6.4 Battery Charging Fuse Modification 30-60
model Tactical Quiet
Generator Sets MEP-
805B, MEP-815B, MEP-806B, MEP-816B
The MEP-805B, MEP-815B, MEP-806B, MEP-816B, models of the Tactical Quiet Generator
(TQG) family of generator sets have a problem with the battery charging fuse. The battery charging fuse
has a high rate of blowing. This requires the soldier to keep many spare fuses on hand for replacements.
A blown fuse caused two problems. The obvious problem is the loss of the ability to charge the batteries.
The more critical problem is the loss of DC control power during mission operations.
The blown battery charging fuse problem is caused by the charging characteristics of the Optima
battery. The Optima batteries have a low internal resistance enabling the battery to receive a higher than
normal charging current. The alternator has a continuous current capacity of 45 Amps, with a peak of 60
Amps. With the Optima battery and this alternator, the battery charging current, at times, can exceed the
maximum current capacity of the fuse therefore the fuse blows. The 6TMF, 6TL, etc., batteries have a
higher internal resistance and will not accept current higher than the current capacity of the fuse. The
solution to this problem is to replace the 30 A fuse and the 18 gauge wire with a 50 A circuit breaker and
a 12 gauge wire. The procedures and materials are described below.
The control power loss problem is caused by the location of the control power circuit take off.
The control power is connected to the battery terminal and not the battery charging alternator. While the
generator set is operating, the battery charging alternator provides the DC control power through battery
charging system. When the fuse blows, the source of generator set DC control power becomes the
batteries until available battery power is consumed. With no DC control power, the generator set shuts
down. There is another set of instructions to move the DC control power wire to the back of the
alternator in order to prevent this failure mode.
The modification below is designed to replace the battery charging fuse circuit with a circuit
breaker and a larger wire. The instructions for the DC control power modification are including as
Paragraph 6.5. Both
of these modifications must
be accomplished in order
to dead batteries. These modification instructions are authority to modify the generator set until the
formal design change documentation is approved and disseminated to the field.
6.4.2 Parts Required:
Source of Supply
Terminal, Lug, 14-16,
0.164 stud size
Terminal, Lug, 14-16,
3/8 stud size
Circuit breaker, 24 V, 50 A
Bracket, Current Transducer
Wire, Electrical, 12AWG
6.4.3 Repair Procedures:
1. Disconnect the batteries in accordance with BATTERY CONNECTION INSTRUCTION PLATE,
figure 1, located in the battery compartment.