Reduced power. A kind of limp. You drove it home. That is the usual hybrid-battery story. A silent, dark dash is a different one, and it is often the 12-volt.
If the car still has life
This is the picture most people mean when they say the hybrid battery is dying:
Red triangle, “check hybrid system,” reduced power, or a limp you can still drive.
You nursed it home, or you are still driving it that way.
Ready light that will not stay Ready after a few seconds.
Codes in the P0A7x–P0A8x family, especially P0A80.
A sudden, lasting drop in MPG plus those warnings — MPG alone is not a diagnosis.
If that is your picture and you are still inside factory hybrid-battery coverage, stop shopping. Go to the dealer first. That coverage is 8 years / 100,000 miles on 2019 and earlier, 10 years / 150,000 miles on 2020 and newer (Toyota’s 2020 announcement).
On a 2010–2015 (Gen 3), heat-related limp or red-triangle drama that eases when the car cools can be a packed HV intake filter or a dying hatch blower, not “order a reman tonight.” After Ready goes off, a soft whir under the hatch used to be normal; a growl, rattle, or sudden silence there is a clue. Pet hair and cabin junk pack that filter. The fan-first check is on the Gen 3 page — no tear-down, no HV how-to here.
You scanned. It said P0A80.
Red triangle, reduced power, a kind of limp — and the car still drove. You plugged in the scanner. P0A80 came back. That is Toyota’s generic “hybrid battery pack deterioration” code. It is not a purchase order by itself. It does not tell you whether one module, several modules, a fan, or the whole pack is the problem. On many cars it shows up with other block codes in the P3000 family — extra labels on the same story, not a shopping list.
Next step is measurement, not a shopping cart. The kit this site specifies is Dr. Prius / Dr. Hybrid plus a Veepeak OBDCheck BLE — the adapter Dr. Prius documents. A shop can also use Techstream. A single weak block can look like a dead pack on the dash and still be a different repair than a full replacement.
That scan is for reading battery health. It is not a pack install, and it is not a how-to for orange cables. We are not going to walk you through opening the case. If the numbers point at the pack, go to cost and your generation page.
If the car is silent
No dash, no click, or a single sad click: treat it like any other car with a dead 12-volt. On Gen 2 and Gen 3 the auxiliary battery lives in the hatch. Jump it carefully, or load-test it. Many “dead hybrid” tow bills end here.
The 12-volt does not propel the car. It wakes the computers that close contactors on the orange-cabled pack. When it is tired, the hybrid system can look failed even if the traction pack is fine.
12-volt auxiliary battery versus high-voltage traction pack
Usually cheap
12-volt battery
A normal auxiliary battery under the hatch (Gen 2/3) or in the engine bay on some later cars. It boots the computers. If the dash is dark, the car is silent, or it acts like a regular dead car, start here.
Ballpark: often around $80, sometimes more for AGM. We do not have a sourced 2026 national average.
The expensive one
HV traction pack
The orange-cabled hybrid battery that moves the car. The usual picture: red triangle, P0A80, reduced power, a kind of limp — a car that still moves. Many people drive it home.
Public 2026 ranges: about $950 shipped recon up through $3,500–$5,000+ at a dealer. Diagnose before you buy.
Gen 3 extra: the fan and filter
On 2010–2015 cars, a clogged hybrid-battery filter or a dying blower can cook a still-serviceable pack. That check is cheaper than a reman. Details on the Gen 3 page.
You have P0A80. Now you need the numbers.
You already scanned. P0A80 is on the screen. That is not another phone quote, and it is not a shopping cart. You need module voltages and balance — whether one block is weak or the pack is tired. The kit this site specifies is Dr. Prius / Dr. Hybrid plus a Veepeak OBDCheck BLE, the adapter Dr. Prius documents. This guide has not tested that adapter. It is for battery health and codes only. It is not a pack install, and it is not high-voltage work.
Most of the app is free; the actual battery tests are in-app purchases (priusapp.com). In Dr. Prius, select VEEPEAK — NexPower’s own PDF tells users to pick that same adapter name. Get the BLE stick, not the Wi‑Fi one: iPhone talks over Bluetooth Low Energy, Android over classic Bluetooth. Typical list is ~$32 for BLE, about ~$42 for BLE+ if you want the plus model — still Veepeak, still not something this guide tested. Veepeak’s Dr. Prius connection notes.
12-volt battery and cooling fan
Links here are for the Veepeak adapter Dr. Prius documents, plus the 12-volt and a Gen 3 fan. Not Dorman HV packs (out of stock, poor reviews). Not a traction pack of any brand. A generic $20 check-engine dongle is not the default on this site — it will miss hybrid data on some years.
Especially relevant on Gen 3. Confirm the part against your VIN or a parts diagram before you click.
After the scan
Still in factory warranty? Dealer. Toyota’s 2020 announcement set 2020+ HV batteries at 10 years / 150,000 miles; earlier cars are 8 / 100 unless a state emissions rule already gave you 10 / 150. The booklet in the glove box wins arguments.
P0A80 is the generic hybrid code for battery pack deterioration. It is a reason to diagnose module balance and related codes. It is not, by itself, a purchase order.
What scanner should I buy?+−
The default kit on this site is Dr. Prius / Dr. Hybrid plus a Veepeak OBDCheck BLE — the adapter Dr. Prius documents. We have not tested it. In the app, select VEEPEAK. That is for reading battery health, not for installing a pack.
Can a bad 12-volt throw hybrid warnings?+−
Yes. A weak 12-volt can make a Prius act possessed — no Ready, odd warnings, or a no-start that looks like a traction-pack failure. Replace or load-test the 12-volt before you shop an HV pack.