Discussion and questions related to the course Practical Harness Construction - Club Level
I have to disagree with the 5amp peak draw in this example. With numerous tests done and having used these coils long before they were a “in” thing to do I have Found the following to allow max dwell and peak output. Using tefzel 16awg for power/ground and only 22awg for logic ground to Ecu and up to 10ms dwell at peak torque and as much as 7ms at 9k rpm we require 30amp fuses for every 4 coils and use relays for each set of 4. This has provided maximum output of them and have yet to have a failure with authentic units. Knock offs can hardly run 5-6ms dwell at peak trq and have much less spark output than oem units.
Thanks for the information William, always good to get more data. I've never had to run the coils as hard as 10ms dwell, that seems like a lot and the internal drivers would possibly be current limiting by then. Have you got any graphs of actual current measurements across the coil primary at 10ms dwell? As I'm sure you know, spark output is proportional to primary winding current, and if you dwell long enough that the coil winding either saturates, or the driver starts current limiting, you're only generating excess heat, no additional spark energy.
On rotary engine you must also note that at 8500rpm at 5ms dwell you are already at upper limit of 70% DC temporarily allowed for IGN-1A
5ms should pull around 6A but because of 70% duty cycle, you are unlikely to see more than 5A effective draw.