MyVoltControl new release now includes HV Battery Internal Resistance

1067 Views 7 Replies 6 Participants Last post by BarryD, 3 d ago

BarryD

Discussion Starter · 12 d ago

Version 2.4 of the iOS-only app MyVoltControl was released yesterday. This release adds the ability to read the HV battery internal resistance. This, along with the 3 existing battery evaluation sections, makes it possible to get a pretty complete picture of the health of a Volt's traction battery.

In addition to that, a new feature will calculate the distance you've traveled in both ICE and EV modes when you enter the Lifetime Fuel Economy value from your dash. (Saving that information, before you reset the value, will allow a next owner of the car to have that information.)

Finally, support was added for the Apple "Shortcuts" app. This means that you can include MyVoltControl actions as part of animations you are creating with Shortcuts. For example, let’s say you create a “shortcut” and use it to turn on the Driving Focus and then to start MyVoltControl on the Volt Hold screen, and then close your garage door maybe. You might name this “Ready to Drive”. Then all you have to do is say “Hey Siri … Ready to drive” and the magic will happen.

Barry

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BarryD

Discussion Starter · #5 · 12 d ago

TYmrLutz said:
Great news for Volt owners! Thank-you BarryD! My understanding of cell balance voltages regarding overall battery pack health is:
1) best to check a depleted pack, ie zero range Charge Sustain mode, at least an hour after shutdown
2) delta of <50mv = good, >150mv = bad, 100mv iffy, (<20 = great) Propulsion Power Reduced triggers at 250mv
3) fully charged pack variance usually better than depleted pack, but if delta not better (especally if same cell is weak), a PPL may soon appear
Can you share with us how/when/why to interpret HV Battery Internal Resistance?

1) Yes, a depleted pack shows weak cells. What I usually hear on this is to check the pack with just a few miles left (or zero is also OK as long as you're measuring it when you've stopped and the ICE is off). Also need to have the heater on MAX and at Max Temp in order to put a load on the battery. I have never heard that you need to let it sit for an amount of time.
2/3) The spec for warranty replacement of a section is delta > 121mv. I haven't heard of RPP triggering due to a weak cell but I might certainly be wrong on that.

What I've heard about internal resistance is this: If the resistance rises to 400mOhm, you will receive a P0A7F DTC. If the resistance rises to 380mOhm, the car will switch to ICE regardless of SOC (and back to battery if the resistance drops below that, like due to increase in temperature).

I've been trying to collect what we know about the values for all of these. Your input would be most welcome. Take a look at My Volt Diag Expected Values | Craftin De Apps LLC and give me any recommendations you might have. Anything in that table with a ? after it is a number I totally made up.

TYmrLutz said:
Also, best to use Wifi or Bluetooth dongle? Thanks again for this great software tool.

It's best to avoid WiFi dongles these days. Read the first FAQ here for my recommendations:

FAQ | Craftin De Apps LLC

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BarryD

Discussion Starter · #8 · 3 d ago

vap3 said:
so just plug it in and go for an extended test drive and record the data! i can't wait! I plan to screen record with commentary on my test drive.

No actually. For 3 of the 4 tests, it’s reporting saved data so it wouldn’t matter if you’re driving or not. For the Cell Balance test it will mess it up when you’re driving. Park it. Cell Balance information is most useful when observed at a low SOC (nearly depleted battery and with the Heater on Max at Max Temp (eg, with a constant load on the battery)).

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