Hybrid battery dead or is it ???

1. Usual timeframe is dependent on the "severity" of the problem the car had got.
In some cases, of the problem was intermittent, then you get intermittent timeframe, and so on
2. Fan cleaning, is part of maintenance for your hybrid system, specifically, it helps extend the HV battery's lifespan.
But note this would only be helpful, if the HV battery isn't on its way heading South.
The battery swapped may have fixed the issue, if the original battery in the car was dead long time ago.
3. That's a good idea saving for battery though.
But I'd say, IG you've never had issues with the battery before, then you might not bother.
Knowing if its the inverter, would required you having issues related to it.
Get a scantool at hand, so you can do your scanning, just in case that light pops up again.

 

Welcome!

Time will tell, but if the traction battery is failing, the lights will be back in a few days at most.

I would not have replaced the 12V unless I knew it was failing by testing it or if it was just so stinking old it deserved to be replaced just in case.

Next time you get the warning lights, get the codes read by a code reader that's fluent in Prius. Most are not. That means Toyota or an independent hybrid shop. The other and cheaper option is one of the many bluetooth OBDII readers and Torque Pro on an Android Phone. There are other ways, but I don't want to repeat them all here. The main codes and sub codes will tell you pretty precisely what's wrong.

And I should add that with that age and those miles, you definitely should be preparing for a traction battery replacement in the foreseeable future.

 

Asong as that's what you got, that code may probably, return.
Try driving aggressively, and see what happens. Maybe you could simulate the problem.
Driving that way, puts more load on the battery. Sobif there are any issues there, it would pop up immediately.

 

if the battery is over heating, it will set a light. you may have a borderline cell voltage though

 

Try to clarify although others are more expert:
Voltage checks: The computers are checking for voltage differences among the blocks of cells in the HV battery. If the voltage differences amongst the blocks exceed a fairly small threshold , the battery is flagged as failing. When you are driving so as to draw maximal current from the HV battery, those voltage differences between the best and worst cell assemblies tend to be accentuated.
Overheating: the HV battery has 4 temperature sensors, and if they exceed a high limit (50 degrees Celsius?) a general shut-down of the HV battery is ordered by the computer. Whenever you get even close to that shut-down threshold, the battery cooling fan is running at its absolute highest speed, and you should be able to hear that fan sound from the back seat air intake if the radio is off, you are on smooth pavement, and you have normal hearing acuity.
God luck!

 

Same situation but I'm on day 1 of clearing code and 100 miles!

You're going on 2.5 months has it come back yet? Please update thanks!

 

congrats, all the best!