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 Post subject: ALL POSTS - GOM - Range Meter - Distance To Empty meter
PostPosted: Sun Nov 03, 2013 4:27 pm 
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Joined: Thu Oct 24, 2013 12:17 am
Posts: 13
In general, how close do you push the battery to zero when driving? How accurate is the GOM? Any general rules of thumb regarding how close to the end of the charge do you run?

for instance, fully charged my GOM says 86 miles. if you were planning a trip, would you count on 86 miles exactly round trip or would you ensure a buffer just in case? 20 mile buffer? 10? is there a built in buffer?

Thanks much!

Jeff

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 Post subject: Re: Experience with GOM
PostPosted: Sun Nov 03, 2013 5:16 pm 
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Joined: Thu Jan 17, 2013 11:13 pm
Posts: 1605
Location: Los Altos, CA
I just had an unusually high mileage day (for me), so I will share the numbers.

I did an extended charge and the GOM showed 110 miles. I reset Trip A and went about my day.
At the end of the day the trip meter said 108 miles and I still had 4 fuel bars left on the gauge and I think the GOM said I had 33 miles. However, now that I think about it, I don't think that's right. Each fuel bar is approximately 2kWh, so I had roughly 8kWh left. At 3.3mi/kWh, my efficiency for that day, it would only go about 26 miles. I'm probably remembering the number wrong. In any case, I was able to travel more than what the GOM said and I made my own buffer by doing the extended charge because I knew it would be a 100 mile day. I could have done the same distance on a standard charge, but doing the extended charge made it so I didn't have to even think about running out.

For trip planning you need to get a feel for the efficiency that you get in your car in various situations then plan accordingly. Also, you should check for charging stations just short of your destination so that you have a backup in case you don't get exactly the range you had planned for. Plugshare.com is a good site to use for this. I have also used the GPS NAV at times, even when I didn't need the driving directions. It shows the miles to destination, so it's a convenient way to check your progress along the way. If you are driving on the freeway and think you will be short on range, you can slow down and it will improve your efficiency. Each 5 miles per hour above 60 mph makes a significant difference.

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 Post subject: Re: Experience with GOM
PostPosted: Sun Nov 03, 2013 5:25 pm 
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Joined: Sat Jun 01, 2013 3:35 pm
Posts: 61
Location: Irvine, CA
I'm sure everyone is different, my preference is to not plan on going below 10mi on the GOM. There is no built in buffer that I'm aware of. The GOM is based on the average of your previous driving. So the more consistent you are in your driving the more accurate the GOM will be. If your planning a trip that will cut it close on your range you should consider what your planned driving is compare to your norm. Higher average speed in general will be less range than the GOM says, lower average speed will give you more range than the GOM. More people in the car than normal will be less range. Use of fan and A/C deducts about 5% range. Use of defroster on cold mornings deducts roughly 10% range on the GOM. Best thing to do is simply get familiar with your driving habits and what affects they have on range, and if you are going to cut it close on a trip be familiar with charging stations on your route in case you use more range than expected.

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 Post subject: Re: Experience with GOM
PostPosted: Sun Nov 03, 2013 5:41 pm 
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Joined: Tue Aug 13, 2013 1:13 am
Posts: 84
I too had a long drive the other day. On the way back home, I had a chance to do some opportunity charging while having lunch. My drive back home was 81 miles, and the GOM had a range of 85 miles. Most of my trip was on the freeway, and my speeds ranged from stop-and-go to 72 mph. I'd say may average speed was around 50 mph. By the time I pulled into my driveway, I had 19 miles left on the GOM. That's good. I'd rather have a GOM that underestimates than the other way around.

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 Post subject: Re: Experience with GOM
PostPosted: Sun Nov 03, 2013 7:07 pm 
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Joined: Sun Aug 18, 2013 5:37 am
Posts: 13
In my experience, the GOM is on the conservative side, so I get more miles out of a charge than the GOM says at the start of my trip. However, if you change your driving habits change abruptly (e.g., your spouse drives for the day with a lead foot and the heater cranked up more than you do normally), then the GOM could very well fall short.

