Inconsistent instruments

[dhanson865]

OK, found the thread where mwalsh was discussing this. Below is my reply summarizing the AHr at loss discussion

Losses are triggered at
56 AHr (12 down to 11)
52 AHr (11 down to 10)
48 AHr (10 down to 9)
44 AHr (9 down to 8)

with a disclaimer that you may see it drop 2.x AHr past that if in extremely hot conditions.

or if you prefer bands maybe something like

Loss of bar 12 - between 53.75 AHr and 56 AHr
Loss of bar 11 - between 49.75 AHr and 52 AHr
Loss of bar 10 - between 45.75 AHr and 48 AHr
Loss of bar 9 - between 41.75 AHr and 44 AHr

Again, and with all due respect, I don't think it's necessary to tweak the numbers I've used unless more data to support the range you've suggested is forthcoming. For example, bar 9 - we have never seen anyone loose it as low as 41.75AHr and only one person thus far (whom I personally think was either mistaken or is a complete outlier) who lost bar 9 (well) below 42AHr. We have also never seen anyone loose bar 9 at anything close to 44AHr, with 43.56AHr being the highest reading at bar loss thus far.

The premise is it isn't losing the bar at 41.x AHr, It's losing the bar because it dropped below 44. Theoretically if you put it in an paint oven and baked the battery you could get it to show some larger amount of loss before the hysteresis allows the bar to drop off the dash.

In this line of thinking there is no significance to the lower number. It doesn't matter what the number was when you saw the loss if you know the higher number that triggered the loss.

 

[TomT]

I lost my ninth at 43.47...

In this line of thinking there is no significance to the lower number. It doesn't matter what the number was when you saw the loss if you know the higher number that triggered the loss.

 

[dhanson865]

I lost my ninth at 43.47...

In this line of thinking there is no significance to the lower number. It doesn't matter what the number was when you saw the loss if you know the higher number that triggered the loss.

I had a typo, see edit.

 

[kolmstead]

I'm pretty sure that Ahr is only part of the bar loss algorithm. Almost no one reports a lost bar in the winter time. In my case, the battery was down to 46.01 Ahr on March 2 of this year when I lost bar ten, vs the 48 Ahr limit stated above. It had been below 48 Ahr since the fall of 2014. I suspect that Nissan blocks bar loss when the battery is cold, since the capacity is reduced temporarily just due to temperature. Nobody wants to see capacity bars disappear in November, just to reappear in February or March.

In other words, the decision to turn off a battery capacity bar might be something like:

IF Ahr is less than 48 AND has been there more than 30 days AND battery temperature has been above 70 F all that time, THEN turn off bar 10.

This concerns me because I expect to see my battery's capacity drop into the low 43s in September or October, but then the battery will cool down and the ninth bar might not get turned off until March of next year, three months after the warranty expires. 44.12 Ahr today...

-Karl

 

[Stanton]

This concerns me because I expect to see my battery's capacity drop into the low 43s in September or October, but then the battery will cool down and the ninth bar might not get turned off until March of next year, three months after the warranty expires. 44.12 Ahr today...

I share your pain: I'm around 44.9 Ahr today and am wondering if the sequence you describe will drop my 4th bar before the weather cools (usually in October/November here).

 

[mwalsh]

I suspect that Nissan blocks bar loss when the battery is cold, since the capacity is reduced temporarily just due to temperature. Nobody wants to see capacity bars disappear in November, just to reappear in February or March.

This concerns me because I expect to see my battery's capacity drop into the low 43s in September or October, but then the battery will cool down and the ninth bar might not get turned off until March of next year, three months after the warranty expires. 44.12 Ahr today...

-Karl

It's going to be close for both of us. I'm a little ahead of you on AHr, but it's not 100% certain for me either. Looking back at my previous numbers, by the latter part of October last year my AHrs had already started the fall/winter rebound. Should that happen this year, without me loosing bar 9, it will be game over with a January warranty expiration. That's when I'll seriously consider heating my garage to 80 degrees. Just so it will be a comfortable when I'm working out there, naturally (and by naturally I mean naked).

But I very much doubt that a capacity bar gone is going to reappear without a systems reset.

 

[kolmstead]

44.04 Ahr tonight. Hopefully joining you in the 43s tomorrow. I now have this mental picture of you cavorting au naturel in your garage, working on those Minis. I think I need another beer!

-Karl

 

[devoneh]

I'm at 42.21 AHr, with 9 bars still remaining.

We are now almost to October so my hot days are running out. Any advice on how to push it over the edge?

I always charge to 100% and park in the sun whenever possible. I just went to my first quick charger this morning, but it didn't appear to have any noticeable effect (42.22 to 42.21 after it was done). I'm to the point of not being able to make it to work in the winter without a new battery so I'm very hopeful the bar will drop sometime.

 

[kolmstead]

Access to QC can help. From what we understand, heat kills the battery. Ideally you'd like to keep it over 100 F just as much as you can. Charge, jump in, drive fast (uphill, if possible) until battery is low, then charge again immediately. On my car, the seventh temp bar comes on at about 103 F average (of the four battery temp sensors).

-Karl

 

[iamchemist]

Valdemar,

Do you or does anyone have any idea what kind of "long time" average is involved in the LEAF software calculation of battery capacity to determine Capacity Bars shown on the display? For example, are we talking an average over a week or six months?

For my LEAF the last 10 full charges have averaged 70.6% of full capacity, based on my GID Meter. Yet I have not yet lost my 10th Capacity Bar - the bottom end of the range for which is 72.5%. I assume the Capacity Bar display IS based on an average?

 

[Valdemar]

Valdemar,

Do you or does anyone have any idea what kind of "long time" average is involved in the LEAF software calculation of battery capacity to determine Capacity Bars shown on the display? For example, are we talking an average over a week or six months?

For my LEAF the last 10 full charges have averaged 70.6% of full capacity, based on my GID Meter. Yet I have not yet lost my 10th Capacity Bar - the bottom end of the range for which is 72.5%. I assume the Capacity Bar display IS based on an average?

I don't think we know the exact formula, but if I were to guess it should be on the order of several months, plus there is a theory that this time effectively increases when it is cold.