AutoVolt DC

AutoVolt DC is a calculation and measurement aid for 12/24 V low-voltage automotive DC systems. It helps document cable voltage drop, wire-size candidates, battery runtime, starter-circuit facts, and alternator charging balance. Every calculation result shows its formula, inputs, units, assumptions, and methodology source. AutoVolt DC does not hide uncertainty behind one “correct number” and does not replace the vehicle manufacturer's service information or a component datasheet. CORE FEATURES • Wire and fuse workflow: calculate a copper wire-size candidate from the permitted voltage drop, then separately check manufacturer-supplied cable ampacity and fuse data. • Voltage-drop measurement: guided positive-side, ground-side, and whole-circuit measurement points; before/after history; and an optional manufacturer or methodology limit entered by the user. • Battery runtime estimate: lead-acid and LiFePO₄ profiles with depth of discharge, temperature, age, and efficiency factors. The Peukert model is available only with a sourced lead-acid profile. • Starter-circuit facts: use measured voltage drop and current to calculate apparent connection resistance, instantaneous loss, and total positive-plus-ground cable-path drop. • Charging balance: compare sourced alternator current availability with vehicle, accessory, and battery-charging demand; calculate alternator shaft speed from pulley data. • Projects and reports: save calculations and measurements, search projects, create an HTML report, and export or restore a JSON backup. OFFLINE, ADS, AND PRIVACY All calculations, measurements, projects, search, and reports work without an internet connection. The free edition displays a Google Mobile Ads banner and uses Google UMP to manage consent choices. Failure to load an ad never blocks a calculation. Project data stays on the device unless the user initiates export or sharing. An optional €4.99 one-time Pro upgrade permanently removes ads. There is no subscription or recurring fee, and the purchase can be restored with the same Google Play account. TECHNICAL TRANSPARENCY Copper-wire calculations use a NIST Copper Wire Tables source profile with temperature correction. The app methodology also references ISO 19642, ISO 16750-2, and ISO 8820 overviews and guidance from Victron, Fluke, and PicoScope. In the cable workflow, CCA means copper-clad aluminium cable, not battery cold-cranking amps. The app does not guess a universal CCA-cable resistivity or cable ampacity. Thermal and fuse checks require data for the specific manufacturer's cable. SAFETY AutoVolt DC is a calculation and measurement aid, not a vehicle-specific repair manual. The vehicle manufacturer's wiring diagram, service information, component datasheet, and safety procedure always take precedence. Use a suitably rated DC current clamp or shunt for high-current measurements and keep clear of moving and hot engine components.