{"query": "How long a battery runs a load", "count": 20, "results": [{"id": "card_theory_electrochemistry", "title": "Electrochemistry & the battery (Volta, Faraday, and stored charge)", "shelf": "theories", "surface": "secular", "snippet": "Electrochemistry & the battery (Volta, Faraday, and stored charge) — an engine domain that can touch it: chemistry. Calibration: seals — cell voltages, Faraday's laws of electrolysis and Nernst shifts", "authority_tier": "reference", "source": "The Theory Assay — calibrated, not judged (docs/THEORY_CATALOG.md)", "readable": false, "generated": false}, {"id": "card_works_battery", "title": "How long a battery runs a load", "shelf": "the-works", "surface": "secular", "snippet": "A 100 Wh battery driving a 50 W load lasts two hours — energy divided by power. The arithmetic behind every off-grid design.  Worked & sealed by the engine — runtime = 100 Wh / 50 W = 2 h.  [HOLDS; op", "authority_tier": "verified", "source": "The Works — worked & sealed", "readable": false, "generated": false}, {"id": "card_power_basics", "title": "Volts, amps, watts — the words you need", "shelf": "energy", "surface": "secular", "snippet": "Three words run everything. VOLTS (V) are the push (like water pressure); AMPS (A) are the flow (like the current in a pipe); WATTS (W) are the actual power, and Watts = Volts × Amps. Energy over time", "authority_tier": "reference", "source": "Basic electrical law (Ohm's law; power = volts × amps) — public fact", "readable": false, "generated": false}, {"id": "card_n_cdb747a427d2", "title": "Electronics — the resonant chain, from Ohm's law to the radio wave", "shelf": "science", "surface": "secular", "snippet": "One sealed chain runs the whole bench: Ohm's law (V = I·R), the capacitor's\nexponential clock (one time constant → 63.2% charged), the diode's exponential gate (current\ndoubles every ln2·nVT ≈ 17.9 mV", "authority_tier": "engine_derived", "source": "Concordance assay — 2026-07-09", "readable": false, "generated": false}, {"id": "card_bridge_master_nernst_potential", "title": "Master equation: V = (RT / zF) * ln(C_out / C_in)", "shelf": "bridges", "surface": "secular", "snippet": "a voltage from the log of a concentration ratio — the same equation in a battery and a neuron. ONE equation, 2 domains, connected by a change of variable: electrochemistry [the electrode potential of ", "authority_tier": "reference", "source": "The Bridges — cross-domain isomorphisms", "readable": false, "generated": false}, {"id": "card_comms_power_field", "title": "Powering a radio in the field", "shelf": "communications", "surface": "secular", "snippet": "Comms fail when the batteries do, so plan power like water. Handhelds sip current on RECEIVE and gulp on TRANSMIT — listen more, key up briefly, and turn power DOWN when the other station is close (lo", "authority_tier": "reference", "source": "U.S. Army field antenna & signaling references (public domain)", "readable": false, "generated": false}, {"id": "card_spine_power", "title": "The off-grid power shelf — keeping the lights and the radio on", "shelf": "spine", "surface": "secular", "snippet": "Off-grid electricity for the prepared home and the mesh node: volts/amps/watts, sizing a system to your real load, batteries (lead-acid vs lithium), solar panels and charge controllers, inverters, saf", "authority_tier": "reference", "source": "The off-grid power shelf (curated, public domain)", "readable": false, "generated": false}, {"id": "card_pchem_electrochemistry", "title": "Electrochemistry — the cell potential", "shelf": "codex", "surface": "secular", "snippet": "A redox reaction splits into two half-cells; the cell potential is E-cathode - E-anode. The Daniell cell (copper, zinc) gives 1.10 V (sealed) - the first practical battery. Redox is electrons moving, ", "authority_tier": "engine_derived", "source": "Narrow Highway — physical chemistry", "readable": false, "generated": false}, {"id": "card_power_batteries", "title": "Batteries — the store, and how not to wreck it", "shelf": "energy", "surface": "secular", "snippet": "The battery is your reservoir. LEAD-ACID (flooded/AGM) is cheap but heavy, and you must not regularly drain it below ~50% or it dies young — so a 100 Ah lead-acid battery gives ~50 Ah of usable energy", "authority_tier": "reference", "source": "U.S. Department of Energy / NREL consumer energy guidance (public domain)", "readable": false, "generated": false}, {"id": "card_power_generator_safety", "title": "Generators — and the invisible killer, carbon monoxide", "shelf": "energy", "surface": "secular", "snippet": "A fuel generator is a strong backup, but its exhaust contains CARBON MONOXIDE — an invisible, odorless gas that kills quickly. NEVER run a generator indoors, in a garage, basement, crawlspace, or near", "authority_tier": "reference", "source": "CDC / U.S. government carbon-monoxide safety guidance (public domain)", "readable": false, "generated": false}, {"id": "card_power_charge_controller", "title": "The charge controller — protect the battery", "shelf": "energy", "surface": "secular", "snippet": "Never wire a solar panel straight to a battery — a CHARGE CONTROLLER sits between them and regulates the charge so the panel can't overcharge and destroy the battery. Two