How many amps used from 12v battery?

From what I understand the 12v battery is used to boot up the main ECU. After that the HV battery does the majority, if not all, the battery duties. This is one of the reasons why CCA ratings don't mean squat to a Prius.

 

Seems like the OP had more specific questions in mind. I know there has been plenty of past discussion ... my sense was that the load when the car is off might be somewhere around 30 mA. With the interior lights left on, probably somewhere in the neighborhood of an amp (I have not measured this, I'm just estimating based on the idea of one or two several-watt dome light bulbs).

When the start button is pressed once, foot off brake (ACC mode): haven't measured, would guess several amps (depending on how loudly you're playing the radio).

Start button pressed twice (foot off brake - IG ON mode): I haven't measured, I'm thinking tens of amps (again depending on what you've turned on, you might near 100 if you have window defoggers, wipers, seat heaters, and heater blower all cranked up).

Start button pressed twice, pressing the brake pedal: is this a trick question?

Start button pressed, pressing the brake pedal (READY ON mode): I think it's been reported to peak around 30 amps briefly, just until the main relays and the hybrid system come on line in a split second; after that the current flow is into the 12 volt battery, because the DC/DC converter has taken over supplying it. The charging current (into the battery) is not supposed to exceed about 5 amps.

To find other threads that may have more definitive, measured information, you probably can search here on PriusChat a little harder, and also don't overlook hobbit's many Prius links.

-Chap

 

Well, if it's Prius technical information you're looking for, sooner or later you're going to know hobbit's site inside and out.

You might start with his 12 volt battery page, and his tech training page at the sections for "Startup" and "12V currents".

Each of those sections shows a scope trace, so you get a good qualitative idea, though it's funny I never noticed before the vertical scales are both unlabeled. (Or rather, the second one has the scale labeled 50 mV, so he was apparently measuring across a shunt or using a Hall-effect clamp, but I don't see those details in the page for you to get from the scope's millivolts back to amps.)

I notice he measured the resting current of his Gen 2 (without smartkey) at around 11ish milliamps. That's lower than I've ever measured my Gen 3, I think I was seeing around 30 mA even with smartkey off.

You could take some measurements yourself and add to the body of knowledge ... you can probably also get the volts-to-amps relationship for hobbit's scope traces if you communicate with him. (Maybe that training page is just a summary and he has more detailed pages for the various sections ... I haven't found them just poking around this morning, but that doesn't mean they're not there.)

-Chap

 

Thinking my 2007 has a high amp draw at 10.5 amps just hitting the button twice with foot off the brake no access on ,the hv relays getting 11 volts and won't kick in

Posted via the PriusChat mobile app.

 

You might try pulling different fuses to find which circuit is shorting out, probably starting with the Dome Light Fuse, since many of the accessories draw their power through it.

Gen2-Dome Light fuse | PriusChat

 

Actually, before you even start thinking about accessories that might be drawing down your power, though, you would be better off checking the fusible link that @TMR-JWAP pointed you towards in your other post.

Low voltage to traction battery relays. (11.2) , inverter pump doesn't run | PriusChat

 

Yes.....check the fusible link....or just pull the two abs relays.

Otherwise you're going to drain the 12v battery pretty quick if you leave the car powered up.
or you'll burn up whatever is drawing that 10 amp load..i haven't really dug into that yet, but since it's the abs system pulling the current, my initial guess would be the abs pump trying to run because it's lost it's ecu sensors or something.

 

It is not a great idea to be posting about the same problem in two (or more) different threads. Pick one and use only that one.