12 v battery

nope stereo is 12 volt im sure

 

<div class='quotetop'>QUOTE(toolbox\";p=\"44251)</div>

What second 12V? I thought there was only 1, behind the right rear tire.

 

as i understand it, the traction battery pretty much does the traction and nothing else. the 12 volt battery performs all the same functions of any 12 volt battery in a regular car except starting the engine of course.

the reason why a normal car has such a large battery is to have the power to crank the engine. eliminate that need and there is little reason to have a large battery.

 

Im not 100% sure, but I think you will find that the NV system also provideds 12V for accessories etc via an inverter after the car has started, in addition to re-charging the 12V battery.

 

well yes technically you can say that the inverter does supply the electricity for everything. as with all cars the inverter provides power directly to 12 volt sources and charges the battery at the same time. howver for surge suppression, voltage control, etc, the battery is used as a balancing load.

but your question is asking what the battery is used for and when the car is not running that is what its used for. if you run the accessories too long, the 12 volt battery will not take power from the traction battery, it will die. there are many many posts here detailing dead 12 volt batteries. being cheap, expendable, and for eliminating the danger of draining the traction battery through neglect is the whole reason the 12 volt battery is there.

if the inverter did the job all the time, then why have the 12 volt battery at all?? why not just make a bigger traction battery? well the answer is simple. the two systems are not electrically connected when the vehicle is not running or at any other time.

i dont understand your questioning here. are you suggesting the 12 v battery is extraneous?? i can assure you it is not. the two batteries provide separate irreplaceable functions and are both very necessary.

 

I didnt quite say that, I said after the car has started. I base this on something I read about the electrics in the Prius and the attached PFD.

If you look at it , both the HV and the auxillery batteries feed into the inverter via another box I can translate.

 

ok the traction battery will not power anything the 12 volt battery powers at any time.

 

Is that definative then ??? :lol:

If you want I can email you the circuit diagrams and you can take a more detailed look. As I said originally, Im not 100% sure, but I understand that... Take a look at the PDF above.

I could be wrong, often am. :lol:

 

yes the 12 volt battery controls the relays for the traction battery. just as the 12 volt battery controls relays on a regular car. the duties of the 12 volt battery in the Prius is not much different than a regular car.

and i dont know how else to put it other than the two batteries DO NOT share any duties.

it is possible to drain one battery without affecting the other.

with that, make your own conclusions.

 

I still dont think you are correct. I have a document (attached) that states that the 201.6Vdc voltage is converted to 12VDC to provide power to ancillery equipment such as lights, Stereo and Climate Control (except the compressor) as well as all eUC's as well as recharging the 12V battery.

Ive attached the original document. The description is on page 8 under Spannungswandler.

I will look into this further (Im on a 12hr night shift with not much to do ) and if I find more I will report on it here.

Dave, If you have documentation that shows Im wrong, pleae post it. I would love to find out the 100% correct answer.

 

Page 123 of wiring diagram:

3. Converter
The power source for auxiliary equipment of the vehicle such as the lights, audio system, and the air conditioning system, as
well as the ECUs, is based on a rated voltage of DC 12V system. Because the generator outputs at DC 201.6V, the
converter is used to transform the voltage from rated voltage of DC 201.6V to DC 12V in order to recharge the auxiliary
battery. The converter is installed on the underside of the inverter.

 

Thanks DanMan,

Thats the same text I have in German (but was struggleing to think of some of the English terms!)

Now, how do you interperate it in turms of if the HV system is supplying the 12V system.

I did see another reference to the 12V system in another table. It gave the same basic information.

 

Well, with understanding how the charging system works on a conventional car, the converter provides the 12V when the hybrid is operational, and is charging the battery.
There is a signal on the converter to change its ouput voltage from 13.8V to 14V; the former for general power, the latter being a voltage boost to charge the battery.
While the hybrid is running, the battery would mostly be to handle sudden load variations, kind of like a big capacitor.
The interesting thing though is that the battery is directly connected to a 120A fusable link, while the power from the converter to the battery has a 100A fusable link.

 

What's the expected life of the 12V battery? Most 12V batteries in my previous cars usually died after 4-5 years.

 

Probably the same as any other battery. It is a lead/acid battery. Only difference is that it is a smaller battery, as a smaller load is required of it under normal conditions.
Come to think of it, that smaller load requirement may make it viable longer. In a conventional car, the battery may seem good until you try and start the car, because a great deal of current is required of it to start the engine. In the Prius, the battery only powers the electronics that engages the hybrid battery, and then the converter takes over the 12V load.

 

the 12 volt battery will probably go 4-6 years as a normal car battery only has a life of 3-4 years (less in the colder climates)

one thing you need to realize is that running the battery to a very low state as little as a half dozen times is enough to shorten the life of the battery by as much as 50%. so it would depend on whether you disconnected the battery if you plan to park it for extended periods of time and so on. in this case, driving it every day will help it and since it doesnt have to worry about providing the huge load neccessary to start a car will help out a lot.

 

<div class='quotetop'>QUOTE(DaveinOlyWA\";p=\"45094)</div>

I can vouch for this. Heck, if it were economically feasible, we who live in cold climates could sell our "useless" batteries to people in warm climates and they could get a couple more years out of them. Why? Because when the car won't start at -10F or -20F in Dec-Feb, we take the battery to Sears for the $5 recycle credit and buy a new one. That same battery would be fine all summer long here, or all year in TX. Our cold cranking amps have to work in COLD!

Years ago, I tried to start my car on a very cold morning until the starter didn't make a peep. Caught a ride to work with a neighbor. When I got home it was sunny and about +25F. The car started without any charging or jump. I expect my Prius 12V battery will last at least twice as long as those in my prior cars.