MJM Yachts 29z Outboard - Manual (Page 23)

CHAPTER 6 ELECTRICAL SYSTEM
- 23 - 29z
6.1 GENERAL
The 29z’s electrical system is probably more advanced than what you may be accustomed to. It
combines DC and may include optional AC power. An understanding of how the system works
will aid you in your ownership.
12 volt DC power is stored in your batteries. This power is replenished either by an engine-driven
alternator or by a battery charger converting AC power to DC power. Most of the electrical
components on your boat use DC power.
120 volt AC power is what is typically found in homes. It is supplied to the boat in 3 ways: (1) via
an optional shore-power cord plugged into a shoreside receptacle (2) by the optional generator
running onboard (3) by inverting DC power from a battery into AC power. The AC components
aboard your boat include the cooktop, microwave, flat-screen TV, air-conditioning, AC water
heater, inverter, and receptacles (for use with your own AC equipment).
Both AC and DC electrical power sources are potentially dangerous. Do
not attempt to work on any part of your boat’s electrical system if you are not a qualified
marine electrician.
6.2 DC SYSTEM
There are two battery banks on your boat. The house bank consists of (1) one or two (option)
200Ah, absorbed-glass mat (AGM) batteries. The engine bank consists of a single 105Ah AGM
battery, and it is used to start the engine and also to run the optional windlass and bow-thruster.
Whenever a charging source is present (either from the battery charger or an engine-driven
alternator) both banks are automatically charged. AGM batteries are essentially no-maintenance.
Do not attempt to open the batteries. Other than keeping them properly charged, stored, and
clean (especially between the terminals), there is virtually nothing you need to do to them. The
battery charger is factory set specifically for AGMs.
MOMENTARY PARALLEL SWITCH This is located under the ignition switch and is used to
combine the capacity of both the house bank and start battery in case the start battery voltage is
low. The spring-loaded parallel switch must be held up while the ignition is turned on.