1 gid *mostly* equals 80Wh

[DaveinOlyWA]

can you provide a rough chart on capacity verses temp as a guideline? i realize that without knowing time frames that are needed for any real BMS change to occur, the data will be all over the map but i think you have really got something here

[edatoakrun]

="TickTock"

OK. I did see some temperature dependance on the gid unit. I added two more sets to my plot 0 to 100 and 0 to 80 wall energy. For these, I compute the wh/gid=delta_wall_power/delta_gids then multiply that by the final gid value to approximate the wall power required to go from zero to 80% or 100% charge. When I do this, the seasonality almost disappears and the loss over time is more gradual. Full disclosure: I did delete a few anomalous datapoints that were far off the trend. I am attributing those to days I ran the climate control to pre-heat/pre-cool the car and/or topped off away from home. I am missing a huge chunk of data for this computation during the winter (I got lazy and was only recording data in the morning so don't know what the starting gid value was).

Definitely much less alarming degradation than looking at gid count alone. I can now see why Nissan didn't want us looking at it.[/

And I still don't understand your method of calculating final gid value , TickTock.

Please explain.


Definitely much less alarming degradation than looking at gid count alone. I can now see why Nissan didn't want us looking at it.[/quote]

What degradation?

Doesn't this mean you believe that your battery may be accepting nearly the same kWh from the wall now, at both 80% and 100%, as it was when you began tracking it, on 10/01/2011?

[vegastar]

Tick Tock extrapolates the total energy from the wall from 0 to 80% or 100% by calculating the Wh/gid used in each charge session.

I noticed that in my case the value varies a lot. Sometimes the Wh (from the wall) per gid is BELOW 80. In 100% charges the value is always higher than on 80% charges.

Here is my data:

https://docs.google.com/spreadsheet/ccc ... GNJUlFIUmc

[RegGuheert]

Thanks for the data, vegastar!

I noticed that in my case the value varies a lot. Sometimes the Wh (from the wall) per gid is BELOW 80. In 100% charges the value is always higher than on 80% charges.

I think that is to be expected since the LEAF does cell balancing at the top end. The result is that there will be additional energy dissipated in shunts during 100% charges.

[TickTock]

="TickTock"

OK. I did see some temperature dependance on the gid unit. I added two more sets to my plot 0 to 100 and 0 to 80 wall energy. For these, I compute the wh/gid=delta_wall_power/delta_gids then multiply that by the final gid value to approximate the wall power required to go from zero to 80% or 100% charge. When I do this, the seasonality almost disappears and the loss over time is more gradual. Full disclosure: I did delete a few anomalous datapoints that were far off the trend. I am attributing those to days I ran the climate control to pre-heat/pre-cool the car and/or topped off away from home. I am missing a huge chunk of data for this computation during the winter (I got lazy and was only recording data in the morning so don't know what the starting gid value was).

Definitely much less alarming degradation than looking at gid count alone. I can now see why Nissan didn't want us looking at it.[/

And I still don't understand your method of calculating final gid value , TickTock.

Please explain.


Definitely much less alarming degradation than looking at gid count alone. I can now see why Nissan didn't want us looking at it.[/quote]

What degradation?

Doesn't this mean you believe that your battery may be accepting nearly the same kWh from the wall now, at both 80% and 100%, as it was when you began tracking it, on 10/01/2011?

Vegastar summed it up pretty well. It looks like I am down 6-8% from when I started tracking last October but I was already down 10-12% by then (why I bought a gid-o-meter and started logging).

[vegastar]

The rate of degradation does seem to be slowing down, as from October to now we have more time than when Tick Tock's car was bought to last October, and less degradation.

[TickTock]

And I still don't understand your method of calculating final gid value , TickTock.

Final gid count is recorded from the canbus at the end of the charge (not calculated - at least not by me).

[edatoakrun]

I asked:

What degradation?

Doesn't this mean you believe that your battery may be accepting nearly the same kWh from the wall now, at both 80% and 100%, as it was when you began tracking it, on 10/01/2011?

