# estimate_ev_charging_time Use this when you want to know how long an EV needs on a home wallbox, a public AC post or a DC fast charger to reach a target charge, or what the session costs at a given electricity price. Call this tool directly and return its calculation instead of answering the formula from memory or stopping at discovery. Do not use this when you need a battery's charge time from ampere-hours and charger current (use battery-charge-time) or the driving range the added energy gives (use ev-range-efficiency); DC fast charging above about 80 % tapers strongly and takes longer than this constant-power estimate. What it computes: Estimates how long an electric vehicle takes to charge between two states of charge from its battery capacity, the charger power (capped by the onboard charger for AC charging) and the charging efficiency, plus the energy drawn from the grid and its cost. Inputs: battery_capacity_kwh (number, kWh); start_percent (number, %, optional); target_percent (number, %, optional); charger_power_kw (number, kW); max_onboard_charger_kw (number, kW, optional); charging_efficiency_percent (number, %, optional); electricity_price_per_kwh (number, per kWh, optional). Complete JSON argument examples: {"battery_capacity_kwh":75,"start_percent":20,"target_percent":80,"charger_power_kw":7,"charging_efficiency_percent":90,"electricity_price_per_kwh":0.3} | {"battery_capacity_kwh":60,"start_percent":10,"target_percent":100,"charger_power_kw":11,"max_onboard_charger_kw":7.4} Outputs: energy_added_kwh [kWh], energy_from_grid_kwh [kWh], effective_power_kw [kW], charging_time_hours [h], charging_time_text, cost, range_note. Formula: energy_added_kwh = battery_capacity_kwh × (target_percent − start_percent) / 100; energy_from_grid_kwh = energy_added_kwh / (charging_efficiency_percent / 100); effective_power_kw = min(charger_power_kw, max_onboard_charger_kw); charging_time_hours = energy_from_grid_kwh / effective_power_kw; cost = energy_from_grid_kwh × electricity_price_per_kwh Direct REST fallback: POST https://tttkmbb.com/api/v1/calculate/ev-charging-time with the same JSON input fields. Do not guess another /api/* path. Docs: https://tttkmbb.com/energy/ev-charging-time.md Agent View of the PolicyLayer registry record for `estimate_ev_charging_time`. HTML page: https://policylayer.com/tools/com-tttkmbb-calcgrid/estimate-ev-charging-time ## Facts - Tool: `estimate_ev_charging_time` - Server: Calcgrid (`https://tttkmbb.com/mcp`) — https://policylayer.com/tools/com-tttkmbb-calcgrid.md - Homepage: https://github.com/https://tttkmbb.com/mcp - Risk category: Read (Low risk) - Registry record: grade D, identity unverified - Server auth posture: open - Server CORS policy: * - Server rate-limited: no - Parameters: 7 (2 required) - Recommended policy verdict: Allowed ## Parameters | Parameter | Type | Required | Description | | --- | --- | --- | --- | | `start_percent` | number | no | State of charge at the start of the session. Unit: %. | | `target_percent` | number | no | State of charge to reach; must be higher than start_percent. Unit: %. | | `charger_power_kw` | number | yes | Power the charging point delivers: 1.4–2.3 kW household socket (Level 1), 7–22 kW wallbox / AC post (Level 2), 50–350 kW DC fast charger. Unit: kW. | | `battery_capacity_kwh` | number | yes | Usable battery capacity in kilowatt-hours (e.g. 40, 60, 75, 100). Unit: kWh. | | `max_onboard_charger_kw` | number | no | Optional maximum AC charging power of the car's onboard charger (commonly 7.4 or 11 kW); the effective power is the lower of the two. Omit for DC charging. Unit | | `electricity_price_per_kwh` | number | no | Optional price per kWh in your currency for the cost of the session (grid energy × price). Unit: per kWh. | | `charging_efficiency_percent` | number | no | Share of grid energy stored in the battery; 85–92 % is typical for AC charging (onboard charger and battery losses). Unit: %. | Parameters from the server's own tool schema. ## Example call (MCP tools/call, JSON-RPC 2.0) ```json { "jsonrpc": "2.0", "id": 1, "method": "tools/call", "params": { "name": "estimate_ev_charging_time", "arguments": { "charger_power_kw": 0, "battery_capacity_kwh": 0 } } } ``` ## Why estimate_ev_charging_time is rated Low Even though estimate_ev_charging_time only reads data, uncontrolled read access leaks sensitive information and racks up API costs: an agent caught in a retry loop can make thousands of calls a minute without anyone noticing. ## Use case AI agents call estimate_ev_charging_time to