Installation to model
The most important rule covering battery ignition systems first:
Never ever switch the system on without the spark plug cap being on the spark plug!
Keep all parts of the battery ignition as far as possible from the receiver, minimum distance being 25 cm.
The microprocessor Ignition is protected with a tough metal case and the electronics inside are encapsulated to protect against vibration. In spite of this it is not a good idea to simply mount the ignition box onto the firewall with a couple of cable ties.
Please fit the cables very carefully into your model, especially the high tension cable, as this will not contain the 21,000 volts if it is damaged due to scuffing against the cowl inner surface. If the screening flex is damaged due to scuffing when threaded through a GRP cowl opening, it will not be long before the inner insulation is damaged also. Then the HT will short out to the screening flex and this may cause massive radio interference and will of course lead to an ignition cutout.
Mechanical damage caused to the HT cable is not covered by the guarantee!
Take care with plugging together the JR-plugs and sockets by noting that the colours should line up on opposite sides. It is possible with a little extra effort to push these together with reverse polarity. No damage will be done but the ignition will of course be dead. I tape these plugs and sockets with insulation tape for additional safety.
Use only knife edge contact switches such as the Graupner receiver cable with charger socket order no. 3046. Toggle switches with roller contacts are not suitable as these are intended for 240 V. Used on 6 V, oxidation can occur, this increases the contact resistance and will lead to ignition failure.
The battery should be either a 4 cell NiCd or NiMH type with 1000 mAh capacity at least. More capacity will certainly do no harm. The power consumption is dependant on the rpm. At 2,000 rpm the ignition unit draws 200 mA, at 8,000 rpm it is 680 mA. Under normal conditions, you will not fly at full throttle the whole time, so a 1400 mAh battery, that is carefully managed, will suffice for two hours with safety. Using a 5,5 V linear voltage controller, like the "Digi-Switch" , you can also use twin cell Lipos.
The text comes from Toni Clark practical scale GmbH