100Ah and 12V battery runtime calculator for RV loads
Estimate watt-hours and battery runtime from voltage, amp-hours, usable capacity, conversion losses and appliance duty cycle.
Guides & tools / OffGrid Energy Tools
Tools, guides and equipment decision library
Browse all free calculators, practical measurement guides and independent equipment checklists.
Start with a real problem, work through transparent calculations, then compare equipment requirements. The tools are free. No article pretends to have measured product performance or search demand.
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Interactive calculators
RV solar recharge calculator — panel watts, sun and daily loads
Plan daily off-grid energy balance with realistic editable solar derating and consumption estimates.
RV battery bank size calculator — Wh to Ah with reserve days
Size an RV battery energy budget using daily Wh, autonomy days, usable capacity and system efficiency.
RV power planner — build your battery and solar plan
Build a customized RV appliance energy budget, compare battery and solar scenarios, check your own equipment specifications and export a decision plan.
Home battery backup planner: size an outage energy budget
Estimate battery energy for your household's measured loads, compare outage duration and losses, and separate portable backup from whole-home installation.
CPAP battery backup calculator: watts, hours and nights
Calculate an energy scenario from your CPAP's documented average draw, session duration, reserve and losses. Check power compatibility separately with the device supplier.
How-to and measurement guides
How long will a 100Ah battery run an RV fridge?
A worked battery runtime example that shows the impact of fridge cycling, capacity and conversion losses.
RV power audit: make a daily watt-hour budget before buying
Measure RV appliance watts, duty cycles, inverter standby and recharge needs in one practical energy worksheet.
How many solar panel watts does an RV need?
Turn a measured RV Wh/day load into a solar panel estimate with peak-sun-hour and loss assumptions.
RV inverter idle draw: the invisible battery drain
Estimate how overnight inverter standby consumption changes a 12V RV battery runtime calculation.
LiFePO4 vs AGM for an RV: usable energy and tradeoffs
Compare battery chemistries for RV duty cycles using usable capacity, charging limits and real total cost criteria.
How to measure RV fridge watt-hours per day
Measure a cycling RV refrigerator before estimating battery runtime or solar charging requirements.
Battery reserve for cloudy RV days: an autonomy worksheet
Estimate multi-day reserve requirements when solar production is uncertain, using explicit daily-load assumptions.
Equipment decisions
RV battery monitors — voltage meter, shunt or portable power station?
A buyer checklist explaining when monitoring matters and how to compare equipment before purchasing.
Portable power station vs DIY RV battery: what to compare
Compare portable stations and installed RV battery systems by usable capacity, outputs, monitoring and serviceability.
RV solar charge controller buying checklist
Understand the questions to ask about battery profiles, array limits and monitoring before comparing RV solar charge controllers.
RV battery and solar shopping checklist: ask these questions first
A practical RV battery, inverter, power station and solar shopping checklist grounded in your daily energy budget.
RV power equipment buying hub: match your energy budget
Choose which RV power equipment category to research after estimating battery runtime, storage size and solar needs.
From research to decision
Explore the buying guide →Turn your result into an equipment checklist
No fabricated product tests or affiliate claims. Compare verified specifications before buying.