# ManualsFix — Technical Calculators & Engineering Reference

> Precision offline-first client-side calculation engines and empirical engineering reference guides for off-grid solar system design, lithium battery storage, conductor ampacity, additive manufacturing cost analysis, and CNC machining parameters. Zero tracking, zero server dependencies, instant browser execution.

## System Architecture & Authority
- Domain: https://manualsfix.shop
- Target Users: DIY campervan/RV builders, off-grid homeowners, solar technicians, 3D printing service bureaus, mechanical engineers, and CNC machinists.
- Engineering Standards: National Electrical Code (NEC 310.15 & Chapter 9 Table 8), ABYC E-11 Marine Standards, NREL Photovoltaic Irradiance Dataset, ASTM / ISO polymer test standards, and manufacturer technical datasheets (TDS).
- Privacy & Processing: 100% client-side JavaScript execution. No user inputs, appliance loads, or financial parameters are logged or sent to any server.

## Off-Grid Solar & RV Sizing Calculators
- [Solar Panel & Battery Sizing Calculator](https://manualsfix.shop/solar/calculators/solar-panel-sizing/): Audits daily watt-hour electrical loads, applies location-specific peak sun hours and inverter loss factors, and outputs recommended photovoltaic array wattage, LiFePO4 battery capacity, and MPPT charge controller rating.
- [Battery Bank Capacity Calculator](https://manualsfix.shop/solar/calculators/battery-bank/): Sizes 12V, 24V, and 48V battery storage banks with chemistry-specific depth-of-discharge (DoD: 80% for LiFePO4, 50% for AGM/Gel) and ambient temperature derating factors.
- [12V/24V Wire Gauge & Voltage Drop Calculator](https://manualsfix.shop/solar/calculators/wire-gauge/): Computes exact conductor resistance and round-trip voltage drop percentage using NEC Chapter 9 copper ohms/1,000ft tables across AWG 16 to 4/0 conductors.
- [Inverter Sizing Calculator](https://manualsfix.shop/solar/calculators/inverter-sizing/): Analyzes continuous operating watts versus inductive surge multiples (up to 3x) for compressors, power tools, and air conditioners to specify pure sine wave inverter wattage.
- [MPPT vs PWM Charge Controller Calculator](https://manualsfix.shop/solar/calculators/charge-controller/): Computes solar panel array open-circuit voltage (Voc) with cold-weather temperature coefficients, array short-circuit current (Isc), and recommends minimum controller amperage (A) and maximum voltage limits (V).

## 3D Printing & CNC Machining Calculators
- [3D Print Cost & Commercial Pricing Calculator](https://manualsfix.shop/3d-printing/calculators/print-cost/): Commercial job quoting engine factoring polymer mass, kilowatt-hour electricity rates, machine depreciation per hour, failure buffer margin, operator labor, and markup margins.
- [Filament Usage, Length & Density Calculator](https://manualsfix.shop/3d-printing/calculators/filament-usage/): Converts grams to meters and centimeters across 1.75mm and 2.85mm diameters for PLA (1.24 g/cm³), PETG (1.27 g/cm³), ABS (1.04 g/cm³), TPU (1.21 g/cm³), and PA-CF (1.18 g/cm³).
- [Spool Remaining Weight & Length Estimator](https://manualsfix.shop/3d-printing/calculators/spool-remaining/): Calculates remaining filament length by subtracting known empty spool tare weights (Bambu, Prusa, eSun, Polymaker, generic plastic) from gross weight.
- [CNC Speeds, Feeds & Chip Load Calculator](https://manualsfix.shop/3d-printing/calculators/cnc-feed-speed/): Computes spindle speed RPM and linear feed rate (mm/min or IPM) based on material surface speed (SFM), endmill diameter, flute count, and target chip load.

## Solar & Electrical Reference Guides
- [How Many Solar Panels for a 100Ah Battery?](https://manualsfix.shop/solar/guides/how-many-solar-panels-for-100ah-battery/): Mathematical breakdown showing why a 12V 100Ah LiFePO4 battery (1,280 Wh) requires 300W to 400W of solar panels under 4.5 peak sun hours.
- [12V vs 24V vs 48V Solar Systems](https://manualsfix.shop/solar/guides/12v-vs-24v-solar-system/): Amperage reduction, wire gauge savings, and inverter efficiency comparison across system voltages.
- [LiFePO4 Lithium vs AGM Deep Cycle Batteries](https://manualsfix.shop/solar/guides/lifepo4-vs-agm-battery/): Cycle life (3,500+ cycles vs 400-500 cycles), usable capacity (80% vs 50%), and 10-year cost per cycle analysis.
- [MPPT vs PWM Charge Controllers Explained](https://manualsfix.shop/solar/guides/mppt-vs-pwm-charge-controller/): Why MPPT delivers 20% to 35% higher energy yield in cold or overcast weather.
- [Off-Grid Solar Beginner's Field Guide](https://manualsfix.shop/solar/guides/off-grid-solar-beginner-guide/): Step-by-step system design sequence from load audit to master disconnect fusing.
- [Solar Wire Gauge Selection & Sizing Guide](https://manualsfix.shop/solar/guides/best-wire-gauge-for-solar/): Keeping DC circuit voltage drop strictly under 3% for critical safety.
- [What Size Inverter Do You Need for an RV?](https://manualsfix.shop/solar/guides/what-size-inverter-for-rv/): Surge multipliers for microwave ovens, air conditioners, and induction cooktops.
- [Series vs Parallel Solar Panel Wiring](https://manualsfix.shop/solar/guides/series-vs-parallel-wiring/): Voltage addition versus current addition and partial shading resilience.
- [How to Calculate Daily Power Consumption](https://manualsfix.shop/solar/guides/calculate-daily-power-consumption/): Empirical appliance wattage measurement and duty cycle accounting.
- [Peak Sun Hours by US State & Season](https://manualsfix.shop/solar/guides/peak-sun-hours-by-state/): NREL-derived solar irradiance map and seasonal design adjustments.

