maintaining settings while changing the 12v battery

Yes.

 

Just be careful with the cables at the car's 12v battery, they'll be energized the whole time. Don't let the positive/red one touch any metal on the car.

 

How about a 9 volt battery to the outlet in the console

 

That won't work, for a couple of reasons. First, the console 12 volt outlets are off when the car's off. Plus a 9 volt battery might not be enough, wherever you connect.

My jump pack has a 12 volt accessory outlet. I purchased a cord with a 12 volt accessory plug at one end, and an OBDII plug at the other, which has ONLY the pins for supplying 12 volts. It also has an indicator light, to let you know it's hooked up correctly. You could also use some sort of 110 to 12 volt connector, in place of a jump pack.

 

Yes. So would just starting the car before swapping the battery. (In older cars you wouldn't want to do that, because the battery was important in absorbing voltage swings at the alternator. Voltage in the Prius is regulated much more like it is in other modern electronics, and will stay rock steady while you swap batteries.)

The point raised by vskid3 about not wanting to short your positive cable to ground is a good one, but the easy way to avoid that is to unplug the positive cable connector(s) you'll find simply snapped into the positive battery terminal. They're housed in plastic like the car's other plug-in connectors, and fairly unshortable (unless you've got an infant to stick silverware in them).

-Chap

 

A charger to the Jumper point will retain all settings. That's how I changed mine.

 

Exactly what settings will get lost when changing the 12v? I changed mine last week and the only settings I lost were the radio presets. Everything else that I had done through Techstream was still there, windows, the reverse beep, didn't had to take care of that again.

 

AFAIK, only the radio and clock need to be reset. The ECU may have to relearn the mapping of air fuel ratios, but you probably won't notice anything.

 

All of your trip info are gone too.

 

I disconnected my 12v two weeks ago to work on my front brakes. My car is equipped with OEM navigation. I didn't find any settings gone that I would miss. Here's the data I lost:

1) Date/Time reset
2) Trip A/B reset
3) Estimated distance to empty reset to 860km.

Here's what I didn't lose:
1) All my navigation address favourites were still there
2) Monthly fuel usage history was still there, but at the wrong months. This was fixed by setting the date.

I didn't notice anything else other than the above. I was very happy that my navigation addresses were still there.

 

That might work, but would scare me, because chargers can have voltage peaks well above what the system would normally see. I used a small power supply closer to 12 volts output, and didn't lose any memories.

 

trickle charge setting is barely above the battery's idle voltage. Set to trickle charge and it'll be fine. My trickle charge setting can't even break 13V.

 

This is the type of obd memory saver cord I'm using. Works with jump packs having a 12 volt outlet:

 

You guys are all worrying for nothing. The Prius is not going to explode. trickle charge setting will not even come close to 14V even at no load. Once you've placed a charger to the jump port, remove the negative and positive post and put something over the positive terminal so it doesn't make contact with the body. replace the battery and reattach the terminals. Amount of time the Prius will go without a battery attached, is less than 30 seconds. If you're worry about using a charger, then use a 12V drill battery instead then. Just make sure you get the polarity correct.

 

The one solution that doesn't require bringing along extra equipment is to just start the silly car, unplug the positive cable(s) (the plugin connector is insulated, so you don't need to bring something to put over it, either), swap batteries, plug the cable(s) back in and shut off the car.

I say cable(s) because (at least for Gen 1) there are two: a fat one delivering power and a skinny one sensing voltage. Both plug in at the positive clamp/fuse unit.

On the whole topic of memory preservers, there is one reminder worth making ... it's in the manual, but just so no one forgets. Gadgets to preserve the memory can be really convenient, but don't make such a habit of it that you might forget to put them all away out of reach if your work is going to involve the airbags or belt pretensioners! Just let the memories get erased in that case. Putting the radio stations back in will be ok....

-Chap

 

D.O. for brake work: just disconnect the battery completely, lest the car attempts to pressurize the system while the calipers are pulled off.

 

Not sure about the Prius charging system but removing the battery while the engine is running on a regular car is the last thing you want to do. When the engine is running, the battery becomes a load. This load is needed to stablise the voltage. Without the battery, the voltage could spike beyond what the ECU is designed to handle.
If you rely on Trip A and Trip B info to keep track MPG and miles driven for the tank and its history, disconnecting the battery will erase those infos. If you don't care about those info, then disconnect the battery without backups. If you do care, use either a charger or another 12V battery and hook it up to the jumper terminal under the hood.