Battery Calculators

Batteries are judged on capacity, voltage, chemistry, and how they behave under real loads—not just nameplate numbers. Runtime depends on discharge rate, temperature, age, and how deeply you cycle each day. A 100 Ah label does not guarantee 100 Ah of usable energy in every scenario. Peukert effects, BMS limits, and inverter cutoff voltages all shrink practical runtime.

Charging strategy is equally important. Bulk, absorption, and float stages exist because chemistries respond differently to current over time. Charging too fast generates heat and gas in flooded lead-acid. Charging too slow leaves lithium cells at partial state of charge too long. Match charger amperage to manufacturer guidance and to what your generator or solar array can sustain.

State-of-charge (SoC) estimation drives user decisions: when to start a generator, when to shed loads, and when a bank is healthy enough for an overnight outage. Voltage-based SoC is approximate—especially under load—but still useful when calibrated for your chemistry and resting intervals. Coulomb counting and shunt monitors improve accuracy when you invest in instrumentation.

Temperature changes effective capacity. Cold reduces lithium and lead-acid performance; heat accelerates aging. If your bank lives in an unconditioned garage, RV bay, or engine compartment, derate capacity and revisit charging voltage temperature compensation.

Use WattQuick battery calculators to estimate runtime from capacity and load, model charging duration from charger amps, and translate vendor specs into comparable watt-hours. Run the same scenarios at summer and winter temperatures when your application is exposed. Document assumptions so future upgrades start from a clear baseline.