The thing is: The charger that sells FriendlyElec with the board is a copy of the Oneplus Dash charger and maybe for this charger to deliver all the power (nearly 4 amps) needs to have some negotiation between the load and the psu. As far as I know, the oneplus devices dont enter into this mode until something happens in the phone like 1 second after plugging in.
I don't think the charger is delivering this amount of amps but maybe 2'5.
I'll have to test it one of these days.
EDIT: Confirmed, the Dash charger from oneplus complies with a protocol for the 4 amps to be delivered.
This quote is extracted from the post from xda: https://forum.xda-developers.com/oneplus-3/accessories/dash-charge-protocol-analysis-t3431917/post68125991
"The charger waits for a current draw (i didn't bother testing it's thresholds) and then reads/checks-for the E²PROM embedded in the plug of the cable (presumably containing an authentication for dash).
At a similar time the phone sends a kind of "preamble" consisting of high-low transitions of varying lengths (but this doesn't seem to important to the charger, it tries to "dash" even without it).
Afterwards the phone and charger start exchanging 9 bits of data in bursts. One USB-Data-Line is clock, the other one is data. The chargers supplies the clock and the first 9 bits and after a short pause the phone gets to reply with another 9 bits as the charger supplies another "clock-burst".
At the beginning (before dash-charging is in effect), the charger sends 150h and the phone replys with 158h.
Once the phone is ready to begin dash-charging it replys with 178h instead.
The charger then configures it's Step-Down Converter for ~4.5V of output voltage and then sends 148h to the phone.
It either replies with 170h if the voltage is too high or 178h if the voltage is correct (I didn't see a reply for "too low", but it might exist).
If the phone replies 170h the charger lowers the voltage by about 100mV-200mV and "asks" again.
Once the phone replies with 178h the charger stops lowering the voltage and sends 14Ch to which the phone replies with 141h.
During the dash-charging process the charger periodically sends 144h to which the phone replies with a number which seems to roughly coincide with the state of charge (i have seen values from 16Eh to 178h).
The charger seems to nudge-up the voltage every once in a while (presumably when the current dropped below a threshold).
If the battery is relatively full (i tested at 90% charge) the "dash-charging-cycle" doesn't even start and the communication stays at an exchange of 150h/158h data "words".
I did some minor probing on the wall-wart with a stripped USB 3.0 extension and found that it uses the same commands but with the lowest bit set (i.e. it adds 1 to the command codes). Unfortunately the USB 3.0 cable had some internal resistance ruining most of the analog measurements. "
