Why Charging Preferences Matter
Charging preferences are the instructions you give Stekker about when your car needs to be ready and how full the battery should be. The more accurate these preferences are, the better Stekker can optimize — shifting charging to cheaper hours, using more solar energy, and keeping your site within its grid limits.
Think of it this way: if you tell Stekker your car needs to be ready at 7:00 AM and you plug in at 6:00 PM, that gives Stekker 13 hours of flexibility. If you plug in at 6:00 AM, there is only one hour — and Stekker has no choice but to charge at maximum power immediately.
Departure Time
The departure time tells Stekker when you need your car ready to drive. This is the single most important preference because it defines the optimization window.
Stekker guarantees your car will reach the target charge level by the departure time. Within that window, it has full freedom to schedule charging at the most cost-effective moments. A longer window almost always means greater savings.
Tip: Set your departure time to when you actually leave, not when you think charging should start. If you leave for work at 8:00 AM, set 8:00 AM — not midnight.
Smart Charging Target
The smart charging target is the battery level Stekker aims for during a normal optimized session. The default is 90%.
Why 90% and not 100%? Most EV manufacturers recommend staying below 90% for daily use to preserve battery health. The last 10% also charges significantly slower, which limits Stekker’s ability to optimize. Of course, you can adjust this to any level that suits your needs.
When a session is in smart charging mode, Stekker distributes the energy needed to reach this target across the available time window, prioritizing the cheapest and greenest hours.
Fast Charging Target
Sometimes you need a quick top-up and cannot wait for the full optimization window. That is what the fast charging target is for. The default is 20%.
When you select fast charging, Stekker charges at maximum available power until the battery reaches this target level (measured as the amount added on top of the current level). Fast charging skips most optimization — it prioritizes speed over cost savings.
Use fast charging when you have a short stop and need enough range to get to your next destination. For all other situations, smart charging will save you more money.
How Preferences Affect Optimization
Stekker’s optimizer considers your preferences alongside electricity prices, solar forecasts, and site power limits. Here is how the math works in practice:
- Long window + moderate target = maximum savings. Stekker can cherry-pick the cheapest hours and avoid peak prices entirely.
- Short window + high target = minimal savings. Stekker must charge at high power with little flexibility.
- Solar site + daytime departure = high solar self-consumption. Stekker aligns charging with peak solar production hours.
Per-Vehicle and Per-Site Settings
Preferences can be configured at different levels:
- Per vehicle — If a vehicle is linked to your account (via card or vehicle connection), you can set specific preferences for that vehicle. This is useful when different cars have different usage patterns.
- Per site — Site-level defaults apply to all sessions at that location unless overridden by vehicle-specific settings.
Vehicle-level preferences take priority over site-level defaults.
Priority Settings
Each card or vehicle can be assigned a priority level: high or normal.
When site power is limited and multiple vehicles are charging simultaneously, high-priority vehicles receive power first. This is particularly useful for fleet operations where certain vehicles have critical schedules — for example, a delivery van that must leave at 6:00 AM versus an employee car that is parked all day.
Normal priority is the default. Only set high priority for vehicles that genuinely need preferential treatment, as overusing it reduces its effectiveness.
For an overview of how these settings appear in your dashboard, see Understanding Your Dashboard. If you are just getting started, Your First Week with Stekker covers the full onboarding process including setting up preferences for the first time.
