Prius 12V battery charging at 14.9V/10A???

it sounds to me like you got a new battery that had been sitting for some time, and need a charge before installation, which most places never do.

i would either buy a smart charger, insist the place you purchased from put it on a charger, or call around to auto parts stores to see if anyone will give you a free charge.

a new battery should be reading close to 13v after a full charge and sitting overnight.

then the charge voltage from the car would be interesting to know.

 

Undoubtedly for ease of assembly, and figuring nobody has a good reason to be there.

So, it's a feature, a deterrent, not a bug... That's their story, and they're sticking with it.

 

As promised, we have a result.

1. Measured 21 ma steady state current. Varied from 20.3 ma - 25 ma. It was 20.3 about 95% of the time.

2. Opening hatch or a door would draw 1750 ma dropping to 21 ma within 75 seconds after closing the door.

I did not break the 12v current path to insert the ammeter, so no major sleep delays occurred. I used a $400 meter and then a free Harbor Freight meter. The results were identical.

Process to insert ammeter withou opening battery circuit:
Added a jumper from the neg terminal to a grounded hold down bolt. This provided an alternate negative current path. Then disconnected the neg battery terminal at its adjacent chassis ground bolt. This allowed me to hook a ma meter in series to the disconnected cable end and back to chassis. Then removed the first jumper and all the current was flowing through the meter without actually opening the circuit. After sequentially observing the current using two different meters, I connected the first jumper to carry the current and reattached the normal gnd cable. No computer startups.

 

Would it be fewer steps to just have the ammeter in series with the added jumper, disconnect the original ground to get ammeter readings, then put it back when done?

 

No user setups are lost and no unlocking steps. it just takes longer to make valid parasitic measurements.

As far as the wiring goes it only took a couple of minutes. I did run the wires out of the hatch so that I could close it with the meter outside. I swapped in different meters and took a few other measurements. For example the homelink autodim rearview mirror takes 6 ma.

 

Sounds like you have it under control. Remote start is probably drawing 30 ma since it has to be on 24x7 to work. Fob too close may have been the root cause of the last battery's early demise.

I did not remember the option to turn off smart key. My 21 ma may go down to 11 ma when needed. Looks like there are built in power savings strategies but they take 14 days to totally disable. See pic.

Be sure to let your service advisor know, you may want to be on his good side sometime in the future. Tell him you rev'd it up and everything just fell into place.

 

Have you checked the battery connections on the battery that they installed and made sure that they are clean and tight?

 

And the other end of the negative cable

 

So....now I think you need to consider that there really IS a problem.....but it's not what you have been chasing.
It is likely, I think, that there is something that is drawing excessive current from the 12 V system while the car is running.
This causes it to think that the battery is low when it really isn't.
I would normally say this is the battery itself but you have already put in a new one, so that is not likely to be the cause.

Continuously charging the battery at 14.9 will shorten it's life.
And there is something that is not working right that needs to be located and fixed.

 

He knows the last battery was bad, he knows if the battery is fully charged the voltage goes down, he knows that his aftermarket remote start is pulling 30 ma continuously, he knows his key fob was stored close and he knows he could get it down to 11 ma drain once he finds the remote start. As is, its 50 ma and more with the fob nearby, which over a period of years, shortened the life of the last battery, especially this year when he did not drive it for extended periods. He bought a solar charger and has an easy and effective way to check the results.

 

Yes.
And NONE of that fully explains why it is over-charging with a new battery in place.
If the 14.9 really is continuous, as in: it does that immediately after the battery is fully charged, then SOMETHING IS WRONG.

 

Your battery voltage seems to be ok, but what is the actual charge percentage when load tested. Back before Thanksgiving when I was going thru the same thing, a load test at two different places showed a 82 and 84 percent charge. The major chain parts stores won’t “normally” test a hybrid 12v while installed, but maybe a repair shop other then the dealer will.

 

This was ign on, brake pump on before going to ready. After ready, 13.95 on the voltage.

 

That is the ONLY way to see the actual battery voltage.
The MFD display is always low by several tenths.....and tenths are important.

When the car is "running", you aren't seeing the actual battery voltage but the CHARGING VOLTAGE and 14.9 is too high for continuous operation. Way too high. Something is wrong and needs to be fixed.

I think this is about the third time I've said that.
Now I'm done.