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Discussion Starter #1 (Edited)
I welcome any better test suggestions, or help with this one.

Several great ideas have all failed to clearly show battery health*, but apparently a good indicator is voltage drop under load**. If you have at least a $17 Konnwei KW902 scanner & free AlfaOBD app (or similar), please submit your results to compare & help us discover if/how we can measure voltage drop to finally estimate battery health.

The easiest test I can think of is selecting voltage gauges in AlfaOBD graph mode (bottom right icon), then floor it to check voltage drop under max(?) load***. To get a baseline voltage I started graphing (big red arrow) beside an open 50mph road with the car in "D", held stopped with the brake pedal. Then from around 20mph or so I floored it & kept it there for a few seconds. I then braked to around 20 again, did it 2 more times to check consistency, & then stopped graphing ("hand" icon). Here are my maximum voltage drops:

1) Max Cell Voltage dropped about 288 mV, ~7.4% (from ~3893 to 3605)
2) Min Cell Voltage dropped about 406 mV, ~10.4% (from ~3888 to 3482)
3) High Voltage Sensor (pack) fell ~29 V, ~7.7% (from ~378 to 348.8)
4) Battery Voltage (cell sum) fell ~28 V, ~7.3% (from ~377 to 349.5)
Screenshot_20200214-233653_AlfaOBD_Demo[1].jpg
Click thumbnail for full image. I cut & pasted 2 screen shots, but feel free to just attach your own 2 separately.
500e built 07/2013, 24.2k miles, 50% charge, 50F ambient.
5) "Bus Voltage" excluded (AlfaOBD only graphs 4 at once).

*** Maybe better to check at steady load? (like 15kW, around 55mph).

* Unfortunately, we can't use OBD's Full AmpH Capacity, HV Bat SOH, HV Bat SOH-R, or HV Bat SOH-C, since it seems the 500e's data output for them is undependable based on about 80 user reports so far here, where each of those readings shows no clear, reliable trend over distance or time, with widely scattered numbers. Others have reported the car's own % gauge becoming highly inaccurate, so we can't go by it, or any calculations based on it.

** It's a sign of unwanted internal resistance, whose only direct measurements I can find are "Battery Impedance" & "Max Cell Resistance", but they always show zero on the free AlfaOBD (stationary OR driving). Please let us know if it shows on the paid version, or another app or scanner.
 

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I'll post some data on this when I have the time to record the data. I have been monitoring this information myself, but the voltage drop seems to vary based on the temperature of the battery and the ambient temperature around the car. I'll try to get the car warmed up and happy before recording data.
 

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Discussion Starter #3
CRAP! I hadn't tried at different temperatures. I'm disappointed this seems like yet another dead end, but there's another idea we can try, that's even easier, so maybe we can get more people to respond.

HOWEVER, we may not need anyone else, if YOU report on your brand new battery ? .....
 

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Discussion Starter #4
After charging until it auto-stops, what is your KEY-OUT* voltage on OBD?



*Check OBD right after opening/closing the driver's door. If it times out before you get readings, just open/close again.

If a new battery is different from an old one, the "virtual battery" software is fooling us into thinking we have less degradation than we really do.
 

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Discussion Starter #5
3013, 24k miles:

1st check 1/17/20:
Max Cell Voltage: 4113 mV
Min Cell Voltage: 4107 mV

Battery Voltage (cell sum): 398.70 V
High Voltage Sensor (Pack): 399.10 V
Bus Voltage: 399.30 V


2nd check 3/9/20:
Max Cell Voltage: 4108 mV
Min Cell Voltage: 4103 mV

Battery Voltage (cell sum): 398.20 V
High Voltage Sensor (Pack): 398.70 V
Bus Voltage: 398.50 V


PLEASE make SURE to do it with the KEY OUT, & try to have the dome lights off & your foot off the brake pedal.

That is because voltage is lowered with the key on one click, & lowered even more if the motor is "ready", if the daytime running lights or headlights are on, etc....
 

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I'll get some of that data over the weekend.
The voltage drop under load is still a good measurement I think, but we would need to record ambient temperature with it and wait for the battery heater pwm to be close to none.
 

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Discussion Starter #7
Ya. I almost hope we find a difference in max voltage, since it's so much easier to measure.

Unfortunately that would mean we're being fooled by the software, & later our range could start to drop rather quickly. I strongly doubt it though, based on lab tests I've seen for our batteries with 80% capacity retained after 3,200 cycles to 20% from 100% (which we can't even inflict) at 12kW charging (which we also can't inflict).
 

