Prius 12V Battery is a Wimp

If one reads the owners manual, it is clear that the jump point for the battery is at the front of the car in the engine compartment, at the main fuse block.

With most battery failures, the car could still be jumped from there, and then the rear hatch unlocked to gain access to the battery.


There may be the rare case when a cell is shorted, as this appears to be.

 

If I was designing the Prius, I think I would have included mechanical key entry for the hatch.

 

No. My salesguy's delivery spiel including the steps necessary to get the car open when the battery is dead, how to jump from the front, and how to get physical access to the battery.

 

Bah. My dad's 2005 Prius which has spent it's life in northern California not too far away from Monterey still works fine. Since it's been fine in my experience, it must be OK!

This guy is just whining because he got a weak battery that failed early. Replace it with a sealed gel unit (like the yellow-top Optima) and that battery will likely last longer than you own the car.

 

It would be nice if his rant actually included facts! When you come to a stop the engine does shut off. This in -no way- affects the 12V system! It is charged from the traction battery! It remains at a constant 13.8 V until you shut the car off. Even with a "dead" 12V battery. He must have a pretty lousy charger! Any charger I've seen will keep a "dead" 12V battery (one with no capacity) at 12+ volts (usually at the charge voltage the charger puts out). Yup, the battery won't charge. It's dead Jim! Perhaps his battery was shorted internally, in which case, again, it's dead Jim!

I suspect his battery was fully discharged a few times, either before he got it, or during it's stay with him. BTW, just because -he- thinks the battery is "wimpy", doesn't mean it is! It's a 30ish A-Hr battery. A "real" battery (according to him) is about 50 A-Hr, so in his hands I guess it would go dead about half as often. It would still go dead if you leave something in the car on (usually lights) when you turn the car off. It would just take almost twice as long to destroy the battery.

Note that there is nothing wrong with Toyota's engineering. This 12V battery is not used for "starting applications". It only powers up the electronic systems and the lights in the car. It -doesn't need- to be twice as heavy, twice as large, and presumably twice as hard on the environment!
Pearl's 12V battery has worked just fine thank you in our -very- challenging environment for two winters now. But -I- (so far) don't leave lights etc. on when I shut off the car.

 

David's comments are very accurate. The 12v battery does not need to start the ICE; it only runs the lower current items. Hence the battery does not need to be as large as that for a conventional auto.

Zen, your situation brings in a new twist, namely that the front end jump point was difficult to get access. I agree that a manual trunk release would be helpful. However, this deficiency in the design is not a hidden fact, although not being able to put the car in neutral could certainly be a surprise!

I carry a combination battery jumper/tire inflator in my Prius at all times. It's basically a sealed 12v battery in a case that includes an electric tire pump. I've already used it to jump start my minivan, and it worked very well. You recharge it via a small AC adapter on an overnight charge. I would recommend it to all Prius owners.

Mine is made by Black and Decker. If you do a thread search for it you will find a picture that I posted. But there are other brands available.

Best wishes,

Frank

 

Comment left on page. Withheld my comments regarding it apparently taking someone smarter than a monkey to operate a prius.

 

and another:

 

It's not just the Prius that has a rear hatch that fails upon loss of power. So does the FJ Cruiser. Even though there is a manual lever above the rear license plate holder, the lock/unlock is purely electric

So, with an FJ Cruiser, you lock it at the airport or wherever, are gone 2-4 weeks, and upon return the battery is dead. The keyhole in the rear hatch is just to actuate the electric locks and open the rear window.

With no power, you're not going to be able to open the FJ rear door or window. There is a procedure in the manual to manually open the rear door, but it's easier to just boost the vehicle and use the power locks

 

I agree, it's one step forward and two steps backward. I do know a lot of FJ drivers are surprised to learn that even with that keyhole in the rear door, it's not actually hooked up to anything except a small box with wires coming out of it