#ev

Photographic exposure maths as an API, computed locally and deterministically — the exposure-value, equivalent-exposure and Sunny-16 numbers a photographer, camera-app developer or educator works the exposure triangle with. The exposure-value endpoint gives EV = log₂(aperture² ÷ shutter) and the ISO-100-normalised EV100 (subtracting log₂(ISO/100)) — every one-EV step is a stop, a doubling or halving of light — so bright sun reads about EV 15 and a typical interior EV 6–8, and equal-EV settings give the same exposure. The equivalent endpoint applies the reciprocity at the heart of the triangle: exposure ∝ shutter × ISO ÷ f-number², so when you close the aperture or drop the ISO it returns the new shutter that keeps the brightness constant — going from f/2.8 to f/5.6 needs four times the shutter time. The sunny16 endpoint gives the classic meterless rule: in bright sun shoot f/16 at about 1/ISO (1/125 s at ISO 100), opening up in stops for softer light — slight overcast f/11, overcast f/8, heavy overcast f/5.6, open shade f/4, and f/22 on snow or sand — solving the shutter for your chosen ISO and aperture. Everything is computed locally and deterministically, so it is instant and private. Ideal for camera and photography apps, exposure-calculator and teaching tools, and metering and automation utilities. Pure local computation — no key, no third-party service, instant. 3 compute endpoints. For depth of field and hyperfocal distance use a photography (optics) API.

api.oanor.com/exposure-api

Battery-pack design maths as an API, computed locally and deterministically — the voltage, capacity, energy, current and charge-time numbers an EV, e-bike, solar or robotics pack builder lays out a battery with. The configuration endpoint turns a series-parallel cell layout into the pack: cells in series add their voltages (the series count sets the pack voltage) and cells in parallel add their amp-hours (the parallel count sets the capacity), with the energy in watt-hours = voltage × capacity — a 13S4P pack of 3.6 V / 3.5 Ah cells is 46.8 V, 14 Ah and about 655 Wh from 52 cells, and it also reports the full-charge voltage (series × 4.2 V for Li-ion) to size the charger and BMS. The c-rate endpoint relates current to capacity both ways — give a C-rate to get the current, or a current to get the C-rate — because 1C draws or charges the whole capacity in an hour, so a 14 Ah pack at 2C is 28 A, and it returns the power if you pass the pack voltage. The charge-time endpoint gives the time to charge between two states of charge from the charge current. Everything is computed locally and deterministically, so it is instant and private. Ideal for EV and e-bike builders, solar and off-grid storage tools, robotics and drone packs, and battery-engineering apps. Pure local computation — no key, no third-party service, instant. Pack-design estimates — real cells taper on charge and sag under load. 3 compute endpoints. For runtime under a load use a battery API; for EV charging an EV-charging API.

api.oanor.com/batterypack-api

Electric-vehicle charging maths as an API, computed locally and deterministically — the three numbers every EV driver and charging app actually needs. The charge-time endpoint gives how long a session takes: from the battery size and the gap between the starting and target state of charge it works out the energy to add and the time at a given charger power and efficiency — a 60 kWh battery from 20 % to 80 % on a 7.2 kW home charger at 90 % efficiency takes about 5.6 hours, and it reminds you that DC fast charging slows sharply above 80 % so road trips should be planned around the fast part of the curve. The range-added endpoint turns a charging session into miles: from the charger power, the minutes plugged in and the car's miles per kWh it gives the energy and range added, plus the handy "miles per hour of charging" figure — a 7 kW home charger adds roughly 22 mi/hr, a 150 kW DC station hundreds. The cost endpoint gives what a charge costs, correctly billing the energy drawn from the grid (the energy to the battery divided by the charging efficiency) times the price per kWh, with the effective cost per usable kWh — home overnight rates make EV miles very cheap while DC fast chargers cost several times more. Everything is computed locally and deterministically, so it is instant and private. Ideal for EV apps, route and trip planners, fleet and charging-station tools, charge-cost calculators and dashboards. Pure local computation — no key, no third-party service, instant. Estimates — real DC charging tapers above 80 % and cold weather cuts range. 3 compute endpoints. For battery runtime use a battery API; for generic energy cost use an energy-cost API.

api.oanor.com/evcharging-api