kinds: PWM is cheap and fine ", "authority_tier": "reference", "source": "U.S. Department of Energy / NREL consumer energy guidance (public domain)", "readable": false, "generated": false}, {"id": "card_power_keep_devices_alive", "title": "Keeping phones, radios, and lights alive", "shelf": "energy", "surface": "secular", "snippet": "When power is scarce, discipline stretches it far. Charge small devices from 12 V or USB directly (a car socket or a small solar/USB panel), skipping the inverter's losses. Keep a couple of charged PO", "authority_tier": "reference", "source": "U.S. Department of Energy / NREL consumer energy guidance (public domain)", "readable": false, "generated": false}, {"id": "card_power_wiring_fuses", "title": "Wire thick, fuse close — the safety that prevents fires", "shelf": "energy", "surface": "secular", "snippet": "Low-voltage DC carries BIG amps, so undersized wire overheats and starts fires. Use wire thick enough for the current and the run length (thicker for more amps and longer runs), keep connections tight", "authority_tier": "reference", "source": "U.S. Department of Energy / NREL consumer energy guidance (public domain)", "readable": false, "generated": false}, {"id": "card_power_power_budget", "title": "Size the system to your load, not the other way", "shelf": "energy", "surface": "secular", "snippet": "Design from your NEEDS. List each device, its watts, and hours per day: watts × hours = watt-hours/day. Add them up — that daily total is what your system must supply and your battery must store (plus", "authority_tier": "reference", "source": "U.S. Department of Energy / NREL consumer energy guidance (public domain)", "readable": false, "generated": false}, {"id": "card_power_inverter", "title": "The inverter — DC battery to household AC", "shelf": "energy", "surface": "secular", "snippet": "Batteries and solar are DC (12/24/48 V); most household devices want AC (120 V in the US). An INVERTER converts it. Size it to your biggest simultaneous load PLUS surge — motors (fridge, pump, power t", "authority_tier": "reference", "source": "U.S. Department of Energy / NREL consumer energy guidance (public domain)", "readable": false, "generated": false}, {"id": "card_src_openstax_algebra_1_estimate_time_to_charge_a_battery_54615230", "title": "Estimate Time to Charge a Battery — Algebra 1", "shelf": "mathematics", "surface": "secular", "snippet": "Estimate Time to Charge a Battery\n\nEstimate Time to Charge a Battery\n\nFor this project, think about an electronic device with a battery that you have to charge on a regular basis.\n\nWhat device is it?\n", "authority_tier": "reference", "source": "OpenStax: Algebra 1 (CC-BY 4.0)", "readable": false, "generated": false}, {"id": "card_src_openstax_university_physics_volume_2_conceptual_questions_406a5e60", "title": "Conceptual Questions — University Physics Volume 2", "shelf": "physics", "surface": "secular", "snippet": "Conceptual Questions\n\n10.1\n\nElectromotive Force\n\n1.\n\nWhat effect will the internal resistance of a rechargeable battery have on the energy being used to recharge the battery?\n\n2.\n\nA battery with an in", "authority_tier": "reference", "source": "OpenStax: University Physics Volume 2 (CC-BY 4.0)", "readable": false, "generated": false}, {"id": "card_src_openstax_college_physics_2e_21_2_electromotive_force_terminal_voltag_70fce0a0", "title": "21.2 Electromotive Force: Terminal Voltage — College Physics 2e", "shelf": "physics", "surface": "secular", "snippet": "21.2\n\nElectromotive Force: Terminal Voltage\n\nLearning Objectives\n\nBy the end of this section, you will be able to:\n\nCompare and contrast the voltage and the electromagnetic force of an electric power ", "authority_tier": "reference", "source": "OpenStax: College Physics 2e (CC-BY 4.0)", "readable": false, "generated": false}, {"id": "card_src_openstax_college_physics_ap_courses_2e_21_2_electromotive_force_terminal_voltag_70fce0a0", "title": "21.2 Electromotive Force: Terminal Voltage — College Physics for AP® Courses 2e", "shelf": "physics", "surface": "secular", "snippet": "21.2\n\nElectromotive Force: Terminal Voltage\n\nLearning Objectives\n\nBy the end of this section, you will be able to:\n\nCompare and contrast the voltage and the electromagnetic force of an electric power ", "authority_tier": "reference", "source": "OpenStax: College Physics for AP® Courses 2e (CC-BY 4.0)", "readable": false, "generated": false}, {"id": "card_src_book_58531", "title": "History of the Second Massachusetts Battery (Nims' Battery) of Light Artillery, 1861-1865 — Caroline Elizabeth Whitcomb", "shelf": "gutenberg", "surface": "secular", "snippet": "History of the Second Massachusetts Battery (Nims' Battery) of Light Artillery, 1861-1865, by Caroline Elizabeth Whitcomb. Subjects: United States -- History -- Civil War, 1861-1865 -- Regimental hist", "authority_tier": "reference", "source": "Project Gutenberg (public domain)", "readable": true, "generated": false}], "house": {"door": "FIND", "kind": "cards", "trail": "results", "seal": null, "next_step": {"do": "open the top card", "door": "FIND", "tool": "card_get", "params": {"id": "card_theory_electrochemistry"}}, "ends": "a verdict or a card · the trail · a seal · one next step"}}