Replacing 12volt battery-saving settings..??

if that's a 12v battery charger, yes.

 

Maybe? Probably?

I'm using a jump pack with a memory saver cable, goes from outlet on the jump pack to the car's OBD port. The cable is purpose-built for memory saving, and has indicator light to verify you have good connection.



Jump Starters - 1700 Peak Amp Volt JNC660 | Call us at 1-800-328-2921 |Clore Automotive



Memory Saver Cord - ESA30 | Call us at 1-800-328-2921 | Clore Automotive

In past I used a small/simple (0.5 amp) motorcycle trickle charger, just hooked up prior to removing the battery, and it worked as well.

 

One thing, are the disconnected cables sort of "hot" if you do this? I'm not bright enough to know, so always try to isolated disconnected cables as soon as I pull them off, stuff them into heavy gloves, and work with one cable at a time.

 

I've never checked, but I would think the positive cable would have to be hot at the battery end with 12V connected to the other end under the hood.

 

What would be good is to test the jump starter on a separate 12 v load like a 12v compressor or trouble light to verify that it will put out power without another partially charged battery in the system. A lot of chargers and jump start systems check for the other battery voltage and proper polarity before enabling themselves. I recently swapped my prius v 12v battery by using a small alarm system battery that I temporary removed from the home alarm. Could have used a 12v lantern battery as well. Only needed thin 18 gauge jumper wires hooked up under the hood. A red light on the dash remained on after disconnecting the old battery in the back, verifying that my little alarm system battery was working. By the way, an Optima battery handle can get in the way of the battery cover, check or remove before securing the car battery cables.

 

And yes the disconnected battery cables are hot from the other source. So don't short the red lead with your tools even when it is disconnected. My jumper up front had a small inline fuse just in case.

 

Another point on that particular jump charger and most others like it. The manufacturer says it will disconnect automatically if the current draw is too low. They don't define "low" but keep in mind the Prius off state current draw is very low once the computers initialize, I believe around 6 ma (6 thousands of an amp). Your interior lights will shutoff automatically by themselves so maybe run the parking lights concurrently. Or do something like I did with a regular 12v battery.

From Unyson's Amazon sales page: "We do not have [an] always on feature either. If the charging current is too low the device will shut off automatically."

 

I attempted to preserve my settings while changing the battery. Not sure why this didn't work. I setup jumper cables correctly to another car. I tested that the voltage was present. When I disconnected the negative terminal, the map lights went out. I still had a voltmeter connected to the positive blade next to the jumper cable, and to the metal next to where I connected the negative jumper cable. Still got the voltage reading (The voltmeter doesn't report amps, but is backlit, and was bright.) After I finished changing the battery, the setting were lost. I have the ATP, so hope I didn't loose any setting that I can't re-train.

What did I do wrong?

 

If you did this, I don't see how it would not work. Can you be more specific? Just where did you connect the cables to both cars?

 

First, I find almost all settings remain on my v if the 12v battery is disconnected. I might lose the last selected radio channel but all the presets are still there.

When the map light went off as you disconnected the battery negative, a the jumper cable was not electrically connected. Guaranteed. While it is not clear where you hooked up the jumper cables, the best place is up front at the jump point in the engine fuse box. Primarily because you won't inadvertently disconnect them.

Possibly the jump cable ground was not making electrical contact, especially if it was in the back where almost all the metal is coated.

 

Large jump cable clamps and the small positive blade in fuse box often do not make a good combination or electrical connection.

 

I did use big jumpers, and it was getting dark. I attached the positive to the blade, and the voltmeter gator clip next to it on the blade. The only thing I can think of that could have gone wrong is that the gator was touching the positive jumper, and not making a good connection to the blade. The Prius 12V was reading 12.3V, and so was the battery in the donor car. The voltmeter read 12.3V when both were connected, and when the map lights went out. I connected the ground to unpainted metal on the inverter box (not my first choice, but the only unpainted metal the cable could reach.)

Afterward, when I tried to start the car, all the trouble lights came on, and the Navigation unit had to re-load maps. The trip odometer & MPG went to zero. Clock went to 1:10. READY was not lit. After powering down, and re-starting, READY lit, and the ICE came on. Everything seems normal, but haven't tried auto-park, or presets on the radio. I did put the windows all the way down & up as someone suggested to retrain auto up & down.

I replaced the battery in the donor car today for $75 @ Costco vs $193 for the Prius 12V. Can't complain about the TrueStart. The original lasted 9 years & 155K miles (still looks new).