Battery Master Switch and Cut Off Switch
The battery master switch can be used between the negative battery terminal and ground lead to the car body. This is the most common application for this kind of switch, and only useful when the engine is not running!
This type of connection has no security aspect to stop a rotating engine.
The engine runs on by the output voltage of the alternator!
Basic diagram switching of the negative battery terminal and ground
Battery Master Cut Off Switch (FIA)
To stop a running engine, switching off the main electrical circuit between the positive pool and the starter/alternator must be done. To avoid damage to de alternator (diodes), a keramic resister should be used between alternator B+ and ground, including the cut off ignition between terminal 54/15 and the ignition coil terminal 15.
Therefore you need a modified mainswitch with built-in two secondary switches, see the diagram below.
Diagram battery Master Cut off switch for NSU
Maintenance requirements
It is recommended to check ones a year the positive lead and the ground connection of the battery and all other connecting leads to the car body.
Alternator fitted cars with a very flat battery cannot be pushed or tow started.
There is not enough current available to begin the current generation cycle.
The most important is the starter motor circuit. Ensure that the connections in the main supply lead remain tight, clean and free from corrosion.
Alternator warnings
- Never charge the battery of an alternator fitted car or remove the alternator from the engine, withhout disconnecting the battery earth lead.
- Don't disconnect any charching circuit lead, including battery leads, when the alternator is running.
- Don't run the alternator with any of its leads disconnected.
- Remember that reversing battery polarity will damage alternators.
- Disconnect the battery before attempting any work on the alternator.