Prius battery and going on vacation

That's true for any vehicle, not just Prius. The 12-volt can only keep the security system running for so long before it is drained entirely. So you are best off to disconnect it.

The battery-pack is pretty much immune to long-storage drain, simply because a relay seperates it from the system each time shut the Prius off.

 

<div class='quotetop'>QUOTE(erwin @ Nov 24 2006, 12:32 AM) [snapback]353629[/snapback]</div>

There is a push in/out switch labled "key" on my 2006 that shuts down the keyless entry/start and would help stop battery drain during a long idle period. It is located under the steering wheel.

 

<div class='quotetop'>QUOTE(john1701a @ Nov 24 2006, 05:49 AM) [snapback]353633[/snapback]</div>

Hi John,

I presume you mean disconnect the 12v battery rather than the security system.

If so, wont that damage the HV battery? I thought the 12v battery trickle charges the HV battery? Any idea how long the HV battery can stand the 12vbattery disconnected without being damaged?

what about connecting a second 12v battery in parallel to the first 12v battery?

Mark

 

<div class='quotetop'>QUOTE(rathercasually @ Dec 8 2006, 09:50 AM) [snapback]359287[/snapback]</div>

Yes, he means the 12V battery

The HV battery can be thought of as 20 12V batteries tied together. When the car is running and you're driving around, the HV batteries are charged from the motors (through regenerative braking, or from the ICE). There's then a step down converter that ties into the 12V system to provide power to the accessories, lights, etc and recharge the 12V battery.

When the car is turned off, the HV batteries are physically disconnected to keep them safe - they can sit for weeks and months without being damaged. The 12V battery, as in any car, provides a small amount of power for things like the security system, and as such can be run down to the point where it won't start the car.

You could do that... but i don't see much reason for it. If you're only gone for 1-2 weeks, the car should be fine. as an added safety measure, you should turn off the SKS using the key button under the steering wheel, since that will lower the drain on the 12V battery. you then have to use the metal key in the FOB to unlock the drivers door when you return.

Other options, if you really want to make sure your 12V battery is ok after your trip, include disconnecting it (you can still unlock the car with the metal key, crawl into the back and reconnect it - it's in the TRUNK, if you didn't already know) and hooking it up to a battery minder - essentially a 12V battery charger that plugs into the wall.


to answer the other question in your original post, if the 12V battery dies, you can jump the car just like any other car. If you pop the hood, there's a fuse box (with a black cover) on the drivers side - take the cover off, and there are terminals there for jumping the car - that way you don't have to go digging around in the trunk. Since starting involves booting up the computers and connecting a few relays to the HV battery, it's actually easier to jump a Prius than other cars, which require a massive surge of current to start.

 

<div class='quotetop'>QUOTE(eagle33199 @ Dec 8 2006, 12:14 PM) [snapback]359335[/snapback]</div>

Thank you, I hadn't realized that.

Given that the Prius auxiliary battery is so small, is it still practical to use the Prius to jump another car?

Blair

 

Before Charles posts to tell you to read the manual...

No, jumping another car in not recommended. It's possible, and people have posted that they did it without any problem, however it could cause problems.

When a typical car starts up, the started draws a lot of power from the battery. in trying to jump, it's drawing the power from the other car. There's a high amperage fuse (100A, 120A? i can't remember) protecting the link between the HV batteries and the 12V system. With the high current draw from another cars starter, and the current draw from your accessories, you risk blowing this fuse, which then essentially makes the car inoperable until you replace it - and it can be expensive.

 

With great success I have used a solar trickle charger 9 (which came with my TDI) that plugs into my underdash power port.

The only challenge is that that the mod has to be done that changes the circuit from ignition open to being contantly open so you could charge your cell phone as I do.

I have been away up to a month with no ill effect.

 

How much you should worry about this is a function of how long you're going to be gone. I took a 3 week vacation last month and all I did was turn off the smart key function. The car started with no problem when I got home. With smart key turned off I don't think there is any drain on the battery unless you have an alarm. If you do have an alarm, you might want to turn that off too if you're parked in a secure place.

 

There is a small drain, between 20 - 30 mA, without smartkey. This
is just keepalive for various processor memory, minimal standby
power for the body ECU and RF-remote-clicker receiver, etc. I think
if you pull the DOME fuse, as long as you're muckin' around under
the hood, that kills all that stuff too. But I haven't actually
checked this for zero current draw... doing this has the downside
that the engine ECU has to re-learn a bunch of maps, you lose your
seatbelt/backup beep settings and MPG average, clock, etc too. And
more subtle, all the OBDII monitor tests have to re-run once the car
is powered up, which may take a few more drive cycles before you can
pass emissions inspection.
.
So balance your needs and trip duration...
.
_H*

 

OK, I just got my new Prius last week (YEA!) only to have a blizzard here in Denver. So I haven't driven it since Tuesday and, because of my vacation, won't be driving it again until next Wednesday -- 8 days. Not too long, so do I even need to disable the SmartKey? If I do, can someone remind me how to do that (I left my manual at the office.) And how to restart SmartKey when I get back. Thanks!!

Prius Newbie,
Aimee

 

Hi rathercasually

Quote: "I presume you mean disconnect the 12v battery rather than the security system. "

Disconnecting the 12v auxiliary battery would delete all your radio presets and, if I remember correctly, the memory points in your NAV system. As others have posted, I have left my Prius parked for 2 weeks having only disabled the SmartKeySystem, without problems - she started up just as usual.

