Gids/bars...

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GregH

Well-known member
Joined
Jul 1, 2011
Messages
860
Location
Irvine, CA
Ever notice the Leaf like to take away a bar or a gid here and there when you power down and back up again? So tonight I was at 2 bars, 64 gids and powered down for a bite for dinner. 40min later power up and it's down to 1 bar (no big surprise) and 63 gids..hmm.. So I power down and power back up again.. 1 bar, 62 gids..! Power down and back up again.. 1 bar and 61 gids!!!! Power down and back up again.. 1 bar and 60 gids (gee, if I just sit here in the parking lot for 10 mins cycling power, I might see the turtle!) Power down and back up.. Stays at 60 gids (phew!) but now it's up to 2 bars! Huh?
 
I believe this belongs here or elsewhere, not in a new thread. Please try to keep related topics together or in related threads.Threads are not intended for every question.

http://www.mynissanleaf.com/viewtopic.php?f=44&t=6305" onclick="window.open(this.href);return false;
 
Actually I haven't seen a thread discussion that related to this, but I did notice that as well with bars (I don't have gid meter) where I would power the car down and power it back up with one bar gone. I never really bothered with it though.
 
EVDRIVER said:
I believe this belongs here or elsewhere, not in a new thread. Please try to keep related topics together or in related threads.Threads are not intended for every question.

http://www.mynissanleaf.com/viewtopic.php?f=44&t=6305" onclick="window.open(this.href);return false;
?!?!? This has nothing to do with CAN-Do...
I guess my points were:
A. Why does the car take away estimated capacity when power is cycled? Is this just to get my attention/make me more conscious of remaining energy?
B. Is there an correlation between bars and gids? I used to think so, but now I'm not so sure.

If this does belong in another thread, please forgive me.. I don't log in here all that often and am not intimate with all the various threads..
 
GregH said:
B. Is there an correlation between bars and gids? I used to think so, but now I'm not so sure.
..

No, not really. That's not to say the firmware code doesn't consider Gids; I'm sure it does.

A battery with 50% degradation, showing 12 full bars at 100% charge will also have maybe 140 Gid (but still show fully charged with an SOC meter?).

The things that are hard links to Gids are the battery warnings at 49 and 24 Gid
 
GregH said:
A. Why does the car take away estimated capacity when power is cycled? Is this just to get my attention/make me more conscious of remaining energy?
Phil (Ingineer) has answered this question a number of times and places. I don't claim to really understand it, but he says the car does coulomb counting, in and out of the battery, while it is running, but that is an imprecise science so the count can drift away from reality. When you power up, the car can do some more accurate static measurements. ... At least I think that is what he is saying. Me, I'm just parroting words I don't understand.

Ray
 
When the car powers up it measures the OCV and temperature of the battery and estimates the SOC. The gids are a stored energy value so they depend on the SOC and in the estimated total capacity of the pack. As there is always some noise in the OCV measurement and the SOC varies a lot by small diferrences in OCV I think it is normall for the gid vary some after power up. This happens to my LEAF all the time.

The fact that 2 bars showed with less gids is a little stranger, but has happened to my LEAF also. The only reasons I find for this is a different estimated total pack capacity (can't find any reason for it to be different), or the pack temperature is near a threshold and so the estimated full capacity varies each time the car is started.
 
1. Right, this has nothing to do with CAN-Do, or even the SOC-Meter (except that it displays the LEAF's internal "GID" value read from the EV-CAN bus).

2. Known Behavior: Even if the GIDs did not change, it is normal to "lose a Bar" when restarting the LEAF. When driving (battery decreasing) if one gets into the bottom half of a Bar, the Bar still shows (until the Bar is "empty"). However, when Charging (or Regen, battery increasing), a Bar does not come on until it is over half full.

When turning the LEAF ON, the Bars behave as if they are being "filled", so a 10.3 Bars will only show 10 bars, not the 11 Bars that was being displayed when driving previously.

3. New Info: I believe that this is the first report of repeated OFF/ON cycles losing multiple GIDs during several cycles. Apparently there are some "estimations" and "corrections" going on, where the internal Energy "estimates" (present level and capacity) are being "corrected".

4. Remember, even with an "old" reduced-capacity Pack (like 86% of new capacity), the LEAF would show 12 "fuel" Bars after a "full" charge (rather misleading), AND still show 12 Capacity Bars (also somewhat misleading), but we think that GIDs would show something near 86%, which might actually be useful.

