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We are six weeks now waiting for a Silver Seven and, in the mean time, it has been interesting reading these posts about the car. I feel like I know a lot about the car, perhaps as much as some Toyota dealer techies.

It seems to me that, after reading these posts, those of us who are used to using the car's 12 Volt accessory receptacles for powering accessories while camping or at other times with the car's system off are going to have to change our ways-the auxillary battery system just isn't strong enough to support that. :( . If it won't keep itself powered for longer than a couple of weeks, off, certainly running a small TV for an evening is out for sure. I suppose one has to use a separate battery pack to enjoy the car when it's not running. Comments?
 

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On the classic Prius, the 12v accessory
outlet is powered off when the car is off.

On the 2004 Prius, the 12v accessory
outlet by the passenger's seat is
powered off when the car is off. I
haven't tested the 2nd 12v accessory
outlet in the center console to see
if it also powers off with the car.
 

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Lemme extend Michelle's comment a bit....
Indeed, both 12V outlets power off when the car is powered off. If you desired to power an accessory via the Prius you could always put the car into the IG ON mode (two pushes of the power button without depressing the brake). I THINK this would allow you to use the 12V outlets and the HV would continually recharge the 12V battery giving you a pretty long duration of power.

Alternatively, you could power the prius all the way up to READY mode and just let the ICE run as needed. I think that would be a pretty minimal amount over the course of an evening if the only power drain was a TV or something like that.
--evan
 

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efusco said:
Lemme extend Michelle's comment a bit....
Indeed, both 12V outlets power off when the car is powered off. If you desired to power an accessory via the Prius you could always put the car into the IG ON mode (two pushes of the power button without depressing the brake). I THINK this would allow you to use the 12V outlets and the HV would continually recharge the 12V battery giving you a pretty long duration of power.

Alternatively, you could power the prius all the way up to READY mode and just let the ICE run as needed. I think that would be a pretty minimal amount over the course of an evening if the only power drain was a TV or something like that.
--evan
The hybrid traction battery is only
connected when the car is in the
READY state.

It is the hybrid traction battery
that charges the 12v accessory battery.

Based on other posts, I think the
center console outlet is powered
on at all times, though.
 

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efusco said:
Lemme extend Michelle's comment a bit....
Indeed, both 12V outlets power off when the car is powered off. If you desired to power an accessory via the Prius you could always put the car into the IG ON mode (two pushes of the power button without depressing the brake). I THINK this would allow you to use the 12V outlets and the HV would continually recharge the 12V battery giving you a pretty long duration of power.

Alternatively, you could power the prius all the way up to READY mode and just let the ICE run as needed. I think that would be a pretty minimal amount over the course of an evening if the only power drain was a TV or something like that.
--evan
forgot to mention that the ICE will
come on not only to power the
hybrid battery when it gets discharged
(from powering the 12v accessory
battery, which is providing power to
your TV, the car's clock, the car's
alarm (if so equipped), and the car's
computers) but the ICE will come on
to keep itself warmed up. In the
summer this may not occur very often
(15+ minutes), but if it's a cool
evening or even worse winter the
ICE may rarely ever go off.
 

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There are several accesory 12 volt battery thingies on the market. Plug one into a Prius accessory socket and it will remain charged while driving and will provide power when the car is OFF. If the convenient batt packs don't have enough amp-hours for your needs, get a deep cycle 12v batt and put it in a plastic battery box (Wally world or auto parts store). Take this camping with you.

If you can get the spec on the maximum current the accessory outlet is designed to handle then you can arrange to charge the battery from the accessory outlet. Lets say, worst case, you aren't a moron and wouldn't discharge a nominal 12 volt battery (14.2 volts at full charge) below 10.2 volts. Then, when discharged (10.2 volts) there is a 4 volt differential between your accessory batt and the running Prius battery. Mr. Ohm said that current is directly proportional to voltage and inversely proportional to resistance (current equals voltage divided by resistance). So you need a resistor, the value of which in ohms is found by a little algebraic manipulation which shows us that the resistance is equal to the voltage divided by the current. The volage in question is the difference voltage of 4 volts. The current in amps is whatever the outlet is rated for. So 4 divided by the rated current gives the ohms of resistance needed.

That max current rating times the 4 volts is the max power dissipated by the resistor. (Power in Watts is equal to current times the voltage)

Now you know the minimum safe ressitance to use and the minimum safe power rating of the resistor. Now what do you do with this resistor? Place it in series with the charging current flowing between the accessory receptacle and the battery to be charged. Take the power to run your TV or whatever directly from the accessory battery NOT through the resistor.

This resistor will prevent overloading the accessory outlet so long as you do not connect a battery that is discharged below about 10.2 volts. It will get hot if the accessory batt charge is low and the Prius is "ON." This is normal and it requires caution so it doesn't constitute a safety hazard. If the accessory batt is not discharged very far the resistor will not heat so much when the Prius is started up. The higher the level of charge in the accessory battery the cooler the resistor will get.

There are much more sophisticated ways to accomplish what I have described but this method is dead simple and is cheap to do.

If someone will supply the specs on max current draw from a Prius acceessory outlet, I will calculate the the resistance and suggest values for the ohms and watts ratings. A couple years ago you could have bought a resistor at Radio Shack but they are or have phased out electronic components pretty much except for batteries. (BOO HISS!!)

:D Pat :D
 
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