SECTION 1
INTRODUCTION AND DESCRIPTION
1.1
The ST-375 (P/N 37512) High Rate Discharge Unit is For testing SLI (Starting, Lighting, Ignition) engine start
batteries. It is used to accept or reject reject 12-Volt engine start batteries which have been fully charged prior to
testing. The ST-375 is designed to work on batteries that have CCA (Cold Cranking Amps) ratings in the
approximate range of 700 CCA to 1,000 CCA. However it will also accurately test batteries with a higher CCA
rating such as those used in large commercial trucks and military tactical vehicles. The unit is essentially an
SAE (Society of Automotive Engineers) tester which places a 375 Ampere load on the battery for a period of 15
seconds. A digital voltmeter on the unit reads and holds the battery voltage at the end of 15 seconds. If the
voltage is at or above 10.0 volts, the battery is ready for issue. If the voltage is below 10.0 volts the battery is
rejected. The battery may be recharged for another test depending on circumstances such as if this were a first
attempt to condition the rejected battery. The ST-375 has a high wattage resistive load bank. The resistors do
not glow during the 15 second test. The control switch has an automatic position which is pressed, released, and
tests for 15 seconds. A manual position can be pressed for less then 15 seconds. An internal 500 Ampere Shunt
has its test terminals (Kelvin Terminals) connected to a pair of test points on the front panel. The voltmeter also
has test points.
1.2 This procedure describes the verification of accuracy of Power Products High rate Discharger Tester P/N
37512. The 37512 being verified is referred to herein as the TI (Test Instrument). The TI operates from the
battery being tested and does not require any other power.
1.3
This procedure includes tests of essential performance parameters only. Any malfunction or out of limit
readings noticed during these procedures, whether specifically tested for or not, should be referred to power
products.
Table 1. Verification Description
TI Characteristics
Performance Specification
Test Method
Voltmeter
Internal shunt and load current
(NOTE: Shunt is 500Amp.
50 Millivolt)
2 internal timers. Timer 1
holds the voltmeter reading at
the end of 15 second test.
Timer 2 disconnects load 3
seconds after voltage hold (18
seconds total)
Range: 0 to 13 V (Meter range 99.9 V)
Tolerance: 0.2 V
Range: 0 to 38MV/380Amp
Tolerance: 1.0 Millivolts/ 10 Amps
Actual load tolerance is 375 Amps ± 10
Amps at 10.5 Volts 10 Seconds of load
(.028 Ohms at 10 Seconds)
TIME: tolerance 2 Seconds
TIME: tolerance 2 Seconds
Connect to battery or power supply, keep
TI power switch OFF. Compare TI
voltmeter reading with multi-meter.
Load the TI with a battery or high current
12 volt power supply. Use external shunt
and 2 multi-meters. Compare TI reading
with one multi-meter and with external
shunt and second multi-meter.
NOTE: Amp reading is 10X millivolt
reading
Check with Quartz stop-watch or timer.
Check with Quartz stop-watch or timer.
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