On recent +700 mi trips from Huntsville AL to Coffeyville KS and later Huntsville to Richardson TX (aka., Dallas,) I got a lot of cross country charging experience and began to wonder about charging strategies. For example, which makes more sense: $0.26/min - tier 2 above 60 kw, short and fast for shortest range $0.13/min - tier 1 below 60 kw, long and slower for maximum range Tier 2 is the most expensive per minute but also adds miles the fastest. But to use it, the battery has to be run down to a minimum reserve battery range, 0-30 miles. "Tickling the dragon," this requires close monitoring and adjusting speed, usually downward, to reach the next SuperCharger. But what happens in tier 1 charging? This is what my earliest SuperCharger session looked like: So I blew up the tier 2 session to get: The initial charging is slow, probably to measure the battery state. Then it reaches a peak of 101 kW. I then digitized the profile to make this table: Code: min kW kWh total kWh $/kWh Total $ 1 65 1.08 1.08 $0.24 $0.26 2 73 1.22 2.30 $0.21 $0.52 3 80 1.33 3.63 $0.20 $0.78 4 90 1.50 5.13 $0.17 $1.04 5 97 1.62 6.75 $0.16 $1.30 6 101 1.68 8.43 $0.15 $1.56 6 101 1.68 10.12 $0.15 $1.82 7 101 1.68 11.80 $0.15 $2.08 8 101 1.68 13.48 $0.15 $2.34 9 101 1.68 15.17 $0.15 $2.60 10 101 1.68 16.85 $0.15 $2.86 11 101 1.68 18.53 $0.15 $3.12 12 101 1.68 20.22 $0.15 $3.38 13 101 1.68 21.90 $0.15 $3.64 14 94 1.57 23.47 $0.17 $3.90 15 75 1.25 24.72 $0.21 $4.16 16 54 0.90 25.62 $0.29 $4.42 Domestic charge rates in Huntsville are $0.11/kWh so the peak charging rate on the road is just 50% higher and quite affordable. So here are the actual SuperCharger costs on the Huntsville to Richardson and back trip: Code: date time Tier 2 Tier 1 mi (PS) location 05/18 15:30 0 0 0 Huntsville AL 05/18 19:30 16 50 206 Memphis TN (1) 05/19 01:12 16 23 163 Little Rock AR 05/19 04:30 14 20 133 Texarkana TX 05/19 06:50 6 19 98 Sulphur Springs TX (2) 05/19 10:00 81 LaQuinta 05/19 17:22 12 99 Plano TX (3) 05/21 13:13 4 16 101 Lindale TX 05/21 16:00 0 0 103 Shreveport LA (4) 05/21 17:59 6 34 104 Monroe LA 05/22 00:38 12 17 Pearl MS (5) 05/22 09:36 12 7 118 Pearl MS 05/22 11:41 13 11 91 Meridian MS 05/22 18:16 16 8 144 Birmingham AL (6) 05/22 20:50 106 Huntsville AL Huntsville-to-Memphis exceeds the 80% range, 192 mi. This suggests the longest segments should start with a non-SuperCharger charge session using a distribution, J1772, or NEMA 14-50 EVSE overnight. Sulphur Springs was more of a biology break to get out of reserve range management. The rest of the trip was normal car behavior. The distribution and J1772 ESVEs at the hotel/motel were powered off and this was Sunday. We weren't sure we'd get them turned on Monday so I drove downtown to use the Plano SuperCharger. Sunday afternoon it was very busy and I picked up a quick charge but by 7PM it was all but empty and there were restaurants calling my name. Open question, if you use the phone app to stop charging before reaching the car, do you still get idle or other tier 1 charges? Shreveport never charged for our session ... Thanks TESLA. We stopped at Vicksburg and put the portable kennel up on a nearby RV park but we didn't have the right electrical plug for 30A service. Using 12A, 120VAC it was obvious we were losing charge and it wasn't clear we'd have enough to reach Perl MS the next morning. So I took a midnight trip to Perl to put on a strong charge, 144 mi battery range at the RV park and left the kennel in operation. I visited the casino and left with an extra $79 and took at nap in the room. With unusual speed, my wife got ready quickly to see her dogs and we were on the road by 8AM. We didn't realize how bad the I-20 backup would be so we took a detour and in the heat, AC was necessary. Then about 20 miles beyond the construction, another backup as a truck had rolled off the road and a fire truck was blocking lanes. Autopilot worked great and someone in a tall work truck rolled down their window to ask if I was driving without using my hands . . . he was impressed. We barely found the Birmingham SuperChargers which due to construction was accessible by only one road. The battery was so low we initially lost AC. Once we had enough to reach home, we were off. I used the map to take short-cuts in Birmingham and Huntsville. LESSONS LEARNED First segment should be from a non-SuperCharger source, a hotel/motel or RV park, where a full charge can be put on the car. This avoids the more expensive, slower tier 1, charge. Always leave with a 30 mi reserve range to the next SuperCharger but have handy the PlugShare map of RV parks, J1772, and distribution chargers along the route. If the reserve range reaches 10 mi, divert to these alternate charging sources. If using an RV park, make sure you have a set of 30A plugs and/or adapters. There are different styles. Bob Wilson
I didn't like the quality of my first report so I repeated it using iPhone, 'TIME-LAPSE' to record the session: Standard Range Plus Model 3, V19.16.2 climate control was off 20 mi indicated battery range at start 237 mi stopped recording data in spreadsheet frame numbers to reconstruct true time kW rate mi/hr rate battery mi first and last frame times Here is the battery range in miles during the session: One goal is resolving the optimum charge session for cost and speed, the green dashed rectangular box: too short duration - the ramp up slows getting back on the road. It is cheapest BUT a slower trip end-to-end speed. too long duration - the battery taper slows getting back on the road. It is also more expensive while giving a slower trip end-to-end speed. Adding the charge and travel time at 65 mph with the distance covered gives a curve showing the optimum, battery charge: What this means is attempts to charge to the vehicle maximum range is both expensive and causes the trip to take longer. It is slightly faster and cheaper to go shorter distance, SuperCharger-to-SuperCharge when in SuperCharger mode. This does not apply on the first trip of the day leaving with the car at maximum charge. This busy chart combines the costs and battery mi level with the X-axis, charge rate: $0.025/mi = $2.50/100 mi - optimum route, expected cost. With gas at $2.50/gal, in effect, 100 MPG equivalent. longer distance legs will give a slower trip time and higher cost but if you have to reach a SuperCharger, there is only one alternative . . . slower speed than 65 mph. But it will be faster than stopped or using an L1 or L2 charger. On long range trips that require multiple SuperCharger sessions, there may be more than one route. Choose the route with the closest SuperChargers and do multiple, short charges. Avoid routes that have a lot of maximum range segments. Bob Wilson
