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Discussion Starter #1
So this morning on my way to work I noticed that I was getting record mileage for some reason. I was shocked because I wasn't driving any different than before. AND it was raining and had to have the heat on here and there to defrost the windows, and the seat heaters were on. So for me to get to work with an all time best mileage did not seem likely. Also I noticed about 5 miles from work (all freeway going 65 mph) when the gauge hit about the 76% mark it did not move the rest of the way to work. At this point I knew something was not right. I then turned the car off and back on a couple times to reset the meter and it kept going back to 76%. I then pulled up my vh.smart.com and it read 76%. I don't get it. It should not be at 76%. I have never made it to work with over 73% and that was in the summer when I did not have to use any accessories and it was warm.

It concerns me because now I question the accuracy of the gauge. Has anyone else seen this happen?

I will be having the gauge checked next week when it is in the shop.
 

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I don't think it's all that accurate. There are clearly ranges in the SOC the drop faster than others, but those ranges (i.e. the 60 - 40% range) consistently drop at the same rate for me. I have found that the actual 100% reading may be variable and can impact the range achieved from 100 down to 90%, therefore however many Kms I am off by at 90% will be the same number of Kms I will be off by at every other SOC.

I don't find that rain impacts my range.
 

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I've had a couple of short-term issues with the SOC gauge, but nothing serious. I'll pull into my driveway with the SOC showing 50%, then when I drive off again it drops to 45% in a block or two. Sometimes I can actually see the needle drop a couple of percent while driving, after it has held steady for awhile.

I would guess that the battery monitoring computer updates are often a work in progress, when you think about how much info you need to get to keep 93 batteries accurately monitored.
 

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I find on occasion when I turn on the car the needle only jumps up to 50 or 60% and then when I start to move it will go the rest of the way up.
 

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Discussion Starter #5
I don't find that rain impacts my range.
When you use the wipers a lot it definitely impacts range. I have read that the wipers use quite a bit of juice.

I've had a couple of short-term issues with the SOC gauge, but nothing serious. I'll pull into my driveway with the SOC showing 50%, then when I drive off again it drops to 45% in a block or two. Sometimes I can actually see the needle drop a couple of percent while driving, after it has held steady for awhile.
Yes I have seen this myself.

I find on occasion when I turn on the car the needle only jumps up to 50 or 60% and then when I start to move it will go the rest of the way up.
Have not seen this yet.


I am curious to see what the gauge does when I leave work this afternoon :huh:
 

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I would guess that the battery monitoring computer updates are often a work in progress, when you think about how much info you need to get to keep 93 batteries accurately monitored.
I agree the battery monitoring updates are a work in process. I haven't experienced any of those issues. My driving is local and I rarely fill up the pack. I don't think it is the complexity of the cell monitoring though. My guess is that the individual cells are monitored for voltage and temperature and that is all. It would be too expensive to monitor each cell for the amp hours in and out. On a balance pack the amps into each cell would be the total amp hours divided by the number of cells. The entire pack is monitored for voltage and amp hours in and amp hours out. Those data are what go into the calculation of SOC. There must be some reset of the SOC to 100% when the back is charged all the way to the top and presumably balanced. Others have observed some skewing of the SOC from time to time and currently there is no good explanation.

The part I find interesting is that the SOC meter seems to move around but the miles to go doesn't change. If the mileage to go was altered, then one might conclude it was a result of the moving average of kWhrs/mile being continuously updated and adjusted as a result of driving style and kWhrs being consumed by all parts of the system. All I can conclude is that miles to go is conservative like most BEV's out there. The RAV4EV, and as far as I know, the Leaf do not furnish an SOC value. So I assumed SOC it was as simple as the amphour counting SOC meters on DIY cars. That appears to not be the case and that is certainly the biggest mystery. I wish MB/Smart would release more details.
 

