12V battery measurements after 44 months in service. Replace or not yet?

Others might disagree but I'd say the battery is probably ok. The cold temperature can account for at least a 0.2V drop in the open circuit voltage and a bigger discrepancy under load (eg Ig-on). Overall it could account for about 0.5 volts suppression of those Ig-on readings.

To me the fact that it booted the car without any issues after three days of sitting in freezing conditions is testimony that the battery isn't all that bad.

BTW. What exactly was the temperature when you made those measurements?

 

You can wait for a while to see if it shows further weakness

You dealer will most likely balk at using a third party battery. Any decent gas station mechanic can install it for you using the instructions that come with a yellow top and the installation kit from:
Toyota Prius 12 Volt Auxiliary Battery with install kit for 2004 - 10

JeffD

 

30 minutes of charging time won't make much difference. You would need to keep the car READY overnight (or hook up a battery charger for that period of time) if you wish to see whether the battery can be charged more fully.

I doubt that your service dept will agree to make modifications (new battery terminals) to your car, which are required if you wish to install an Optima or other non-standard battery.

 

Check the battery voltage the next morning, in both ACC-ON and IG-ON modes. It would be nice to see the voltages increase at least 0.4V. If they remain down near 12.1 / 11.8 then I would suggest replacing the battery soon - if you desire to maximize your car's reliability.

 

No I do not. Please google " Car Battery Sulfation" There to many hits to list.

#1--- Prius stock battery is not a great battery to begin with.

#2----One of the worst things to do is to leave a battery for +30 days with no input. At the very least mild sulfation begins. Early battery death. See any google post concerning battery health.

#3----Prius car battery issues pretty much made this site. I say that because the battery issue posts are endless.

#4----You want to do all you can to avoid a dead battery car jump on this car. Its truly its achilles heel. Many many posts about major damage on a a simple car jump. Alot of people say that every single complaint is because of wrong polarity jumps. If so thats alot of AAA tow truck drivers who can't figure out the difference between red & black & hot & ground.

#5----Constant beep. Inexplicable. No. Classic. Yes.

#6----Its a 4 year old piece of junk battery.

#7---And best of all your $4000 Inverter really enjoys charging your soon to be dead battery.

 

It will make it long enough to order your Optima kit from elearnaid.com!

If, after looking at the instructions, you don't feel comfortable with DIY or having a friend help, then look for a Toyota and/or hybrid specialty independent shop in your area.

 

No. I suggest you replace the 12V battery at your earliest convenience.

 

I may still be in denial since I bought the car new and it is still young, though the 12V battery may have been sitting in the dealer's lot without charging for months before I bought the car. During Christmas it sat 10 days with SKS left on - I thought it would automatically turn off after some days but it didn't. On the first working day the IGN-ON mode read 11.5V and dropped down to 10.7V with both headlights and rear defogger on. The car started fine and did a day of commuting, about 40 minutes each way. The next morning the readings came back up to 11.8V and 10.9V, not particularly impressive but not far off from previously measured "norm" either. I do garage the car so temp was at least above freezing. Still unwilling to give up yet ...

 

A fully-charged new 12V battery should measure ~12.9V (no load voltage) out of the box. Pls tell us what you measure when the car is IG-ON.

MSRP of the 12V battery is $138.70 (at the parts counter) and the part number is 28800-21170 for the Smart-equipped 2G. I assume that the quotes you received include labor.

 

Seems reasonable; the battery that I bought for my 2007 a couple of months ago had been received by my local dealer one day before I bought it, and measured 12.9V out of the box. However its manufacture date in Japan was around four months prior to the dealer's receipt.

 

I'm not; but it appears that several active PC members are.

My thinking is that the original equipment battery has met my needs. The batteries on my 2001 and 2004 lasted 6 years before I replaced them as preventive maintenance (they were still functioning at the time they were retired.) The 2007's battery died after 4 years but that car is currently used on an infrequent basis. Since then, I'm pursuing a more diligent program of keeping the 12V batteries in all four household vehicles charged up on a regular basis.

I don't feel that the incremental value from the Optima is worth that battery's price and the work to replace the battery connectors. (I've already done the drill of replacing the battery connectors on my 2001 when I installed a Panasonic 12V battery which was stocked by Toyota dealers as a higher capacity alternative to the original equipment battery.)

 

Yes.