The cheapest way to cover a long distance isn't one big charge to full, it's several smaller stops at stations you picked for their price before you left, not the first one you find with the battery low. Planning ahead turns charging from a forced stop into a choice you control.
Why splitting the charge usually costs less
Every lithium-ion battery accepts power fastest when it's emptier and slower as it fills. That means the last portion of any DC fast charge, often somewhere past 80%, takes longer for the same kWh than the first portion did. On a per-minute or time-sensitive tariff, that slow tail costs you more per kWh than the earlier, faster part of the same session. Stopping a charge before the taper kicks in and doing another shorter stop later, rather than pushing one session all the way to full, keeps more of your charging in the fast, cheap part of the curve.
Working the actual cost of two strategies
Say your route needs 60 kWh in total. One option is a single stop at a motorway station priced at €0.55 per kWh: that's €33 for the full 60 kWh. Another option is two shorter stops of 30 kWh each, one at €0.40 per kWh and one at €0.45 per kWh: that's €12 plus €13.50, or €25.50 total. Same distance covered, same energy delivered, €7.50 less, just from choosing where you stop rather than stopping wherever the battery forces you to.
The numbers change with every trip and every tariff, which is exactly why it's worth running this arithmetic on your own route rather than assuming either strategy always wins.
Build in a buffer, not a guess
Plan to arrive at each stop with charge to spare, commonly discussed as somewhere around a tenth to a fifth of the battery, rather than aiming to arrive at zero. A charger that's occupied, broken, or slower than listed is common enough that arriving with nothing left turns a minor inconvenience into a real problem. The buffer costs you a little extra charging time earlier in the trip, in exchange for not being stranded later.
Plan the stops, not just the route
A route planner tells you where chargers exist along the way. Checking prices at those same stops before you leave, rather than after you're already low, is what turns that list of chargers into a list you can actually choose from. goodcharge lets you compare the stations along your route in advance, so the stop you pick is the cheap one, not just the nearest one.
Don't charge to 100% unless it's your last stop
Because of the taper, charging past roughly 80% on a fast DC charger is slow and, on time-based tariffs, expensive per kWh. Save the full top-up for your last stop of the day, when you have somewhere to park overnight anyway, and keep the stops in between shorter and cheaper.