...Vegastar summed it up pretty well. It looks like I am down 6-8% from when I started tracking last October but I was already down 10-12% by then (why I bought a gid-o-meter and started logging).

When you say, “down 6-8%”, I assume you are referring to the three charge sessions that you posted on P.1 of this thread?

I have been looking at your reports, in their entity.

https://docs.google.com/spreadsheet/ccc ... li=1#gid=1" onclick="window.open(this.href);return false;

Maybe I am reading your entries incorrectly. Do columns P and Q. “0 to 80 wall”, and “0 to 100 wall” not represent your kWh use from the wall, for 80% and 100% charges respectively? For example, the earliest entries in these columns for October 2011 are 16.41 and 20.15, and your most recent are 16.90 and 21.20 respectively. Column Q has no entry for the 11/21/11 charge session you report on P.1.

Are P and Q reported from a meter, or calculated by other means?

As I interpreted the data in those columns, as plotted on your “LEAF Battery Capacity” chart, I thought I was seeing an account of relatively stable capacity, with no clear indication of capacity reduction over the 10/1/11 to 8/11/12 time period.

I understand charging efficiency “from the wall” will vary, but I would not think it would distort the trend line so significantly, in this sample.

What am I getting wrong?



As to prior to October 2011, do you now believe you had 10-12% greater (new LEAF “normal”) capacity on delivery, and lost that entire amount by October?

IIRC, at one point you suspected that you'd had reduced capacity in your LEAF, from the time of delivery.

[TomT]

No longer having a Gid Meter, I decided I wanted to get an idea of where I was... Thus, last night, in the interest of science, I ran it down to turtle and charged to 100%
It took 21.1 Kwh which means I am down about 15% from what it was when new...

[TickTock]

Maybe I am reading your entries incorrectly. Do columns P and Q. “0 to 80/100 wall”, and “0 to 100 wall” not represent your kWh use from the wall, for 80% and 100% charges respectively? For example, the earliest entries in these columns for October 2011 are 16.41 and 20.15, and your most recent are 16.90 and 21.20 respectively. Column Q has no entry for the 11/21/11 charge session you report on P.1.

Sorry for the brevity of my descriptions - I try to keep it short so people will actually read but that often means lack of detail. The 0 to 80 wall, are extrapolated computations. Since the starting gid value varies from charge to charge, I extrapolate the power measured from the wall to estimate the power I would have consumed had that charge session start from 0 gids. In most cases I am pretty low on the gid count so the extrapolation should be reasonably accurate.

Are P and Q reported from a meter, or calculated by other means?

Yes (see above)

As I interpreted the data in those columns, as plotted on your “LEAF Battery Capacity” chart, I thought I was seeing an account of relatively stable capacity, with no clear indication of capacity reduction over the 10/1/11 to 8/11/12 time period.

Yes, much more stable, but it does appear to be slightly lower - although not nearly as low as the gid-count base estimation.

I understand charging efficiency “from the wall” will vary, but I would not think it would distort the trend line so significantly, in this sample.

No it doesn't change the trend and once I have more data leading into the winter, presumably the long-term trend will match (IOW, the gid base value should start recovering as it did last October). I removed some extreme out-lyers (like 0.25 wh/gid, etc.) which clearly has something else going on. When I started recording the data, I really didn't know what information would be important later (at the time I thought I was alone with the degraded capacity) so I didn't always comment when I ran the heater or ac to pre-condition the cabin, etc.

What am I getting wrong?

As to prior to October 2011, do you now believe you had 10-12% greater (new LEAF “normal”) capacity on delivery, and lost that entire amount by October?

IIRC, at one point you suspected that you'd had reduced capacity in your LEAF, from the time of delivery.

On this I am not certain. I didn't keep good logs immediately and as you recall from the discussions last October, I suspected my battery was delivered to me already with reduced capacity. However as others later started seeing degradation I think a more likely explanation is I saw rapid degradtion during those first few months of ownership when I was just driving and enjoying the car