Break-Even Mode

Two input values are used to calculate the raw break-even-miles value for each provider subscription. It is a blunt instrument because it offers no information about overall journey costs and timings. These are available in Cost-Reducation Mode, which requires far more information for its calculations.

1. Vehicle Efficiency (Miles per kilowatt-hour) This determines the extent of your range from a single charge. You'll already know that your EV efficiency changes with the seasons, so enter an up-to-date value to get the most accurate calculation.
2. Typical Average PAYG Public Rate You Pay (pence per kilowatt-hour) This is the average PAYG rate you expect to pay at public chargers. It serves as the baseline for comparing PAYG costs against provider subscription plans..

Cost-Reduction Mode

10 different input values are used in a complex series of calculations to provide not only the lowest cost for your journey(s) but also provide a comparison between the cheapest subscription provider and PAYG rates, the amount of overall charging time needed for the specified journey length(s), and even a real-world itinerary detailing the charging points and durations. It ain't rocket science, but it's the next best thing.

1. Journey Distance (miles) This is the total distance you plan to travel; from leaving home to arriving back at home. During the journey, you'll be charging one or more times.
2. Usable Battery Size (kilowatt-hours) This is used for calculating your distance between charges and is used in conjunction with your recharge threshold (%) and departing battery level (%).
3. Pre-Charge Battery Level (battery %) This is the charge level your battery will be at before you charge for your journey. It will be used to calculate how much your pre-charge will cost.
4. Departure Battery Level (battery %) This is the battery level you plan to charge to before you set off on your journey. It is part of the pre-journey-charge cost calculation. While you should normally charge to 80% most of the time, it's OK to charge to 100% (long-distance mode) before a long drive, although you should set off within a few hours of charging to 100%.
5. Minimum Desired Charging Speed (kilowatts) This is the lowest speed you want to charge at when you use public charging. Since some providers offer lower rates for slower chargers, applying a minimum of, say, 50kW will prevent chargers slower than that from skewing your results if you prefer faster charging turnaround times.
6. Vehicle Efficiency (Miles per kilowatt-hour) Your EV's efficiency value determines how far you can drive, based on the size of your battery and the percentage charge it has. EV efficiency changes with temperature, of course (higher in the warmth of summer and lower in the cold of winter), so you'll need to enter an up-to-date value to get the most accurate calculation.
7. Pre-Charge Rate (pence per kilowatt-hour) This is the rate you use to charge your battery before departing (e.g., your cheap overnight tariff). The calculator uses it to figure out he pre-charge cost and the overall journey total cost.
8. Max. Charging Speed (kilowatts) This is your battery's maximum charging speed. The calculator uses it to figure out realistic charging durations. If, for example, your battery supports a charging speed of 38kW and you enter that value, the calculator will use that value to work out how long you are likely to need to charge, even if you're hooked up to a 150kW charger.
9. Recharge Threshold (battery %) This is the minimum level you allow your battery to drop to before recharging. The calculator uses it to determine the number of charging stops you will need throughout your entire journey. While you are unlikely to recharge at the exact-same level each time, it should be within a few percentage points and will therefore average out over your journey. It defaults to 20%, which is the industry standard level for long-term battery health, but you can set it to whatever you like.
10. Typical Average PAYG Public Rate You Pay (pence per kilowatt-hour) This value is the average PAYG rate (in pence per kWh) that you expect to pay at public chargers. It serves as the baseline for comparing PAYG charges against provider subscription plans.