Toyota Prius Forum banner

1 - 8 of 8 Posts
G

·
Guest
Joined
·
0 Posts
Discussion Starter #1
I am a little confused on the purpose of the so called Motorcycle 12 volt battery. I have been trying to digest just what the purpose is, from that Yahoo message board. Is it used only for starting and maintaining the screens, computers, anti theft stuff etc??? The reason I am concerned, is because when my wife goes shopping, sometimes I sit in the car and play the radio for an hour or two with the ignition swictch in accessory. Now is this radio running on the 12 volt battery or the Hybrid battery??? Also, what about other accessories like Fan, wipers, window up & down etc??? If the ready light is on and I switch to Accessory, the Monitor stil shows the data and Green battery. If I lock first, and then switch to Accessory, The monitor shows no green on the battery. These are just a few observations. Also, sometimes the drivers window will operate and other times it will not???

Help, please!

Don Good
 
G

·
Guest
Joined
·
0 Posts
Discussion Starter #2
The driver's window will operate after the key is turned off until you open a door. Many Toyotas do this.
 
G

·
Guest
Joined
·
0 Posts
Discussion Starter #3
> Now is this radio running on the 12 volt battery or the
> Hybrid battery???

The radio operates on the 12 Volt system.

> Also, what about other accessories like Fan, wipers,
> window up & down etc???

Yes, all 12 Volts just like other cars.

The 12 V battery gets charged by the 273 Volt HV battery through a DC to DC converter when the car is READY. The HV battery is disconnected when the car is not READY (off).

When the Prius is in ACC the 12V battery provides power to the center display, stereo system, numerous computers, as well as numerous energized relays. Using the stereo in ACC for a couple hours could be a bit much to ask from the little sealed 12 Volt battery. If the battery has a full charge you should not have any problems, but in case you start off with a 12 V battery that is a little low you may want to become familiar with the jump start procedure. :)


Ed
 
G

·
Guest
Joined
·
0 Posts
Discussion Starter #4
Thanks Ed

Guess from now on, if it's more than 5 or 10 minutes, I'll only run the radio when the Ready Light is ON

regards,
Don Good
 
G

·
Guest
Joined
·
0 Posts
Discussion Starter #5
Does anyone actually have the amp-hour numbers? Intuitively, it does nto seem like having the radio on for a couple hours would put a crimp in the battery's charge.

Just as a thought experiment (which we do when we do not have the numbers :) how long would you expect the headlights to last when not in ready mode? Surely the headlights draw 10 or 20 amps. Surely the radio is on the order of 1 or 2 amps. Thus if you think the headlights should last, say one hour then I would expect the radio should last 10 or 20.

I know that someone in the Yahoo tech forum posted some numbers for the amp-hours of the battery as well as the current drain with no accessories on, so some of the numbers are there. I'm just a bit too lazy to find them tonight :)

[%sig%]
 
G

·
Guest
Joined
·
0 Posts
Discussion Starter #6
Burns,

This may be what you are looking for.

<http://groups.yahoo.com/group/Prius_Technical_Stuff/files/12V%20Battery/12VBattery.htm>

The Prius New Car features book lists the 12V battery at 28 amp-hour. At the link above you can see that Julian measured his Prius battery to be 26.3 amp-hour.

I do not know that anyone has measured the load on the 12V battery with key in ACC listening to stereo. This would be interesting. If it is only one or two amps then I agree with you that one could listen to the radio for many hours. However, I have a feeling that when the key is in ACC there will be more things consuming power than just the radio.

By the way, the key-off load of the Prius was measured by Ernst Schmidbauer to be about 75 mA.
<http://groups.yahoo.com/group/toyota-prius/message/10890>

Julian measured the key-off load to be about 35 mA.
<http://groups.yahoo.com/group/Prius_Technical_Stuff/message/1642>

Ernst comments on Julians measurement. Ernst suggests that the "self-discharge" current of the battery is not taken into consideration and that 35 mA might be too small for estimating battery life.
<http://groups.yahoo.com/group/Prius_Technical_Stuff/message/1646>

I guess I'll estimate the key off load at 55 mA +/- 20 mA. :)

Ed
 
G

·
Guest
Joined
·
0 Posts
Discussion Starter #7
Thanks for doing the work for me Ed. 1 or 2 amps for the radio sounds reasonable (that's somewhere between 12 and 24 watts) . I'll bet the MD takes a bit of current. The LCD display on my digital camera takes over an amp at 6V.

Burns

[%sig%]
 
G

·
Guest
Joined
·
0 Posts
Discussion Starter #8
I'M WANTING TO HOOK UP A DCTO AC CONVERTER 300WATTS (600 MAX), 30AMP FUSE. I AM PLANNING TO CONNECT TO 12 V BATTERY (POS ONLY) NEG TO SEAT FRAME. WILL MOST LIKELY ONLY USE IT WITH CAR IN "READY " MODE.

BEING A SOCIAL WORKER NOT ELECTRICAL ENG. IS THIS GOING TO CAUSE A PROBLEM!

STEVE BOWLAND
CROSSVILLE TN
02 MOON BLUE
GOT IT 04/26/02
1100 MILES
(I'M TOLD 'JUST DRIVE IT" SO I DID)
 
1 - 8 of 8 Posts
Top