACC mode, I can see the voltage.  By comparing the reading when just parked after driving for a while, with a reading when the car has stood unused for a day or two, and then watch to see if the reading drops while leaving the car in ACC for several minutes, I can judge whether I'm heading for further problems.

In READY mode, it will show near 14V, 12-13 when just parked, and around 12V after a day or two.  If it drops below 11, I will start to worry.

[drives]

There’s a way in the gen 3 so would have thought it would be the same or similar? Involves pressing one of the console buttons and switching the headlights on and off to access the maintenance mode

[Catlover]

Simon, can you expand on that procedure for the Gen3 please.

[drives]

Here's a link which appears to explain how to do it on the gen 4

https://priuschat.com/threads/maintenance-mode.172652/

As for the gen 3 this is from a previous post:

Put vehicle in Ready or Acc mode (you may press EV to prevent the engine starting and wasting fuel if in Ready mode)

Hold down the "INFO-TEL" button on the NAV

Turn the headlamps on and off 4 times.

The diagnostic screen appears on the NAV.

On the first screen, press; "Function check/Setting"

then on the second: "Vehicle signal"

Battery voltage is the first on the list on the third screen that appears.

This shows the voltage under load in Ready or ACC mode

[thud]

Thank you all for your comments and suggestions.

i have now worked out how to get into the maintenance menu on the gen 4. It’s actually quite simple.  

Igntion in either accessory or ready mode.

hold media button, switch light from auto to side lights 4 times and maintenance menu pops up.

go to Function Check/Setting, then Vehicle Signal and Battery voltage displayed.

hope this is useful to others.

[Joseph D]

On 24/02/2018 at 10:37 PM, drives said:

Turn the headlamps on and off 4 times.

It is not necessary to turn on the headlights; the sidelights will suffice. Saves your headlight bulbs, especially if they are HID.