Saga of Prius Prime Flat

bummer!
was the car in ready when you used the inflator?

 

No TPMS warning? Doesn't change the outcome, but perhaps it was on when you started the car and you didn't notice it. Not sure about the Prime, but the TPMS light on my hatchback is way out of the driver's normal line of sight at the right side of the display, which is already in the center of the dash. There is a warning beep that accompanies it, but maybe masked by other sounds when powering on.

 

When you say "car stayed powered on", was it in READY (word READY showing in the instrument cluster), or just ON (instrument cluster lit up but no READY)?

ON mode will flatten your 12 volt battery in short order, with or without the inflator. There's a lot of stuff in the car drawing power in ON, and nothing putting it back.

 

It’s just designed that way. Need the READY mode for the power to come from the hybrid battery, then when hybrid battery is depleted the engine.

 

ON is equivalent to turning the key part way in a traditional car to keep the radio on.

There is a physical switch to the traction battery that is only on when the car is in READY.

 

Cars usually have a position called ACCessory that only powers the radio and maybe one or two other things, and also one called ON where most stuff in the car has power, but the power isn't being replaced.

Prius is the same. ONE button push without the brakes is ACC, and you can play the radio, plug stuff in the power outlets, etc. TWO pushes without the brake and most stuff in the car is powered (instruments, computers, HVAC blower, coolant pump(s) depending on generation, etc.) and none of that power is being replaced.

For the power to be getting replaced, the conventional car needs to have the engine started; the Prius needs to be in READY.

 

You may have a weak 12v battery. Make sure the dealer tests it.

 

I think the OP's suspicion that using the repair kit, weakend the 12 volt- probably a good bet.
There's so many benefits provided by driving a Hybrid and a Prius with HSD, but perhaps one drawback of the system is that since the Prius doesn't crank over the engine like a regular ICE, and doesn't have an alternator, it's harder to gauge or get warning the 12 volt is weakening.
When I owned my Prius, I just avoided using any accessories designed to be plugged into the AC socket. I bought a portable, but household chargeable unit that was a jumper/tire inflation and stand alone AC power unit. Maybe unnecessary, but with a Prius, and all the electronics, gave me piece of mind that I didn't have to tap the system in most cases.

 

you have to be in ready mode for the car to use the hybrid battery, and/or the engine. on mode just depletes the 12v.
the check engine light is just from the low 12v.

 

Being in ON mode for that long would have been hard on the 12 volt battery whether or not the inflator was used. Just remember all the other equipment in the car that is powered up and consuming power when ON.

 

doesn't gen4 have auto shut down?

 

still no low 12v cutofff, amazing.

 

But there IS a cut-off. As @Tideland Prius said, it's 20 minutes.

Here's how I handled my tire issue a few months ago. It was about as carefree as you could ask for.

• I was starting out on an errand about 20 miles away (40 mile round trip). I almost always take a quick look at the tires before I get in the car. They looked OK. Looks can be deceiving.
• After a few miles, I noticed that pesky tire pressure warning. They all looked roughly the same. Had to use the tire pressure gauge. Found that the left rear was down to about 28 psi or something like that. I opened the back seat arm rest storage and took out my 12V pump. (The OEM slimy POS is in a drawer in my garage pending the eventual day when I trade or sell the car.)
• I left the car in READY and pumped up the tire. Then I finished my errand.
• When I got home, I jacked up the left rear so I could spin the wheel and found two little pieces of wire that were smaller than a pencil lead. Some spit confirmed that they were the culprits.
• I marked the tire with chalk, called the shop to see if they could fit me in. They said yes.
• I took the car over there and they patched it under the road hazard warranty while I took a walk and looked at the new cars.
• Total cost was $0 plus a change in when and where I took my walk that day. Doesn't get much easier.

The secret sauce was having a regular pump, keeping the car in READY when using it, and having a spare tire if worse comes to worse.

Now, had there been a blowout or a sidewall puncture, then I'd have had the added chore of removing the tire and putting on the donut spare I keep strapped in the cargo area. But I've changed gobs of tires and it's not that big of a deal.

 

right, i mean before the battery gets too low. it ain't hard to kill these cheesy little batteries very quickly

 

I don't know if Gen4s and Primes are different, but Gen3's charge their 12V surprisingly slowly. 10 miles does very little, it takes many hours, e.g. an all-day drive, to reach full charge.

It is part of the safety design to protect both auto mechanics, and first responders who may have to cut the car apart. Unless the car is in READY, the hybrid battery is electrically disconnected, inside the battery case!, from the rest of the car.

 

Gen 3s will recharge the 12 volt faster than gen 1s and gen 2s.

The Gen 1 and 2 charging voltage maxes at around 13.8, which rarely translates into more than a few amps going into the battery. Take a 45 amp hour battery and that's over ten hours for a full charge.

Gen 3 charging voltage can go up to 14.7 or so, and produce double-digit amps into the battery, at least early on and if the battery is quite drained. AHetaFan measured it here. (Gen 3 also has a temperature sensor above the battery, to avoid overdoing it.)