#### docj

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Also what does Hx mean? We use the term alot in medicine. If it means some history in the car,

then what is it Hx of? Thanks in advance

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Also what does Hx mean? We use the term alot in medicine. If it means some history in the car,

then what is it Hx of? Thanks in advance

As mentioned a number of times, Hx data with regard to Leaf1 represents battery conductance (the reciprocal of battery resistance),

Also what does Hx mean? We use the term alot in medicine. If it means some history in the car,

then what is it Hx of? Thanks in advance

and highly correlated to SOH. If one does a search on the Forum, there're multi-year data presented to support this. With regard to Leaf2,

Hx data appears to be somewhat random, presently ranging from the lower 100s to the lower 90s. Until a longer trend becomes apparent,

HX for Leaf2 is more or less a random variable, lacking any correlation to SOH.

Thank you all

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In medicine, "Hx" is indeed an abbreviation for "history." It's commonly used in patient charts and medical records to refer to the patient's medical history

Also what does Hx mean? We use the term alot in medicine. If it means some history in the car,

then what is it Hx of? Thanks in advance

Hx is one of multiple coefficients the battery uses internally to characterize its polarization (internal resistance) characteristic. The polarization characteristic tells you how much the battery voltage decreases or increases as a function of (sustained) current draw. Batteries typically have a fast and slow response; when you suddenly draw a large current it will first decrease in voltage quickly, then continue decreasing more slowly. This characteristic is usually algebraically represented as:

dV = A(Be^(-ct) - De^(-et))

Coefficients A, B, c, D and e are tracked by the BMS. Hx is equal to 1/A.

It's hypothesized (but nobody has done the work yet) that B and D are missing from the BMS's internal resistance calculations on the first-gen Leaf, and have been added in in later generations. This would explain why it tracks SOH so well on gen1 batteries, and so poorly on later models. c and e are likely hard-coded constants.

Hx is one of multiple coefficients the battery uses internally to characterize its polarization (internal resistance) characteristic. The polarization characteristic tells you how much the battery voltage decreases or increases as a function of (sustained) current draw. Batteries typically have a fast and slow response; when you suddenly draw a large current it will first decrease in voltage quickly, then continue decreasing more slowly. This characteristic is usually algebraically represented as:

dV = A(Be^(-ct) - De^(-et))

Coefficients A, B, c, D and e are tracked by the BMS. Hx is equal to 1/A.

It's hypothesized (but nobody has done the work yet) that B and D are missing from the BMS's internal resistance calculations on the first-gen Leaf, and have been added in in later generations. This would explain why it tracks SOH so well on gen1 batteries, and so poorly on later models. c and e are likely hard-coded constants.

Yes Hx = 1/A, where A = resistance, as indicated by multi-year time series data posted on this forum for Leaf1

The time series data of A indicate an increasing value as the battery ages, which causes the battery's output

voltage to decline under load, i.e. an indication of battery resistance, or that Hx is battery**conductance**.

Furthermore, Hx and SOH are highly correlated, and they both decline as the battery ages, which would NOT

be the case if Hx were battery resistance. It's a simple first year EE lab class analysis! It really doesn't require

differential calculus to basically describe what occurs to any battery when it ages.

Typically, the correct differential equation form would be; dV = A(Be^(-ct) - De^(-et)) dt

If anyone can provide the research paper where this equation is defined, it would be an interesting review.

The time series data of A indicate an increasing value as the battery ages, which causes the battery's output

voltage to decline under load, i.e. an indication of battery resistance, or that Hx is battery

Furthermore, Hx and SOH are highly correlated, and they both decline as the battery ages, which would NOT

be the case if Hx were battery resistance. It's a simple first year EE lab class analysis! It really doesn't require

differential calculus to basically describe what occurs to any battery when it ages.

Typically, the correct differential equation form would be; dV = A(Be^(-ct) - De^(-et)) dt

If anyone can provide the research paper where this equation is defined, it would be an interesting review.

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