Ultimate DC Cable Sizing / System Calculator for RVs/Caravans

Author: Solar 4 RVs  

This interactive calculator will help you understand your RV's full power system, including the inverter, battery charger, DC-DC Charger, battery, solar panels, MPPT, and cable sizing with voltage drop. Simply select the voltages and size of your equipment, and the calculator will recommend the optimal cable, fuse, and busbar size, and provide the expected voltage drop.

How to Use the Calculator

All data entry fields are adjustable to match your system's specifications. You can even change the battery voltage to 12, 24, 36, or 48V using the drop-down/select box. Any change you make will automatically update all values.Data entry example

Output and Results

As you adjust the input values, the calculator automatically recalculates all outputs. Output example

Limitations

Please note that the visual representation will only show up to 2 panels in series, 2 panels in parallel, and a maximum of 2 batteries. Any further increase won't display additional panels or batteries, but the calculations will still be accurate.

Calculator limitations example

Request a System Quote

Once you have your results, you can email a screenshot to us at info@solar4rvs.com.au to request a system quote. We're here to help make your RV or caravan's power system as efficient and reliable as possible.

Start Battery Voltage
Start Battery V...
Solar Charge Controller
Solar Charge Control...
Solar Charge Controller
Solar Charge Control...
Number of panels in series
Number of pane...
Number of parallel strings
Number of paral...
DC-DC Charger
DC-DC Charger
Panel Vmp
Panel Vmp
Panel Imp
Panel Imp
Starter Battery
Starter Battery
House Battery
House Battery
ON/OFF Switch
ON/OFF S...
Main Switch Min Current Required
Main Switch Min...
 
B1
House Battery
Number of batteries in parallel
Number of batteri...
NOTE: Negative battery cable lengths MUST be equal
NOTE: Negative batter...
NOTE: Positive battery cable lengths MUST be equal
NOTE: Positive batter...
500mA Fuse
500mA...
 
RJ12
Battery Monitor Display
Battery Monit...
RJ12
RJ12
RJ12
RJ12
Busbar
Busbar
Busbar Min. Current Required
Busbar Min. Current Required
15A
15A
70A
70A
60A
60A
60A
60A
Busbar
Busbar
Busbar Min. Current Required
Busbar Min. Current Required
Mains Charger
Mains Charger
Min Cable Size
Min Cable Size
Min Cable Size
Min Cable Size
Min Cable Size
Min Cable Size
BMV-7XX
BMV-7XX
400A
300A
300A
Min Cable Size
Min Cable Size
Distance (m)
Distance (m)
Distance (m)
Distance (m)
Distance (m)
Distance (m)
Enter distance
Enter distance
40A
40A
Min Cable Size
Min Cable Size
Distance (m)
Distance (m)
Inverter
Inverter
400A
400A
Min Cable Size
Min Cable Size
Distance (m)
Distance (m)
Size (A)
Size (A)
Size (A)
Size (A)
Size (VA) or (W)
Size (VA) or (W)
NOTE: Most panels approx 200W or less will have a Vmp of between 17-20V.
 
Panels 300W+ usually have a Vmp between 32 to 40V.
 
Imp can be calculated -> Imp = Watts / Vmp
NOTE: Most panels approx 200W or less will hav...
Distance (m)
Distance (m)
Min Cable Size
Min Cable Size
Size (A)
Size (A)
B1
B1
RJ12
RJ12
Battery Voltage
Battery Voltage
m
m
A
A
Vd%
Vd%
Vd
Vd
m
m
Vd%
Vd%
Vd
Vd
m
m
Vd%
Vd%
Vd
Vd
m
m
Vd%
Vd%
Vd
Vd
m
m
Vd%
Vd%
Vd
Vd
m
m
Vd%
Vd%
Vd
Vd
m
m
Vd%
Vd%
Vd
Vd
Number of parallel strings
Number of paral...
Volt Drop (%)
Volt Drop (...
Volt Drop (V)
Distance (m)
Volt Drop (V)
Volt Drop (...
Volt Drop (%)
Volt Drop (...
Volt Drop (V)
Volt Drop (...
Volt Drop (%)
Volt Drop (...
Volt Drop (V)
Volt Drop (...
Volt Drop (%)
Volt Drop (...
Volt Drop (V)
Distance (m)
Volt Drop (%)
Volt Drop (...
Volt Drop (%)
Volt Drop (...
Volt Drop (V)
Distance (m)
Volt Drop (V)
Distance (m)
Volt Drop (%)
Volt Drop (...
Inverter
Inverter
Number of parallel strings
Number of paral...

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