Every tether system needs a BPU of some description. In simplest terms it is a box that takes in mains electricity, generator, batteries, whatever power source you have... and outputs 160 - 250V DC (higher the voltage the lower the current and therefore the lighter the cable).
Do remember to install safety cut off fuses and take every measure to prevent electrocution should anything happen to the cable or drone whilst in use.
We recommend you build or source your own so that it works with your chosen setup. However we can provide you with some options for BPUs if you need.
Our current favorite is this low cost power unit from Yueqing Sense Group in Zhejiang, China.
Dimensions: 262mm x 105mm x 65mm with adjustable voltage control.
It outputs a steady 250V under a range of load conditions and can reach a maximum of 500W which would suite one APU nicely. It's also excellent value and they ship quickly. Available to suit either 110V or 240V AC input.
To purchase: Follow this ebay link
Or email: Jackson Qian on firstname.lastname@example.org
Cable, we highly recommend a very high spec cable that is designed for the voltage and current you choose to use. Since the system runs on DC we use a shielded single core (which reduces tangling as there is less twisted tension in the cable) and run the negative down the cable shield.
Due to the power going through the system and for health and safety reasons, it's not advisable to have a long cable for low altitude flights, heat can build up inside a spooled cable or unspooled cables can cause people to trip. So perhaps have multiple interchangeable lengths for different applications.
We use AWG 26 cables for single APUs (running at 250V) but would recommend a thicker cable if you intend to operate more APUs together, or at a lower voltage.
Again we can help you source cable if you need.
Our preferred cable of choice is a:
Back up battery interface, a beautifully simple switching system that protects the drone should you lose ground power. Simply plug in a charged matching 3S or 4S battery and you can use it as an emergency landing capability, or drop the cable in flight and proceed on battery power alone. Either are possible.
Tethered power systems give you the potential for unparalleled situational awareness. An enduring eye in the sky.
It’s $799 (shipped from the UK so we’ll add VAT tax for UK and EU customers and $20 shipping).
If you can make the case to us that you’re going to use our system on a very worthy and good cause, we also offer a 10% “Drones for Good” discount.
The Airborne Power Unit (APU) Features:
Just for reference, a DJI Phantom 3 uses approximately 150W to hover so a similar weight drone (say an F450 for example) with equivalent sized props would use similar. A F550 Hex with camera uses around 400W so for this setup we would advise using 2 APUs together to give you redundancy.
We strongly recommend using a short length of protective PVC tube to protect the power cable from the props in take off and landings.
Pictured as delivered
Battery and cable connectors not supplied as standard.
Size comparison next to a 4S 4000mAh battery