5. We think that for the more extreme 50% case mentioned above, 12 "fuel" bars would show (when "full"), but GIDs would show about 50% (of 281). The Capacity Bars would (should) show this extreme loss, in some manner.
 
i see it all the time. i documented it when i did my "100 miles in winter" range test.

i have actually seen 3-4 GIDS added back. now seeing one GID missing on power up is expected since "180" could actually be "179.5" or whatever (granularity is actually not that fine most of the time...just an example)

i "think" the reason for this is the display is providing measurement on the fly so at times, the display may read lower than actual due to inaccuracies of "on the fly" measurements

also, "adjustments are also made and as i understand it, its usually due to voltage calculations taken "at rest" which means it is sort of a "power up" calibration ?

obtw; i lose a bar all the time, but also have gained one several times as well, so it works both ways. the "new bar" usually only lasts a few miles...but i dont really look at the bars much any more...
 
garygid said:
4. Remember, even with an "old" reduced-capacity Pack (like 86% of new capacity), the LEAF would show 12 "fuel" Bars after a "full" charge (rather misleading), AND still show 12 Capacity Bars (also somewhat misleading), but we think that GIDs would show something near 86%, which might actually be useful.

The only way you would know is with a meter, hopefully we wont see too many reports of 241 GIDs from our high mileage* friends this year... but surely by next year.

* 24k miles a year
 
TonyWilliams said:
The Gid, I predict, will ultimately be more useful to us than real SOC.
Absolutely! The Gid tells us how much "gas" we have in a tank of unchanging size. SOC tells us how much of shrinking tank is filled. Which would you want to know?
 
coqui said:
Forgive me for asking a stupid question, but what is a "gid"?

For the history or source of the GID ...

http://www.mynissanleaf.com/viewtopic.php?f=8&t=7828&p=175288&hilit=GID#p175288" onclick="window.open(this.href);return false;
 
Short History of the GID:

The LEAF has a useful internal value that appears on the EV-CAN bus.
When you Drive, it goes down, and when you Charge or Regen it goes up.

It has been observed to have about 281 steps from "full" to "empty",
in a typical new, full-capacity battery.

So, our "SOC-Meter" displays this value to be used as an
approximate, higher-resolution "fuel" gauge. It has been reported
by many to be quite useful, but occasionally a bit misleading.
Sometimes the low end seems to contain less energy than indicated.

Without a name, it was hard to talk about this value,
until one member called it a "GID", after my forum UserID.

Apparently, the GIDs are supposed to (approximately) represent
(when scaled properly) the Watt-hours "put into" the Battery Pack.

However, knowing how to calibrate the "bottom" of the Pack's
useful energy is not easy, and apparently the LEAF
"adjusts" this value occasionally.

But, it seems more useful than the 12 "Fuel-Bars", which
will still show "Full" (12 Bars) even when the Pack Capacity
is substantially diminished. At this time, without the SOC-Meter,
the owner/driver has no real indication of Capacity Loss until a full
15% is Gone. A bit late to inform the owner, I believe!
 
That's why I'm changing the name of my LEAF gauge to BCM...battery capacity meter. Now that a lot of us are losing some capacity (and if someone says they haven't lost ANY, then they need a meter to show them that they have), the actual SoC% isn't very valuable. I think a lot of LEAF drivers everywhere are going to be surprised when they see how much battery capacity they have lost in one year when they either get Gary's meter or Jim's LEAFSCAN.
 
Yes, the Pack Capacity of year-old LEAFs is probably creaping down.

My lowest ever "100% Charge" GID reading was 274 (97.5%)
yesterday morning, but maybe my LEAFs cells need equalizing.

My "Maple" LEAF is at least 14 months old ...
I should look at the Production Date, not my Delivery Date.
 
garygid said:
Yes, the Pack Capacity of year-old LEAFs is probably creaping down.

My lowest ever "100% Charge" GID reading was 274 (97.5%)
yesterday morning, but maybe my LEAFs cells need equalizing.

My "Maple" LEAF is at least 14 months old ...
I should look at the Production Date, not my Delivery Date.

i think you do to. i normally dont drive much during the week but gas prices has changed our driving a bit so i am in the Prius more now.

but i usually run an SOC from 30-70% or so. i plug in a few hours every morning. but have been using Prius and SO will not drive Leaf unless its full which is ok because she is doing 64-65 miles mostly freeway. my GID count from a few weeks ago was

274, 276, 280, 279, 280

so i go back to not full charging a few weeks then switch cars and then its

273, 275, 279, 280, 279, 280

so it seems like i have to do a full charge for a few days to get back up to my 99.2-99.6%
 
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