Any warning signs a gen3 hybrid battery is failing?

Wait for the obvious signs. Clear signs are the hv battery charge bar graph goes from decent to low at a traffic light. It may go so low that the engine is lugging or pinging as you start moving again. If you are over 175k miles and live in a hot climate, its days are numbered. But the number might be 300-700 days, not tomorrow. Rarely will a hv battery strand you. An inverter might. A water pump might.

In the meantime clean your battery fan again. Toyota Master mechanics recommend this. Not expensive chargers for hv batteries or whack a mole module replacements, regardless if Dorman does it with a fresh paint job or you do it in the driveway.

 

To see what the 'obvious signs' might be, go to this page for more information: HybridAutomovieFAQ.

This is a page from Hybrid Automotive, which produces the Prolong battery reconditioning system. I have a 2010 Prius IV with lower mileage than yours, which showed some of these signs, so I obtained one of his reconditioning systems, which appears to work quite well. Cheaper than a new battery, and far less work.

 

i said the same in the past, got poo poo’d. Waiting for those people to reply.

 

"i said the same in the past, got poo poo’d. Waiting for those people to reply."

YMMV

 

Not so sure I would change them preemptively at 150k but its your choice. From what I have read, there are counterfeit "oem" pumps out there that fail too quickly. So I might consider shopping the online Toyota dealers for a genuine pump even though they are pricey. The key is don't drive further if your temp alerts come up. Unless your safety at the time is more important.

 

It’s by @NutzAboutBolts. There’s a thread pinned in 3rd gen maintenance forum linking a bunch of his videos.
One caveat: they pull out the rear seat bottom, but that’s really not necessary, and might break some retainer tabs. There’s a a single bolt in behind the seat cushion needing to be removed, but it can be reached with extensions on a ratchet wrench. IIRC the socket size is 12 mm. Just push apart the seat and back and reach through. Be very careful not to drop it; unscrew tho bolt with one hand and hold it with your other hand. A head band light helps.

 

150-200

 

i would start the prolong conditioning now

 

What about changing just this part, and the gasket?
New Engine Electric Water Pump magnet For 161A0-29015 for Toyota Prius 10-15 | eBay

 

More appropriate to think in terms of time instead of distance.

You'll be losing that battery between tomorrow and 2026. The management system has been designed to absorb minor flaws, so it isn't going to notify you until it's already time.

So far, "Watch for the triangle; have $3k ready" has worked. More notice and overall cheaper results? Still in development.