I want my 281!

[jkirkebo]

Reading this topic has made it quite clear to me why Nissan didn't include a proper SOC meter in the car. Imagine all the people running down the dealerships complaining that their batteries have degraded and aren't charging to 100%

So the after-market solution seems actually better as those who do buy the SOC meter has a technical understanding (to some degree at least) to why the results might vary with temperature and other environmental variables.

 

[TomT]

Actually, a simple solution to that problem would be to make it display 100 percent SOC for whatever the maximum capacity of the battery is. That way, as battery capacity declined, it would still always show 100 percent for a full charge regardless of how much the battery had deteriorated. This would be relatively easy for Nissan to do at the native vehicle level but is much harder for someone like Gary to do after the fact from just the CAN buss.

Reading this topic has made it quite clear to me why Nissan didn't include a proper SOC meter in the car. Imagine all the people running down the dealerships complaining that their batteries have degraded and aren't charging to 100%
So the after-market solution seems actually better as those who do buy the SOC meter has a technical understanding (to some degree at least) to why the results might vary with temperature and other environmental variables.

 

[garygid]

1. It is my understanding that Nissan intends that the Fuel-Gauge Bars will still show 12 Bars (full) even after the Battery has lost Capacity, even 1 or 2 Capacity-Bars worth. Thus, our "SOC" value might NOT drop with "real" Capacity loss.

Just the short Capacity-Bars (hash-marks) would show fewer hashes as the Capacity drops. Yes, to me too, that seems like a rather misleading way to do it!

2. It looks like the charger is using about 450 to 500 watts.

The noticably worse efficiency when charging at L1 might be one reason that Nissan recommends L2 charging?

 

[TomT]

Are you sure about this, Gary? I was very specifically told that as the battery capacity dropped over time, the hash marks on the far right of the "fuel" bar graph would also drop from the maximum of 12.

1. It is my understanding that Nissan intends that the Fuel-Gauge Bars will still show 12 Bars (full) even after the Battery has lost Capacity, even 1 or 2 Capacity-Bars worth. Thus, our "SOC" value might NOT drop with "real" Capacity loss.

 

[evnow]

Are you sure about this, Gary? I was very specifically told that as the battery capacity dropped over time, the hash marks on the far right of the "fuel" bar graph would also drop from the maximum of 12.

Right, the capacity short bars would drop - but the long SOC bars would still go to 12 after 100% charge.

 

[garygid]

I am hoping to find the "battery capacity" value in the EV-CAN messages, so that the SOC-Meter can display that value, and perhaps the product of the two.

 

[GregH]

It is interesting that the Leaf (like the Honda EV+) has hash marks by the fuel "bars" to show the user degraded capacity over time. The EV1 had no such indication. Without tapping into the serial data bus, all you had to go on was your morning "wake up" range (what the guess-o-meter said assuming you drove fairly consistently).

 

[tbleakne]

Last night I did another 100% charge, this time taking pains to reduce the temperature. The overnight minimum was 64F. I arranged active ventilation in the garage, and the garage was 69 degrees most of the night. I programmed the charge to start at 3AM, later than usual, but still time to complete before the end of Super-Off_Peak rates at 6AM.

Yesterday I drove the car very lightly, no freeway driving, last drive of 10 miles concluded at 9:30PM.
This morning the results of the 100% L2 charge:
97.1%, 273 "clicks" 393.6V Disappointing

I tried forcing more charge. It lasted about 10 minutes, tapering from 3KW down to 2 KW in first 1.5min, then tapering more slowly down below 1 KW.
clicks: -> 274 right away, then 275, then back to 274 just before cutoff.

Once again it appears mwalsh lives a "charmed" life with his 100% 281 result. His Leaf is 5 months older than mine with lots more miles and probably more aggressive driving. Perhaps he has a 10-ton A/C that keeps his garage at an optimum temperature, 48F or whatever .

 

[mwalsh]

Once again it appears mwalsh lives a "charmed" life with his 100% 281 result. His Leaf is 5 months older than mine with lots more miles and probably more aggressive driving. Perhaps he has a 10-ton A/C that keeps his garage at an optimum temperature, 48F or whatever .

My car sits out - too many other vehicles that need the protection more.

Last night I should have had a pretty poor result - I got home at 10pm, with charging set to start a midnight, I was down to around 32% SOC, and it was a warmish night (or at least it was warmer than the previous nights this week). I really should have done quite badly, but I got 98.6% / 278. So I don't know what to make of that <shrug>.

 

[tbleakne]

L1 (12A) .95KW/1.4KW = 68%
L2: (16A) 3.3KW/3.8KW = 87%
<snip>
Note L1/L2 = .95/3.3 = 29%. L1 takes 3.5 times as long as L2.

Thank you for providing actual measured values, but if you don't mind, I'd like to see a confirming test. You call 87% disappointing, but it was about what I was expecting. 68%, on the other hand, I would call horrifying. Nissan has claimed that L1 takes 3 times as long as L2 (21 hours vs. 7 hours), not 3.5 times. Like surfingslovak, I've assumed something closer to 1.1kW at the battery for L1.

