48120 - Diode Battery Isolators Series

48120
For vehicles with two batteries, these devices electrically isolate the batteries to prevent the battery with the higher charge from draining into that with the lower charge. In addition, both batteries can be charged simultaneously from one source.

The amp rating of each item is the maximum alternator rating. Most alternators on new vehicles have an integral electronic voltage regulator that requires the use of the 4-stud battery isolator. The small 4th stud is for connection to a circuit switched by the ignition switch. The newer alternators were first introduced by Delco and are therefore sometimes called ‘Delcotron-type alternators’. A 4-stud battery isolator can be used with older pattern alternators (in this case the 4th stud will remain unconnected), but a 3-stud battery isolator cannot be used with the Delcotron-type alternator.

Features

General purpose Battery Isolators for 12-36V DC negative ground systems
Electronic components are embedded to give excellent protection from adverse conditions, such as contamination and vibration
Integral heat sink provides efficient heat dissipation

Per Leg Ratings

Battery isolators have a ‘per leg’ rating which indicates the maximum current it can deliver to either battery. All Littelfuse–Cole Hersee brand battery isolators have a per leg rating equal to half the alternator rating. For example, the 48051 with a rating of 75A has a per leg rating of 37.5A per leg.

Ordering Information

Part Number Amp Notes
48051 75 A Used to isolate medical equipment batteries from vehicle batteries. With Schottky diode, to comply with Federal Spec. KKK-A-1822B
48070 70 A Use with alternators that do not have integral electronic voltage regulator
48090 90 A Use with alternators that do not have integral electronic voltage regulator
48092 90 A For use with Delcotron-type alternators
48120 140 A Use with alternators that do not have integral electronic voltage regulator
48122 140 A For use with Delcotron-type alternators
48160 200 A Use with alternators that do not have integral electronic voltage regulator
48161 250 A Used to isolate medical equipment batteries from vehicle batteries. With Schottky diode, to comply with Federal Spec. KKK-A-1822B
48162 200 A For use with Delcotron-type alternators
Property (Mouseover for details) Value
Description 140 A Battery Isolator
Details Use with Alternators without Integral Electronic Voltage Regulator
Installation Two 9/32 dia holes
Rating 12-36 Vdc Negative Ground Systems
Sealing Fully Sealed
Size 6L x 4-3/16W x 3-11/32H
Terminals Three 5/16 studs

pdf icon Battery Isolators 2D Prints

Battery Isolator Part Numbers: 48092 48122 48162 48080 48070 48090 48120 48160 48051 48161

pdf icon Battery Isolator Wiring Guide for Delcotron Alternators

IF-128