Measure 11.9V, Should I replace my 12V battery?

Yes.

 

Agree with Patrick, but I must say, several threads like this lately from 2007ish model year. Making me nervous about mine! So far so good (cross-fingers).

- D

 

You got 4 years of service, anything more is nice but not expected. I would begin to plan what life is like after the original 12 volt is dead.

 

Me? Yeah I know. I tell myself that between regular long drives, garage parking and occasional doses of Battery Minder TLC I should expect longer than usual survival, but I'm resolved to the fact that I'll have to replace it eventually.

- D

 

The original equipment 12V battery from my 2007 died last month after four years of age. I was a bit surprised as I had gotten six years of service from the original batteries in the 2001 and 2004 - and replaced them at that time although they were still functioning.

One problem is that the 2007 is lightly used, so the battery probably spent lots of time in a partially discharged state. I'm using the battery charger more frequently now to maintain the battery charge at a high level.

 

Oh sure! You had to say it. Pearl is still ok but now that it's been posted.....

 

:d :d

 

You could try something like this. It will attempt to bring it back, if unsuccesful it will show on the status lights. You download a pdf of the manual to see in more detail.

MUS 3300 - CTEK SWEDEN AB

Even if you do manage to restore it, sounds like a new battery should be your next priority: they are a "consumable".

 

Yes me too. MY similarly driven very low miles 07 measures 12 sometimes 12.1
first thing in the AM. Its seen alot of battery tending too.

Never had to jump it. Time for a yellowtop I think. I see some new yellowtops on eBay for a good deal but there different "D" versions.
Was hoping would find one there with proper version but no luck yet.

 

Always lock the car no matter where you leave it. If the most common battery-draining conditions exist it will give a long warning beep.

 

I just bought the 8071-167 D51 from Amazon for $140.00. Not a direct fit, but fashioning the adaptation is relatively simple and cheap.

 

Cool...linky please.

 

D51 Yellow Top

You can fashion your own conversion parts for ~ $5.00, or order this kit from elearnaid.com.

 

I now have a inventory of 4 batteries (12V). It does not matter which battery is installed they all read about 12.3Volts, ( with no drains ) They all show 13.9 to 14.1 Volts on the MFD when in auto charging state. Local or distance driving doesn't matter. Since I have never measured a full charge on even a new battery, after it has been installed in the car for a few days, I am slowly concluding that the Prius charging system has some sort of current limiting circuitry that prevents the battery from showing a full charge. This even happens after cherging a battery to 15-16Volts on the bench before installing in the car. I have never experienced any starting problems.

 

That is why it's so important to fully and properly charge the replacement battery before installation

With my '04, the first winter I had it the battery ran down. Conditions: temps down to -40, auto headlights on (Driving to work in the dark, driving home in the dark), Max Heat, and electric defrost

I hooked up a VDC Battery Minder and kept the Prius battery plugged in whenever the Prius sat parked overnight at my condo underground parking. That solved the problem

 

I didn't wait for my original 12v battery to go bad in my 07. I replaced it with a yellow top from eLearnaid about three months ago. The installation was easy.

 

Your solution with the battery minder is perfect Jayman. Sticking to the lead acid technology, when purchasing a battery, it is recommended that it be precharged before installation, your local garage or battery store is not going to do it. In my case I did charge it first for a couple of days ( readings were in excess of 13 volts) but after hooking up the battery to the car, it only read 12.3 volts. Perhaps the parasitic drains are more than previously discussed? Where is that charge disappearing to? I suppose the DCV should be measured unconnected to the car for a true reading. I hope that's -40 Centergrade?

 

Depending on how low the battery is allowed to go on the shelf, at a low amp setting, say 5 amps, it could take a couple of days. A good automatic "smart" charger will taper the charge to prevent overcharging

Even brand new batteries will have sulphation from sitting. A desulphation cycle is good.

With my Prius, I would leave the VDC disconnected but after 6 hours would measure the voltage using a Fluke DMM at the VDC charge harness pigtail. It would usually be 12.9-13.2 vdc

As far as temp, -40 C and -40 F are the same thing. Translated: WAY too cold!