Ray

L1 efficiency: The indicated power level jumps around. Some of the time it was a little above 1KW, most of the time it was below. A data log might well show an average below .95KW. abasile has made the point that the active cooling system for the charger draws power that must be subtracted from the net power. Although you would expect the charger to dissipate less heat on L1 than L2, Nissan may well just run the cooling loop at the same speed.

The charger circuitry just might also be less efficient on the lower voltage.

 

[Boomer23]

Once again it appears mwalsh lives a "charmed" life with his 100% 281 result. His Leaf is 5 months older than mine with lots more miles and probably more aggressive driving. Perhaps he has a 10-ton A/C that keeps his garage at an optimum temperature, 48F or whatever .

My car sits out - too many other vehicles that need the protection more.

Last night I should have had a pretty poor result - I got home at 10pm, with charging set to start a midnight, I was down to around 32% SOC, and it was a warmish night (or at least it was warmer than the previous nights this week). I really should have done quite badly, but I got 98.6% / 278. So I don't know what to make of that <shrug>.

Mine was 98.2% and 276 this morning. Routine 100% charge from 7 bars and 65.1% the night before, car last driven around 6:30 pm.

 

[GregH]

So after a long (24hr) cold soak in the garage, then a mild evening drive, then another 12 hours in the cool garage I started charge at about 65% to see how full I could get... 272#. Sigh.

 

[SanDust]

It may have been reported elsewhere, but here are my results on charging efficiency, using the rev8 display of power going directly into the battery (voltage*current)
...
While 87% at L2 is disappointingly low, this room for improvement suggests to me that a better-designed 6.6KW charger, operating at perhaps 94% efficiency, would dissipate the same amount of waste heat, and so it could run with the present cooling system.
...
When I was out of town for a week, I left my Leaf in its hot garage with 50% (6 bars) of charge. This is recommended for Li-cobalt batteries.

When you say "display of power going directly into the battery" do you mean that literally or do you mean "display of power in the battery"? There is a cyclic energy loss of about 10% so the power going to the battery would not be the power that ends up in the battery. Note that if you're measuring power in the battery then other than the unavoidable losses inherent in recharging Li-ion batteries the L2 charging is about 97% efficient. IOW 87% is a good and expected efficiency. The L1 charging efficiency seems very low.

Storing any Li-ion battery fully charged in high heat would not be a good thing. I think a 40% SOC is considered ideal but 50% should not make a difference.

 

[mwalsh]

90.3% / 254 for me last night. The worst set of numbers since I got my unit built. No physical changes from previous recent "normal" days.

How about this for a thesis......we get numbers that are progressively worse until the BMS, for whatever reason, decides it's time to balance the pack. After which we see a "good" number (though not necessarily 100%) followed by a gradual apparent decline until the next balancing event?

Now, I've got to say that I've not followed the presented number for a period of time to see if this holds true. But it does appear that once a week or so I get a good number followed by some that aren't so good.

BTW, I also thought we'd loose bars eventually with battery degradation.

 

[GregH]

90.3% / 254 for me last night. The worst set of numbers since I got my unit built. No physical changes from previous recent "normal" days.

!! That's insane.. Did you notice what the SOC# was when the 12th bar went away while driving?

 

[mwalsh]

!! That's insane.. Did you notice what the SOC# was when the 12th bar went away while driving?

I think you're misunderstanding something. What we're talking about here is SOC fully charged the next morning. In this instances I was charging from around 30% remaining charge (pretty typical for me following a normal day of driving).

 

[garygid]

Charging to 100%, with no apparent interrupt in the charging, right?

Maybe the low SOC values are after the battery HAS done some equalizing?

If we get some logs that include an hour before starting to charge,
and maybe the 4 hours after charging is "done", maybe we will be able
to learn more about the equalizing cycles.

I think CAN-Do has memory space to record the EV-CAN for about 18 to 20 hours,
continuous logging (about 20 million messages).

 

[Stoaty]

Maybe the low SOC values are after the battery HAS done some equalizing?

Wouldn't the SOC values be HIGHER after equalizing?

 

[garygid]

Apparently the LEAF "equalizes" by bleeding off charge from
the higher-voltage cells. Then, the cells are closer to being "even".

At some later time, unknown exactly when, the battery can "top-up".
However, if the battery is too warm, the "top-up" might be delayed
until another time. All conjecture.

 

[GregH]

!! That's insane.. Did you notice what the SOC# was when the 12th bar went away while driving?

I think you're misunderstanding something. What we're talking about here is SOC fully charged the next morning. In this instances I was charging from around 30% remaining charge (pretty typical for me following a normal day of driving).

254# for "100%" sounds really low to me.. I've been complaining about 271# and 272#.
The reason I asked about the 12th bar is that it seems the car re-scales the 12 bars based on whatever "full" is that day.. So regardless of full being 254# or 281#, I'd expect to see a similar number of miles (or ticks on the #) before losing a bar (proportional to the ratio 254:281). In another thread someone noted that the 12th bar vanishes at 255# (I think) but that was with full being 281#.. with my 272# full charge, the 12th bar lasted down to 250#.