How to connect 4 ESCs to one LiPo battery (Make a power distribution board)
The first time I built a power distribution / wiring harness for a tri / quadcopter was back in December 2010 (http://fangin.com/blog/2010/12/07/tricopter-build-wiring-harness/) and I chose the most direct solution which was to solder all the cables together. I say "most direct solution" because in hindsight, it's not the simplest solution. The drawbacks of this solution include;
- It's more difficult to layout all the wires and get the lengths planned up front.
- Twisting the wire together and soldering 4 or 5 wires at one junction gets messy.
- I tried to link all the wires at one point (http://fangin.com/blog/wp-content/uploads/2010/12/1000000286-Large.jpg) to go into the battery which made it difficult to get the wire into the XT60 connector.
A neater, simpler and all round better solution is a power distribution board where a central, double sided PCB board (copper on both sides) is located centrally in relation to the ESCs / motors and all the wires connect back to this PCB.
What you'll need.
- PCB - Double sided.
- Cutters
- Red / Black Wire
- Solder / Soldering iron
- 20mm heatshrink tube.
- Cut a small board approximately 35 x 15 mm of the double sided PCB.
- Prepare the wires and board by soldering the ends of each wire and the board where the wires will go. You may want to consider orienting the wire to suit the layout of your multirotor. For example an X-Quad you may want to have four wires coming off the board in an X layout.
- Solder the wires to the board. Turn the board over and repeat for the other polarity wires.
- At this point you're almost ready to seal the board up with some heatshrink tube. Before you do! Use a continuity test on a multimeter to ensure 1) All the ground wires are connected and 2) There is no connection between the positive and ground planes.
- If you're worried about wires moving or foreign objects getting into the heatshrink, smother both sides of the board with glue from a hot glue gun. That will help keep the wires in the right place and prevent a short circuit between the two polarities should something conductive work it's way into the housing.
- Now you can solder your favourite connectors at the end of each pair of wires. In the photo shown below I've used XT60 connectors on a harness made for a tricopter.
GoPro Hero, External LiPo power
I recently tried my hand at making a timelapse video using the GoPro (http://www.youtube.com/watch?v=rO3IPMI9TEI) video and still image functions. I was a bit disappointed with the battery life and because I didn't have a spare battery, or access to power the device via a USB charger.
I needed a portable power supply to plug in via USB port on the side of the GoPro. To this end I took a UBEC, hooked it up to the balance tap of a 3S lipo and the output to a USB cable. In the photo below, I added the HK Wattmeter to see if I could measure any current draw by the GoPro. The lowest resolution of the Wattmeter is 100mA and didn't register.
Next to do is maybe add a voltage detector so I can leave it running and get an audible warning if the LiPo gets low however I hope a 2650mAH battery will outlast a 32GB SD card in the camera. I'll have to hook up a proper multimeter and measure the average current draw and figure out how long batteries might last. Maybe integrate a low voltage cut-off circuit as well.
Multi charge leads
I was charging an 800mah 2S battery via the JST connector on my multi-charge lead. After the charge was finished, I went to unplug the battery and dragged it toward me over my bench, when the lipo started fizzing and smoking. I suspect the Tplug that wasn't in use at the time shorted out on a pen clip. The effect is as good as shorting out a Lipo across it's terminals.
The terminals have melted and the lipo has puffed so I've junked the battery. To avoid this in the future, I took an unused T connector and covered the terminals in silicone. When you look at all the leads on the harness, if a short is going to happen, it's going to be on the T connector with those exposed terminals sticking out.
