I am working on the power module system with ON / OFF switch. I can see a big need for ON / OFF switch to cut the power without disconnecting battery each time from the system, especially on big drones I noticed a spark when I plug the battery each time to the connector. To make life a little bit easier and safer I designed a High Voltage 40V, High Current 100A Power module with ON / OFF switch which cuts the power from battery completely.
Also, I added Power distribution to the same PCB to make assembly easier.
I have added 6 motor connection each motor line can stand 60 A
2 x Battery connection with two different voltage / current measurement. I used two Hall sensor, one for each battery, to get the precise battery reading.
Added 2 separate 5v out to power the pixhawk / Cube autopilots.
12 V out and connector for ON/OFF switch.
Will be available in Dronee Store soon
But still I have a question: is it really necessary to have a switch? Isn’t a resistor or a electronic spark protection enough and isn’t a switch another source of errors?
Another thing, I wonder if it would be good to place some isolation between the minus and plus poles, if something ever accidentally bridges those contacts the whole thing will melt down.
Switch is not just to prevent from spark, it is also usefull when you just want to turn on the drone without removing the battery each time, it is like a car key switch. Switch doesnt add point off failure if the hardware designed correctly.about contacts, i spend a lot of time to look for plastic covered connectors, simply, they make the board almost 2 times bigger. On first version i use these metal high current connectors. Movable plastic cover i will add to the case , after installing cables to put the plastic cover over it to provent from shorts, good idea thanks Tobias
Did you calculated the inrush current (the one that causes the spark) and designed the switch to withstand it ? The resistors in the anti spark connectors have a well defined role to limit inrush current. It can be multiple times of the max current of the system.
I think spark comes from the big capacitors on ESCs , but the main reason of the ON/OFF switch is not the prevention from spark. As i am a drone user, i dont want to unplugh the battery each time. Maybe you might not need this switch, i saw a need for myself i think there many other users need this ON / OFF switch on their drone. There is no any electronics deveice without on/off switch.
Artem, please do not misunderstand me. I really appreciate your work, and like the product. But like to pinpoint, that there are certain design elements that need to be take care when you design such a switch, one of them is the inrush current caused by the big capacitors on the ESC’s. If those capacitors are discharged when you switch on your drone, they act like a short circuit for the battery, which means that for a small amount of time it put a load to the batteries that only limited by the internal resistance of the batteries. (It can be many hundreds of amps). If the FET’s in your switch is not designed to handle such load then they will eventually fail, if lucky during switch on, if unlucky then during flight.
And a switch is risky, because it is easier to turn the vehicle on and off. An unplugged lipo does not get plugged in by accident. A switch can be bumped or misinterpreted.
I use an XT60 connector as a breaker in the plus lead from the battery to the system on my rover. It is clearly visible, can not be switched on by accident and the contacts can take the current.
For switch I used 4 mosfets in parallel // SQM40031EL_GE3
Each mosfet has peak current 300A so in total they can hold 1200 peak current
Even continuous drain current for each 120A // I used 4 in parallel to get less switch resistance and less heat loss
I’ve been waiting for so long for a safe switch. It would be amazing to switch on / restart my aircraft without undoing canopies and digging to find and unplug leads!
Not interested at all. IMNSHO, using a switch is a VERY BAD idea, for the simple fact that Pixhawk resets battery capacity to 100% each time the power is turned on. This one thing defeats the purpose of the low battery failsafe. Your idea will cause more crashes because people being people are going to forget to change the battery before they fly again…
If you are worried about sparks, AMASS makes XT-90 connectors with built in spark suppression. I use 'em, and they work.
