trevmar
Posts: 25
Joined: Sat Jan 21, 2017 8:08 pm

YAMMV - Close call

Thu Oct 25, 2018 2:26 pm

We are a couple of old retired duffers, so our usage pattern is overwhelmingly urban and typically no more than 30 miles a day (i.e. boring and pottering), but today we did a freeway run (Orcutt to SBA airport, hwy 101) that was almost exclusively at 67mph, set on the cruise control.

We set off at 191 miles range, but it was only showing 28 when we returned home, for a trip that Google maps has at 62.6 miles each way - so we were off by a long way (66 miles)

Could the guessometer have gotten too "used" to our normal routine, and been fooled by the long freeway run?

Also, in what was basically a "warm fog" at 46 to 59 deg F around 4 a.m., we found it best to have the fan on the lowest setting and air directed at screen and feet (no recirculation) - this combination just kept the screen clear and our heads unchilled so neither heat nor a/c was used.

SeanNelson
Posts: 1437
Joined: Tue Jul 05, 2016 2:43 am
Location: Vancouver, BC

Re: YAMMV - Close call

Thu Oct 25, 2018 3:04 pm

trevmar wrote:Could the guessometer have gotten too "used" to our normal routine, and been fooled by the long freeway run?

It takes a lot more power to drive at freeway speeds than it does to just putter around town. So the guessometer says "oh! - you're going to drive like this now, are you? Well if that's how you want to play it, then you're not going to be able to go nearly as far!".

If you putter around town over the next week or so the guessometer will go back to its old ways.

DNAinaGoodWay
Posts: 247
Joined: Fri Sep 23, 2016 11:19 am
Location: Central Massachusetts

Re: YAMMV - Close call

Sun Oct 28, 2018 1:30 am

And you only lost 38 miles to speed, relative to your puttering average, not 66.

28 miles remaining is pretty good, not a close call.
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theothertom
Posts: 48
Joined: Wed Sep 19, 2018 4:13 pm

Re: YAMMV - Close call

Mon Oct 29, 2018 12:59 am

DNAinaGoodWay wrote:And you only lost 38 miles to speed, relative to your puttering average, not 66.

28 miles remaining is pretty good, not a close call.

GOM was 57% off. That's huge. But I agree that it's probably based on previous driving habits. So the lesson is, if you're going to change your driving habits, the GOM can be waaaay off.

GetOffYourGas
Posts: 1147
Joined: Tue Oct 20, 2015 5:25 pm
Location: Syracuse, NY

Re: YAMMV - Close call

Mon Oct 29, 2018 2:52 pm

theothertom wrote:
DNAinaGoodWay wrote:And you only lost 38 miles to speed, relative to your puttering average, not 66.

28 miles remaining is pretty good, not a close call.

GOM was 57% off. That's huge. But I agree that it's probably based on previous driving habits. So the lesson is, if you're going to change your driving habits, the GOM can be waaaay off.


Your range estimate was 25% off.

Initial guess was 191 miles.

Actual range was 2*62.6 + 28 remaining = 153.2 miles.

The initial guess was off by 37.8 miles, not 66 miles.

37.8 miles (error) / 153.2 miles (truth) = 25%.

But yes, bottom line is the estimate will be off when you suddenly change your driving habits.
~Brian

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awillcox
Posts: 6
Joined: Wed Oct 03, 2018 6:57 am

Re: YAMMV - Close call

Wed Jan 02, 2019 11:43 pm

I got a similar lesson when taking my first long distance multiple fast charge trip. It was only then that I truly learned what the thin indicator on the far left of the guessometer was. It was a great indicator of how much the guessometer will change with time as you drive. I'd love to know over what period of time that little meter is taking data though.

BoltEV
Posts: 193
Joined: Thu Feb 01, 2018 5:58 am

Re: YAMMV - Close call

Sun Jan 06, 2019 7:21 pm

My G-O-M has been showing full capacity at a much smaller amount (170s-180s) in recent weeks, due to what I assume was the temperature in the low 50s in my garage overnight.

I went on a 264 mile drive last Friday before returning home and putting it on my L2 charger.

For me, the more accurate guide is the amount of KWh Energy Used on the home page of the Infotainment Screen.

When I hit 53 KWh, the Low Power Mode option came up and I declined.

At 54 KWh it went into Low Propulsion Mode.

At 55.5 KWh, I was home and put it on L2 recharger at about 11:30pm. Next time I will take a look at the My Chevrolet app and see what percentage charge was remaining.

The next day, at 1:08pm, the G-O-M reported that I had 253 miles available; so you can see why I always use the Energy Used vs. mileage remaining as a better guide!

gpsman
Posts: 506
Joined: Thu Oct 20, 2016 9:10 pm

Re: YAMMV - Close call

Tue Feb 12, 2019 3:38 pm

The GOM is using the same data to calculate a number as you and I do.

Miles per kWh and kWh in the battery.

It’s really simple. No magic involved.

You have a FIXED amount of kWh in your battery.
Probably 58.5 out of 60 advertised is usable.
So use 58.5.

If your miles per kWh goes down (as speed or heater use goes up) your range will go down. Simple.

You can “reset” your trip odometer at any time. This resets your power use at any time.

Go from no heat yesterday to using heat today? Reset your trip odometer after you turn the heat on and wait 5 minutes for a more accurate number on the screen. Do the math yourself.

Easy as pie. And easier than pi!

The GOM will “average” the two days, one without heat and today with heat. If you KNOW you will use heat the rest of the day, the do the RESET mentioned above since you don’t care about your “tank” average, you care if you will make it home or not.

JoeS
Posts: 29
Joined: Mon Jun 19, 2017 3:14 am
Location: Los Altos Hills, CA

Re: YAMMV - Close call

Tue Feb 12, 2019 4:36 pm

BoltEV and gpsman, excellent information from both of you! Sorry to be asking a dumb question as I haven't run across this, but has anyone sussed out the algorithm(s) used for the various Range Remaining computations displayed, and how much each is affected by the different HVAC settings? TIA.

BoltEV
Posts: 193
Joined: Thu Feb 01, 2018 5:58 am

Re: YAMMV - Close call

Wed Feb 13, 2019 7:04 pm

With cold weather finally arrived in Los Angeles, I've noticed that when I put my heat on, the GOM immediately drops 10 miles. If I shut it off, the 10 miles returns to the range.

Of course without severe cold weather here, when range becomes important, I heat up the cabin and seats (and steering wheel) and then I push the heat/cool button to turn off the cabin heat, but leave the fan going to circulate the interior heat. On longer trips I can repeat this cycle to conserve energy and maximize range.

To answer your question, I have no idea how the algorithm is defined. However, it is clearly looking at how I recently drove. In cold weather my fully charged range "drops" to about 180. But in practice I have easily exceeded that amount with careful and reasonable hypermiling habits, and then the next full charge returns the GOM to 220+

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