Charging A Discharged Battery; Winter Storage Of Batteries - Mercury 15XD Service Manual

BATTERY CHARGING AND STARTING SYSTEMS

Charging A Discharged Battery

The following basic rules apply to any battery charging situation:
1. Any battery may be charged at any rate (in amperes) as long as spilling of electrolyte
(from violent gassing) does not occur and as long as electrolyte temperature does not
exceed 125°F (52°C). If spewing of electrolyte occurs, or if electrolyte temperature
exceeds 125°F, charging rate (in amperes) must be reduced or temporarily halted to
avoid damage to the battery.
2. Battery is fully charged when, over a 2-hour period at a low charging rate (in amperes),
all cells are gassing freely (not spewing liquid electrolyte), and no change in specific
gravity occurs. Full charge specific gravity is 1.260-1.275, corrected for electrolyte
temperature with electrolyte level at 3/16"(4.8mm) over plate. For most satisfactory
charging, lower charging rates in amperes are recommended.
3. If, after prolonged charging, specific gravity of at least 1.230 on all cells cannot be
reached, battery is not in optimum condition and will not provide optimum perform-
ance; however, it may continue to provide additional service, if it has performed satis-
factorily in the past.
4. To check battery voltage while cranking engine with electric starter motor, place RED
(+) lead of tester on POSITIVE (+) battery terminal and BLACK (--) lead of tester on
NEGATIVE (--) battery terminal. If the voltage drops below 9-1/2 volts while cranking,
the battery is weak and should be recharged or replaced.

Winter Storage of Batteries

Battery companies are not responsible for battery damage, either in winter storage or in
dealer stock, if the following instructions are not observed:
1. Remove battery from its installation as soon as possible and remove all grease, sul-
fate and dirt from top surface by running water over top of battery. Be sure, however,
that vent caps are tight beforehand and blow off all excess water thoroughly with com-
pressed air. Check water level, making sure that plates are covered.
2. When adding distilled water to battery, be extremely careful not to fill more than 3/16"
(4.8mm) over plate inside battery. Battery solution or electrolyte expands from heat
caused by charging. Overfilling battery will cause electrolyte to overflow (if filled be-
yond 3/16"over plate).
3. Grease terminal bolts well with Quicksilver 2-4-C Marine Lubricant, and store battery
in COOL-DRY place. Remove battery from storage every 30-45 days, check water
level (add water if necessary), and put on charge for 5 or 6 hours at 6 amperes. DO
NOT FAST CHARGE.
4. If specific gravity drops below 1.240, check battery for reason, and then recharge.
When gravity reaches 1.260, discontinue charging. To check specific gravity, use a
hydrometer, which can be purchased locally.
5. Repeat preceding charging procedure every 30-45 days, as long as battery is in stor-
age. When ready to place battery back in service, remove excess grease from termi-
nals (a small amount is desirable on terminals at all times), recharge again as neces-
sary and re-install battery.
Hydrogen and oxygen gases are produced during normal battery operation or
charging. Sparks or flame can cause this mixture to ignite and explode, if they are
brought near the battery. Sulfuric acid in battery can cause serious burns, if
spilled on skin or in eyes. Flush or wash away immediately with clear water.
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WARNING
90-826883R2 JUNE 1998