Do not attempt to modify the current limit unless you fully understand what you sre doing and are proficient to do so. Modified controllers are unlikely to be accepted for repair by the factory.
There is a position on the Uni series controllers where an additional resistor can be added to reduce the current limit from its factory setting. This resistor is indicated in the diagram below as 'C/L adjust'. It is on the left hand side of the diagram.
To engage this resistor a scratch through track is present beneath the resistor (on the underside of the board). The track shorts out this resistor and must be scratched through to break it or the extra resistor will have no effect.
The graph below shows the typical shape of the motor current limit per MOSFET, plotted against the value of this additional resistor. MOSFETs used change from time to time and current limit component values change with them so the values here are illustrative only.
The Uni-4 has one drive MOSFET: the currents are correct for this controller. The Uni 8 has two drive MOSFETs, so currents will be double that shown in the graph.
There is no point in trying to be too exact with the expected current as electronic components are subject to normal manufacturing tolerances. However you will see from the graph that standard value resistors will give approximately the following results:
| 220K | Zero current |
| 150K | 11 amps |
| 100K | 22 amps |
| 68K | 30 amps |
| 47K | 36 amps |
| 33K | 40 amps |
Remember that as MOSFETs get hot, the current limit will decrease, so at higher currents you may get less current than the theoretical value.
The above graph and figures were based on MOSFETs having an Rds(on) of 14 milliohms. MOSFETs are still improving and as their Rds(on) reduces, these currents will increase, so treat these figures as a guide only. We make no guarantees about the values of MOSFETs used in your controller!