Originally Posted by
Blackwidow
Thanks for the feedback! I guess I don't quite understand the power factor issue. If I understood you correctly (certainly not a given) if the issue is not the amount of current I am drawing through the switch but rather the "Input voltage vs the output voltage" i.e. power factor I do not see how installing two switches with just one battery will solve the problem. Isn't the voltage ratio (input vs output) at each switch the same in this scenario?
To answer your second question I am using 5.9V output from the sparkswitch at the recommendation of Gotz Vogelsang. We do not fly the ship at full throttle very often I find 1/2 to 3/4 throttle is plenty. I understood ignition voltages below 5.9 would produce a weak spark to the plugs. Good to know we have some margin there.
Thanks as always for your feedback!
Hi Tom
The power (i.e.heat) the Spark has to dissipate equals the current draw times the voltage drop. So for example if you have a fresh 2 cell lithium ion battery at 8.4V and a 5.9V Spark switch, with 1 amp draw you will dissipate 1 x (8.4-5.9) = 2.5 watts. At 2 amps it is 5 watts but if you use two switches each Spark is only dissipating 2.5 watts each.
If you were running a LiFePO4 battery at 6.6V, then at the same 1 amp current the power is only 1 x (6.6-5.9) = 0.7 watt. Nearly 1/4 the power/heat for the same current draw. I hope this helps rather than confuse.
I respect Gotz's opinion as he has helped me quite a few times with Moki but I can confirm that 5.9V is too much for the old top hat ignition at full RPM. I have tested this with a couple of the old ignitions. They were designed for a 4 cell 4.8V NiCad battery and I found 5.3V gives plenty of spark and you can run full RPM all day without the ignition getting too hot.