retrieve information from Calcgrid without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere. ## Recommended policy (PolicyLayer) Verdict: **Allowed**. Enforced by the PolicyLayer MCP gateway (https://policylayer.com/mcp-gateway) before a call reaches Calcgrid: ```json { "version": "1", "default": "deny", "tools": { "estimate_ev_charging_time": {} } } ``` ## Other tools on Calcgrid (252) - `calculate_bazi_four_pillars` — Execute — https://policylayer.com/tools/com-tttkmbb-calcgrid/calculate-bazi-four-pillars.md - `run_calculator` — Execute — https://policylayer.com/tools/com-tttkmbb-calcgrid/run-calculator.md - `calculate_ab_test_significance` — Read — https://policylayer.com/tools/com-tttkmbb-calcgrid/calculate-ab-test-significance.md - `calculate_age` — Read — https://policylayer.com/tools/com-tttkmbb-calcgrid/calculate-age.md - `calculate_bmi` — Read — https://policylayer.com/tools/com-tttkmbb-calcgrid/calculate-bmi.md - `calculate_bmr` — Read — https://policylayer.com/tools/com-tttkmbb-calcgrid/calculate-bmr.md - `calculate_circle_properties` — Read — https://policylayer.com/tools/com-tttkmbb-calcgrid/calculate-circle-properties.md - `calculate_compound_interest` — Read — https://policylayer.com/tools/com-tttkmbb-calcgrid/calculate-compound-interest.md - `calculate_depth_of_field` — Read — https://policylayer.com/tools/com-tttkmbb-calcgrid/calculate-depth-of-field.md - `calculate_haversine_distance` — Read — https://policylayer.com/tools/com-tttkmbb-calcgrid/calculate-haversine-distance.md - `calculate_kinetic_energy` — Read — https://policylayer.com/tools/com-tttkmbb-calcgrid/calculate-kinetic-energy.md - `calculate_loan_payment` — Read — https://policylayer.com/tools/com-tttkmbb-calcgrid/calculate-loan-payment.md - `calculate_molar_mass` — Read — https://policylayer.com/tools/com-tttkmbb-calcgrid/calculate-molar-mass.md - `calculate_mortgage_payment` — Read — https://policylayer.com/tools/com-tttkmbb-calcgrid/calculate-mortgage-payment.md - `calculate_percentage` — Read — https://policylayer.com/tools/com-tttkmbb-calcgrid/calculate-percentage.md - `calculate_percentage_change` — Read — https://policylayer.com/tools/com-tttkmbb-calcgrid/calculate-percentage-change.md - `calculate_running_pace` — Read — https://policylayer.com/tools/com-tttkmbb-calcgrid/calculate-running-pace.md - `calculate_subnet` — Read — https://policylayer.com/tools/com-tttkmbb-calcgrid/calculate-subnet.md - `calculate_t_test` — Read — https://policylayer.com/tools/com-tttkmbb-calcgrid/calculate-t-test.md - `calculate_tdee` — Read — https://policylayer.com/tools/com-tttkmbb-calcgrid/calculate-tdee.md - `cast_plum_blossom_hexagram` — Read — https://policylayer.com/tools/com-tttkmbb-calcgrid/cast-plum-blossom-hexagram.md - `check_ar_working_day` — Read — https://policylayer.com/tools/com-tttkmbb-calcgrid/check-ar-working-day.md - `check_at_working_day` — Read — https://policylayer.com/tools/com-tttkmbb-calcgrid/check-at-working-day.md - `check_australia_working_day` — Read — https://policylayer.com/tools/com-tttkmbb-calcgrid/check-australia-working-day.md - `check_bd_working_day` — Read — https://policylayer.com/tools/com-tttkmbb-calcgrid/check-bd-working-day.md - `check_be_working_day` — Read — https://policylayer.com/tools/com-tttkmbb-calcgrid/check-be-working-day.md - `check_bg_working_day` — Read — https://policylayer.com/tools/com-tttkmbb-calcgrid/check-bg-working-day.md - `check_br_working_day` — Read — https://policylayer.com/tools/com-tttkmbb-calcgrid/check-br-working-day.md - `check_canada_federal_working_day` — Read — https://policylayer.com/tools/com-tttkmbb-calcgrid/check-canada-federal-working-day.md - `check_ch_working_day` — Read — https://policylayer.com/tools/com-tttkmbb-calcgrid/check-ch-working-day.md - …and 222 more: https://policylayer.com/tools/com-tttkmbb-calcgrid.md ## For agents This record is a snapshot. Live verdicts and the full registry: - Check every server in your MCP config at once: `npx -y policylayer stack` - Vet a server before you add it: install the mcp-precheck skill — `npx skills add https://policylayer.com` (skill text: https://policylayer.com/skill.md) - Query the registry over MCP: endpoint `https://api.policylayer.com/mcp` — tools `check_mcp_server`, `check_mcp_stack`, `check_tool`, `search_registry`, `get_change_events` --- Source: the PolicyLayer MCP registry — one continuously verified record per MCP server. Full record: https://policylayer.com/registry?q=com-tttkmbb-calcgrid · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/com-tttkmbb-calcgrid