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TickTock
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Re: What is a "Gid"?

Fri Feb 10, 2012 9:30 pm

lenny wrote:
garygid wrote:If the Gids are essentially 80 watt-hours each, why are the top 20 or so "always" used up so much quicker than those in the center of the range?

Less regeneration when the battery is full? Not enough details regarding your observation.

At least now I know what's a "gid" :)


(So I like graphs in case you hadn't noticed) I took a log last night of a 100% charge and another of my commute to work. During this drive I observed the gids being used up quicker at the beginning of the drive. However, upon plotting the data, it appears to be accurate. In this graph, I logged the V*I*delta_time into the battery and plotted the accumulated total both during the 100% charge and during the first part of my drive. Zoomed in to the top 80 gids for detail and there is no evidence of significant difference in the amount of charge associated with a gid during the start of the drive and later. During the charge it looks like just over 80wh per gid at the top 3kwh and during discharge it is just over 70wh. Indeed, it appears any faster drop in gids I may have observed was due to more energy consumption (lack of regen?) rather than "gid correction" as I previously suspected. Also interesting to note that there *does* seem to be a correction during the charge.
Image

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garygid
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Re: What is a "Gid"?

Fri Feb 10, 2012 10:24 pm

Looks like the top 13 GIDs during discharge drop quickly even though not much energy appears to be used.

At 14 kWh there is 184 discharging, but 204 when charging.

But, we really only care if the GIDs are a repeatable indicator of discharging "progress".

As the battery loses capacity, we do not know if the GIDs decrease.

Nissan seems to say that the Fuel-Bars will still "100% fill" to 12 Bars even if the Capacity is only 70%. Thus the Fuel-Bars will shrink in energy capacity (and range) as the battery ages. Yes, that makes the fuel bars even more useless.
See SOC/GID-Meter and CAN-Do Info
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surfingslovak
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Re: What is a "Gid"?

Fri Feb 10, 2012 10:37 pm

garygid wrote:As the battery loses capacity, we do not know if the GIDs decrease.

That would be a reasonable assumption, I believe. Didn't we see this effect with some drivers in Seattle during the recent snow storm? Battery capacity contracts in low ambient temps.

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TonyWilliams
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Re: What is a "Gid"?

Sat Feb 11, 2012 12:37 am

surfingslovak wrote:
garygid wrote:As the battery loses capacity, we do not know if the GIDs decrease.

That would be a reasonable assumption, I believe. Didn't we see this effect with some drivers in Seattle during the recent snow storm? Battery capacity contracts in low ambient temps.


Yes, we have several runs like that:

"started trip 5:30 AM 97.8 SOC GID 274 temp 38º "

100.1 miles / 5.3 miles per kWh = 18.88kWh burned.

Based on this run with a Gidmeter at a cold battery temperature, it once again appears that the Gids are elastic, much like the battery level bars are. The Gids did not significantly read lower, even though there was an over 10% demonstrated loss of battery capacity due to cold weather.



Here's another data point, albeit without a Gidmeter:

100% charge (usable, not SOC) to Turtle

Assumed battery temperature at start: -13C (8.6F) up to -10C ambient (14F)
Final Dash Km/kWh: 7.0 (4.34 miles/kWh)
Km traveled total: 125.1 (77.56 miles)

Calculated Battery Capacity: 17.87 kWh - 85%

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Ingineer
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Re: What is a "Gid"?

Sat Feb 11, 2012 1:04 am

The "gids" will read lower as the battery ages, as the stored kWh will be lower.

-Phil
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garygid
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Re: What is a "Gid"?

Sun Feb 12, 2012 8:38 am

If GIDs decrease with age-related capacity loss, then
there must be a "Capacity" value that is used to:
1. create the Capacity Bars
2. scale the GIDs when creating the 12 Fuel-Bars
(which Nissan says do NOT diminish with diminished Capacity).
See SOC/GID-Meter and CAN-Do Info
2011 LEAF, sold in 2015
2010 Prius, 2014 silver Tesla S
Nissan EVSE, mod to 240/120v 16A
PU: SDG&E
Solar PV: 33 x 225W -> 7 kW max AC
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Ingineer
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Re: What is a "Gid"?

Sun Feb 12, 2012 11:41 am

garygid wrote:If GIDs decrease with age-related capacity loss, then
there must be a "Capacity" value that is used to:
1. create the Capacity Bars
2. scale the GIDs when creating the 12 Fuel-Bars
(which Nissan says do NOT diminish with diminished Capacity).
There is. There is an actual number generated called "HV Batt Gradual Capacity Loss Display" and even a "Gradual Capacity Loss Segments" that is sent to the CM (Combination Meter).

The "Gids" (Stored Watt-Hours) aren't being scaled, they are being calculated. Another number that is tracked is total current capacity in amp-hours, along with many other interesting parameters, such as the "Gradual Capacity Loss Coefficient".

-Phil
Easily Learn Electricity HERE! - - - - Website: http://evseupgrade.com/ - - - - Like us on Facebook: EVSE Upgrade

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garygid
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Re: What is a "Gid"?

Sun Feb 12, 2012 3:36 pm

The trick is finding these fields in the CAN-bua data.
See SOC/GID-Meter and CAN-Do Info
2011 LEAF, sold in 2015
2010 Prius, 2014 silver Tesla S
Nissan EVSE, mod to 240/120v 16A
PU: SDG&E
Solar PV: 33 x 225W -> 7 kW max AC
To Sell: X-treme 5000Li EV motorcycle

Stoaty
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Re: What is a "Gid"?

Sun Feb 12, 2012 3:39 pm

Ingineer wrote:The "gids" will read lower as the battery ages, as the stored kWh will be lower.

Does this mean that the number of gids reading on a properly balanced and fully charged battery is a good proxy for battery capacity?
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Ingineer
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Re: What is a "Gid"?

Sun Feb 12, 2012 3:47 pm

garygid wrote:The trick is finding these fields in the CAN-bua data.
As soon as I can, I will have this information available.

-Phil
Easily Learn Electricity HERE! - - - - Website: http://evseupgrade.com/ - - - - Like us on Facebook: EVSE Upgrade

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