DC-to-DC Voltage Conversion Calculators
Calculate input-to-output current transformations, thermal dissipation losses, inrush pre-charge suppression, and conductor sizing for boost, buck, and isolated converters.
Voltage Conversion
DC-to-DC Voltage Step-Up/Down Converter Sizer
Calculates primary input current spikes, waste heat dissipation, and wire/fuse sizing when stepping 12V to 24V/48V, or stepping 24V/48V down to 12V.
Off-Grid Communications
Starlink DC Conversion & Boost Wire Sizer
Sizes 12V/24V input conductors, boost converters, PoE voltage drop, and daily battery savings for off-grid Starlink Gen 3, Gen 2, and Mini.
Capacitor Pre-Charge
Inverter Pre-Charge Resistor Calculator
Calculates RC time constants, 5τ charge duration, peak inrush current, and pulse energy dissipation (Joules) to eliminate LiFePO4 BMS trips.
Alternator Charging
Alternator DC-DC Charger Thermal Sizer
Sizes continuous DC-DC charging amperage safely based on OEM alternator ratings, 50% idle RPM derating, vehicle chassis load, and engine bay heat.
Energy Autonomy
DC Direct vs Inverter Idle Loss Calculator
Quantifies daily Wh and Ah saved by running loads natively on DC or via DC-DC converters vs maintaining a 24/7 AC inverter with tare losses.
Grounding & Isolation
Isolated vs Non-Isolated DC-DC Converter Selector
Decision matrix to select between galvanically isolated and non-isolated common-ground converters based on marine hull corrosion and ground loops.
Battery Charger Feeder
DC-to-DC Charger Cable Sizer
Sizes input vehicle alternator run and output house battery run conductors and fuses for smart DC-DC multistage chargers.
Power Conservation & Thermal Dissipation in DC-DC Converters
In direct-current conversion, output power cannot exceed input power minus internal thermal switching losses. Under the first law of thermodynamics:
Power Conversion Conservation Law
Pin = Pout / η = (Vout × Iout) / η
Where:
• Pin = Primary battery input power in Watts.
• Pout = Secondary load power in Watts.
• η = Converter efficiency factor (typically 0.88 to 0.96).
• Pin = Primary battery input power in Watts.
• Pout = Secondary load power in Watts.
• η = Converter efficiency factor (typically 0.88 to 0.96).
This governing relationship creates distinct engineering challenges depending on whether the converter steps voltage up or down:
- Step-Up (Boost) Converters: When stepping 12V up to 24V or 48V (common for trolling motors, communications gear, and high-efficiency lithium sub-banks), input current is significantly higher than output load current. A 10A load at 24V (240W) draws over 22A from a 12V source at 90% efficiency. Primary input conductors and upstream fuses must be sized for this amplified current to prevent catastrophic voltage sag and thermal overload.
- Step-Down (Buck) Converters: When stepping 24V or 48V battery banks down to feed standard 12V automotive and RV loads, input current is reduced, but the converter housing must dissipate continuous heat proportional to switching inefficiencies ($P_{waste} = P_{in} - P_{out}$). Enclosed installations require adequate ambient convective airflow to prevent thermal throttling.
- Galvanic Isolation vs. Non-Isolated Converters: Non-isolated converters share a common negative ground bus, which is ideal for standard vehicle chassis returns. Isolated converters maintain complete physical galvanic separation between input and output grounds, which is essential for eliminating marine ground loops, high-frequency audio noise, and cathodic hull corrosion.
- Quiescent Current Draw: Always account for parasitic standby current draw when converters remain energized while idling, which can deplete unmonitored battery banks over extended storage.