12v battery

it's borderline. i would say yes, others may disagree. it also depends on your risk tolerance.

 

Appears within norm readings....

 

Thank you for your replies.

I based my concerns on a previous posting with the chart below

 

No it is NOT.
Or might not be.

If the 12.1 reading was when there truly was NO load on it.....or an extremely small load.....then either the battery is weak or it is not being charged enough. An AGM battery that reads 12.1 with no load is at less than 50% capacity.

That chart is for conventional wet cell batteries.

P.S. HEAT kill batteries. South Florida and similar climates can sometimes cut the battery life in half.

 

See what it reads measuring the voltage with a digital multimeter, first thing in the morning, at the under-hood jump point. For most "unbiased" reading, if it's not a security risk: pop the hood the night before. At the least, get in through the passenger door to pop the hood, to avoid activating the brake system. You want the car as "sleepy" as possible.

If you're reading 12.4 I'd say you're ok, but straying into the rough, time to start researching batteries.

If it's lower than 12.4 I'd replace it as soon as practical. No panic, but don't let it slide.

The voltage check with a digital multimeter is so-so: for a better assessment, either drive it to the dealer or an automotive retailer and get an electronic load test. The automotive retailer will likely do it for free, it's easy for them, and they might make a sale. Verify before driving to either of the above, what they have, what they're willing to do, the cost.

Or DIY, get something like Solar BA9.

 

I'm not sure why people keep looking for load tests. For the hybrid systems, voltage is everything. So unless the testing gear being used can track voltage in various load states, it isn't useful information. Nor is the average knuckle-dragger going to be able to interpret the load test. Even dealer techs don't often know what to look for.

A couple facts to consider:
1) Borderline voltage will result in erratic problems. Sometimes it starts, sometimes it doesn't. Also can result in a variety of failed system initializations and bizarre error messages. You have a car possessed by gremlins.
2) Being left out in the cold in some parking lot is expensive and no fun at all.

Replacing a 12v battery seems pretty simple and cheap enough, considering the above. A 4-5 yr old battery should be replaced on spec IMO, especially if its an OE battery. If its EVER been drained to dead-ness, replace it at 3 years.

 

Thank you again for all the information.

I’m at the dealership service department now getting the battery replaced. Had it last replaced 9/17. Service rep said he couldn’t prove it was bad, guess he was thinking I wanted a warranty replacement??
told him to go ahead and put the new battery in. $313 installed.

I don’t want to take any chances of my wife getting stuck somewhere.

 

A fully charged AGM battery should hold 12.8 to 12.66 volts depending on the temperature. (120f to 0f). Every meter I have seen that has a scale for AGM batteries shows somewhere in this range as fully charged.

 

Voltage can jump around quite a bit. If I check ours first thing in the morning at the jump point, when the hood was popped the night before, I might read 12.9. Open/close the driver's door, and it'll drop to 12.8.

That where an electronic load tester (I use a Solar BA5) is handy: it does read voltage, but also, after you enter battery type and rated Cold Cranking Amps, it will test it for CCA, display that value, and a verdict.

It's worthwhile to some extent to test volts, but the load testers test the the battery's "legs".

Off-topic, but interesting video on smart charger:

 

Had the battery replaced , drove home and the reading is 12.2 on my info screen.

first thing this morning before driving was 12.1.

not much difference unless the driving home means something to the reading ?

 

the battery needs a charge.
desk monkeys at the dealership think they can just grab one off the shelf with no thought to how long it's been sitting.
you either have to go back and ask them to charge it up, or buy a smart charger.

 

Sorry, I don’t understand. But they just installed it?

 

A few days driving will likely perk it up. That said, the elephant in the room is your measurement method. Get a cheap digital mutlimeter at least. Measure it first thing in the morning, see what get then.

 

How do I charge it, by driving or...

thank you

 

sorry, see my edit above

 

you can drive it for a few days as mendel says above, and see if it goes up, but prius is more of a maintainer than charger

 

pardon my ignorance but I don’t know what that is or how/where to use it.

thank you all again for all your help and advice!

 

FWIW, whenever I get a new battery I like to:

1. Verify it's voltage and CCA in the store. Either dealership or most any automotive retailer should have a pro-level electronic load tester on hand, and be willing to show you what it reads, gratis, to make a sale. I bring my own tester (Solar BA5), keep it simple.

2. Hook up the battery to a smart charger (3~4 amp range) and fully charge it, prior to install. Some dealerships or aftermarket stores might do this for you. It's debatable benefit. A new battery might have voltage dropped a bit, due to sitting on shelf for a few months, but still have lots of "legs", ie it'll be fine with a bit of charging. Again, any brand new battery in decent shape should bounce back with a few days driving. My current charger is a CTEK 4.3, it's worked well for me.

 

A digital multimeter is a meter with a digital display, capable of reading volts, ohms, amperage. Most any multimeter will do: something $20~30 is good enough.

Pop the hood, pull off the fuse box cover, flip up the little red tab towards the rear: that is the under-hood source of plus 12 volts.

Set your meter to Direct Current Volts (DC Volts), and if it's not auto-ranging, choose a scale that something like 0-25 volts, something where 12 volts is within the range.

On the meter, connect the black and red leads, red to positive volts terminal, black to "common" terminal. Then touch red lead probe to that +12 volts terminal in the fuse box, and the black lead to a bare metal bolt, something substantial on the engine or car body, unpainted.

If you've done it right you should be seeing 12 point something displaying on the meter. This is what I use:

 

If you live in a glass house, be careful about throwing rocks.

A battery load test: Apply a known load resistance and see what happens to the voltage.
Kind of hard to mis-interpret red and green indicator lights......or similar.

Doing a load test is a LOT better than taking a single voltage reading and putting too much stock in the result of that.
But it is not perfect. The most common mistake is leaving it connected to the load tester for only a couple of seconds, seeing the "pass" indication and calling it good........when it might have changed to "bad" if left connected for just a bit longer.