According to their literature, “... Most (not all) CruzPro SARs, including the SAR20
(*2), require that you have a P type(*1) alternator with an external regulator
. If you have an N type alternator, or an alternator with a built-in voltage regulator
it may need to be modified by a competent electrical
installer(*3) to be compatible with a SAR ...”
(*1) Types ‘N’ and ‘P’ differentiate between where the regulation occurs in the Alternator circuitry.
alternator has a set of diodes, called the diode trio, which supply the positive DC potential required for the rotating field current
. The actual regulator switches the negative to achieve the proper field strength to create the desired correct alternator output. The brushes
are not grounded.
alternator is one which one end of the coil which supplies the rotating magnetic field is connected to the negative and the regulator controls the positive side of the coil to regulate the alternator output. One side of the brush will be grounded.
ie: Yanmar alternators (AKA Hitachi alternators) are N type and are internally regulated. Many after market regulators are P type. For a N type alternator to work it must be modified.
*2 From CruzPro: http://www.cruzpro.com/sreg.html
: “Drive Capability: P type alternators up to 160 amps (8 amp maximum field winding current).”
(Manual Alternator Controller/Alarm) handles P and N type alternators to 160 amps... “
*3 Usually an Alternator Shop is the best choice for converting from N-Type to P-Type, though a talented amateur can DIY. I always gave this job to my Alternator Shop (about $75 with a 'tune-up'), and don’t recommend this as a DIY project
To convert to “P-Type”, disconnect both brushes
, reconnect 1 brush to ground, connect a new wire to the other brush, and lead the new wire outside the alternator case. Label new wire “Field Type-P”, or simply “F”.
Converting “N“ Field Alternator to “P“ Field External Regulation”