After reading several posts on this forum about the small 12 volt battery used in our cars, and what people have said about dead batteries after only leaving the car parked for a few days, I have been thinking about some sort of back-up. This link will take you to a site with pictures of my back-up jumper battery and cables that is stored out of the way and ready for use, however, I hope that I don't ever have to use it. Use this link: http://www.wbcoxco.com/priusbat.htm
<div class='quotetop'>QUOTE(lenjack @ Jul 4 2007, 07:28 PM) [snapback]473215[/snapback]</div> I plan on charging it about once a month. It has been in the car for almost a month and I checked it today and the voltage was 12.9V. As the summer gets hotter it could drain it a little faster, but once a month should be plenty. I have a little one amp charger that works fine on these batteries.
<div class='quotetop'>QUOTE(okiebutnotfrommuskogee @ Jul 4 2007, 07:41 PM) [snapback]473218[/snapback]</div> I've been thinking about doing something similar, but I think that I have a way to make it mindless. Use a relay that closes a switch every time the brake lights are on. Since the brake lights are LEDs, and you don't have to power up the car to light the brake lights, the relay will turn on unless the battery is totally totally dead. (Make sure you put a reverse biased diode across the relay coil to protect the car from the relay coil inductance). Now, attach one side of the relay contacts to the aux battery, and the other side to your added 12 volt battery. During normal operation, your added battery will get topped off every time you put your foot on the brake. But, if you accidentally drain the aux battery, then all you need to do to start the car is put your foot on the brake (connecting your battery to the aux battery) and hold it there to get a bit of charge back into the aux battery. Then, start as normal. If you install a bypass switch (for when your aux battery is really REALLY dead) you can make this pretty low maintenance. No worring about taking the battery out to charge it, yet you don't have to worry about it ever draining (unless you leave something pressing on the brake pedal). Love to know your thoughts! - k.
<div class='quotetop'>QUOTE(okiebutnotfrommuskogee @ Jul 4 2007, 04:14 PM) [snapback]473186[/snapback]</div> Having a battery go dead after a few days is definitely not normal. Either it's user error or their battery is kaput and needs replacement. I've left my Prius idle for a week and no had any trouble.
This is sort of SILLY............... Do you think Toyota would design a car that would go dead in a couple of days. I have left my car sit for weeks and once for a month with no problem. Also I have not read of other people having this problem, you are creating the problem...................... While you are at it, How about a extra gas tank just in case..............Certainly a bigger problem then the battery going dead............................ And of course a backup for the Brake fluid......Steering fluid........Coolant Tank ........... Extra battery for the Smart key.................. Have I covered them all ???????
<div class='quotetop'>QUOTE(Traffic @ Jul 5 2007, 07:36 AM) [snapback]473403[/snapback]</div> Lets see about some answers, First of all, I don't plan on having to use this extra battery, but if I should need to it will be there, and wouldn't you rather be self sufficient rather than having to ask someone or call Triple A for a jump. If you have ever looked at the little terminal that is available for the positive cable clamp in the fuse box under the hood, you would see that it would be no easy task to put a big old corrosion covered jumper clamp on it. Also it would be safer for your car to jump it from a dedicated battery rather than one that brings all the voltage spikes, etc. from the other vehicle. If there is a concern about gas, just fill the tank up when the gage reaches 1/2 full. I have never filled up with less than two pips showing and usually do it with three still showing. As far as the other fluids go, that is what the clear tanks are for. Just look at them once in a while. The little battery doesn't weigh much and that space wasn't being used for anything anyway. Not worried about the smart key.
You can purchase a handle equipped device with a battery inside, including a charger, sometimes even an air pump. These can be used to boost a car, fill your tires, etc. They are very inexpensive. They also just plug in to recharge. You might even find one that plugs into the cig. lighter socket. For those living in northern states or Canada, who know they can't help someone else who needs a boost (Prius battery is not designed to start engines and can be damaged by this). Just something simple, easy, and handy you -could- carry around.
Interesting solution to a potential time-costly problem. I particularly like the idea of jumper cables which will connect to the 'engine comprtment' jumper posts. Thanks for posting your idea with very good pictures. To another previous poster: :angry: It's really not nice to call someone here "Silly." Most PriusChat forum members are helpful, considerate folks who provide scads of good and useful information. Good manners are always welcomed.
It is my understanding that when the 12V battery is dead, the rear hatch will not open. To access your supplemental battery in the left well, you will have to climb over the rear seats to get to it. I would practice that. I keep my jumper cables under the passenger seat, not in the rear. Mike (There is a manual release for the rear hatch, but one has to remove the rear storage tub (with the hatch closed) to get to it).
<div class='quotetop'>QUOTE(count_on_mike @ Jul 5 2007, 01:15 PM) [snapback]473562[/snapback]</div> Yup. That's why I had the idea of pressing on the brake to connect the two batteries. You won't have to open the hatch. As for this idea being stupid, the aux battery can be accidentally drained, or can fail. And besides, we like to hack our cars for the fun of it. Regarding a previous comment - the coil of a 12 Volt relay doesn't pull much current at all, so it would be unlikely to overload the brake light circuit. However, make sure that you put in a back-biased diode to prevent the voltage transient that occurs when you stop putting current to the relay.
<div class='quotetop'>QUOTE(David Beale @ Jul 5 2007, 09:20 AM) [snapback]473432[/snapback]</div> I have a couple of those, one has a compressor and one doesn't. They are larger and can't hide in that little compartment. So I decided to make the little kit just for the prius.
Two minor points. You could hook it up to a solar panel to keep it topped up, do less monkeying with the car. You should also put in a strap to tie the battery and holder down.
