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Charging and Starting System
Recommended Battery
A 12 volt battery with a minimum rating of 465 marine cranking amps (MCA) or 350 cold cranking amps (CCA) is
recommended. For operation below 0 °C (32 °F), a rating of 1000 marine cranking amps (MCA) or 775 cold cranking amps
(CCA) is recommended.
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 any rate (in 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.
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 4.8 mm (3/16 in.) over plate, unless electrolyte loss has occurred (from
age or overfilling), in which case, specific gravity reading will be lower. 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 performance; however, it may continue to provide additional service, if it has
performed satisfactorily in the past.
4.
To check the battery voltage while cranking the engine with an electric starting motor at ambient air temperature of 23.8 °C
(75 °F), place the red (+) lead of the tester on the positive (+) battery terminal and the black (–) lead of the tester on the
negative (–) battery terminal. If the voltage drops below 10‑1/2 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, sulfate, and dirt from the top surface by
running water over top of the battery. Be sure, however, the vent caps are tight beforehand and blow off all excess water
thoroughly with compressed air. Check water level, making sure the plates are covered.
2.
When adding distilled water to the battery, be extremely careful not to fill more than 4.8 mm (3/16 in.) above perforated
baffles inside the battery. Battery solution or electrolyte expands from heat caused by charging. Overfilling the battery will
cause the electrolyte to overflow (if filled beyond 4.8 mm [3/16 in.] above baffles).
3.
Grease terminal bolts with 2‑4‑C with PTFE and store the battery in a cool‑dry place. Remove the battery from storage
every 30–45 days, check the water level, and put on charge for 5 or 6 amps. Do not fast charge.
Page 2B-14
WARNING
!
WARNING
!
© 2016 Mercury Marine
90-8M0105568 eng MARCH 2016
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