P0A80 What's It All Mean??

Seems to be a few of these lately, and as a Toyota hybrid specialist, I'm here to help ;-)

This Diagnostic Trouble Code (DTC) is set when the Battery Smart Unit detects a difference in voltage between the ten battery blocks larger then "the standard." Toyota doesn't specify what the standard is, but because my oldest son is a Toyota tech here in Japan, I can tell you it's 1.3V. It's a two-trip DTC, meaning it must happen two times within a set period. The first time, it will set a "pending" DTC, but no lights will come on. You may experience the car doing "funny" things, as it goes into a sort of battery protection mode. Engine running, battery not charging or discharging, engine revving when the accelerator pedal is released, etc. Sometimes the cars do this with no DTC, and other than Toyota, who really knows why? If the battery faults again, a current DTC will be set, and the warning lights will come on.

The entire DTC is P0A80-123. There are no other INF codes to give direction. It's a simple "Replace Hybrid Battery Pack."

But how do we know it's actually the battery, and not the Battery Smart Unit? First, there will usually be another DTC set with the P0A80, like a P0A7F or a P0AFC. If the P0A80 is set with one of these other codes, the problem could also be the Battery Smart Unit, wiring, etc., and we would need to look at those things, too. However, it's almost always just the P0A80, usually listed three times as History, Pending, and Current if using a factory or factory-level scan tool (see picture).

To verify it's the battery, you only need to look at the DTC freeze frame data. When the DTC is set, the ECM takes a snap-shot of a list of PID's that pertain to the DTC in question so we can see what was happening at the time. You only need to look at the battery block voltages, and see what the difference is from highest to lowest (see picture). Usually, one block will stand out as being abnormally high or low (usually low) among the others. This is verification that the problem is indeed the battery.

This happens because of a resistance change in the battery block (age). When the blocks are all hooked together, they naturally balance,so when just sitting, all the blocks will look close. But when current is applied, either positive or negative (discharging or charging), the different resistance in the bad block (usually one module), will show as a higher or lower voltage in that block.

This DTC usually sets, or is easiest to set, when the battery is in a low state of charge (SOC), and a large demand is put on it. Like when you're driving on battery power, and the SOC is near 30%, discharging, and the ICE kicks on, putting an instantaneous high demand on the battery.

Cheating. Can you reset the DTC and continue to drive the car? Sure can. Is it a good idea? Probably not. First, it usually happens when the battery is hot from begin exercised. When reset, the battery is still hot, and can do all kinds of scary things. The DTC can not set again for ten minutes, and I've experienced the battery SOC going to 98% and all the way down to 0%. The engine still won't shut down, shunting and grunting at a stop light, etc. It's as if the whole system is confused and freaking out because of what's going on with the battery. When cold, they seem to work like normal for short commutes, as long as the SOC is not allowed to bottom out. Heat will mess with the resistance of the battery modules, so the longer you drive, the more chance it will start acting up.

In my experience, there is no long-term fix for this except to change the battery. Current price here in Japan is about $1,250 for the battery and less than $1,500 total to have it changed at the dealer. Confirmation of the battery failing is 5 minutes, and it's 1.8hrs book to change it.

Change it yourself? Sure. However, at least here in Japan, there's programming they've started doing during battery replacement. They never used to do it, and my guess is that it's a change to the battery maintenance strategy. Something to keep in mind.

What I've seen (and what Toyota here says) is that hot and humid environments kill batteries quicker. Stop and go driving will result in less mileage than highway driving, as the battery gets "cycled" less. On my personal Aqua, which I bought new in 2012, the battery failed at 8 years and 142,000km of all congested start-stop driving. Hot and humid, salt air. I paid about $1,000 over what a comparable 1.5 liter class Toyota would have cost, but saved about $4,700 in fuel over that same car. I'm already winning by a long shot, and that's not even factoring in the much lower maintenance costs.

 

Takes me about an hour if I'm taking my time. Dealer is going to charge what they charge, which is why I advise people to find an independent who specializes in Toyota hybrid. Once a job is well known, many good shops don't bill jobs by the "book hour," but by the job. Flat-rate pay has destroyed the industry in the US. A person who's competent in repairing modern automobiles can make a lot more money in other industries, so many have left for those industries. The dealers here charge about $180 to change the battery.

Programming is often required when changing electronic components in modern automobiles. Toyota is probably the best brand for being able to do repairs and not have to do any programming, or any work needing a scan tool. The Toyota hybrid batteries can be changed without having to do anything special. However, Toyota in Japan has a TSB for programming after a battery change. No idea what it does. They only recently started doing it, and the average shop just changes the battery IAW the OEM SI.