Time lost when Supercharging in the taper zone - Chart

[animorph]

We're always telling people to use the bottom half of their battery during long trips and I thought a chart might help explain why.

I grabbed real data from a Supercharger session where I needed to charge close to 100%. This was for a 2017 X 100D. I subtracted from that curve a hypothetical charge curve that assumed the peak power (115 kW in this case) was maintained throughout the charge session. So as long as I'm charging at peak power there is no difference between the actual charge time and the "ideal" charge time, a zero on the chart.

Charging to 80%, for example, requires a little over 5 minutes more than if you could charge at peak power the entire time. That might be about the break even point between adding more energy at the current Supercharger or adding another Supercharger stop with an additional 5 minutes of overhead but faster charging at a lower charge level. I'd try to avoid charging above 80% just to be able to skip a Supercharger stop.

If you're charging to 100% during your trip when all you need is 60% to make it comfortably to the next Supercharger, you are wasting about 40 extra minutes by charging in the taper region instead of in the peak power region. That's not 40 minutes you'll make up later, it's just lost, unless you needed extra time for dinner or sleep.

I hope this chart makes it easy to see the time cost of charging above 80%.

 

[suwaneedad]

Nice visual; thank you. It underscores why my preferred roadtripping habit is to leave home with 100%, drive 210mi to a SC and charge to 60%, then drive about 90 mins between SC stops the rest of the way. If a longer break happens to happen on one of the charge cycles and I get beyond 60%, so be it (and can occasionally therefore skip the next SC stop). But I like my general habit of a 3hr leg, followed by 90min legs, punctuated by ~15min SC stops throughout. The future is here, and it is spelled SUPERCHARGER NETWORK.

 

[ByByGas]

Good data collection. I appreciate the work you did with the graph. Thanks

 

[Silicon Desert]

nice graph and info. And after a couple of years driving coast to coast, I have noticed that my X pretty much takes this into consideration. It's been using the lower part of the charge curve to get me to the next SC with some extra security juice.

 

[Gwgan]

I have given feedback to T before that a graph of predicted minutes required per mile gained during a charging session would be more useful in demonstrating this same point than just showing the instantaneous rate as they do now. I think a graph as dramatic as the OP’s would help people realize when it is worthwhile to leave the charger.

 

[israndy]

Now we need a graph showing how much extra charge time you need for every mile over the speed limit you go.

How did you make this graph? Just video the charging and plot a point for every mile it charged? I should do one for the Model 3 from my recent 150kW charge that I took photos during

-Randy