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I have observed change in the range remaining. Depending on conditions it will actually increase during the trip. This is most prominent if my prior trip was particularly inefficient, and my estimated range for the next trip (after charging) starts off unusually low. For example if I drive very inefficiently on one occasion and then charge back up to full, the range when I take the next trip may only be 100kms, but if I start driving very efficiently, within the first 2 Kms, I might see the range jump up to 120.
 

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That is helpful. What that tells me is the average kWhrs/mile or kilo is more frequently updated than I previously thought. I am still pondering if that could affect SOC.
 

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I also think that if the SOC was based solely on power measured out of the battery then the rate of discharge on the SOC meter would be a lot more consistent/linear. Also, because rate of discharge, temperature and other variables affect how much total energy can be discharged, it would require a very complex algorithm drawing from a robust library of values derived from historical/field data to calculate range SOC. Based on this, I think the the SOC is more likely an actual measurement.

Regarding the estimated range, it may be a little different for my car than yours because mine is in kilometres not miles and therefore has a little higher resolution. This however would not explain increases in range of more than 3Kms.
 

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In my case (and it seems to be quite appropriate that "your's may vary" applies), my SOC meter seems quite linear, and I can project better using it and thinking about my usual average of 7 miles per 10% SOC than paying attention to the range left, until SOC gets below about 60% at which point the two seem to track pretty much together.

I know, for example, that for the first five miles of my morning drive that I will get more miles per 10% SOC than after that because there's a major downhill trend in my route at that time, and I know that coming back up that hill on coming home at the end of the day will be payback time, so that the last 10% SOC doesn't deliver as much. But, I pretty consistently get home at just under 40% SOC and an estimated miles driven, plus range left of just over 70 miles.

I also know that if I feel a little "perky" with my foot on the way home, that my morning range estimate on leaving the house will be in the mid 50's, while if I chill out on the way home, my morning range estimate will be around 70. I'm pretty sure that the morning range is based on the m/kWh measured by the START menu during my drive home the night before

The linearity of the SOC meter for me, is way more linear than any ICE car I have ever owned.
 

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When you use the wipers a lot it definitely impacts range. I have read that the wipers use quite a bit of juice.
:confused: What? Where are you getting that from?

I've used the wipers quite a bit and had no issue. I drove my 65 mile trip in the rain twice during the summer and had no change in the remaining charge (generally ~ 12%). Once was rather heavy rain where the wipers were just "on", the other was with auto-wipers on and the back wiper was also on intermittent because I hadn't realized I hit the stick forward. (Took me 10 minutes to figure out why it was still moving the next time I drove the car.)

I don't think the wipers take much power at all...
 

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:confused: What? Where are you getting that from?

...............
I don't think the wipers take much power at all...
I agree. I think they are on a 10 Amp fuse so lets say they draw 8 Amps.

8 Amps times 12 volts is 96 Watts. If we get four miles per kWatt that means the wipers would take 96/1000 out of our range. At 60 miles per hour that would be 1.5 miles. It could even be less if they were not running full time.
 

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Nice to know the range remaining may depend on your driving style from the day before. I'll keep that at the forefront of my mind from now.
 

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Discussion Starter #14
Only going off of what was mentioned in another thread. Apparently not the case. But if having to use lights, heater and wipers constantly both ways I can tell you that everything will count in my situation.
 

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I haven't driven mine in the rain yet. Not sure that I will, might take the truck when it rains here. Nice to have a car that is still un-muddied everywhere.
 

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The accumulation of accessory usage will have an impact on range. I rarely use my wipers on full speed; I find with with using rain-X washer fluid, I don't need to.
 

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:confused: What? Where are you getting that from?

I've used the wipers quite a bit and had no issue. I drove my 65 mile trip in the rain twice during the summer and had no change in the remaining charge (generally ~ 12%). Once was rather heavy rain where the wipers were just "on", the other was with auto-wipers on and the back wiper was also on intermittent because I hadn't realized I hit the stick forward. (Took me 10 minutes to figure out why it was still moving the next time I drove the car.)

I don't think the wipers take much power at all...



You can't tell he's being sarcastic?
 
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