Power cable extension (12 V systems)
Power cable extension
The power cable for each unit in your system should be run as a separate, single length of 2-wire cable from the unit to the vessel's battery or distribution panel.
Ensure that the extension cable is of a sufficient gauge for the supply voltage, the total current load of the device, and the length of the cable run — as the cable run length increases, the greater the voltage drop will be from one end of the power cable to the other.
Refer to the following table for typical minimum power cable wire gauges:
Cable length in meters (feet) |
Wire gauge in AWG (mm2) for 12 V supply |
|---|---|
<8 (<25) |
16 (1.31 mm2) |
16 (50) |
14 (2.08 mm2) |
24 (75) |
12 (3.31 mm2) |
>32 (>100) |
10 (5.26 mm2) |
Be aware that some products in your system (such as sonar modules) can create voltage peaks at certain times, which may impact the voltage available to other products during the peaks.
To ensure power cables (including any extension) are of a sufficient gauge, ensure that there is a continuous minimum voltage of 10.8 V dc at the end of the cable where it enters the product’s power connector, even with a fully flat battery at 11 V dc. (Do not assume that a flat battery is at 0 V dc. Due to the discharge profile and internal chemistry of batteries, the current drops much faster than the voltage. A “fully flat” battery still shows a positive voltage, even if it doesn’t have enough current to power your device.)