Signs/hints that your hybrid battery was on its last legs

There's so many different scenarios it's hard to say without writing something really long. But basically your charge meter indicating how much battery charge you have barely changes much with a new pack and a realy old pack fluctuates rapidly from full charge to no charge and requires deep cycling to restore capacity. This is a great overview: http://www.hybridautomotive.com/frequently-asked-questions

You can keep your pack going way longer than the Toyota Dealerships wants you to think... Cleaning the corrosion out and inspecting the pack can help prevent lots of failure points. Also deep cycling the pack every 18 months will keep it lasting way longer.

The biggest thing people get wrong is trusting a Toyota Stealership or an auto shop that has lots of overhead, both of which will prefer to replace everything with brand new rather than taking care of what you already got to keep costs down.

Do you or friend or family member have experience working on cars? Because that's going to be the best path forward and PriusChat folks will walk you through all the details.

 

I am very interested in this topic because my battery is in a downward spiral too at 143K. I am now beginning to learn and these are the videos I have watched (or queued up) so far:

Gregg Festo's introduction to refurbishing a hybrid battery pack with the CQ3 charger:

Some very ingenious methods to streamline and make the charging efficient by Fix it Fox:

A three part series on battery charging (step by step), also by Fix it Fox:

2 years after refurbishing the battery pack, again by Fix it Fox:

 

Just editorial: what do you mean by “ETA”? Pretty sure not “Estimated Time of Arrival”.

 

The most important parameter I have observed is how fast the battery is replenished and spent while driving. For me, it happens very fast. Hey, the battery was 80% full just a minute ago, now it's down to 20%. This is a classic sign of poor battery health.

 

There's no such thing as short-cuts! To nail-down an issue, you need to find anything that can cause that issue and start eliminating each potential issue, one by one - thru testing. Some people here just aim a 'parts cannon' at the car and ask why it doesn't fix their problem. Because they skipped step-one to begin with. IMHO; easy answers is just a guess that someone thinks is a solution. It's up to you to test their solution, because they could be dead wrong - same as some questionable YouTube videos - there are NO editors to validate those findings or conclusions. Telling the most experienced and senior people here; that you don't want to hear from them is questionable at best.
A one part solution requires some detective work. Those 'mechanics' that just replace parts that the scanner tell them to, will just keep replacing parts and not nail-down the real problem without some detective work. In other words, their fix is just temporary. Those are the cars that keep returning to the mechanic because the same part or something else broke.

Good Luck.

 

Like PriusCamper said it could be many things. In May of 2022 I tested my battery, it was 48% with 137k miles and listed as bad. Soon after I started looking at options for replacement figuring its death was imminent. It's still going 3+ years later. I'm still on the fence on trying the deep cycling vs just replacement.

 

IMHO; deep-cycling will only buy you a year or two - It's not going to magically rejuvenate the pack. You've got gel solidifying and sulfation of the plates in each of those modules.
Your simply going to get less mpg, until you start getting the death triangle. You just need to figure out if the car is worth putting in a new pack. You already know that the gen3 has the worse reliability track record out of the entire Prius line.

Good Luck.

 

When you see a quote vertical bar (in this case by Dirk) followed by a response, he is not talking to you. Unfortunately the thread you start does not necessarily stay focused on your questions.

Here you say "keep it simple" but the videos you referenced did not keep it simple. So that adds confusion to the rest of us.

Step 1
Fast discharge is a sign of a weak battery and one I saw when my oem pack was going bad. As it progresses you can get to the point where the engine won't stay off during a traffic light stop. That is weaker yet. When it further loses capacity it might be noticeably slower accelerating from a stop. Truly weak results in lower mpg of at least 5 mpg - sometimes 10 mpg.

All the above without throwing a code or "the red triangle of death".

Step 2
Even when it throws a code and lights up the dash, the car will normally still run for a month or more. Your time is short.

Step 3
The real problem is when the hybrid battery is so weak (after coding in 95% of the cases) that it can not supply the nominal 201 vdc long enough to spin the engine to a start.

I elected to change the hv battery after Step 1 had been going on for two months. I did not want to tear it down and replace bad modules after spending days or weeks of effort.

I did not go refurbished due to poor reliability. I wanted 10-12 more years of no battery issues, not 10-12 months typical of mix and match refurbs.

I did not go new aftermarket nimh or lithium modules because the companies selling them were not engineering outfits and relied on beta testers/salesmen on this forum like Priuscamper to hype their product for a commission. The aftermarket cells were from China and packaged to fit in the existing case. The nimh versions failed in less than two years and the company disappeared. The lithium also failed quickly and dome burned. The company and their salesmen denied anything until the day a new sodium version was ready for business. THEN the lithium was admitted to be flawed.

So factory oem was my choice. If serious financial concerns required refurb, I would go that route and save for new oem or trade the car.