Gidds?

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docj

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Joined
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What do Gidds tell that range info & other basic info does not?
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
 
GIDs is a measure of the estimated power in an unknown unit of measurement. LeafSpy was reverse engineered from the data available without the help of Nissan. This created some uncertainty. What exactly is a GID? Is there a proper/improper way to measure some of the things in LeafSpy? What is the accuracy and what things make it less accurate? My home has solar and battery backup. The system in my home does not have the same BMS accuracy as these cars. When it doesn’t charge to 100 for awhile like in the winter when power is sparse it shows a higher than actual SOC. I look at the voltage and if the system is reporting an SOC that is obviously incorrect I have to recalibrate. This is not really necessary with my car thankfully. Judging from the experience of others shared on here the SOC only becomes unreliable when there is unusual conditions. A weak cell, extreme cold, extreme performance requirements (hill on the freeway at high speed) and usually a perfect storm of these kind of factors. I usually don’t worry about the GID. I look at the SOC, SOH, efficiency, battery temp, or the more traditional measurement like total available AHr.
 
Hx is a State of Health related to the gradual capacity decline of the cells. A new cell starts at 100% capacity and goes down over time and cycles of use.

Gidds or Giggs or gids is just mathurbation in non-engineering units
 
What do Gidds tell that range info & other basic info does not?
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),
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.
 
Credit for the term GID should go to it's creator, Gary Giddings, who identified this measurement of Leaf "energy" with his initials, helping thousands of Leaf owners save thousands of hours of "guessing" how much capacity was (left) in their battery pack. May he RIP.
 
What do Gidds tell that range info & other basic info does not?
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
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
 
GIDs are the Leaf's internal accounting for energy, 1 GID is exactly 80Wh of reported capacity. There's really no need to know this outside of specific engineering contexts and kWh are a much more logical unit to use.

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.
 
GIDs are the Leaf's internal accounting for energy, 1 GID is exactly 80Wh of reported capacity. There's really no need to know this outside of specific engineering contexts and kWh are a much more logical unit to use.

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.
 
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