Prius 12 V Battery Drain

[PeteB]

PeteB, just curious, how often (if ever) has the voltage protection kicked in and shutdown your dash cam?

Never whilst parked, including after 10 days. Occasionally if I sit for a while in ACC mode or IGN ON but not READY it will kick in.

[jgodfrey]

Final update I hope! The garage replaced the 12v Battery under warranty as it failed their tests; might have been a duff Battery from the outset, but undoubtedly the 4 times it went flat will have finished it off.

Hopefully this will solve all of the non-starting issues we've been having.

Thanks for all the assistance!

[kithmo]

Fingers crossed ;o)

[Daneshwar]

Having the same problem

Battery becomes dead and car gives P message 

Jump starting twice in last 15 days

Is Battery replacement a solution

 

[Joseph D]

3 hours ago, Daneshwar said:

Having the same problem

Battery becomes dead and car gives P message 

Jump starting twice in last 15 days

Is battery replacement a solution

 

Only you can answer this question.

What testing have you done to confirm whether the Battery is good or bad?

In any case, if your Battery has gone flat enough to require 2 jump starts in 15 days, then I'd be leaning towards the Battery needing to be replaced.

[Younis]

On 5/12/2015 at 3:01 PM, jgodfrey said:

Final update I hope! The garage replaced the 12v battery under warranty as it failed their tests; might have been a duff battery from the outset, but undoubtedly the 4 times it went flat will have finished it off.

Hopefully this will solve all of the non-starting issues we've been having.

Thanks for all the assistance!

Hi I have the same problem changed V12 Battery 2 times but still not able to start the car. Every time I changed the Battery only last about 3 weeks then not able start the car. So can plz tell how did you solve the problem with your car finally? 

[Ross McC]

On 5/7/2015 at 11:24 PM, Joseph D said:

14.4 V+ in READY mode on an ongoing basis is not normal. Let me explain a bit more. Even though you will see it, possibly often, if your 12 V battery is healthy you should to expect to see the voltage to drop to 13.8 V after a time. If it does not, it further points to the 12 V battery being in poor condition. At 13.8, the charge has moved to a float charge. After further time you should see the voltage drop again to around 13.5 V, which indicates the 12 V battery is now fully charged and on a trickle charge.

So to summarise:

14.4-14.7 V = Charging discharged to severely discharged battery

13.8 = Float charging nearly full battery

13.5 = Trickle charging fully charge battery.

I know this is an old post, but your information has just been exactly what I needed, thank you very much. Today I tracked my low 12V Battery to the OBD2 speedometer I fitted about 4 years ago. No problem when the car was used every day, but we bought a Nissan Leaf before Christmas and now the Toyota can sit unused for a couple of weeks. I bought the OBD2 speedo because the car's big digital speedo is just so wrong, between 5 and 11 km/h over true speed (that's 3 to nearly 7 MPH). Incidentally the Leaf 12V system seems to charge in a similar manner, getting the full 14.4V charge only for a short time, then going into float mode. The 12V system is at the root of so many problems in a Leaf, it's a bit of a standing joke. On the suggestion of a Leaf forum member I have unplugged the electrical load detector, which on the Nissan is on the negative terminal of the Battery, now it runs 14.4V all the time it's in "Ready" mode, just like car alternators have been charging batteries for the last 50 years!