As others have posted, you can adjust your driving and make up the difference though (e.g., drive slower). There are two tricks I've learned to figure out how much to adjust my driving:
1. Use the navigator to see how many miles you have to go and compare it to the GOM miles, and adjust accordingly.
2. Monitor if you're using GOM miles faster or slower than your actual driving. The way I do this is to take the last digit from adding up the last digit of the GOM and the last digit of the odometer every few minutes and see the trend. For example: GOM is x5 and odometer is xxx2 (last digit of total is 7), a few minutes later GOM is x2 and odometer is xxx4 (last digit of total is 6), and a few minutes later the GOM is x9 and the odometer is xxx6 (last digit of total is 5). In this example, you've 'lost' 2 miles of range over the course of these readings (from 7 to 5) because your GOM is dropping faster than you're clocking miles on the odometer.


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 Post subject: Re: Experience with GOM
PostPosted: Sun Nov 03, 2013 7:18 pm 
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Joined: Mon Sep 02, 2013 6:47 pm
Posts: 144
Location: Los Angeles, CA
The Guess O Meter ( GOM) is very conservative.
Last thursday, it was a cold morning and i started with a FULL normal charge with 81 on the GOM.
driving around LA, mostly freeway 405 and 5 with moderate traffic.
"Using the carpool lane ( thanks white sticker!) and cruise control and doing 65-75mph when possible.
i drive the RAV4EV the same way i drive my other ICE cars, so nothing special here.

at the end of the day i did a 79 mile commute ( trip A always starts at 0)
and i have 19 miles on my GOM.

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 Post subject: Re: Experience with GOM
PostPosted: Sun Nov 03, 2013 8:28 pm 
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Joined: Fri Aug 30, 2013 6:23 am
Posts: 106
Ultimately it all depends on how you are driving relative to your previous trip. If you are driving faster, you will have less mileage than GOM shows, if you are driving slower, you will have more mileage than GOM. The closer the GOM gets to the zero, however, the more accurate it will get. It is just applying a mileage per KWH, but if the KWH keeps getting closer to zero the mileage will obviously reduce as well in proportion. You will never have 15 miles left when you are on LO at highway speeds.

What I normally do to make sure I have enough battery to get home, is check my mile distance to home on my Nav vs. the GOM. I normally give myself about a 1-3 mile buffer between the two. I always check it the closer I get to home as the GOM gets more accurate to make sure I keep that buffer. If I don't for some reason, I will slow down until I get it again. This is a pretty fool proof way of making sure you get home. If you have a one to two mile buffer you will always have enough juice to get home even if you make wrong turn.


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 Post subject: Re: Experience with GOM
PostPosted: Mon Nov 04, 2013 2:44 am 
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Joined: Wed Nov 07, 2012 6:50 am
Posts: 1213
Location: San Jose, CA
A few other driving activities can also contribute to the "buffer" . . .

1. If it is daylight, turn off your DRLs.
2. Unless you are using your NAV, turn off the Infotainment system.
3. Use "B" as much as possible instead of manual braking.

You can also do a simple "brain teaser" by multiplying the value for your driving efficiency average, times the remaining no. of lit GoM bar segments, times 2. For example, say your indicated average efficiency is 3.0mi/kWh and you have 2 bars left. 3 x 2 x 2 = 12, so you should have a minimum of 12 miles range remaining. If your average is only 2.5mi/kWh, then you would have 2.5 x 2 x 2, or 10 miles range remaining. Cross check the GoM with the results of your arithmetic each time. They should agree fairly closely, but if not, go with the lower of the two just to be conservative. After you get down to one bar, I believe the GoM no longer display your range, but displays a warning message instead. At this point, you still should have a few more miles of range remaining. Try not to miss when that second to last bar extinquishes, and note your mileage right then. Do the calculation one last time, and do not exceed that no. of miles or risk running out of charge!

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 Post subject: Re: Experience with GOM
PostPosted: Mon Nov 04, 2013 7:08 am 
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Joined: Thu Oct 24, 2013 12:17 am
Posts: 13
This is superb information thanks to all, extremely helpful.

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2013 Toyota RAV4 EV Blizzard Pearl
Solar: Sunpower CEC–AC Rated: 4.802 kW
JESLA, the 40 amp J1772 portable charging solution
JLong the J1772 extension cord solution


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 Post subject: Re: Experience with GOM
PostPosted: Mon Nov 04, 2013 10:35 am 
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Joined: Sat Mar 30, 2013 9:20 am
Posts: 691
Location: Seal Beach, CA
I completely ignore the GOM, as there's no way to map its prediction to a known miles/kwh figure. Refer to Tony's range chart for a realistic mapping of the bars you see to range with a given efficiency/speed, and/or use the range estimator in RavCharge to predict your range at a given efficiency for your current state of charge.

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