Distance to empty (GOM)

[doogie63]

With everyone saying GOM doesn't work right. Has anyone ran out of charge thinking they still had more range? Example trip plan says your will reach destination with 10% left. But didn't make it and now in area with no charger.

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[portlandg]

I am sorry to have to say this but with all the talk from owners of many EV's, not just MME owners, saying how unreliable their GOM ( Guess - o - meter), clue is in the name, it never ceases to amaze me that people STILL believe in it on long journeys. It is there as an estimate, not accurate. Most people would not let their ICE car get below 25% before thinking about finding a gas station so why do it in an EV. Whatever your destination is, if you can charge there then stop and do a splash and dash, you don't have to "fill it up".

 

[doogie63]

I am sorry to have to say this but with all the talk from owners of many EV's, not just MME owners, saying how unreliable their GOM ( Guess - o - meter), clue is in the name, it never ceases to amaze me that people STILL believe in it on long journeys. It is there as an estimate, not accurate. Most people would not let their ICE car get below 25% before thinking about finding a gas station so why do it in an EV. Whatever your destination is, if you can charge there then stop and do a splash and dash, you don't have to "fill it up".

I agree with you. But I just put in trip and it had me arriving back home with 10%. And if you are driving out on hwy and say it does tell you to stop at 15-20. But then you find out charger is out of order. And you are really down to 5% not the 15-20% it said it should be. That's a problem.

 

[JamieGeek]

I agree with you. But I just put in trip and it had me arriving back home with 10%. And if you are driving out on hwy and say it does tell you to stop at 15-20. But then you find out charger is out of order. And you are really down to 5% not the 15-20% it said it should be. That's a problem.

This is why you plan contingencies and redundancies: Don't plan on that charger at 5%, plan on the charger at 20%. Look at plugshare, are there more than one available at the next stop? Some routes you simply can't go on at the moment.

Use the trip meter and the miles/kwh display. Using that and watching the % you can do your own "GOM" estimates (since the ER battery is close to 100 kwh a simple estimate is 1% is 1 kwh--ok a little more but you can give yourself some wiggle room). So you're on the highway and the trip meter says you're getting 2.5 miles/kWh and you have 30% left. Then you know you have less than 75 miles (I usually use 2/3rds of that for my target so 50 miles; in reality 1% is ~0.88 kWh so 30% would be around 65 miles at 2.5 miles/kwh). You can also use the miles/kwh display to stretch it: If you know you need 2.75 miles/kwh to get to some point but you're currently at 2.6 miles/kwh, slow down and reset a trip meter--adjust your speed until you get your 2.75 miles/kwh.

There are tons of ways you can use to not run out of gas

Its really just like driving an ICE with fewer gas station options (a couple of years ago we were driving our RV through the middle of Kansas--off the interstate--the only cars that passed us on the two lane roads were tractors. Not a gas station in sight for miles).

 

[TKG]

I just did a long trip (around 640 miles round trip) and mine was consistent the whole way. For instance I noted at one stop it said I had 180 miles left and I was 105 miles to the destination. When I got there it said I had 71 miles left - and this was going 70+ mph most of the way.

 

[evfinder]

I've found the GOM to be a pretty good estimate for the most part but I had a strange occurrence today. I had charged to 100% in anticipation of a long drive but it turned out that we would not be taking the trip until tomorrow. This afternoon I unplugged with the GOM saying 255 miles at 100%. I drove 2.5 miles to pick up some food and the GOM said the range was 250 miles but still said 100%. I drove home and when I pulled into my garage the GOM said 240 miles range but still indicated 100%.

There was heavy rain during the drive with temps around 70F. Heat was on and set to 75F so I would have expected the range to have dropped a bit but dropping 15 miles on a 5 mile trip and still showing 100% seems weird. The update that was supposed to make the GOM more accurate appears to have done the opposite on my Mach-e. I'll see how it performs tomorrow when I should be driving somewhere around 100 miles plus.

 

[evfinder]

When I went to leave this morning after the car had been parked overnight not plugged in, the GOM had dropped to show a range of 234 miles and 98%. Once again I drove a 5 mile round trip and the GOM now shows a range of 224 miles and 96%. There was light drizzle and the temp was 57F. The heat was on and set to 75F. All the driving was on surface streets with a speed limit of 35mph and I was driving at the limit for most. I will be out on the freeway this afternoon but should have plenty of range for my trip.

I've found the GOM to be a pretty good estimate for the most part but I had a strange occurrence today. I had charged to 100% in anticipation of a long drive but it turned out that we would not be taking the trip until tomorrow. This afternoon I unplugged with the GOM saying 255 miles at 100%. I drove 2.5 miles to pick up some food and the GOM said the range was 250 miles but still said 100%. I drove home and when I pulled into my garage the GOM said 240 miles range but still indicated 100%.

