3. ALTERNATORS: Modification to the charging system
is not permitted. The alternator must be charging at all times.
No switches disconnecting the alternator are permitted.
The engine must continue to run at an idle with the battery
disconnected.
6. BATTERY: Only a lead acid or gel cell battery ( 25lbs.
min.) may be used. The approximate dimensions are 71/8â€
X 8 X 61/2â€. A top post or side post battery may be used.
Motorcycle batteries may not be used. The battery must
remain in its stock location and securely mounted. The
original stock battery bracket may not be altered in any way.
A battery box, terminal coverings or rubber padding around
rear end is also highly recommended. A battery shut-off
switch is optional.
I believe the actual tech operation for the alternator rule is to start the car then pull off a battery cable. If you are not bypassing the alternator the car will continue to run. On the otherhand, the battery cut off switch is a safety system to shut down the entire electrical system in case of an emergency.
Link to simple wiring diagram:
http://www.hmsmotorsport.com/docs/Battery_Disconnect_Instructions.pdf