At what point do you replace the 12v battery?

Might also want to check your HV battery cooling fan intake, to see if it is clear. (passenger side back seat, next to door)
After that cleaning and 12V battery replacement, and if the mpg does not increase,
you could also do a full cleaning of the hybrid cooling fan.

 

Is it vented?

 

I did the diagnostic test through the head unit. The 12.4 Volt is with the car off and the 14.4 is with the car on. So am I in the green with my battery health?

 

If the car has been off overnight, yes, it is healthy.

 

Here’s the “Installing Instructions” that came with the LiFePO4 battery:

“Please test the battery voltage before installing. Press the white button on top, If the voltage indicator shows arount 13.2v,that means normal.

Please check the layout of the batteries,to see if it is the same as the original battery.....

After the installation please test the instant starting current. If the voltage drops to around 12.50v it is normal. Then try to increase of rotational speed at idle statue until 3000 rpm, then the normal voltage is around 14.2v. If the voltage is over 15v or under 13v, both prove that there is a problem with the charging system of the vehicle.

Please turn off the white button after the above test. It will cause power leakage. The white button is a switch both for the indicator and the emergency power.”

I’m pretty sure the Techinfo specs note the same 13v to 15v nominal range so I just went and installed it. Less than 25k mi on ODO I didn’t expect any issues yet...

 

bostonbruins8703, for some reason the instructions note to measure at the terminals. There could be something that happens along the way from the battery to the Infotainment screen that skews the readout, but it does look healthy.

I’m personally a proponent of proper testing before replacing. Some driving conditions are good for keeping batteries healthy. (Everyone drives in different conditions).

 

The wife came home from work and reported that the 2012 Prius v had multiple idiot lights on and the steering & brakes felt different.
So i went out and looked- sure enough, the ABS, Brake, Exclamation Point, & a couple of other lights are lit up like an Xmas tree!

The car has 115K on the original battery, and starts and runs normal. I noted that the HV battery indicator shows 80% full.

I measured the 12v battery and it shows 12.2 volts after sitting overnight.

The steering is hard and the brakes require more pressure. I attached my battery minder and will hope that helps, but.....

The question is, does this seem like it is an old (8 years) 12v battery causing this, or will I be looking at a new HV battery?

Thank you in advance for any help....

 

8 years old and 12.2 volts, all says replacement.

 

Hi Mendel, Thank you for your quick answer, I just ordered a 12 v battery, I hope that clears up the xmas tree!

Can I leave my battery minder connected to the battery leads while I swap out the 12v battery?
That way I won't have to reset the window, door locks, & radio presets.
Or does the computer & other power backups draw too much current for the battery minder to handle?

 

I had lunch, then a nap on the couch, and you go and order a 12 V already. Can check the DC-DC converter:

Power READY. Headlight AND blower motor on HIGH, rear defogger ON.

Clamp on/Inductive ammeter on positive cable should show 0 A or less, meaning no current or current into the battery.

Aux battery voltage at + and - terminals 13 - 15 V.

moto g(7) power ?

 

I'm not sure. In past I've used a simple 1/2 amp trickle charger for that task, with no ill effects. What I use now is what's termed a "memory saver cable", that plugs into my jumpstart pack, and the other end connects to the OBD terminal under the dash. It has just the 12 volt pins. It also has indicator light for confirm you have a good connection.

In a pinch, a cheapie 1/2 amp trickle charger would work. I would suggest to connect it at the jump start point under the hood, so you can work on the battery swap without fear of dislodging the trickle charger clamps.

FWIW, it's not the end of world if you lose power. I do that on purpose everytime I do a brake service, and it's relatively minor to recover. The window auto-up and down is easy to reteach if needed, and I've found it's usually ok anyway. I believe the method is to run window down, then run it right up while steadlily pressing the rocker switch, then continue to hold the switch a couple more seconds.

Radio presets I don't much care about. Oh and the clock needs reset.

I also notice: odd rev-up when starting, for the first 2 or 3 starts up post disconnection, like the car is reesablishing some parameters.

 

The 12V battery in our Prius v Five died yesterday which was about 7 years, 3 months after buying the car new. The car has 43,xxx miles on it. The sign of failure was the dashboard lights coming on for maybe a second before going out.

At least the battery died in our garage. I put it on a charger to verify that it wouldn't take a charge.

I didn't bother trying to find an aftermarket replacement battery due to its unusual size - didn't think there was any point and my wife wanted her car to work NOW. I printed a Costco Auto Program 15% discount coupon and bought a new OEM battery at a Toyota dealership that participates in the Costco program.

 

Thanks for your replies, I'll let you know how I make out when the battery arrives on Monday.

 

mine died at the exact same age

 

i'm not sure a weak 12v will affect the operation of a running prius. i hope that's the problem. if not, it needs to be replaced anyway.

 

While that sounds logical.......it really isn't.

The computer boards "boot up" BEFORE the car is "running".
At that point, the battery is the ONLY power source.
If the initialization of the boards doesn't go quite right because of low power all kinds of strange things might happen, if it starts at all.

 

I'm in that school too. But: I've really coddled our latest battery. Our use of the car is piddling; it can sit for multiple days. I hook it up to a CTEK 4.3 charger during those idle times, and leave it on till the car next sees use. Also, I occasionally check it's health with a Solar BA5 tester, which tests voltage and Cold Cranking Amps, and gives a verdict.

With all this attention and monitoring, it's more-n-likely not going to be replacement time at the five year mark. For one thing, if it is starting to fail, I think I'll get lots of warning. And it's starting to be my science experiment, lol.

 

that doesn't make any sense. we are talking about a running prius, everything has already 'booted up'
'the steering is hard, and the brakes required more pressure'. i take that to mean the car is ready, but perhaps i'm mistaken.