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Those numbers are worthless the number you should be looking at is “full amp hour capacity” it is 63.0ah when the car was new and the only number that doesn’t fluctuate and goes down as the car ages and miles are piled on. Gives you the batteries capacity, what you do is multiply the amp hours x volts in our cars it’s 364volts, then divide that by 1000 to get battery pack capacity.
I don't know why you think it's worthless. The SOH-C has jived well with the Ah recorded for my case as far as I understand. Here are the additional numbers in Ah I recorded for those miles.

In any case, I want to share that I am losing 3% per 5k miles so far.

MilesSOHSOH-RSOH-CAhkVoltkWh
5052248.63%84.31%77.65%50.60.36418.42
5591473.73%82.75%74.51%48.60.36417.69
 

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2017 Fiat 500e (Billet Argento), 2015 VW Golf Sportwagen TSI 5MT (Tungsten Silver), 2002 Honda VFR
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I don't know why you think it's worthless. The SOH-C has jived well with the Ah recorded for my case as far as I understand. Here are the additional numbers in Ah I recorded for those miles.

In any case, I want to share that I am losing 3% per 5k miles so far.

MilesSOHSOH-RSOH-CAhkVoltkWh
5052248.63%84.31%77.65%50.60.36418.42
5591473.73%82.75%74.51%48.60.36417.69
Because the numbers fluctuate up and down you don’t know since there’s no steady decline, but the aH always goes down with time and miles. It’s the only thing that is consistent. I’ve checked mine on Alfa obd and it’s all over the place on the SOC readings up and down all the time. Only numbers that was consistently declined is amp hours.
 

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Because the numbers fluctuate up and down you don’t know since there’s no steady decline, but the aH always goes down with time and miles. It’s the only thing that is consistent. I’ve checked mine on Alfa obd and it’s all over the price on the SOC readings up and down all the time.
Well yes, the SOC reading depends on how full the battery is when you are reading the OBD. So you can ignore that. For my use case (consistent commute at consistent times), the SOH-C has trended down in line with the Ah for the past 5k miles or so. I have 5 other datapoints in between.
 

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multiply the amp hours x volts in our cars it’s 364volts, then divide that by 1000 to get battery pack capacity.
So by @hastalavista amp-hours it's down 1.8% per 5,000 miles, or 3.6%/10k in our more common units.

With that much loss, after only 167,000 miles it would need to recharge after every average US daily drive. Good thing it does that overnight from a standard wall outlet.
 

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For my car, I lost 2 Ah in ~5k miles. 2 Ah lost out of the full 61.7 Ah is 3.2% in ~5k miles.
Similarly after converting to kWh as suggested: I lost 0.73kWh in ~5k miles. 0.73kWh out of the full 24kW is 3% in the 5k miles.
Therefore I concluded it was a ~6% degradation in 10k miles.

Is my math wrong @Electric Tire Shredder ? Can you show how you did your math?
 

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I don't really trust the OBD numbers though. I think someone saw capacity go UP when they drove slower.

So I still think the only way to really check current capacity is to duplicate the EPA test & compare to their 25kWh spec:

1) Discharge to motor shutoff by driving to 0% near a 120v outlet & doing a simulated hill-start (press both pedals) til it stops.

2) Fully charge in 68F - 77F ambient on 120V with the OEM cord in a $20 metered smart plug & divide the kWh by the EPA's 25kW spec to get % of original capacity.
 

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Thank you for the explanation.

You are calculating the decline starting from mile 0. I am starting the decline during my ownership with my use case. For my use case, the BMS estimates battery degradation is 6% every 10k mile. At the end, this is what's important for me because I will be using this car for my commute-charging use case and I would like to know at what point is it not usable for me.

Now, as you mentioned.. Whether the BMS is accurate or not, it is a different matter. I do not know how Bosch designed the BMS, but it can be a complicated algorithm (or simple) .

One example: Does it make sense for the BMS to calculate the capacity based on the total power put into the battery during charging? I can see how it can be misleading because as the battery wear, resistance increases and more of the power is wasted as heat both during charging and discharge. (And think about how the cooling/other systems drawing power from the EVSE during charge might skew the EPA method). It's an imperfect method good only to compare results of the same car multiple times.

I can see how the BMS for a car that's driven at a constant 20mph for example (after being previously driven at a constant 70mph) can think it should adjust its battery capacity number up because of the concept above and voltage sag.
 

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All very good points.

Although I'm not quite sure what you mean about the EPA method.
They measured a:
- 500e's total OEM EVSE power draw including cooling
So we can compare to our own:
- 500e's total OEM EVSE power draw including cooling

IF we do it at the same ambient temperature, which I'm not certain of: I assume it's a standard lab room temperature like 20 or 25C (68 or 77F).

