Toyota Lexus, and Nissan Hybrid Checking the state of health of the traction battery.
Worried about the large battery in your Toyota Hybrid? How can it be checked?
When the battery starts to go the battery computer attempts to restore it and will discharging the battery all the way and and charging it all the way. As the batteries age this happens more often till eventually they do fail.
You see this in the colored area (green, purple bars etc.) in the battery on the energy screen.
If you notice the gasoline engine does not shut down when it normally does, look at the energy screen if the charge charge level is not normal you might see it go all the way to the bottom and then all the way to the top.
You might also notice the charge level in the battery moves up and down faster than it used to.
But as far as an instant check that shows the voltages of each battery unit their voltage and the variation, sorry you can not do this from the center console.
You can also read each battery modules voltage with an expensive OBD II reader that reads the Toyota specific messages. These give the highest and lowest voltages of the various battery blocks (groups of 12 to 18 cells). As the battery ages the voltage differences increase but this can be fixed with by reconditioning the pack (which the car does to some degree) or replacing individual packs of 6 cells. We now offer this service.
In the 2004 Prius the battery modules were improved with a metal jacket to better dissipate heat and the electrical connections were
improved to reduce electrolyte leakage. However, even the 2001 to 2003 Prius battery packs are often lasting far longer than 150,000 miles. If you use your car almost every day the pack can last over 200,000 miles. (My pack went failed at 206K and is still working with three modules replaced.) When they go you can replace individual battery modules or replace the whole pack. So when the main battery it does not have to be a huge financial hit.
When there is too much voltage variation between cells the computers in your car will generate error messages. At that point, you can get a whole new pack from Toyota, a rebuilt pack from several companies that do this or just replace the individual modules that have lower voltages. Individual modules are for sale at ebay. If you are in the Los Angeles area we can rebuild your pack for you.