Replaced 12v battery after red triangle warning - still low voltage

"New" does not mean it is a quality part or that it was fully charged when installed... it SHOULD mean both those things, but sadly not necessarily true.

The 12v battery is maintained by the inverter, where the high voltage is lowered to "charge" the 12v battery. If there is an over-night drain on the 12v, the inverter will NOT be able to correctly maintain the 12v battery as it really cannot "charge" it like a traditional alternator or battery charger could.

Was there a fat spark when you connected your new battery? If so, I would have the vehicle checked for an excessive parasitic drain. If not, the new battery may not have been fully charged when installed and given that the inverter effectively cannot charge it, you may have to apply a battery charger to bring it up to full charge. The inverter should be able to take it from there, if it is working correctly.

 

When you say "on the display", do you mean in the Vehicle Signal Check screen on the MFD ?

That came up in another thread just last night. I beat you by 0.4 volts, mine showed 11.2 in ACC and that's with a splendid new Toyota battery from just this last winter that got a full charge before installation, and there aren't any problems with my car.

I would suggest stressing less about the battery right now, and just proceeding to ask your car why it is lighting the triangle. From your post it sounds like you haven't done that yet.

 

As Chap said, the red triangle means read the codes to find out which of the gazillion things that can light that triangle lit it. And use a Prius literate reader, not a generic one that doesn't do hybrids. Lots and lots of threads here about that.

 

There may be other problems too but...............
Almost without exception, batteries shipped directly to you MUST be manually charged before being used
AND they have an instruction sheet saying that.

 

what brand did you buy?

 

Regardless, you should manually charge your new battery and test the charging voltage in the car BEFORE you run off chasing potential ghosts.
But given the age of your car, you probably are looking at other major problems developing.......like a hybrid battery.

 

Exactly. My brand new 12V was a volt low, had to charge it before using it

 

Dont stress about charging it and just drive it a while. Either go for a drive to get out of the house or even just start the car and leave it parked in the driveway for like 30min . Also when on acc mode things are being powered which is causing your voltage to be low. Only way to test the battery is with eveything off it should be over 12v

For fun you can power the car up and then check the battery. just have it in park and e brake one. The volts will be 13v+

If the trouble code stays on then you can just stop at autozone and they will check the code for you. I dont have anything special for checking and mine showed all my 240v battery issues just fine.

 

... which only tells you that the charging system is working. You aren't able to get a battery voltage measurement in that condition, because your meter will be showing you the charging voltage.

 

Um, no. The DC-DC converter is NOT designed to "recharge" the 12v, only to maintain system voltage in use.

Nope. If the car is "on" the DC-DC is powering it, if your voltage is much below 13.5vdc in that condition, the DC-DC is not working correctly or the 12v is badly discharged and MUST be fully recharged using an off-board charger.

 

I've 'recharged' a Gen 2 by leaving it on for a while after a severe discharge, but it sure didn't take 30 minutes. It's a forty-some-amphour battery, and the charging system might be seen putting 7 amps or so into it initially but quickly falling back to under 5 amps for the bulk of the time. So it's an overnight sort of proposition, if you have a place to safely leave the car in READY overnight.

Of course if you have a ten or twelve hour road trip you need to make, you can do it that way too. It won't be fully recharged by your first stop for gas, but it will be enough to start up again.

 

Sorry but most of that is BAD advice.
Many cars these days will NOT fully charge an almost dead battery, no matter how far you drive it (well, hundreds of miles maybe).
Second, 12.0 volts is half discharged and is NOT considered "good".

If your battery is really low, it NEEDS to be manually charged before testing.

 

Incorrect. The 12V charging on a Gen2 is not quick. It will take a very long drive to top-off a new battery which sat in a warehouse for months. You are better off spending an afternoon letting AutoZone charge It for you and then be done with it.

 

Did you get something that looked like a turtle on the MFD in addition to the Red Triangle? Generally a low 12v voltage does not make the red triangle go on.