Maybe you mean that if the EPA charges right after running it dead, the battery is warmer than ambient, by an amount that depends on how hard they were running it, which we don't know.

One more point to consider: Before doing the EPA test you'd have to charge to 100% in order to balance the cells. That takes a bit of extra power if they're imbalanced, which would skew the results.

SOH-C has jived well with the Ah... Here are the additional numbers...
SOH-C is based on Ah. They're always exactly proportional, which means they must be based on the same data point, so they can't honestly be considered as additional data. Same goes for kWh: It's taken from Ah, so I shouldn't have mentioned it "matching" above, since it's actually just different units for the same single data point.
 

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What I meant is that the rate of cooling differs as the battery degrades and there is more resistance in the battery. The battery resistance (in ohm) increases as it degrades. This means that a higher percentage of the power you are putting into the battery goes into heat (because of resistance) and the cooling of the battery. This is part of the reason other electric cars with fast DC charging would not be able to charge as fast when their battery degrades. Not to digress.. Therefore I don't think the EPA way is necessarily an accurate indicator of battery capacity.

The way EPA measures kW is only useful for their purposes: that is to measure efficiency and how much power the car uses in their city and highway cycles when new and to compare it on a level field with other electric cars. IMO it is not a perfect way to measure battery degradation and might not even be better than reading the BMS if the BMS is measuring the actual power output of the battery.

The actual battery capacity (starting from a certain voltage when full and cutting off at a certain low voltage cut-off) also depends on power draw.

On the topic of SOH-C, that's exactly what I was trying to say. That my initial data is not worthless without the Ah because I have had correlation between Ah and SOH-C. That's why I didn't share the Ah data initially.

What I meant by additional data points is that I actually have measured these same SOH-C, Ah, etc at other mileages between 50k and 55k besides the end points I shared.
 

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IMO it is not a perfect way to measure battery degradation and might not even be better than reading the BMS if the BMS is measuring the actual power output of the battery.

The actual battery capacity... also depends on power draw.
Right, & power draw is extremely variable depending on how hard you drive, so the BMS/OBD reading would be more accurate if it measures actual charging power INPUT to the battery, since that is much more consistent than output.

On the topic of SOH-C, that's exactly what I was trying to say. That my initial data is not worthless without the Ah because I have had correlation between Ah and SOH-C.
I was trying to say that your initial SOH-C data is neither more valid nor less valid by also noting it in different units (Ah). SOH-C is simply the same single Ah data point, just shown as a % of the original total gross Ah including the unusable buffers:

If you check each of your readings, including the in-between mileages, you'll see that SOH-C is just Ah ÷ 65.9 (give or take a % or two, possibly from rounding errors)

That's the original total Ah including buffers: 24,000Wh* ÷ 364V = 56.9Ah
* 24kWh

Now I'm trying to figure out how that relates to our calculations above, since OBD actually seems to be trying to show total gross Ah, not total usable.
 

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This discussion between power input and output is moot in my opinion. The power input has inaccuracy due to heat. That inaccuracy might artificially inflate the battery capacity reading. Reading the power output for a relatively consistent commute over time in my opinion is more accurate. However, I don't know of a good way to do this and could only assume this is what the BMS does.

I just meant to share my data. My take is that given my use case and power output, this is the capacity I am getting for my battery per BMS. That capacity is degrading by 3% over 5k miles. This battery degradation was calculated over 5k miles. I will continue to monitor this through the OBD over time. If this amount of battery degradation continues, I will probably only have a couple more years of use out of this car for my commute to around 100k miles.

The current battery degradation per BMS unfortunately shows that the battery is degrading significantly more per cycle and time compared to Tesla model S from the same era for example. Although I have a couple theories, I am not sure why that is.

If there are others with similar use cases and have a different battery degradation, please share your use cases.
 

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Your battery loss is not as bad as it shows, based on my observations.

Thanks for making me recheck my spreadsheet of user-submitted OBD data*:

After discarding the outliers, there are still:
  • 12 showing under 1% loss per 10k mi.
  • 14 showing over 10% loss per 10k mi.
That's out of 127 submissions. Discarding all the lowest & highest ones (8 of them are 64.9Ah) the rest vary from an unbelievably-low 0.66% loss per 10k, all the way up to an unbelievably high 19% per 10k.

I don't see how any of those readings could possibly be trusted, even the ones that happen to look reasonable just because they aren't extreme. If @twinturboz sees that, he might agree that even Ah & SOH-C from OBD are "worthless".

