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

Car scanner pro for iPhone.

 

That is the charging system voltage.
You can NOT deduce much about the state of charge from that.

 

I agree that is a reasonable assumption.

If it is indeed true, then there is a fault in your charging system that REALLY needs to be fixed.
OR there is an unusually high continuous load somewhere other than the battery that makes it charge at a higher voltage.

While it is possible for a battery to fail in a manner so that it will continue to accept a high charging current without actually charging much, it doesn't look like this is the case here.

To review, the symptoms were basically the same before and after putting in a new battery, right ?

 

Must be a thing. After three cold days, single digits, and a snowstorm, I just went out and it gave me that tired, I'm Really Old and Cold sound. I suspect that after 7 and a half years, it's just too old to put up with this crap. Wish I started it yesterday, now it's Friday, as usual.

 

The OEM Toyo A20s were horrible in rain and snow. Continental ecoPlus PureContacts year round, and Dunlop M3 Wintersports for the heavy stuff.

 

Classic case of battery comorbidity - age and cold.

 

Covid-related, hadn't started it since Monday.


Santa got me a new 1200 portable battery thingie. How handy.

 

I had such good luck with Generals, I have a new set of the AltiMax Artic snows on this year, and studded too. Interesting the the Generals are amongst the cheapest, perform excellently, and have lasted me longer than any other tire.

 

Well Santa's Schumacker batter worked, Prius all started and happy. wished the cables were longer. It really needed about 5-10 minutes just hooked up before it would charge. Since it's an easy fix, I might just want to go to the dealer and have them put another one in. This is not the kind of thing I want to do often.

 

Every seven years, whether you need it or not...

 

I don't understand.
I don't think that there are Schumacker brand batteries.
So..... what exactly did you replace ?
And how are you gauging "charging" ??

 

It is a jump starter for his 7.5 year old battery. He is getting a new battery because "its an easy fix". "Charging" as related to a dead battery and a jump start module means leaving the jump on long enough to pull the car battery up some to allow the Prius to initialize.

 

For conventional cars the typical alternator IC regulator voltage is 14.3 V, with 13.5–15.1 V being considered a normal rage.

Looking at the Prius Prime OEM repair manual, the specified range is 13–15 V.

If you are using an external charger, the OEM repair manual is recommending 5 A for normal charge and 15 A for quick charge.

So, everything is fine.

 

Yes, that's what I meant. I saw that online in a couple of places, so I didn't worry when the first try failed. After probably 15-20 minutes hooked up, it finally started.

 

Yes, batteries have an internal resistance, that's why you see a voltage drop when a current passes:

V = ( V open circuit ) − ( I × R internal )

If the voltage drop is 0.4 V @ 10 A, it means R internal = 0.04 Ω. This corresponds to an SOC of roughly 35% according to the plot below; so, you still need to charge your battery.



Likewise, you can use the open-circuit voltage per cell to estimate the SOC. Yours is 12.4 / 6 = 2.07 V. This corresponds to an SOC of roughly 50%. 11.8 V is almost fully discharged and 13.1 V is fully charged (SOC at 100%).

 

Not exactly sure what you mean by "standby" but in "accessory only" mode, I'm pretty sure that it should not draw anywhere near 10 amps with all of the obvious things that you mentioned switched OFF.

If it starts at 12.6 or above, a .5 V drop when a 10 amp load is applied wouldn't be particularly noteworthy. It IS a fairly small battery.