evtlfp20 via EV wrote:
http://priusapp.com/
Notice that it doesn't specify what it really does. It confuses "cell" with "battery" and "module" (perhaps deliberately, since most people don't know the difference).
A "cell" is just one; like a AA cell. Some people call that a "battery", but it's reall just one cell.
A "battery" is a number of cells merged into a single battery. A 12v car battery has 6 cells. It's cheaper and easier to handle than a bunch of separate cells.
A "module" is a part of a big battery. If you need a really large number of cells, it's more reliable and easier to manufacturer if you break it into a number of modules.
Most Prius use nimh cells. They are combined into modules of 6 cells each. There are no external connections to the middle cells, and no way to monitor the individual cells inside. You could call it a "battery", especially if used all by itself. But Toyota uses it as one of 28 (or 38) modules to make up the big hybrid battery.
Then, they only connect to every *other* module. So the best any device can do is measure *pairs* of module voltages. Roughly 14.4v for each pair.
Now, that is still useful information for servicing. It can narrow down a problem to one pair (out of the 14 or 19 pairs of modules). Once you get the pack apart, it's easy tell tell with a voltmeter which of the pair is the bad one. You have to replace entire modules anyway; so there is no point in measuring individual cell voltages.
Also, every Prius already reports module voltages, without any special apps. Any OBD2 scangauge code reader can read them. Many auto parts stores will read the codes for free.
The Plug-In Prius use lithium cells. They are dangerous if abused (fires!), so good engineering requires that every single cell be monitored for problems, so things can be shut down before there is a safety problem. That means it *is* possible to measure every cell voltage with an external device.
I hope this helps. Sorry to sound like a nit-picker. But it is important to get the terminology right. Otherwise, you will get sold something that doesn't really do the job you think it does.
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