Tag Archives: Battery


Googling the P0A80 code that the ODB II scanner had plucked out of my non-functioning Prius was not a happy process. I had never really looked it up, but I read somewhere recently that the expected lifespan of the 2nd generation battery was 10 years. As mine is a 2004, it’s unfortunately right on schedule. After sufficiently stressing myself out about the giant bill that had just fallen in my lap, I figured the first sensible step would be to stop reading forums and actually get a real life quote. I called a couple Toyota dealerships, and the all said the same thing – “We can’t sell you the battery”. While opinions vary about the different real and theoretical risks of AC vs DC power and the relative impact of voltage and current, the ~200VDC battery is enough to cause issues if misused. When I pushed for a price just to wrap my head around it, I was quoted 2628.63 for the battery alone, or somewhere >3000$ after installation and tax.

The dealership insisted that they had replaced only one or two batteries ever in the 2nd generation Priuses. Speaking with the Toyota parts people, they echoed that opinion. In all likelihood, it was not the battery itself that had failed, I just need to bring it in so they can run their diagnostics on it. That means there is a chance that by bringing it into the dealership I can actually save money, providing it’s a small fix. You can try your local independent mechanic, but my money is on them not feeling totally comfortable playing with the HV battery. Again, trying to not get screwed, I went online and purchased the “Techstream Diagnostic Cable” (~20$ on Amazon). From my understanding, that cable would provide me with the manufacturer specific codes that were out of reach of my ODB II tool. With Amazon’s lovely 2-day shipping, I had the cable before my appointment with the dealer.

I’m not entirely clear on what’s going on with the cable, it seems like it’s a legitimate product that comes bundled with potentially pirated software? Or maybe Toyota disowns older versions of the Techstream software? Either way, the mainstream internet sold it to me, so I’m not going to question it. It shipped as a mini CD with the software and an ODB II to USB cable.

ODB II to USB Cable

Only being compatible with 32-bit Windows XP, I spun up a VM to install it. The set up and installation went pretty much according to plan. It was a little finicky installing the driver into the VM, but nothing really unexpected. I had to drag out an old external CD drive though, it’s been a couple years since I’ve purchased software on CD… ODB II to USB plugged into the laptop, Windows XP VM capturing the USB port, and everything is looking good.Toyota techician

Cross my fingers, and click “Connect to Vehicle”:

Connecting!Follow along in the menu, and next thing you know:

Techstream Diagnostic SoftwareEverything is connected, and the car is about to start talking. I didn’t stop to read the manual, and credit to Toyota (or whomever), the software is decently intuitive. I clicked on “Health Check” and waited while the car fed up all its juicy details.

Health CheckP3000, P0A80, C1310, B1421, B1423… That’s a lot of codes. Admittedly I haven’t looked at the codes for the air conditioner, that seems like less of an issue for now. Going in for some more detail, I got this:

Diagnostic CodeSo… on the one hand, I really don’t like to see “Replace Hybrid Battery Pack”. That’s explicitly what I don’t want to do. More hopeful is “Battery Block 7 Becomes Weak”. That’s actually pretty much my best case scenario, hopefully a single block is toast. People on the internet have fixed that!

Red Triangle of Death

At the beginning of May, my beloved 2004 Toyota Prius started complaining. All of the sudden, it threw up all the warning lights you never want to see. For anyone who has been lucky enough to never have seen the red triangle of death, nor the dreaded “VSC”, it looks something like this (although potentially less blurry in real life):

Lights you never want to seeThat is the first sign that something is very wrong. It has happened to me in the past, when the 12 volt battery died the first time. This time, unfortunately, the 12 volt battery was fine. Not being thrilled to part with money to have a mechanic, or even worse – the dealer, plug in their diagnostic tool, the last time I ran in to trouble I picked up an ODB II reader (~20$ on Amazon). It is rarely particularly definitive, but it at least gives me some sense of comfort knowing anything beyond that I couldn’t have reasonably done myself. It also helps me mentally prepare for the order of magnitude of the repair bill. I connected to it with the free version of the Torque app for Android (Google Play Store Link), and the error code it spit out was P0A80. Googling this lead me to discover the ominous description for that particular error – “Replace Hybrid Battery Pack”. I’ve heard it referred to as the “HV battery” (high voltage), or the “traction battery”, or just the “hybrid battery”. Any way you say it, it’s the big one in the back, under the rear seats. The advice I came upon readily via Google all agreed – this was not an error you could just ignore and keep driving with.

I didn’t want to pay for a tow truck (there’s a theme here…), so I ignored the warning lights and kept driving. I dropped it off at my mechanic’s and caught a ride from my girlfriend. When I got home, I entered the research phase. Not really knowing where to start with this problem, I read the Wikipedia entry for the Prius, which states:

The Second Generation Prius contains a 1.310kWh battery, composed of 28 modules. Each battery module is made of 6 individual 1.2v 6.5Ah Prismatic NiMH cells in series forming a 7.2v 6.5Ah module. Each module contains an integrated charge controller and relay. These modules are connected 28 in series to form a 201.6v 6.5Ah battery (traction battery), also known as the energy storage system. The computer controlled charge controller and battery management computer systems keep this battery between 38% and 82% state of charge, with a tendency to keep the average state of charge around 60%.

So… 1.2v 6.5Ah Prismatic NiMH cells. At least that’s a starting point.