Mysterious Dead 12v Battery

In my '08 car which is exactly like yours for the most part when I had a lot of slipping going on it was because my hybrid battery was just starting to fail 3 months later I had a lot more slipping and the battery was toast red triangle on correct p code etc. During this time all I had to do was step on the gas while the car was moving 45 mph smartly and the car would rev away just like a clutch would be slipping in a manual automobile I did this many times checking and playing around nothing was really wrong with the car other than the hybrid battery didn't have the get up and go that it used to and when you got on it like thinking you were going to pass a car or whatever and you weren't careful you would hear the engine revving away and the car going nowhere additionally. The minute the hybrid battery was changed leaving from the parking lot where I change the battery I could almost break traction just like that that had to be something to do with the failing hybrid battery The minute it was changed out the front end was put on the battery with the computers and relays and it was wired in and two bolts were in it Bam it was a different car immediately so I don't know if you got a new hybrid battery or a rebuilt remanufactured setup maybe you need to revisit that and see if there's any issues with connections growth and frosting of the nuts all of that sort of thing and some countries this can come on very quickly versus other places certainly I'd be looking at that almost immediately If in fact I had a rebuilt battery if I had a new battery from Toyota I would definitely be checking with them and seeing if I have any warranty or how that works

 

Sounds like some type of high parasitic draw- something on the car uses "too much" current when everything's supposed to be off. A common fault is a map light left on, or the tailgate wasn't completely latched.

If it happens again after fully charging the 12V, then you need to do some testing. Not many folk have a milliamp range inductive current probe. So I use a multimeter that has an internal amp shunt.

First I configure the meter to read amps (use the 10A range). Then connect a test light or other small bulb to 12V through the meter- I want to see the light work and a good amp reading to be sure that the fuse inside the meter isn't blown.

Now carefully disconnect the 12V negative clamp and "connect" the meter between the clamp and the battey terminal. Might need spring clamps, (careful use of) vice grips, etc to get solid connections.

The tailgate warning and dome lights should be on. Use a screwdriver to fully "close" the t/g latch (don't forget to release it when done before slamming the t/g).

Check the reading after 10-15 minutes. Should be 15-20 mA.

Posted via the PriusChat mobile app.

 

Don't overlook the obvious.
BRAND new and relatively new batteries sometimes fail.
Try to charge it first.
Does this "new" battery have a warranty ??
Good advice in post #3 above too.

 

Carabiner's work well for this too. I put something through the protruding loop so that I don't forget it's there and close the hatch on it. Pick one roughly the same size as the loop on the tailgate.

The carabiner is also handy if you ever need to move something which is a little to big for the hatch to close. Stuff the carabiner into the latch and attach a rope between it and the loop on the hatch.

 

get the battery fully charged, then load tested. if it passes, record the voltage and let it sit overnight. if it hasn't significantly dropped, reinstall it and do the same measuring overnight.