I've run about 1 meter worth of strip LEDs on 4S for a while now. The LEDS do get very hot.
I had a small electrical mishap that could have set the entire rig ablaze in a few seconds. Those that are using the LED's know that the strips have positive and negative solder tab terminals every 2 inches. While the solder tabs could cause an issue if they are shorted together, it is a bit unlikely, at least in my install. That said, I had an issue where the very end of one of the LED strips - the end where I had soldered the pigtails, shorted to one-another. I think it happened in the car while I was transporting the quad. This was also after several weeks of safe, reliable use. When I installed & soldered up the LED strips, I protected the solder tabs with self-sealing silicon tape. Somehow during transport (perhaps rubbing against the seat or toolbox), the LED strip twisted just enough to bring the two terminals into contact with one another.
All seemed good at my flight site. I ran through the normal precautionary and start-up procedures, then shut the multi down when I realized I hadn't plugged in the LEDs. I plugged in the LEDs and powered up (by connecting the main battery lead). This 'let the smoke out' in a major way. A large stream of smoke immediately began to come from under the multi. I quickly disconnected the battery and stood back to let things settle down. This is the reason that I always keep a set of wire cutters in my back pocket, but luckily the situation allowed for a quick un-plugging of the battery. Anyway.
Post inspection showed that the cheap wires on the pre-made JST plug I used melted instantly, which made a bad situation much worse. The small short on the LED strip heated the JST power wires enough that the rubbery insulation on the JST wires melted away in an instant, allowing the positive & negative wires to fuse. The ends of these wires were soldered directly to the Flamewheel's power ring.
Lessons learned:
1. Insulate & protect the LED solder tabs
2. I will never, ever, ever, again use any wire that has the total crap insulation found on most cheapo (or all?) JST pigtails.
3. A 300 mAh fuse inline with the LEDs power wires is a good idea.
FYI, in reinventing my setup, I created a small dimmer pack. I first step down the 4S voltage to 12v using a 7812 voltage regulator. I then control its output with a small 10k ohm potentiometer.
The biggest problem I had with running the LEDs at 4C (16-14 volts), was that they were uncomfortable to view at night - too bright. They also ran very hot.
At 12 volts, the lights are almost as bright at 16 volts, but the LEDS barely get warm. The difference in heat is remarkable. That must also mean that they are running more efficiently, burning less milliamp hours....
The dimmer is great. I've found that 9-10 volts is just about right at night. +12 volts in bright sunlight is good too.
Cost was about $10 for a multi-pack of 7812 voltage regulators, 2-pack of single-turn board-mount 10k potentiometers, PC board, multi-pack of fuses, and fuse holder.
Next step is to implement the fuse.