* Click here for the Google sheet created by another member of this forum
 

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Just adding that I have a bit over 84k miles on my 2013 and my 40 mile (both ways commute) leaves me at 45%-55% on average (I have seen below 40% on sub freezing days though).

I replaced the onboard charging module last week after it failed, so now I'm leaving the hood open while charging in hot weather just to hopefully milk a few more miles out of this OBCM.

In it's defense, it happened to stop working right after a lightning storm that had some very nearby strikes and it appeared a rectifying diode being blown was the gremlin. I'm not THAT proficient on electronics so that was just a researched guess after looking at a visibly cracked chip on the main board for the OBCM, and could have just been the most visible casualty of the failure.

Edit for clarity: It was connected to my level 2 charger in my garage when the lightning strike occurred. I'm not certain that was the cause, and may have just been coincidental timing. It may have just been years of level 2 charging with a closed hood in a closed garage (heat exposure). Also, the 10 miles I had beyond 0% seemed to correct the gage meaning my remaining percentage was higher after the same commute the following day. Definitely not a complaint though, this car really seems to have shown that degradation is often an overblown worry.

Easy part to replace and it was roughly $1300 for a new one so I didn't mind shelling it out to squeeze a few more years out of her. Love this car to pieces.
 

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That's great, especially since on another thread you said there's still 10+ miles left when it says zero.

Also please clarify if the car was just parked in the thunderstorm (unavoidable) or CHARGING, which we could avoid, to prevent damage.
 

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Your battery loss is not as bad as it shows, based on my observations.

Thanks for making me recheck my spreadsheet of user-submitted OBD data*:

After discarding the outliers, there are still:
  • 12 showing under 1% loss per 10k mi.
  • 14 showing over 10% loss per 10k mi.
That's out of 127 submissions. Discarding all the lowest & highest ones (8 of them are 64.9Ah) the rest vary from an unbelievably-low 0.66% loss per 10k, all the way up to an unbelievably high 19% per 10k.

I don't see how any of those readings could possibly be trusted, even the ones that happen to look reasonable just because they aren't extreme. If @twinturboz sees that, he might agree that even Ah & SOH-C from OBD are "worthless".

* Click here for the Google sheet created by another member of this forum
I guess I would guess mine is closer to the median then? What's the median based on your spreadsheet?

I have a 99K kilometres (62K miles) on the clock. The real life range is pretty much the same - was 144 kilometres, now maybe 140-135.
What's that real life range based on? 90% city driving? My range is probably closer to 60miles of highway driving at around 65mph.

Just adding that I have a bit over 84k miles on my 2013 and my 40 mile (both ways commute) leaves me at 45%-55% on average (I have seen below 40% on sub freezing days though).

I replaced the onboard charging module last week after it failed, so now I'm leaving the hood open while charging in hot weather just to hopefully milk a few more miles out of this OBCM.

In it's defense, it happened to stop working right after a lightning storm that had some very nearby strikes and it appeared a rectifying diode being blown was the gremlin. I'm not THAT proficient on electronics so that was just a researched guess after looking at a visibly cracked chip on the main board for the OBCM, and could have just been the most visible casualty of the failure.

Easy part to replace and it was roughly $1300 for a new one so I didn't mind shelling it out to squeeze a few more years out of her. Love this car to pieces.
What's your commute like? 50% city?

I am pretty sure battery wear depends on the use also. A slower discharge would wear the battery out less than a higher discharge rate.

Part of why I am sharing my data is to try to see how others with a similar commute is doing and what I can do to reduce battery wear.
 

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Thanks for doing the math for me, but I still don't trust any of those numbers.

Even though you narrowed the field to only EIGHT readings, the wear/10kMiles still goes all the way from 2.8% to a whopping 7.6% !

So according to that, one car has 271% as much degradation.
Another way of looking at it: One car has only 37% as much degradation.
To me that's literally unbelievable.

As for what you can do to reduce battery wear, you could just drive a couple mph slower:

If you tap the end of the wiper stalk it shows real-time motor kW where you'll see that it creates a much higher discharge rate at 65mph compared to 60*. So you could reduce battery wear by leaving home a few minutes earlier & driving a few mph slower. That also reduces wear by reducing the cycle depth. That might also allow you to avoid a full charge, which also reduces battery wear.

*I don't do many highway-speed trips, but I did one recently, & when I set my cruise to 55mph I got better mi/kWh than my average 75% stop&go drive. Based on that, 60mph may give about the same range as city stop&go: Yes, you get regen in the city, but it's not 100% efficient, & there's none at all below about 7mph.
 
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