Battery - Guardian 4700 Repair Manual

Section 5
ENGINE DC CONTROL SYSTEM
1
15
14
J3
J2
J1
Figure 5-2. – Engine Controller Circuit Board
PIN WIRE FUNCTION
1 56 Delivers 12 VDC to Starter Contactor (SC)
while cranking only.
2 90 Delivers 12 VDC to Choke Solenoid coil
while cranking only. (Two seconds ON, Two
seconds OFF)
3 — Not used.
4 18A Grounds Magneto for Shutdown.
5 — Not used.
6 17 To Start-Stop switch. When wire is grounded
by setting Start-Stop switch to "START",
engine will crank.
7 17 To Start-Stop switch on optional Remote
Panel.
8 — Not used.
9 4 Field Boost DC to Voltage Regulator and to
Rotor windings.
10 66 Starter Lockout. Prevents cranking while
engine is running.
11 85 Fault shutdown circuit. When grounded by clo-
sure of High Oil Temperature or Low Oil
Pressure Switch engine will shut down.
12 0 Common Ground.
13 16 12 VDC Input to Field Boost circuit while
cranking only.
14 18 To Start-Stop switch. When grounded by set-
ting Switch to "STOP" engine shuts down.
15 18 To Start-Stop Switch on optional Remote Panel.
Figure 5-3. – Receptacle J1
In addition to the 15-pin receptacle (J1), the circuit
board is equipped with two single pin terminals (J2
and J3). These terminals may be identified as follows:
Page 18
PIN LOCATIONS
J1-1 thru J1-15
15
1. Wire 14 connects to Terminal J2. During cranking and running,
the circuit board delivers battery voltage to the Wire 14 circuit
for the following functions:
a. To operate the electric Fuel Pump (FP).
b. To energize the Fuel Solenoid.
c. To operate the Choke Heater.
d. To the Remote Wire Harness to operate an
hourmeter or a light.
2. Wire 15 connects to Terminal J3. This is the power supply (12
VDC) for the circuit board and the DC control system.

BATTERY

RECOMMENDED BATTERY:
When anticipated ambient temperatures will be con-
sistently above 32° F. (0° C.), use a 12 volts automo-
tive type storage battery rated 70 amp-hours and
capable of delivering at least 400 cold cranking
amperes.
If ambient temperatures will be below 32° (0° C.), use
a 12 volt battery rated 95 amp-hours and having a
cold cranking capacity of 400 amperes.
BATTERY CABLES:
Use of battery cables that are too long or too small in
diameter will result in excessive voltage drop. For
best cold weather starting, voltage drop between the
battery and starter should not exceed 0.12 volt per
100 amperes of cranking current.
Select the battery cables based on total cable length
and prevailing ambient temperature. Generally, the
longer the cable and the colder the weather, the larg-
er the required cable diameter.
The following chart applies:
CABLE LENGTH (IN FEET)
0-10
11-15
16-20
EFFECTS OF TEMPERATURE:
Battery efficiency is greatly reduced by a decreased
electrolyte temperature. Such low temperatures have
a decided numbing effect on the electrochemical
action. Under high discharge rates (such as crank-
ing), battery voltage will drop to much lower values in
cold temperatures than in warmer temperatures. The
freezing point of battery electrolyte fluid is affected by
the state of charge of the electrolyte as indicated
below:
RECOMMENDED CABLE SIZE
No. 2
No. 0
No. 000