Battery; Precautions; Recommended Battery; Operating Engine Without Battery - Mercury 45 Jet 50-55 Service Manual

Battery

Precautions

When charging batteries, an explosive gas mixture forms
in each cell. A portion of this gas escapes thru holes in vent
plugs and may form an explosive atmosphere around bat-
tery if ventilation is poor. This explosive gas may remain in
or around 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 be-
cause 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 con-
nections are a common cause of electrical arcs which
cause explosions.
3. DO NOT reverse polarity of battery cables on battery
terminals.
CAUTION
!
If battery acid comes into contact with skin or eyes,
wash skin immediately with a mild soap. Flush eyes
with water immediately and see a doctor.

Recommended Battery

The 2-cycle Outboard type engine requires a 12 volt bat-
tery with a "Cold Cranking Amperage" rating for cranking
and a "Reserve Capacity" rating. The minimum should be
a "Cold Cranking Amperage" of 350 amperes and a "Re-
serve Capacity" of 100 minutes for engines outlined in this
manual.

Operating Engine Without Battery

If desired (or in an emergency), engines equipped with an
alternator can be started and operated without a battery
(either disconnected or removed) if "Warning", below, is fol-
lowed.
WARNING
!
Before operating engine with battery leads discon-
nected from battery, disconnect stator leads (yellow)
from rectifier. Insulate (tape) stator lead ring terminals.
90-817643R1 DECEMBER 1996

Specific Gravity Readings

Use a hydrometer (a) to measure specific gravity of electro-
lyte in each cell.
Hydrometer measures percentage of sulfuric acid in bat-
tery electrolyte in terms of specific gravity. As a battery
drops from a charged to a discharged condition, acid
leaves the solution and chemically combines with the
plates, causing a decrease in specific gravity of electrolyte.
An indication of concentration of electrolyte is obtained
with a hydrometer.
When using a hydrometer, observe the following points:
1. Hydrometer must be clean (inside and out) to insure an
accurate reading.
2. Never take hydrometer readings immediately after wa-
ter has been added. Water must be thoroughly mixed
with electrolyte by charging for at least 15 minutes at
a rate high enough to cause vigorous gassing.
3. If hydrometer has built-in thermometer, draw liquid in
several times to ensure correct temperature before
taking reading.
4. Hold hydrometer vertically and draw in just enough liq-
uid from battery cell so that float is free-floating. Hold
hydrometer at eye level so that float is vertical and free
of outer tube, then take reading at surface of liquid. Dis-
regard curvature where liquid rises against float stem
due to capillary action.
5. Avoid dropping electrolyte on boat or clothing, as it is
extremely corrosive. Wash off immediately with baking
soda solution.
a
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ELECTRICAL and IGNITION - 2B-1