HAPPY CHRISTMAS and a HEALTHY, PROSPEROUS NEW YEAR !!!

 

<div class='quotetop'>QUOTE(emme @ Dec 22 2006, 12:12 PM) [snapback]365773[/snapback]</div>

Just below where the steering column enters the dash board is a push button labled "KEY". Push once to disable; once more to enable again. Most likely you do not need to, but it's easy so why not?

 

First off, the 12V never charges the HV batteries. The ICE does that via MG1 or the momentum of the car through MG2 to some degree using the inverter to convert 500V AC from MG1/2 to 200V DC to the HV. The 12V only runs the electronics to manage the inverter.

There IS a DC-DC converter than changes the 200V DC from the HV battery to 14V for the 12V electrical, but that only operates in READY mode. Outside of READY, the HV battery is totally disconnected at the + and - side of the HV battery (which by the way even the - side of the HV battery is isolated from the chassis, which is the - side of the 12V)

HV battery should sustain enough power for months. The 12V battery is another story for the reasons others have described.
I think you can also disconnect the main 12V from the jumper terminal. Remove the nut and disconnect the wire. At least it is possible in the Classic.

 

thank you thank you.
Toyota doesn't seem to understand battery issues as well as you all do.

I bought my 07 in November 06.
I really like this car except I have been unable to start the car after not driving it for 2 days.

I have had 8 occurrences of dead battery. I had to be towed to the dealer 2 times before the service manager even told me that the failure was caused by letting the car sit - "the car is made to be driven!" he said - Ironic since I bought it to pollute less - now they want me to aimlessly drive to keep the battery charged!?

The first Toyota visit, they had no idea what caused it. The 2nd tow, they replaced the small battery and couldn't seem to explain to me why. He said that the replacement had the same capacity and design as the predecessor.

This past weekend I again didn't use the car and come Monday morning it wouldn't start. I had my 12v charger at the ready and within 20 mins I was able to start the Prius. (I made the connection at the fuse block).

I drove to the doctor's office (20 min drive) and when I got into the car 20 min later I couldn't start it. What is different this time is that I called 2 guys who tried to jump it from batteries and it wouldn't start. Had no choice at this point but to call the Toyota tow service 1 hour away.

Toyota kept the car overnight and called this morning to tell me that they replaced the battery they replaced 4 months ago. I asked once again if it would have more capacity - he couldn't tell me.

So now I know from reading your experiences that my problem would be solved by disabling the remote entry when I don't expect to use the car for a few days. I can not imagine why Toyota doesn't know this!!

I printed this forum and intend to assertively give it to them when I pickup the car in 3 days (they have replacement battery but have to send to LA for a negative post adaptor!)

I can't thank you for your solutions. I am going to reread your posts, though, because at this point I can't figure out which battery starts the car. I still may buy a battery tender.

 

Hi hschessler, welcome to PriusChat! :welcome:
Your car should be able to sit unattended and undriven for a couple of weeks. Turning off the SKS with the button under the steering wheel cuts some drain, but unless some light is on draining your 12V battery, you may have some other power drain that the dealer needs to find. Since the dealer replaced the battery once before, I suspect this may be the case. Some cars had a small defect in the JBL sound system which could drain the 12V battery. You car is not working right if the 12V battery runs down over the weekend with nothing on.

As for which battery starts the car, the 12V battery is always connected, standing by to respond to the fob and flashing the immobilizer light on the dash. When you get in and press the power button, the 12V battery supplies power for the computers and to close the relays to connect the big High Voltage battery. Unless the dash display shows READY, the HV battery isn't connected to anything. As soon as the big HV battery is connected, it supplies the power to run the car, start the engine, and recharge the 12V battery.

 

Toyota recommends that the car be left READY for 30 minutes every two weeks when in storage (the car does not actually have to be driven during this period.)

I assume you have Smart Entry/Smart Start. One 12V battery size is available for cars equipped with that feature, so the replacement is not likely to have more capacity. Turning off the SMART function will help reduce battery drain, but some parasitic drain will continue regardless.

It appears that you do not drive your car often enough to keep the battery charged, so you may find it useful to purchase and use a battery tender that will keep the 12V battery at full charge.

 

Two Bill's possibility of an unfound drain, I suggest adding another possibility of an un-detected fault in the charging system.

Many years ago I had a BMW 2002 which ate batteries. It got about two years apiece out of Sears Diehards. After about the third premature battery replacement I finally replaced the voltage regulator. The next Sears Diehard of the same model as before lasted the remaining life of the car.

In that specific case the original voltage regulator was providing somewhere between a half volt and a full volt lower voltage than did the second regulator that replaced it.

I'm not saying you have the same exact problem, but just illustrating that faults on the charging side can give bad outcomes for battery output and even cause premature actual battery failure (my replaced batteries really were bad by the time they were changed out.)

 

Suggestion number 1:

whenever you leave the car LOCK it, to ensure that no doors are ajar and the lights arn't on and draining your battery.

 

Turning off SKS is a very popular recommendation when owners report a dead 12V battery. It SHOULD NOT be necessary! The SKS shuts itself down after two days of non-use, as I recall.

In the case posted above, there is probably some light etc. that is left on or there is a fault in the electrical system. Check the hatch light. It's dim and can be left on without being noticed. Especially in summer.

DO be aware that if you exit the car from the passenger side if the headlamps are on they will not shut off, even if the car is shut off. You must open and close the drivers door to have the headlamps shut off (if they are left in the "on" switch position).