12v battery / charging questions

Yeah the motor generator that does the generating generates the 211 volts to charge the HV battery The HV battery when the car is ready sends power to the inverter the thing up on top of your transmission right under your nose when you open the hood that has a circuit in it that takes 211 volts and inverts it or changes it to 14.5 volts DC to charge the battery That's why when you're sitting there with the battery in the car hook connected and you hook up your test meter and the car is not on ready or running you see battery voltage let's say 12 volts You leave those terminals connected to your DVLM and sit it up on the back headrest so you can see it get in the car and ready the car the minute you ready the car you see the 12 volt battery voltage where your test leads are connected immediately jump up to say 14.3 to 14.5 volts something like that then if you push the button again and turn the car off that 14 disappears and immediately turns back to right around 12. That 14 you're seeing when the car is ready is the circuit charging your car and if it's doing like it's stated here it's probably in great shape nothing further needs to be checked need to deal with the battery itself the terminals connections whatever could be just a crappy battery that's very easy and very normal little short trips starting the car and going nowhere Prius is not happy with that that's just a fact Make it a 20 minute trip or something along those lines maybe the Prius is not the best choice and best fit for your driving needs That's a great possibility.

 

start with a free load test of the battery at auto zone.

once confirmed good, it should barely drop at all out of the car for a week.

to check the charging circuit, measure the battery with the car ready. it should read 13+ to 14+. and will fluctuate as the battery needs charge.

if all passes, check the battery with in the car with the car off every morning until you get a handle on how fast it's draining.

 

sorry to hear that, i hope one wasn't auto zone. either way, might make sense to call ahead, and a load tester is a hand held device:

ref=asc_df_B000AMBOI0

 

yes, it's check available 'cranking amperage', as if it were trying to start an engine with a starter motor, even though prius uses the hv battery. the starting load on the 12v is pretty light.

 

When testing 12V batteries after use it is important to remove the surface charge before measuring voltage. Otherwise the readings are not very meaningful. Also on this car (in particular) the computers do all sorts of things for quite a while after the car is "off" and those loads can change the voltage if present during testing.

 

about 4 hours, or turn the headlights on for a minute or two.

 

BU-804c: Acid Stratification and Surface Charge - Battery University

Wait 4 hours or overnight. Another wrinkle is that the car wakes up if any of the doors are opened and that pulls a current out of the 12V dropping the voltage (slightly). So to measure it without that complication one must leave the hood released, then open it fully (without touching the fob or opening a door or hatch) and measure at the jump point in the fuse box behind the driver's side headlight. To measure directly at the battery the hatch has to be left open (easier than crawling in through an open window), which normally counts as a "door open" state and will run down the battery. To avoid that, jam an appropriate sized carabiner into the slot where the loop on the hatch normally goes. If done right the latch will audibly "click" and the car will think the hatch is closed because the hatch lock is engaged. To release the carabiner press the button on the hatch as one would normally do to open it. Be really careful not to try to close the hatch with the carabiner in place!

 

sounds like your good. just check it every morning until you're comfortable.
best way is to pop the hood the night before so you don't turn anything on in the morning before testing.
if you can't do that, lean in from the passenger side, that only turns on the interior lights.

 

Passenger door open is 500 mA draw from the 12V with the car off and the car unlocked (for a "long" time). Unlocking the car with a fob right before the door is opened might wake up some computers for a while.

 

Sounds good

 

Just start an off-line log; the ability to edit a post only lasts a few hours.

Too: voltage is just the tip of the iceberg. I'm using the "conductance tester" shown in this video:

Current iteration is Solar BA9.