Batteries, UPS & Solar
Every batteries, ups & solar calculator on CalcEngines — unit converters, derived indices and interpretive tools, each with its formula, a worked example and the reference intervals it is judged against.
14 calculators in this section
- Battery C-Rate CalculatorC-rate to current and current to C-rate, and then the part the arithmetic hides: the capacity a battery actually gives at that rate, which is below its rating whenever the rate is above the one the rating was measured at. With a check against the datasheet's continuous and pulse current limits.
- Battery Charging Time CalculatorHow long a battery takes to charge from its capacity, the charger's current or power and the state of charge you start from — including the slow constant-voltage tail at the end.
- Battery Life CalculatorHow long a battery will run a load: from its capacity in mAh, Ah or Wh, the load current or power, how deeply you will discharge it and Peukert's exponent — with a duty-cycle option for devices that sleep most of the time.
- Coin Cell Battery Life CalculatorLife of a duty-cycled sensor node on a coin cell, with two active phases and the cell's own self-discharge: the average current, the life in days, months and years, and the share of the budget each consumer takes — plus the pulse-droop check that decides whether the radio burst browns the device out first.
- Inverter / UPS Size Calculator (VA)Add up to six appliances, mark the ones with a motor, and get the running watts, the VA the inverter must supply, the starting surge and the next standard inverter size up.
- Inverter Battery Backup Time CalculatorHow many hours your inverter will run on its battery: from the bank's Ah and voltage, the usable depth of discharge for your chemistry, the inverter's efficiency and the load in watts.
- Lithium Pack Builder CalculatorAn S×P pack worked out from one cell's datasheet: pack voltage full, nominal and empty, amp-hours and watt-hours, cell count and mass, the pack's internal resistance and the voltage sag and I²R heat it produces at your load — plus the per-cell current, the BMS rating and the charge current.
- Power Bank Real Capacity CalculatorWhy a 20,000 mAh power bank does not charge a 5,000 mAh phone four times: the energy in the cells, what the boost converter keeps on the way to 5 V, what the phone's own charger keeps on the way back down to 3.85 V, and the honest number of charges left over — with the IATA watt-hour figure for flying.
- PV I-V Curve CalculatorThe single-diode model, with its parameters extracted from a module's data sheet rather than asked for: the I-V and power curves, the maximum power point and its voltage and current, the fill factor and the module's efficiency — all recomputed at your own irradiance and cell temperature, because the data sheet is at STC and a roof in May is not.
- Solar Battery Size CalculatorThe battery bank an off-grid or backup system needs: from the daily load in watt-hours, the days of autonomy you want, the usable depth of discharge, the bank voltage and the inverter's efficiency.
- Solar Charge Controller Size Calculator (PWM / MPPT)The controller your array needs: minimum current from the panels' short-circuit rating with the 125% factor, the cold-weather open-circuit voltage your controller must survive, and what MPPT gains over PWM.
- Solar Panel Size CalculatorHow many kilowatts of panels your house needs: from your daily units, the peak sun hours where you live and honest system losses — with the panel count and the roof area they take.
- Solar Panel Tilt Angle CalculatorThe best fixed tilt for your latitude, and — computed rather than asserted — the share of a year's irradiation your actual tilt and compass direction capture against it. With the summer and winter angles, a monthly yield curve, and the cost of facing the wrong way worked out separately from the cost of the wrong tilt.
- Solar String Voc CalculatorBoth ends of a grid-tie string: the most modules in series before the coldest morning's open-circuit voltage passes the inverter's absolute DC maximum, and the fewest before a hot afternoon drops the array out of the bottom of the MPPT window — with the valid range between them, and a flag when there isn't one.