12V battery - my readings seem low

All,

My Prius is 2 months old and has about 3700 miles on it. My 12V battery has not died, but I was curious to check on its status (armed with the battery checking instructions I've found posted in the past on this site).

I checked it several times in the last 24 hours.

A) Yesterday afternoon before leaving work (temp = 60 F)
B} Yesterday immediately after stopping my car (after driving for ~ 1 hour)
C) This morning after letting it sit overnight (temp = high 40's)
D) After I drove to work (45 minute drive)
E) After letting it sit for 3 hours

When I drive, I typically use the cruise control, have the radio playing, and the NAV screen is on. Headlights are usually on as I've been leaving for work early in the morning or coming home in the evening. Defroster/AC/Fan aren't used. I did use the seat warmers for the first 5 minutes of my 45 minute drive this morning, but turned them off. No other accessories have been added or are used.

The results are fairly comparable each time I've checked it, although the results for the last check (E) are even lower.

For A - D
11.7 V = Initial power up (after getting through the menu to the diagnostic screen)
11.4 V = Pressing the power button a second time to put a minor load on the battery
14.1 V = Putting the car into ready mode

For E (after sitting for 3 hours)
11.4 V = Initial power up (after getting through the menu to the diagnostic screen)
11.2 V = Pressing the power button a second time to put a minor load on the battery
10.5 V = Turning on the lights and putting on the defroster
14.0 V = Putting the car into ready mode.

The instructions I had printed out mentioned that putting the car into the Vehicle signal check mode should show a batter voltage of 12.4 to 12.8 Volts. Similar threads I've read (after doing a search) has show some folks seeing 11.7 V, but they've been in threads inquiring if their batter voltage is too low.

OK - for the people far more knowledgable than I

Do you think my voltages are too low or are within the realm of "normal"? Is there anything else I should check?

 

I've not taken the voltage at the battery terminals (don't have a volt meter), the only values I have are from the Vehicle Service Menu screen.

 

I purchased an inexpensive ($30) meter from Lowes today. My wife had my car, but I checked it after she got home (thus car had been driven for ~ 20 minutes when I got to it).

12.6 Volts standing.

12.4 Volts when I powered it up with a light load.

I put the car in ready mode and the voltage was above 14.0 Volts (14.1 I think)

So it appears that my battery is OK. Thanks for all your help and suggestions.

 

OK, my car has been "starting" to give me some issues with the "Ready" light. I put my foot on the brake and the Start light goes green. At least 4 times over the last 5 days, the car would not go into "Ready" mode after putting my foot on the brake and pressing the Start button. I'll get a lot of icons displayed but no ready light. I've tried altering how hard I press the brake pedal (one time even getting the hill assist to kick on), but that doesn't seem to matter.

This afternoon, before I left work, I checked the battery via the onscreen diagnostic. I got

9.6 V = Initial power up (after getting through the menu to the diagnostic screen)
9.4 V = Pressing the power button a second time to put a minor load on the battery
14.0 V = Putting the car into ready mode

As you can see (from my replied post from May) this is quite a drop over the last 4 months. I've got a volt meter in the garage I can check with tomorrow morning.

One other unusual thing, I'm having a hard time getting into and staying in the diagnostic. Twice, when I was in the diagnostic, the car kicked me out of it (once when I hit the start button to put the car into Ready mode, the other time when I pressed the power button a second time).

Any other thoughts?

 

Planning on calling soon, just so busy at work this week. Hopefully Thursday will work out.

Readings from this morning (using a volt meter)

10.4 V = Initial power up
9.7 V = Putting a minor load on it
14.4 V = Ready mode (engine running, it was first thing in the morning).

I'm also having difficulty getting into the onscreen diagnostic. I press the power button once, then while I'm turning on the headlights, the display screen "resets" with the Toyota emblem and by the time I've done the lights x 3, it's not showing the diagnostic screen (getting the normal radio display instead).

 

Radio, seat warmers, rear window defroster, bright lights, wipers on fastest setting, emergency flashers (am I missing any?) lol

 

Patrick,

You've just touched upon my biggest concern, that the battery is "marginal" and they won't replace under warranty (then I'll be out the $125/hour of inspection + $139 (plus tax) for a new battery.

The car has shown some "symptoms" of a problem by not going into Ready mode (which I assume is a low battery voltage issue (as discussed in the "my prius balks" thread in this forum). But if it isn't consistent, I can't get them there.

I've got data showing the battery at 10.4 V. I checked it last night after driving home (60 min) and the battery was reading 12.5 V. But this morning it was back to 10.4 V. After my drive to work, I checked it after it sat for 3 hours and it was 10.4 V.

Will they look at a 10.4 V battery and say there is an issue or not? That is the $300 question? Does anyone know the answer?

 

Did installing this battery require any modifications to the car in order to connect it? Or were you able to unhook the old battery and install this one with no changes whatsoever?