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Free public beta until December 4, 2026: every course is open, no card needed. After that, the first chapter of each course stays free and full access is a one-time $39 ($19 for up to 100 founding members chosen for helpful feedback). Your progress is kept. How the beta works

derating

Reducing a rating to allow for real-world losses.

Derating applies a factor below 1 to a rating to cover what it doesn't promise in practice, such as a battery's usable capacity at low temperature or with ageing.

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