Posted by fuelzilla.com on February 26, 2008, 6:42 am
Shawn Hirn wrote:
I have left my 2007 Prius at home and at long term parking lots for more
than a week several times and had no problem starting it. I would imagine
the smart key system draws only a trickle of power in the listening mode.
I think the recommendation should read "if you wont's be using your car
for weekS (plural)" or maybe even months.
In this case it's more likely someone left radio on.
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Posted by richard schumacher on February 26, 2008, 2:53 am
Something was left on. Of course now it's impossible to prove either
Posted by TKM on February 26, 2008, 2:13 pm
Thanks for the useful comments. A recheck of everything (lights, radio,
etc.) indicated that nothing was left on; so it was likely the Smart Key
System plus a 12 volt battery that was not at full charge because of short
trips or heavy accessory use just before the week-long shutdown. Very cold
weather during that time may have contributed too.
What I plan to do (when the weather warms up!) is to check the current draw
of the Smart Key System against the capacity of the battery to get some idea
of what Toyota means when they say to turn off the Smart Key System when
"the vehicle is left for a long time". I also think an indication of the
state of the 12 volt battery would be a good addition to the display roster.
Posted by richard schumacher on February 27, 2008, 4:00 am
Ah, now it comes out: "heavy accessory use" is the culprit here. The
ACC position should not be used for more than a very few minutes at a
time because it tends to kill the undersized 12V battery. Unless the
car is in an enclosed space, when accessories are in use it should be
left ON and in Park so that it can manage its own energy as it was
designed to do.
Posted by Chas Gill on February 27, 2008, 9:54 am
If I recall correctly from a couple of years ago, one of the biggest power
drains is the dashboard display. In fact I recall hearing (or reading)
somewhere that it's best to avoid using it in the accessories mode for more
than 30 minutes as it had a tendency to discharge the battery. As a matter
of course, therefore, if I happen to be using the radio in accessory mode I
always turn off the display via the menu, as a precaution. However, the
dealer didn't say WHICH battery and I'm fairly sure I've read somewhere else
since that the 12v unit is really only there to power low wattage critical
systems (such as engine management and other systems at start-up) and that
everything else is energised by the HV unit, so I'm not really sure whether
what he said was true or not. Perhaps there is an expert reading this that
can clear this up?