What is the part number for hybrid battery?

See catalog Figure 82-01, Battery & Battery Cable; the Toyota part number is G9510-76012. At this writing, the list price is $2,588.67, plus a core charge of $1,350, refunded when you return an unmodified old battery.

Keep in mind that the warranty on the replacement HV battery is 36 months if the dealer installs it (except in a commercial, fleet, or livery vehicle), but only 12 months if you buy it over the counter.

 

There are other places to get batteries, for less cost.
He is a place that sells them for around $1600, depending on model.
2k1Toaster | PriusChat

I do not remember the warranty length though.

 

Florida is a big place, but if you're within range of Tampa, you might check with Home - Tampa Hybrids Inc.. Todd is great! He can probably get you a new battery for less than the dealer. Also, he sells slightly used ones. The one I got from him was 2 years old and came with a Car Fax report. Not sure how he's doing it now, but last I knew, he was checking for corrosion and then rebalancing the cells on the used ones. None are refurbished. It was nice not having to swap out the ECU and other stuff that you have to do with a new one from the dealer. You can just give him your old battery and he gives you the new one.

 

List price is the official price, but everyone, dealerships included, discount the price some.

Would any opening of the case be detectable, queer the deal? As an example, I'm thinking someone might for example clean the bus bars.

 

I don’t know what’s allowed in practice. Just removing the cover wouldn’t be a problem, since that’s part of the required procedure to prepare the battery for return shipment at Toyota’s expense, described in Toyota’s PANT Bulletin 2013-009 Rev2 (PDF), revised April 16, 2019.

From that bulletin, and the information in the Toyota Warranty Policy & Procedures Manual, Policy 9.10, “Recovery and Shipment of Hybrid Vehicle High-Voltage (HV) NiMH & Li-Ion Batteries,” I think Toyota’s main concern is that the batteries are in a safe condition to be offered for transportation.

Policy 9.10 also states, “If the vehicle has an aftermarket HVB when it arrives for repair and it is replaced with a Toyota battery, Toyota will accept the aftermarket battery as the core.”