I hope there are still some active X4 users 
.
I have recently purchased an unused X4 from Paul. I am now having two custom-made batteries assembled by a Chinese manufacturer (two 14S 45000mAh, to be plugged in parallel). The batteries are “semi-solid” lipos with high energy density, typically equipped with 6 AWG wire and an AS150U connector. They told me that for XT150, they need to step down to an 8 AWG wire, as 6 AWG is too thick to fit the XT150.
What I am wondering is, the X4 has a single plus and minus male connector sticking out of the frame. Looking at it, the wire must be 8 AWG, I believe. In your experience, has 8 AWG always been sufficient to draw the required amperage for takeoff and climb? Should I consider swapping the wires on the X4 that lead to the main switch for thicker ones? Or would it be overkill?
Regarding lipo batteries, I only have experience with much smaller currents from the RC world… Similar topics were discussed in this forum in the past, but a long time ago, and things may have evolved since then. Thanks for your suggestions!
8 AWG is fine but you need an anti-spark connector. Without it the arcing will damage the connector and degrade the connection. QS-8 Or equivalent would be good.
Hello, many thanks for your useful comment. I will be connecting the batteries through a Y parallel cable. So I assume it will be sufficient to have the anti-spark connector on the side of the Y cable connecting to the X4? (and on the X4 wires, of course). Or would the anti-sparks better be on each battery and the Y-cable (if the Y cable is connected to the X4 first)?
Also, I assume the QS-8 would not fit the charger I am getting, it has an AS150U plug, for which I already got the 150XT adapter for the batteries…
The anti-spark needs to be the connection that closes the circuit. If you connect the batteries to the Y cable first, the circuit will still be open. Then when you connect the Y cable to the machine, that will close the circuit and create a rush of current. The Resistor in the QS-8 will slow down the rush of current and minimize the arcing. Note: you need to plug in the QS-8 slowly because the first few millimeters at the tip of the connector will run the power through the built in resistor, then when you seat the connector all the way it will bypass the resistor so that it doesn’t burn up durning operation.
With what I described above, the switch will need to remain on (or be removed), otherwise the switch will be the mechanism that closes the circuit and the arcing will occur inside the switch. So you need to either use the QS-8 instead of the switch or add a resistor to the switch. Here is a link to my solution back in the day.
Another option is a button the you press while activating the switch. Here is a link showing that idea. I recommend a 22ohm resistor instead of 100ohm as shown in this link:
Thanks. Yes, meanwhile, I figured out the same thing: the switch should be on to avoid arcing inside it, cables should be slowly inserted to give the resistor time to charge the capacitors, and the anti-spark connector must be the last one to close the circuit. So, if I put the QS-8 between the Y cable and X4, it will be fine, as long as it is the last connection to be made.
I will read through the shared link - thanks for it. There were many of these older X4 posts to skim through, and I did not find it before.