The manual says:

the maximum energy transfer is 4096 Flux/tick for a single-phase coil and 8 times as much on the four-phase version.

and also, for electrodes:

The maximum energy transfer rates match those of the corresponding coils, but is split equally between the connections.

However, these numbers do not seem to be correct. In reality, MechPartTwoElectrodes.getMaxBuffer and MechPartSingleCoil are hardcoded at 10,000 joules, which is a variable number of flux depending on config file settings but, with the default joules-per-flux ratio, is 470 flux for the single-phase electrode or 3760 for the four-phase electrode, or almost 9× smaller than it should be according to the manual.