<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; color: rgb(0, 0, 0); font-size: 14px; font-family: Calibri, sans-serif;"><div>The appeal of the ideal miles number is that it's a measurement of the energy in the pack stated in terms of range under standardized circumstances. For the Roadster, an ideal mile is 55 kWh divided by 244 EPA miles = 225.4 Wh. (The 55 kWh value comes from data buried in a spreadsheet that was posted on a Tesla Motors blog, <http://www.teslamotors.com/blog/roadster-efficiency-and-range>) It's a convenient unit of energy because it's stated in terms of range: if I drive about 57 mph on level road in moderate weather, I'll get one actual mile of range per ideal mile of energy.</div><div><br></div><div>Because it's an energy unit, the value after a full charge lets me see in an intuitive way how my pack's energy capacity changes with time, miles, and seasons. Because it's an absolute energy unit, it can be compared across cars and drivers.</div><div><br></div><div>For the 85 kWh Model S, with a range of 300 ideal miles or 265 rated miles, an ideal mile is 283.3 Wh and a rated mile is 320.7 Wh.</div><div><br></div><div>For a 2014 Leaf with an EPA rated range of 84 miles and a nominal usable battery pack capacity of 22 kWh (281 - 6 = 275 Gids with a Gid equal to 80 Wh), a rated mile would be 261.9 Wh.</div><div><br></div><div>Once you have this number, it becomes very easy to estimate range. If I'm driving on level freeway between 55 and 60 mph, I can get that range. If I drive faster, I get less. At lower speeds I get more. Climbing a hill costs 7 ideal miles per 1000 feet and descending yields about 3.5 ideal miles per 1000 feet. In cold weather, around freezing, the range per ideal miles goes down by 10%, plus another 10% if I use heat.</div><div><br></div><div>In practical terms, without needing to do any complicated math, if I have twice as many ideal miles as my distance to home (or other charging), it doesn't matter how I drive. If distance and ideal miles are close to each other, I need to moderate speed accordingly. If I have fewer ideal miles than miles remaining, I need to find a closer place to charge, or find a shorter/slower route to my destination.</div><div><br></div><div>This ability to understand how much energy I have left and how conditions affect my range is impossible with a guess-o-meter that is constantly changing my estimated miles remaining based on how I've driven in the recent past. With a number that ignores capacity variation, trying to build intuition is hampered by not knowing whether my range is higher/lower because of my driving or because of the battery pack's capacity (which changes with season and cell balancing, etc.)</div><div><br></div><div>With this intuition I can not only estimate my remaining range based on how I will be driving, far more important I know how to adjust my driving to get the range I need.</div><div><br></div><div>It would be a great service to EV drivers if OVMS can provide this type of energy-based battery instrumentation. For vehicles that don't provide a charge estimate in energy units, it will be necessary to calculate an estimate based on what the car does offer. This will be especially challenging in cases where there's insufficient data to determine capacity loss.</div><div><br></div><div>Having an estimated range based on recent driving can be useful when you're cruising at constant speed in stable conditions, but that's a completely different thing from knowing how much energy remains in your battery pack in absolute energy units.</div><div><br></div><div> Tom</div><div><br></div><span id="OLK_SRC_BODY_SECTION"><div style="font-family:Calibri; font-size:11pt; text-align:left; color:black; BORDER-BOTTOM: medium none; BORDER-LEFT: medium none; PADDING-BOTTOM: 0in; PADDING-LEFT: 0in; PADDING-RIGHT: 0in; BORDER-TOP: #b5c4df 1pt solid; BORDER-RIGHT: medium none; PADDING-TOP: 3pt"><span style="font-weight:bold">From: </span> Nikki Gordon-Bloomfield <<a href="mailto:nikki@littlecollie.com">nikki@littlecollie.com</a>><br><span style="font-weight:bold">Reply-To: </span> OVMS Developers <<a href="mailto:ovmsdev@lists.teslaclub.hk">ovmsdev@lists.teslaclub.hk</a>><br><span style="font-weight:bold">Date: </span> Wednesday, January 29, 2014 at 1:01 AM<br><span style="font-weight:bold">To: </span> OVMS Developers <<a href="mailto:ovmsdev@lists.teslaclub.hk">ovmsdev@lists.teslaclub.hk</a>><br><span style="font-weight:bold">Cc: </span> OVMS Developers <<a href="mailto:ovmsdev@lists.teslaclub.hk">ovmsdev@lists.teslaclub.hk</a>><br><span style="font-weight:bold">Subject: </span> Re: [Ovmsdev] Tesla Ideal vs Rated Range<br></div><div><br></div><div><meta http-equiv="content-type" content="text/html; charset=utf-8"><div dir="auto"><div>For what it's worth, I like setting it as an option. As in " I know that I can usually get 30 miles per charge". Since it will be different for everyone that seems like a sensible option. <br><br>Sent from my iPhone</div><div><br>On 29 Jan 2014, at 07:17, Paul Churchley <<a href="mailto:paul@churchley.org">paul@churchley.org</a>> wrote:<br><br></div><blockquote type="cite"><div><div dir="ltr">Thanks for that Tom,<div><br></div><div>I am wondering how best to apply that to the Ampera... indeed, to other cars?</div><div><br></div><div>I have made the assumption that the ideal range was the range likely achievable under ideal conditions. i.e. the max range you would expect to get.</div><div><br></div><div>Should we be changing the names, and indeed the purpose altogether, for these two values? Also, EPA does not really apply in other parts of the world where they might have their own range rating system.</div><div><br></div><div>I would prefer to see a more generic range estimation protocol that can be applied across all models and that is user adjustable perhaps through parameters?</div><div><br></div><div>Any thoughts?<br><div class="gmail_extra"><br><div class="gmail_quote">On 29 January 2014 06:11, Tom Saxton <span dir="ltr"><<a href="mailto:tom@idleloop.com" target="_blank">tom@idleloop.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="font-size:14px;font-family:Calibri,sans-serif;word-wrap:break-word"><div>Ideal miles is a terrible name because it implies something very different from what it is.</div><div><br></div><div>Tesla was forced to come with a new name because the EPA changed how they evaluate vehicles, giving less optimistic numbers for gas mileage as well as electric efficiency and range. So Tesla called the new numbers the much more descriptive "rated range miles", while still using the "ideal range miles" as their estimate of what the range would be under the old EPA scheme.</div><div><br></div><div> Tom</div><div><br></div></div></blockquote></div></div></div></div></div></blockquote><blockquote type="cite"><div><span>_______________________________________________</span><br><span>OvmsDev mailing list</span><br><span><a href="mailto:OvmsDev@lists.teslaclub.hk">OvmsDev@lists.teslaclub.hk</a></span><br><span><a href="http://lists.teslaclub.hk/mailman/listinfo/ovmsdev">http://lists.teslaclub.hk/mailman/listinfo/ovmsdev</a></span><br></div></blockquote></div></div>_______________________________________________
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