As to my past comments on upgrading my Headline controller; I first looked at upgrading the FET’s to higher current, lower RDSon versions but soon realised that they were pretty darn good already -and expensive, $12 each! If they weren’t already large TO-247 package devices I might have upgraded from TO-220>TO-247 for the reduced junction to casing thermal resistance and higher current ratings, but of course there was nothing to gain here. Based on my guesstimate of the casing’s thermal mass and heat dissipation, the datasheet suggests the standard MOSFETS are capable of more pulsed current than the controller is rated for so what I did was lower the resistance of the power shunt from the standard 15milliohm down to 10milliohm resulting in a theoretical 50% increase in current switching. I did this by soldering a 30milliohm 5W resistor in parallel with the existing three. This tricks the microcontroller into thinking it hasn’t reached the maximum current limit which according to GGoodrum is 55A (I haven’t yet installed my Cycle Analyst so haven’t measured it myself). Together with this, I also flooded the enamel free sections of the power traces with solder to bolster their current carrying capacity. Visually, I considered these PCB traces the weakest link in terms of resistance between the battery pack and the motor. How much this is helping I don’t know, but I guess every little bit helps. Oh and I also swapped out the 10AWG wires (50A continuous rating) for 8AWG wire (75A continuous rating) that lead through the casing to the PCB. Theoretically it should now be a 82.5A controller but I will wait until i have some Cycle Analyst data before I start recommending this procedure to others.
By the seat of the pants, the motor now feels more powerful after the controller mods and I haven’t noticed substantially more heat from the casing judging only with my hand. I might even be able to extract more power by lowering the shunt resistance further, but without more sophisticated temperature logging I am reluctant to take the risk.
The standard shunts are mounted between the PCB and the bottom of the casing to take advantage of the thermal transfer/heatsinking which they really do need. To mount a 4th shunt resistor in parallel next to the existing shunt resistors requires an annoying dissassembly of all the clamped FETS and reapplication of thermal grease for reassembly. I did this, but in hindsight it might be easier to install a power resistor heatsinked somewhere convieniently to the side wall of the casing and then flywire high current leads between it and the shunt resistor solder pads (being through hole components they are accessable on both sides of the PCB). However if you want to bolster the PCB traces with solder then you will need to dissassemble everything anyway.
EDIT: I have since discovered that this estimate of a 0.825V shunt threshold is wrong! I have now researched the BLDC controller chip datasheet to discover that it is either 0.5V or 1.23V depending on chip option used. Cyclone appear to use both options in different models of controllers. Either Hitachi ECN3031F or ECN3030F. The following calculations should be reworked with knowledge of chip option used
V = I x R (peak voltage accross the standard shunts = peak controller current x shunt resistance)
V = 55A x 0.015 Ohm = 0.825V across standard shunt resistors
P = I x V (peak dissipated power shared between parallel shunt resistors = peak controller current x shunt voltage)
P = 55A x 0.825V = 45W (each of the 3 standard shunt resistors are only rated at 5W each air cooled

and what a waste of battery power :x )
I = V/R (new peak controller current = microcontroller peak shunt voltage threshold / new total shunt resistance)
I = 0.825V/0.010 Ohm = 82.5A
P = I x V (peak dissipated power shared between parallel shunt resistors = peak controller current x microcontroller shunt voltage threshold)
P = 82.5A x 0.825V = 68W (the newly installed 30milliOhm shunt resistor in parallel with the existing three must dissipate 1/3rd of this power (68W/3 = 22.7W - Hence the need for a high power heatsinkable package)