Replacement Parts; Battery Precautions; Charging A Discharged Battery - Mercury V6 175 Diagnostic Manual

NOTE: The voltage reading in step 2 is the base voltage. The base voltage reading will be compared to the voltage
readings obtained in the following steps.
3. With the key switch in the "START" position, measure the voltage from the battery positive post (not the cable clamp) to the
starter post (the stud where the battery positive cable is connected). Record the voltage reading.
4. With the key switch in the "START" position, measure the voltage from the starter case to the battery negative post (not the
cable clamp). Record the voltage reading.
5. If the voltage reading in step 3 was more than 1.0 VDC:
a. Check the cable connections for tightness and corrosion.
b. If the cable is tight and not corroded, replace the cable with a larger diameter cable.
6. If the voltage reading in step 4 was more than 1.0 VDC:
a. Check the cable connections for tightness and corrosion.
b. If the cable is tight and not corroded, replace the cable with a larger diameter cable.
Resistance in the cables can cause a voltage drop and limit current to the starter. If corrosion is present, or if the starter is
worn, there may not be enough amperage to turn the starter motor.
NOTE: If the voltage at the starter is less than 11 VDC, the engine may not start.

Replacement Parts

Avoid fire or explosion hazard. Electrical, ignition, and fuel system components on Mercury Marine products comply with
federal and international standards to minimize risk of fire or explosion. Do not use replacement electrical or fuel system
components that do not comply with these standards. When servicing the electrical and fuel systems, properly install and
tighten all components.
IMPORTANT: Deep‑cycle batteries are not suitable for use as engine starting batteries or for use as accessory batteries that
are connected to high output engine charging systems. Deep‑cycle battery life may be shortened by high output engine
charging systems. Refer to individual battery manufacturer instructions for specific battery charging procedures and
applications.

Battery Precautions

An operating or charging battery produces gas that can ignite and explode, spraying out sulfuric acid, which can cause
severe burns. Ventilate the area around the battery and wear protective equipment when handling or servicing batteries.
When charging batteries, an explosive gas mixture forms in each cell. Part of this gas escapes through holes in the vent plugs
and may form an explosive atmosphere around the battery if ventilation is poor. This explosive gas may remain in or around the
battery for several hours after it has been charged. Sparks or flames can ignite this gas and cause an internal explosion, which
may shatter the battery.
The following precautions should be observed to prevent an explosion:
1. Do not smoke near batteries being charged or which have been charged very recently.
2. Do not break live circuits at terminals of batteries, because a spark usually occurs at the point where a live circuit is broken.
Always be careful when connecting or disconnecting cable clamps on chargers. Poor connections are a common cause of
electrical arcs which cause explosions.
3. Do not reverse polarity of battery terminal to cable connections.

Charging a Discharged Battery

An operating or charging battery produces gas that can ignite and explode, spraying out sulfuric acid, which can cause
severe burns. Ventilate the area around the battery and wear protective equipment when handling or servicing batteries.
The following basic rules apply to any battery charging situation:
1. Any battery may be charged at a maximum rate of 10 amperes, or as long as spewing of electrolyte (from violent gassing)
does not occur, and for as long as electrolyte temperature does not exceed 52 °C (125 °F). If spewing of electrolyte occurs,
or if electrolyte temperature exceeds 52 °C (125 °F), charging rate (in amperes) must be reduced or temporarily halted to
avoid damage to the battery.
90-8M0146617 eng JULY 2018
WARNING
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WARNING
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WARNING
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© 2018 Mercury Marine
Charging and Starting System
Page 6B-3