Hi Gents, Yesterday I used Dr. Prius app for the first time on my cousins gen 2 2009 Prius. This screen shot is the car running on idle. To me this looks like a very weak battery correct?
You will need more data than that. The battery's behavior at idle doesn't tell you much. Monitoring the voltage levels of the different blocks while driving provides more useful information. You want to see the differences between the voltages under load and when the battery is recharging. Dr. Prius also has a Life Expectancy test, which would also provide useful information. For what it's worth, the voltage difference between the lowest voltage block and the highest voltage block of .10V in your screen shot is well within acceptable limits. I believe you won't get any battery error codes until the difference is greater than .3V on a consistent basis.
Are you sure you have Dr. Prius installed correctly? It says the battery is 70.x% SoC, yet all the blocks are reporting in at 5.xx V. Even if it was saying 15.xx V (dropping the leading 1), it is still on the low side. The graphing visually exaggerates the difference between the highest and lowest by the way it sets the values on the vertical axis. It is only a 0.10 V difference, which is fine. As Dave Cook said, it is only showing a draw of 4.1 A, which is pretty tame. It would be good to get that up to 15 or 20 A, by putting the A/C on full cold.
I don't think there is a wrong way to install Dr. Prius? I just downloaded the app and decided to try it out. I will do the full test when I get around to it.
Do not discount the potential of corroded battery monitor cabling, that will give false readings. But yes, the pack in unbalanced, while not great for long term health, but not a panic situation either.
The picture I see says 7.79V. Yeah, I think that looks good, too. As far as it goes. I agree that it needs more of a load to know how good it is. Also, the internal resistance delta might be showing that the battery is aging. But from what I see, it looks serviceable. Just need to put some load on it while watching the voltage.
