Help with Dr. Prius battery monitor readings

Got these links

https://priuschat.com/search/225673208/?q=DR+Prius&o=relevance&c[title_only]=1&c[node]=56

 

Hello and welcome to PriusChat. Dr Prius is a great app for monitoring data from the High Voltage battery ecu. The battery pack is made up of 14 blocks, with each block having 2 modules. So there are 28 modules total, in series. Each sealed module consists of 6 Nimh cells (x 1.2V each), for a total nominal voltage of 201.6V. Dr Prius shows you the voltages for each of the blocks, which can vary from 12.5V to 19.0V- it all depends on the battery condition, present State Of Charge (SOC), how many amps are charging or discharging. The important thing is how even the blocks are with each other. Ideally all should always be within 0.3V of each other. If that difference exceeds 0.3V for any duration, it will reflect that by increasing the Delta SOC - this normally stays at 0%. As the battery deteriorates and blocks voltages vary more for longer then the Delta SOC goes up- I believe it will set a failure code at 30 or 40%?

There is the SOC, which varies from 40% (1 bar on the gauge) to 80% (8 bars). The ecu tries to keep it around 60-70% during driving. If you sit in traffic with the A/C on, it will let it go down to 40%, then start the Internal Combustion Engine (ICE) to charge it up to 45-50%

The block resistance values are typically 20-30 milliohms, and will vary depending on battery SOC, condition, and temperature. I only notice that whatever they are, it is usually even within 3 milliohms or so.

If you have the paid upgrade on the app, you can perform the battery "life expectancy test" which is really a battery capacity test. You "force charge" the HV battery to full and then turn on electrical loads to discharge at around 6 amps until the ecu wants to recharge. (the only way I have found to accomplish this requires that the A/C system functions, otherwise the app will throw an error because there isn't enough load). Anyway the app monitors the pack voltage and amps over time, then does the math to figure out the total power used and gives you an approximate capacity.

One the great features of this app is the ability to read and clear codes from several of the car's computer modules (I believe that is under Special Features).

 

Totally true, I am getting the last miles out of my HV battery as about once a week (in hot weather mostly) it will throw a "Check Hybrid System" error, so i reset it with dr Prius, reboot (restart) the car and i'm on my way again.
I plan on doing this till the errors are regular enough to not recover after clearing the codes. If your not in the position to shell out for a brand new HV battery this can be a lifesaver!

 

driving on bad battery can fry transmission

It's like I can keep driving really low on oil, it might spin a crank bearing but hopefully not

Posted via the PriusChat mobile app.

 

You can keep resetting the ecu as long as you are OK with the eventual fact that it will stop working completely at some point and strand you, and some people have had modules "explode" with a bang.

Posted via the PriusChat mobile app.

 

Great summary. I'm new to Prius, this forum and Dr. Prius App but a bit of a veteran with Hybrid/EV and this was a very clear/comprehensive description I hadn't found elsewhere. Thanks!

 

I haven't been "resetting" (yet) and do intend to replace my pack "soon" but have felt that the high-rev/loading of the engine (through the CVT) seems ultimately unhealthy for the drive-train. I ran my 01 Insight with a weak pack often and for a long time and it (seemed to) take it well (cars these days are nicely over-engineered?)...

Any advice on how to be (most) gentle with the engine/transmission until I can get full E-boost back?