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Discussion Starter · #1 ·
Just had an inspection done on my car and I'm a little confused...


On another thread I read these statements "Fisker guidelines define end of life of the HV battery at 80% or 10 years/100k miles."

And...


"The HV State of Health is a battery algorithm that is based on calendar time and miles driven..."

So, my question...this Fisker has just 6000 miles...and the HV SOH read 76%..?

I'm guessing the reading should have been closer to 90% if the Prodis were working properly.


I've seen guys with 35,000 miles and more that still have 80%.


All modules were tested and performed equally during discharge/charge, but I wonder if there is an underlying issue with the battery somewhere that explains the low miles driven and the low SOH report.


Anyone?

 

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Yes, would be great to know more about the algorithm. Did you get the SOH value from Prodis workshop tester or did someone figure out the PID to request this value from generic scanners like Torque? e.g. SOC is available by EOBD and generic tester.
 

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If you use a reverse Chi Square algorithm for the degradation of charge based on the lithium and cadmium degradation rates factoring in charge amperage and temperature his numbers appear perfectly normal.

Just my 2 cents....
 

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Discussion Starter · #6 ·
If you use a reverse Chi Square algorithm for the degradation of charge based on the lithium and cadmium degradation rates factoring in charge amperage and temperature his numbers appear perfectly normal.

Just my 2 cents....
Ok, so all things being equal, would you estimate this SOH 76% battery to last, what, another 5 years? 8 years?

I just would have thought that a car with only 6000 miles would have more battery life left. I get that not driving it is probably the worst thing you can do for these batteries...
 

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Ok, so all things being equal, would you estimate this SOH 76% battery to last, what, another 5 years? 8 years?

I just would have thought that a car with only 6000 miles would have more battery life left. I get that not driving it is probably the worst thing you can do for these batteries...

The SOH value is complete bogus. It is just some random value that prodis generates. Let's put this issue to rest.
 

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Discussion Starter · #8 ·
Is it bogus, PowerSource? I'm asking seriously. A completely meaningless number? What other metric could I use then to determine the expected remaining life of the battery? I'm a new owner, still learning.
 

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If you use a reverse Chi Square algorithm for the degradation of charge based on the lithium and cadmium degradation rates factoring in charge amperage and temperature his numbers appear perfectly normal.

Just my 2 cents....
 

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Is it bogus, PowerSource? I'm asking seriously. A completely meaningless number? What other metric could I use then to determine the expected remaining life of the battery? I'm a new owner, still learning.

This is a complicated answer and from an end-user perspective would require a large compilation of data in order to determine. Basically you would have to log charge data and dis-charge data. Then one would create a Cycle v Capacity plot. Generically speaking, the amount of cycles will determine battery capacity. Being that the 2012 Fisker Karma only discharges to 15% you would have to determine depth of discharge for every cycle. At the end of the day, the less you discharge the battery the less cycles your pack will have which will mean the greater the capacity.

Basically if you use your pack to only 50% usable... I.e. 26/27 miles your pack will retain its pack capacity more so than discharging to 0 miles (15%). But you also have cell aging & impedance growth and a few other issues which complicate this whole exercise.

To answer your question, I wouldn't worry about it and just enjoy your car because if the pack is operating properly (i.e. no leaking cells, or cells out of balance etc) your pack will likely last a long time before you need to worry about an end of life scenario (80% pack capacity as defined by 2012 Fisker Karma warranty documentation).
 

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Now you know why i said only worry about it if it goes to zero which was a problem before 520 but the problem still surfaces and the BECM needs to be replaced. Software doesn't restore the SOH .
 
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