There was heavy rain during the drive with temps around 70F. Heat was on and set to 75F so I would have expected the range to have dropped a bit but dropping 15 miles on a 5 mile trip and still showing 100% seems weird. The update that was supposed to make the GOM more accurate appears to have done the opposite on my Mach-e. I'll see how it performs tomorrow when I should be driving somewhere around 100 miles plus.

 

[SpaceEVDriver]

For me the gom is no better than the gom in an ice vehicle. I use it as an estimator and don't really rely on it being better than about 10-20% accurate at any given moment.

 

[RickMachE]

I've found the GOM to be a pretty good estimate for the most part but I had a strange occurrence today. I had charged to 100% in anticipation of a long drive but it turned out that we would not be taking the trip until tomorrow. This afternoon I unplugged with the GOM saying 255 miles at 100%. I drove 2.5 miles to pick up some food and the GOM said the range was 250 miles but still said 100%. I drove home and when I pulled into my garage the GOM said 240 miles range but still indicated 100%.

There was heavy rain during the drive with temps around 70F. Heat was on and set to 75F so I would have expected the range to have dropped a bit but dropping 15 miles on a 5 mile trip and still showing 100% seems weird. The update that was supposed to make the GOM more accurate appears to have done the opposite on my Mach-e. I'll see how it performs tomorrow when I should be driving somewhere around 100 miles plus.

This has been explained a few times. When the pack warms up, there is more capacity available, so it will gain a small amount (holding the 100% even though you drove). The range is adjusting based on your driving, but the 100% won't change.

When I went to leave this morning after the car had been parked overnight not plugged in, the GOM had dropped to show a range of 234 miles and 98%. Once again I drove a 5 mile round trip and the GOM now shows a range of 224 miles and 96%. There was light drizzle and the temp was 57F. The heat was on and set to 75F. All the driving was on surface streets with a speed limit of 35mph and I was driving at the limit for most. I will be out on the freeway this afternoon but should have plenty of range for my trip.

So now, overnight, the pack got colder, and both the range drops, as well as the percentage, matching the original first read, less the driving of 5 miles or so. 2% is about 1.8kW, at 3 miles a kW that's 5.4 miles, you drove 5 miles.

Today you drove the same 5 miles in colder weather, running the heat. The range adjusted, and the battery capacity went down.

Totally expected.

 

[D’Roc]

I may be an outlier but I believe my GOM is accurate more than not. So much so it has given me the confidence to skip my planned changer on long trips and go for the next one. I will say I reached my stretch at below 10% SoC.

 

[Pangea]

My GOM has been off for maybe 2 months now? I am in a cold climate, and back in Nov/Dec I was getting around 210 miles a full charge. Suddenly (after an update) my car was showing me like 270, which is a crazy difference and temps are varying from 30-40 degrees, but as I'm driving throughout the day my miles drop super significantly. By the time I get down to like 30% battery I'm back to only like 65 miles left, which would put me closer to my 210 norm again... I kept thinking that as I kept driving it would start becoming more accurate again, but nope, it's super inconsistent. Every day when I get in my car charged to 90% it ranges probably 60 or 70 miles. I park in my home garage.

The frustrating part about this is I live and drive in an area of the country with sparse charging stations so I can't be as flexible as recommended to never let it get under 25%. On Tuesday I'm taking a road trip where one stretch is 167 miles.... that's scary when you can't trust the gage to be at all accurate!

 

[evfinder]

This has been explained a few times. When the pack warms up, there is more capacity available, so it will gain a small amount (holding the 100% even though you drove). The range is adjusting based on your driving, but the 100% won't change.



So now, overnight, the pack got colder, and both the range drops, as well as the percentage, matching the original first read, less the driving of 5 miles or so. 2% is about 1.8kW, at 3 miles a kW that's 5.4 miles, you drove 5 miles.

Today you drove the same 5 miles in colder weather, running the heat. The range adjusted, and the battery capacity went down.

Totally expected.

Thanks for the explanation. Yesterday I drove about 96 miles and the GOM behaved as I expected it to. The range did drop faster than the miles travelled but that was because I was driving at freeway speeds and it was totally expected.

 

[ctenidae]

I think the GOM is very useful, but not directly for what's displayed. I keep an eye on the GOM range and the distance to destination. Once that number settles in I have an idea of the buffer I'm going to have. Better, I have a mark to check against. As long as that mark is stable or improving I can keep an eye on battery % and indicated use. If that calculated range is stable and anything like the buffer # I feel pretty good about what my range ought to be.

What I wonder is how much of a buffer there is beyond the GOM. I know the actual range available is, by definition, not the GOM range indicated, but how much is it different? Another 20 miles? Short 10 miles?

I suspect the topic has been discussed before.

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