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Trip at the edge of battery capacity (Thrice)

Trip at the edge of battery capacity (Thrice)

Made a trip from Logan Utah to Sun Valley earlier this week to see the grandkids in our 2016 MX75. No challenges on the trip up. Even charged a little extra in Twin Falls ID planning for the return trip. Limited charging options available other than a couple of destination chargers 20 miles further up the valley. We woke to a cold soaked battery 15 degrees. As soon as the trip was entered the warning came on to drive below 50 miles per hour in order to arrive a waypoint, Twin Falls Super Charger. Eased it up to 50 and the warning changed to red reading insufficient charge to reach waypoint. My wife is really anxious at this point being something a techniphobe. We pulled to the side of the road and pulled up the Plugshare APP and there was a campground within about 5 miles listed. A call to them got no answer but we headed there anyway. We pulled into a spot and plugged in to a NEMA14-50 and after locating a flipping the breaker we got the dancing green halo. The first 30 minutes were spent seeing no increase in miles as all the energy seemed to be going to heating the battery and keeping us moderately warm. To help track the charging process the navigation helped by being able to monitor the slow disappearance of the red tail of the trip prediction. After an hour we were on our way to the super charger.

Twin Falls required about an hour to get us up to a "safe" level of 95% to continue on our way a long leg between charging opportunities at the best of times. Unfortunately, it be became obvious we still had challenges. Though temperatures were up some, still only in the low 20s and a ~20mph head wind and a growing yellow tail on the trip predictor. I then remember a tip from the forum, Burdogg if I remember correctly, suggesting the benefits of drafting behind big rigs. Speed limit for trucks in Idaho is 70 which in this situation I didn't mind a bit. I pulled in behind the first semi available, engaged AP1 and reduced the spacing setting from 5,4...1, edging in behind the rig a closely as the system would allow. It wasn't not as close as I anticipated so I monitored the guage reading to see if there was any change. The critical number was showing 440 since last charge and it started to slowly move down to lower figures. It seemed to level off at about 380, and more importantly the yellow tail got shorter and shorter.

A quick boost in Tremonton and we were on our way home. A trip that would normally take 4 1/2 to 5 hours took 7 because of environmental conditions. Had we been in an ICE we would have been dumbly unaware of what was happening as the mpg went up to compensate and we would have just paid more at the pump. There are probably somethings that could have been differently. If we hadn't taken our charger with us we could have gone to one of the destination chargers and charged for 2 hours; 1 to compensate for the extra 40 miles up and back and 1 to complete the leg. I could have spent $9000 more 2 years ago to get the then option of a MX90.

This lengthy report almost matches some others that we've seen.

Rocky_H | 2018年3月9日

I live in Boise and drive that route into Utah frequently, although I haven't been up to Sun Valley. Yes, that is a potential surprise when you think you have enough range for the next day, but the car gets down to 15 degrees overnight, so the next day's drive is going to suck up a lot of energy to warm back up.

Two things could have helped on that particular part. Even if you couldn't get very many miles added overnight, having it charging from a regular 120V wall outlet would have kept the battery somewhat warm, so it wouldn't be a huge drain the next day.
Second thing is that if you couldn't have it plugged in, turning on Range Mode for that morning's drive will turn down the really large draw of the battery heater, which wouldn't have been sucking so much energy on your drive down to Twin Falls, so it wouldn't have gotten so low and maybe wouldn't have required the stop at the RV park.

Ah, the drive from Twin Falls to Tremonton is doable but not always easy, even with an 85kWh Model S. With a less aerodynamic X and only 75kWh, yes, it is frequently challenging. I've found that if you map it on EVtripplanner, it won't even put you on that route with a 60 or 75 battery, depending on how cold you set the conditions for, because the distance is too far for the energy use. It instead routes you from Twin Falls to Pocatello and then down to Tremonton because the spaces are shorter. Very glad you found the methods to make it work, though.

kerrjohna | 2018年3月9日

Good tips

zanegler | 2018年3月9日

Drafting is really helpful. In this case, a slower semi, maybe going 60 would have helped even more. Speed and drag are both significant factors on our Tesla's.

burdogg | 2018年3月9日

I wish I could claim credit :) but zanegler is the one that has mentioned that in my post when I talked about my trip to family for thanksgiving and having to go 220 miles between 2 chargers. :)