The Car Sat for a Week and the Battery Died *sigh*

I love happy endings! Glad it all worked out and that the battery was easy to recharge.

 

The car should be able to have the SKS on for a week without any problems. I have left mind for 3 weeks without any problems.

 

<div class='quotetop'>QUOTE(LisaMarli @ Aug 31 2006, 08:22 PM) [snapback]312560[/snapback]</div>

I have also left my car for a couple of weeks with absolutely no problem (and the SKS enabled - infact I left it on last time purposefully to see what would happen). Perhaps you need a new 12v battery?

Dave

 

How do you turn it off? Thanks.

 

<div class='quotetop'>QUOTE(Etel Rose @ Sep 1 2006, 01:13 AM) [snapback]312600[/snapback]</div>

There is a button unter the steering column (where it meets the dash) to turn off the SKS. If you have the tire pressure monitor there will be two buttons so get the correct one!

 

OK, so here is an interesting question - why does the car need to have the small 12V battery anyway? I was just thinking this yesterday as I changed the 12V battery in one of my '02 Prius. I know the previous owner had it die a few times, and lately the dash would dim and the mdf would blank out if left on for more than a minute or so without the car in ready mode. But my point is why is this battery needed, why can't the big HV battery be used to boot the car. It is never drained down below 40% or so, so it seems redundant to have this little battery that runs down anyway - plus we are lugging around extra weight carrying the 12V battery.

 

It's actually rather logical to have. Even when the car is turned off, there is a small current being drawn from the battery (as evidenced by all the "My battery died" threads). If this was coming from the HV battery, it could, potentially, completely drain that battery without the computers being aware (since they aren't booted up). Additionally, when in ACC mode, the computers aren't all booted up (since they draw a lot more power than the radio), so they can't monitor the state of the HV battery (try it yourself - hit the power button once without hitting the gas, you'll see on the neregy screen that the battery is blank).

So in order to preserve the battery and ensure longer life (so you don't have to pay thousands to replace it), they disconnect it from the system when the computers can't monitor it and protect it, preventing any additional battery drain. of course, this isn't perfect, which is why they recommend having someone drive it once in a while if you're going to be away for months at a time.

So think of it this way: You could connect the HV battery and, due to mistakes like the one that start this thread and all the others, have to replace it after it dies every 5 years (spending thousands), or you could lug around this small extra battery and only have to spend a hundred bucks for a replacement when you make a mistake.

The real question should be: why can't we have a normal car battery? multiple models to choose from when replacing it = most likely cheaper, higher capacity = less likely to die if left for a week or two with SKS on.

 

<div class='quotetop'>QUOTE(kirbinster @ Sep 1 2006, 07:20 AM) [snapback]312707[/snapback]</div>

As you point out it could certainly be designed to work without the 12V battery. The reason there is a 12V battery is so the HV battery can be completely disconnected when you turn the car off. Then with the little battery you can still have SKS, lights, accessories etc. and it provides power to operate the HV battery relay when you turn the car on. If it weren't that way you might be in the position of having to find a way to charge the HV battery if you left something on. The extra weight of the small 12V battery is irrelevant.

 

<div class='quotetop'>QUOTE(DaveG @ Aug 31 2006, 11:59 PM) [snapback]312593[/snapback]</div>

I agree, the OP probably has a 12v battery that's on it's way out. I've left my car w/SKS on for more than 2 weeks once, and at least 3 different times for more than 1 week.

Jeff

 

I read somewhere on PC that the Ford Explorer Hybrid has a switch that allows you to charge the 12V from the HV battery if needed. Now that would be a neat idea.

 

<div class='quotetop'>QUOTE(kirbinster @ Sep 1 2006, 07:20 AM) [snapback]312707[/snapback]</div>

I tend to think of it like the CMOS battery on the motherboard. Very limited use but important for starting up.

 

<div class='quotetop'>QUOTE(ScottY @ Sep 1 2006, 10:55 AM) [snapback]312770[/snapback]</div>

Definately a neat idea... i would be worried about implementation, though. How do you ensure that the user flips the switch back to the off position? Even if it's a momentary switch (ie goes back to off when you remove your finger), how do you ensure that a box or something didn't shift and is holding the switch open? Once again, it all comes down to a question of being able to preserve the life of the HV battery, and i'm not sure i see a way that they could safely implement something like that. I could definately see some idiot rigging something up to hold the switch open to "keep his battery charged" the entire time he's away on a business trip, or a family vacation for a month or something, and then Toyota having to foot the bill to replace the battery when it's dead (because, after all, it's still under warrenty, and without the computers turned on, they have no way of knowing the switch was up).

 

eagle33199, good points. Maybe we should head over to the Ford hybrid forum and ask them. Maybe there's a warning about the switch in the user's manual?

 

That charging switch does sound like a good thing.

 

There should be a relay that trips when the 12V battery is low, that syphons some power from the HV battery until the 12V is OK again.

Life-support for another battery should drain the HV slower than moving the whole car around...

 

<div class='quotetop'>QUOTE(mikepaul @ Sep 1 2006, 10:20 AM) [snapback]312817[/snapback]</div>

There could even be a safety feature where the HV battery won't try to charge the small battery it HV battery charge level is too low.

 

<div class='quotetop'>QUOTE(aaf709 @ Sep 1 2006, 12:24 PM) [snapback]312825[/snapback]</div>

Of course, you realize that adding these sensors and controls would only cause the 12V battery to depeat faster due to the increased current required to power the devices... IMO, the best solution is to just get a normal sized car battery in there, then the only complaints would be in situations where a normal gas guzzling car would die too.