Battery SOH - bragging rights or bullshit?

[StevenC56]

How do you check SOH? OBD scanner? If so, which one do most of you use?

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[chl]

All those VW driving on fumes stories brings back memories of being a teenager and barely having any money for gas, coasting down hills in neutral.

I drove an old used 1965 Mercedes 190E gas sedan for a while, with an inscrutable gas gauge that left me stranded several times, and a weird thermometer style speedometer that had Km/H and mph on the vertical scale, could never really figured out whether I was speeding or not on US roads, and to make matters worse, it changed color as it went up from green to yellow to red!

It barely had power to get up a highway hill with 5 passengers in it, but it was very comfy inside when on a date, and the young ladies were often impressed with it - little did they know, lol.

Here it is in 1970, pulled over in the middle of nowhere, no gas stations in sight, me hoping to make it out of the desert alive - apparently I did.

I had some adventures in that car, went to Woodstock 1969 in it with my brother and three friends and convinced the gate keepers we had band equipment so they let us pass - no they never checked the trunk because one of our friends had was wearing an official Woodstock staff jacket he had traded someone something for, lol.

Tickets: $6 per day - yes, we bought 2, two-day tickets before we went, alas
Gas for the trip at $0.35.gallon: 280 miles / 30mpg = $35 one way
Camping in the mud listening to Jimi Hendrix play the star spangled banner Sunday morning: priceless?

 

[ClevelandBeemer]

I suspect we have a much more robust cooling system to allow for towing.

I don’t know about this. I feel if the cooling system was truly robust, DCFC would be able to hold 500a longer.

It would be interesting to get an engineers perspective that was involved with the design.

 

[chl]

Oh yeah, back to the topic...

Why the Mach-e is different - likely a different guess-o-algorithm is used.

As for the SOH numbers car scanner etc will give you, an educated guess-timate, but at least it's a data point to watch and give you a warm fuzzy feeling, or a feeling of dread, depending:

So take the SOH number with a grain of salt but keep an eye on it anyway?

 

[swajames]

Why would the SoH number be bullshit? It isn't a number that's readily available to the driver, you can only access it via a scanner and your OBDII port.

 

[swajames]

I don’t know about this. I feel if the cooling system was truly robust, DCFC would be able to hold 500a longer.

It would be interesting to get an engineers perspective that was involved with the design.

Our charge curve has already been improved via an OTA update to allow higher charge rates for longer. I saw higher rates post update than I saw pre. Maybe Ford will push things out a little further as more data comes in.

 

[chl]

Why would the SoH number be bullshit? It isn't a number that's readily available to the driver, you can only access it via a scanner and your OBDII port.

Maybe the term was used to insinuate Ford is fudging the number to make owners feel good?

State Of Health gotten from the Ford HVB BMS with an OBD canscanner app or similar, is just an estimate, not an exact number.

The BMS produces it using a calculation based on the measurements it collects and processes.
There can be small errors in measurement that accumulate over time, 'BMS drift.'

However, it is an indicator even if it is not 100% accurate.

Owners of EVs have seen the SOH numbers do funny things like go UP over time, due to recalibration of the BMS no doubt.

So while not technically BS unless the calculation were intentionally tampered with to distort the real number (like VW did with it's diesel exhaust calculation for example).

It is not as absurd as the state of the cat (dead or alive) in Schrödinger's box for example...closer maybe to determining/estimating the mood of your spouse after being together for many years?

 

[ClevelandBeemer]

Our charge curve has already been improved via an OTA update to allow higher charge rates for longer. I saw higher rates post update than I saw pre. Maybe Ford will push things out a little further as more data comes in.

Yes, but it is still thermally driven.

 

[swajames]

Maybe the term was used to insinuate Ford is fudging the number to make owners feel good?

Maybe. And of course we're all just speculating. But that would make more sense if the SoH calculation were generally and easily available to owners via the in-vehicle UI, but it isn't. This isn't the GOM or remaining energy calculation, it's an otherwise hidden attribute that requires owners to go to some effort to get it. All the other things you suggest may well be true, but none of us know if they are factored in to the SoH calculation anyway. My main point is it's not a number Ford needs to fudge as it's not readily available.

 

[chl]

Maybe. And of course we're all just speculating. But that would make more sense if the SoH calculation were generally and easily available to owners via the in-vehicle UI, but it isn't. This isn't the GOM or remaining energy calculation, it's an otherwise hidden attribute that requires owners to go to some effort to get it. All the other things you suggest may well be true, but none of us know if they are factored in to the SoH calculation anyway. My main point is it's not a number Ford needs to fudge as it's not readily available.

Ha, yes I guess so, that's true.

I suppose the only reason it is even readable with an the OBD scan is for Ford techs to see?

But these days, a lot of folks have OBD devices and use Car Scanner or equivalent APP, esp owners of EVs.

I also have a 2012 Nissan Leaf bought in Dec 2011, and it wasn't long before the LeafSpy app came along to show what the SOH of the Leaf battery was among other things.

I bought a new OBD device to do some Forscan tweaks - change the headlights to glare-free, turn off the chimes, allow PPOB with the truck off, activate silent mode, and remote front window up and down.

I haven't tried CarScanner, but it is on my to do list.

I will only freak out if the SOH number is really bad - but if it was, I imagine I'd already be seeing issues with the HVB, and I'm not, so it can wait.

 

[chl]

FYI

Capacity loss is steepest at the beginning and end of the battery lifespan.

The average is from 1-2% per year just from age, and fast DC charging can decrease capacity faster than slow AC charging.

With my Leaf I have seen the average loss.

As part of their warranty settlement terms, I used to go in once a year for a battery test, but nothing abnormal arose so after the 5th or 5th year, I let it ride.

 

[ClevelandBeemer]

Well true, but all batteries are thermally driven unless charged well under their max.
Still, yours shows the normal lightning curve, higher power at the beginning, possibly until a certain thermal rise, more or less steady state, then the drop at 80%.

No doubt. I wasn’t not suggesting abnormal performance. Instead I’m merely questioning if the cooling system IS as robust as suggested.

Either way, I’m happy with it being the 400v system that it is.

 

[dmd3home]

I had a 68. Interestingly, “R” meant reserve. You supposedly had 1 gallon remaining between the extremes of the little horizontal tick mark.
At least that was the U.S. spiel. It was probably 4 liters or some other SI measurement.

I had a '56 VW....no gas gauge at all! Had a "reserve" position on a foot lever that gave you 1 more gallon. You need to always remember to kick the lever back to normal when you fill up.....worked perfectly!

 

[mr.Magoo]

Why would the SoH number be bullshit?

It's not BS as such, but it is also not a standardized unit, it's a calculated number or a "guesstimate".
For all we know Ford doesn't even use the same algorithm/formula between the Lightning and the Mach-E.

So, it's a good indicator, but nothing to obsess about.

 

[carys98]

I wonder if we might be misinterpreting what is being measured. Could SOH just be tracking whether balancing is required? We have reports of people seeing the SOH drop into the nineties and then later coming back to 100%. This implies that there must be some treatment available for poor health. There’s really no way to bring back lost capacity so a rising SOH wouldn’t make sense if it was directly related to capacity.

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