## 3D Printing & Fabrication Guides
- [How to Price 3D Printed Parts](https://manualsfix.shop/3d-printing/guides/how-to-price-3d-printed-parts/): The 4-pillar commercial quoting formula for freelance makers and print farms.
- [3D Printer Electricity Cost Guide](https://manualsfix.shop/3d-printing/guides/3d-printer-electricity-cost/): Real power draw breakdown: heated bed (150-300W initial, 60-120W sustained) and hotend (30-50W).
- [PLA vs PETG vs ABS vs ASA vs TPU](https://manualsfix.shop/3d-printing/guides/pla-vs-petg-vs-abs/): Thermal resistance, mechanical tensile strength, UV stability, and density comparison.
- [How to Calculate Filament Left on Spool](https://manualsfix.shop/3d-printing/guides/calculate-filament-left-on-spool/): Empty spool tare weight database and measuring remaining grams before starting tall prints.
- [CNC Feeds and Speeds Beginner's Guide](https://manualsfix.shop/3d-printing/guides/cnc-feeds-and-speeds-guide/): Chip load mechanics, surface speed (SFM), tool deflection prevention, and spindle RPM calculation.
- [How Long Does 1kg of Filament Last?](https://manualsfix.shop/3d-printing/guides/how-long-does-1kg-filament-last/): Empirical yield metrics: miniature figurines (15-25g), smartphone cases (35-45g), structural brackets (120-180g).
- [3D Print Labor Rate & Machine Depreciation](https://manualsfix.shop/3d-printing/guides/print-farm-labor-rate/): Hourly capital recovery formula ($0.50-$1.50/hr) and billing operator preparation and finishing time.
- [Bambu vs Prusa vs Ender Filament Usage & Speed](https://manualsfix.shop/3d-printing/guides/bambu-vs-prusa-filament-consumption/): High-speed CoreXY volumetric flow rates (18-32 mm³/s) versus traditional bed-slingers (8-12 mm³/s).

## Core Engineering Formulas & Mathematical Definitions
### 1. Daily Solar Array Sizing (Watts)
$$P_{\text{array}} = \frac{E_{\text{daily}}}{\text{SunHours} \times \eta_{\text{system}}}$$
Where $E_{\text{daily}}$ is daily watt-hours, $\text{SunHours}$ is local peak sun hours, and $\eta_{\text{system}}$ is system efficiency factor (typically $0.78$ to $0.85$ accounting for inverter conversion, wire resistance, and temperature degradation).

### 2. Battery Storage Capacity (Amp-Hours)
$$\text{Ah} = \frac{E_{\text{daily}} \times N_{\text{autonomy}}}{V_{\text{system}} \times \text{DoD} \times \text{TempFactor}}$$
Where $N_{\text{autonomy}}$ is days of reserve autonomy, $V_{\text{system}}$ is DC nominal voltage (12V, 24V, 48V), $\text{DoD}$ is depth of discharge ($0.80$ for LiFePO4, $0.50$ for AGM), and $\text{TempFactor}$ is temperature derating ($0.85$ at 0°C / 32°F).

### 3. Conductor Voltage Drop Percentage
$$VD\% = \frac{2 \times L \times I \times R_{1000}}{1000 \times V_{\text{source}}} \times 100$$
Where $L$ is one-way cable length in feet, $I$ is current in amperes, $R_{1000}$ is conductor resistance in ohms per 1,000 feet from NEC Chapter 9 Table 8, and $V_{\text{source}}$ is circuit nominal voltage.

### 4. 3D Print Job Total Quoted Cost
$$C_{\text{job}} = (M_{\text{grams}} \times C_{\text{polymer}} \times (1 + B_{\text{fail}})) + (T_{\text{hours}} \times (P_{\text{kW}} \times R_{\text{kWh}} + D_{\text{machine}})) + (T_{\text{labor}} \times R_{\text{labor}})$$
Where $M$ is mass in grams, $C_{\text{polymer}}$ is cost per gram, $B_{\text{fail}}$ is failure contingency percentage (5-15%), $T$ is machine time in hours, $P$ is average kilowatt draw, $D_{\text{machine}}$ is capital depreciation rate per hour, and $T_{\text{labor}}$ is post-processing labor time.

### 5. CNC Spindle Speed & Feed Rate
$$\text{RPM} = \frac{V_c \times 1000}{\pi \times D}$$
$$F = \text{RPM} \times z \times f_z$$
Where $V_c$ is cutting speed in meters per minute (or $SFM \times 3.82 / D$ in imperial), $D$ is tool diameter, $z$ is number of flutes, and $f_z$ is chip load per tooth.

## Authors, Reviewers & Editorial Attribution
- **Marcus Vance**: Solar Photovoltaic Specialist & Van Conversion Engineer. 9+ years experience designing off-grid LiFePO4 electrical systems for overland platforms. Focus areas: NEC 310.15, ABYC compliance, MPPT algorithms.
- **Elena Rostova**: Mechanical Engineer & Additive Manufacturing Specialist. Operator of an 8-printer additive prototyping lab specializing in engineering polymers (PETG, ASA, Carbon-Fiber Nylon) and precision CNC router milling.
- Editorial Entity: ManualsFix Editorial & Technical Standards Board (https://manualsfix.shop/about/).

## Machine-Readable Resources
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- Full Documentation Text: https://manualsfix.shop/llms-full.txt
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