How to test HV battery state of health on your Gen 2 (answer)

Sounds good. I wouldn't regard #1 as necessary. The act of force charging has always resulted in a sufficiently warm engine, but you went at it different. The important thing is you got it fully charged.

Yeah, I'll clarify that the ICE doesn't restart immediately at two bars. It sounds like you have a successful test.

I have found the test fails at some point between 54 and 70°F. I'll add that clarification as well.

 

I ran the test with the car showing 54°F today, and the compressor ran inconsistently. I saw currents between 8 and 11A. It was probably just too cold when you tested it, and you did it correctly. Given that you captured techstream data, there's probably no reason to re-run the test. The current was lower than desired, but it's probably all that was available.

I would go with the computed SoH and investigate grid charging ASAP.

 

I agree. I'm checking the hourly forecast to try and hit 60-65°F. I'm thinking the limit is going to be somewhere around 65°F as that's the lowest specific temperature that can be set.

 

I couldn't find anything that worked this morning at 54°F. If you set to heat, the demand will run the ICE. Setting to a neutral/cold temp with front defroster pulled about the same as partial A/C, and neither were consistent.

I think a no-A/C version can be had with about 6A, which is still a reasonable current with which to test. Unfortunately, that's going to push the test close to 30 minutes.

 

Zero.

 

This is a perfect example of how the 0.2V deltaV rule does not apply. You were barely over 0.2V at the very end of the discharge. This is very good news as I believe these results represent the best potential for recovery through grid charge/discharge reconditioning.

Your computed capacity is 1,090mAh, which is 40% SoH.

Note the red highlighted region representing the 55-65% SoC range, where the car spends a lot of its time. You're subject to a lot of voltage fluctuation in that zone indicating a lot of voltage depression.

Your test lasted 4.72 minutes. 4.72 * 9.5% = 44.8% SoH.

I like that accuracy, but I'm biased.

I'm extremely excited to see your results given your high mileage.

Please keep us posted.

 

Given the age and mileage, I would encourage you to take your time with multiple charge/discharge cycles. Given the uniformity of your block voltage response, I recommend the following for emphasis on both expediency and maximum benefit:

1. Force charge in car to 80% SoC
2. Grid charge for 12 hours (this fills in the last 20% and will balance individual cells).
3. Conduct discharge test to 40% SoC
4. Discharge to 201V w/2X 200W max.
5. Discharge to 135V w/2X 25W max
6. Grid charge for 4 hours (or more until 220V min)
7. 12V reset and idle charge in car until termination.
8. force charge in car to 80% SoC
9. Grid charge for 8 hours (Cells have been mostly bottom-balanced, less grid charging is necessary).
10. Conduct discharge test to 40% SoC
11. Discharge to 185V w/2X 200W max
12. Discharge to 84V w/2X 25W max
13. Grid charge for 4 hours (or more until 220V min)
14. 12V reset and idle charge in car until termination.
15. Force charge in car to 80% SoC
16. Grid charge for 8 hours
17. Drive it for a week
18. Repeat discharge test

NOTE: you will do FINE if you use the HA instructions. The above is what I would do if it were MY car with the goal of doing two conservative discharges to 0.8V/cell and 0.5V/cell successively while saving as much time as possible. Given the age/mileage on your battery, I feel the initial discharge should be to 0.8V/cell with 25W max bulbs when under 1.2V/cell.

Jeff may disagree with the above. If so, follow his lead!

 

Sometimes it's hard to get to the eighth bar. At that point, your're probably at 75%+ SoC. SoC is an approximation based on many factors, and it lags reality. Another parameter may have been limiting the charge, such as the Max block V in relation to the charge current. Fog lights are fine. Level doesn't matter. ATF fluid change doesn't matter. Everything you did is conservative thus, your battery is likely no worse than the computed 53%. I would expect that your car is actually in the high 50s/low 60s. The car can perform very well even at that SoH. I have found it's around 40% where problems start to show up (accelerated SoC gauge movement, reduced mileage). Commuting mileage that involves a lot of non-stop freeway driving hardly uses the hybrid system at all, so it's a poor indicator. In-town typical stop and go is the best measure. 45mpg without conservative driving is pretty good.

No benefit whatsoever. Benefits occur when you take the battery SoC outside the car's operating range.

The behavior you describe has been documented on the Gen1 where it forced charged to near 100% and discharge to the vicinity of 20%; however, I do not have any knowledge of the Gen2 exhibiting this behavior.

 

If you can capture it with Techstream, and upload it... that would be great.

 

I'm still working on that one. I haven't had a chance to test a Gen3 yet. From what I hear, one can only force charge to 60% SoC