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garygid said:
Stoaty,
Are you coming to the Gathering at HTB in Cerritos tomorrow morning?

At the moment I have 2 SOC-Meter Kits available, which I will bring to the Gathering.

Do you want Red or Blue LED digits?
The Logging Port Option?
Can't make it tomorrow, already have hiking plans. Which color looks better? Which is easier to see?
 
garygid said:
Looks like we need to find the Battery Temperature(s) in the CAN-Data!
Yes! I was hoping that it was either already possible or was considered a worthwhile enhancement :)
The battery temperature gauge is very coarse, and if the fine folks from the Chevy Volt universe can be believed, the delta between 70°F (21°C) and 90°F (32°C) can be critical to battery life.
 
surfingslovak said:
The battery temperature gauge is very coarse, and if the fine folks from the Chevy Volt universe can be believed, the delta between 70°F (21°C) and 90°F (32°C) can be critical to battery life.
Very interesting. Now where was that chart that correlates number of bars on the temperature gauge with actual battery temperature? Edit: found it here: http://www.mynissanleaf.com/viewtopic.php?p=103134#p103134" onclick="window.open(this.href);return false; Unfortunately, with the following data:

5 bars - 50.5 degrees F.
6 bars - 75.2
7 bars - 98.2

it doesn't help very much. I run 5 bars (50-75) when at home for a while, and 6 bars when parked in the San Fernando Valley during the day in the summer (75-98). The coarse granularity gives me no useful information about exactly how hot my battery is getting (or how cool at home). This would be high on my list to add to the SOC meter, and the feature that would push me to actually purchase the meter.
 
Stoaty said:
Now where was that chart that correlates number of bars on the temperature gauge with actual battery temperature?
Yes, you beat me to it! It's on page 21 in section MWI. It would be nice to have more granular data, and I would be very interested in logging it, preferably over the lifetime of the vehicle.


Click to enlarge
 
Might be difficult to reach the four sensors that are inside the battery pack.

Perhaps it is better to use (if we can find them) the "calibrated" numbers that the LEAF is using internally?
 
Temperature was more temperate yesterday.

All 80% charges and using my Blink (except as noted).

9/6 77.5%/218 raw -388.5 Battery pack voltage
9/7 77.5%/218 raw -388.5V
9/8 77.2%/217 raw -388.5V
...... 77.5%/218 raw -388.5V (ChargePoint dock)
9/9 78.6%/221 raw -388.5V
9/10 .....95.3%/268 raw ("100%" charge) -393.5V
9/11 80.4%/226 raw -387.5V

It looks like the temperature hypothesis might be correct. What does this tell us about the raw number derivation?
 
garygid said:
231 raw SOC would be 82.1%

It looks like the lower the temperature, the higher the SOC numbers (for 80% or 100% charging).
But I only get 276 (once 279) @ 100%.
 
We should probably stick to the raw # wherever possible.. Only the car knows what 80% and 100% are. Assuming 281# is 100% is probably not very useful... For all we know someone might be getting 282# and as we've seen many are now getting as low as 271# at "100%". We also don't know what the car considers to be 0%. From my last full charge with 80% at 224# and 100% at 271# I'd calculate 0% to be around 36# which is probably around the point the guess-o-meter goes blank with the super low battery warning. I'm not sure we've ever seen the car functioning below 4# either so saying 0% is 0# also doesn't seem useful.
 
The question is whether this raw number is useful in determining the amount of charge we have available to use. It seems that the car does not use it in deciding when to stop charging. So what does it represent and from what is it derived? Is it consistent at the low end of charge or is it as inconsistent as the upper end?

Will tracking any data from the SOC meter help anyone with this?
 
I believe that there MUST be another measurement that is used to:
1. stop charging
2. stop power usage for driving

Most likely:
1. The cell-pair (of 96) with the HIGHEST voltage hits a Upper-Limit to Stop Charging.
2. The cell-pair with the LOWEST voltage hits a Lower-Limit to stop "driving" the car.

The exact limit values might vary with temperature.

Without these safeguards, the highest (lowest) cell-pair can get damaged by over-charging (over-discharging).

The "SOC" that we are presented with is derived from something, but we are not sure what. We do know that it:
1. "generally" represents the "fullness" of the Battery Pack,
2. that it can (occasionally) indicate more energy at the low end than is actually available,
3. it drops noticably faster at the top end than the energy consumed.

Getting a better warning or estimation of the remaining, usable low-end energy is non-trivial, but that is what (one of the things) we are seeking.

Another important parameter is the battery temperature, its rise as we drive and charge, and its fall as we let the LEAF "rest" and cool.

For example, does parking for 8 hours in the summer sun in AZ produce heating equivalent to the heating of 4 Quick-Charges?
 
While I don't have any particularly unique information to share, I figure that it never hurts to add another data point or two. I had the use of an SOC meter for about 24 hours, having borrowed tbleakne's unit. Saturday night and Sunday morning, I charged to 100% using L1 with an average ambient temperature in the 60s. The reading within 15 minutes of charge completion was 276. On Sunday we drove about 40 miles (end SOC ~ 57%), then charged up to 100% at tbleakne's house on L2, with 70ish temps. The reading immediately following charge completion was 275. We've put on over 4500 miles in over 4.5 months of ownership.

Also, we had no trouble driving home to the mountains from tbleakne's house. After a total of ~50 miles and 4900 feet of net elevation gain, we ended up with one full bar of charge (and sadly, no SOC meter; I'll have to order a kit). Of course, that required gentle, efficient, somewhat slow driving on the 210 freeway and Highway 330.
 
abasile said:
Also, we had no trouble driving home to the mountains from tbleakne's house. After a total of ~50 miles and 4900 feet of net elevation gain, we ended up with one full bar of charge (and sadly, no SOC meter; I'll have to order a kit).
OT - I am thinking about buying a kit also. What color was the LED on tbleakne's SOC meter. Did it look good with the car? Was it easy to read (even in sunlight)?
 
Stoaty said:
What color was the LED on tbleakne's SOC meter. Did it look good with the car? Was it easy to read (even in sunlight)?
tbleakne's meter is black, with blue LEDs. It blends in well enough, and looks decent. However, it isn't as easy to read as I would prefer, particularly at an angle. Reading it in sunlight is difficult at best. However, at least for myself, I wouldn't consider that a showstopper.
 
Differences last night.....cooler night and charging from over 50% SOC. So I'm going to put it down to pack temps (which is something I've suspected in the past):

photo%281%29.JPG


photo%282%29.JPG
 
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