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Discussion Starter #8
3rd check 3/18/20, sitting a while after auto-stop:
Max Cell Voltage: 4110 mV
Min Cell Voltage: 4103 mV

Battery Voltage (cell sum): 398.30 V
High Voltage Sensor (Pack): 399.00 V
Bus Voltage: 398.40 V


4th check 3/18/20, re-plugged, & checked right after auto-stop:
Max Cell Voltage: 4114 mV
Min Cell Voltage: 4106 mV

Battery Voltage (cell sum): 398.70 V
High Voltage Sensor (Pack): 399.10 V
Bus Voltage: 399.00 V
 

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2017 Fiat 500e (Billet Argento), 2015 VW Golf Sportwagen TSI 5MT (Tungsten Silver), 2002 Honda VFR
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CRAP! I hadn't tried at different temperatures. I'm disappointed this seems like yet another dead end, but there's another idea we can try, that's even easier, so maybe we can get more people to respond.

HOWEVER, we may not need anyone else, if YOU report on your brand new battery ? .....

Its not brand new, the battery used in warranty scenarios are refurbs, one tech that used to work for OC Fiat says they (FCA) test all cells and salvaged what they can and replace the bad ones with good ones from another, etc. With the high cost of these can you blame them?
 

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Discussion Starter #10
Thanks TT. That just means we need a few other helpful people with OBD readers (& preferably with low or high miles & non-warrantied batteries) to simply report their own 5 OBD HV batt readings WITH THE KEY OUT, when it auto-stops charging.

It should only take a few to see whether or not there's a pattern.
 

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Discussion Starter #11 (Edited)
This topic is still unresolved in other threads:

PLEASE just tell us your KEY-OUT voltage* at 100%! (charge til it stops).


*PLEASE make SURE to check OBD right after opening/closing the driver's door, with the KEY OUT, dome lights off & your foot off the brake pedal. If it times out before you get readings, just open/close again. Around the 4th "screen" down on AlfaOBD, check these:
Page 4.jpg
 

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This topic is still unresolved in other threads:

PLEASE just tell us your KEY-OUT voltage* at 100%! (charge til it stops).


*PLEASE make SURE to check OBD right after opening/closing the driver's door, with the KEY OUT, dome lights off & your foot off the brake pedal. If it times out before you get readings, just open/close again. Around the 4th "screen" down on AlfaOBD, check these:
View attachment 108674
If you don’t want to trip the contactors just do it from passengers door you can do everything from that side and not trip the contactors. The contactors only trip when you open drivers door.
 

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Discussion Starter #13
We WANT to trip the contactors, since that is required for OBD readings.

So we use the driver's door to trip them so we don't have to use the key because that drops the voltage by varying amounts, depending on things like daytime running lights.
 

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Discussion Starter #14
I think we've got it!

Apparently, % of original capacity is just charger kWh, divided by % charged, then divided by 25:

  1. On a metered charger,* charge from as low as possible to as high as possible.
  2. Your approximate % of original capacity is charger kWh, divided by % charged, then divided by 25*.
For example: 13.5kWh to charge from 20% to 80%. 13.5 divided by 60% is 22.5, divided by 25 is 90% of original capacity (10% range loss).
 

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Discussion Starter #15
*Most, if not all public ChargePoints have meters, as do at least some Greenlots, & maybe others, along with many new home L2 units. 25 is the original 0-100% charger kWh, according to EPA tests.

Note that like any estimate based on the % gauge, this will be inaccurate unless you first calibrate that gauge by discharging (with lights, fan, & rear defrost, parked at a charger) until the 12V batt warning shows (or until it drops from 14.x volts to 12.x on OBD or multi-meter), then non-stop full L2 charge, followed by driver's door open/close & once again charging til it stops.

Also note that it varies with temperature, so hopefully one of us can find out what temp EPA uses.
 

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That SOH-C and Ah data looks reasonable to me. The SOH-R and SOH certainly have some anomalies. It is interesting to note that his SOH-R jumps to 99.61 when he is charging. On my car I always have a good SOH-R measurement so it reads 99.61 when charging or not. But clearly this reading is effected by whether the car is charging or not. I think the reason the SOH value didn't change for this measurement is it is calculated periodically while the SOH-R value may be more instantaneous.

But overall the progression seems reasonable to me. I think what is interesting to note is his range estimate for a full charge remain close to the EPA rating up to 65K miles. So depending on how observant you are, you may not think you have lost any range despite a real drop in battery capacity.
 

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Discussion Starter #18
It also seemed reasonable to me, at first glance. Unfortunately, when I checked the user reports here, there's a HUGE range of different AmpH loss per mile, for different user's cars.

Loss per 10,000 miles goes from under 1% to nearly 20%!! That seems like too much difference to be able to trust those numbers.
 

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Discussion Starter #19 (Edited)
I really do appreciate any new theories, & new ideas about existing ones!

I just checked my own car:
  • 1% loss per 10k mi shows on AlfaOBD Full AmpH Capacity, which would be nice, but a bit unbelievable.
  • 4% loss per 10k mi shows from charge-meter, divided by % charged, divided by 25, which seems more realistic.
 
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