Alternators not charging house battery

[Helmsman]

I have a Carver 33 SS 2006 with four batteries. Two engine starters, one house battery, and one generator battery. Connected to shore power, all batteries charge. Running the gennie also successfully charges all the batteries. While underway, the engines are not successfully charging the house battery though the voltmeters for both engines are showing charging at 13 or 14 volts.

I say that because after being underway for 6 or 7 hours the CO monitors beep indicating a low battery charge, and the chart plotter, etc. turns off. Running the gennie re-charges the house battery eventually. Also, as soon as the gennie is on the CO monitors stop beeping and the chart plotter and other instruments are up and running again.

I installed an AGM battery for the house a year ago, when the house battery that was installed failed. The other three battery are conventional wet cell batteries. Any idea about how to go about checking for charge to the house battery from the engines?

[tomschauer]

Others may be able to offer more info on your particular battery configuration, but I believe the engine(s) will only charge the selected batteries(via battery selector switch) The charger should have direct leads to each battery thus always charging all batteries when energized. A quick check would be to put a volt meter directly on the house battery terminal with the charger off and engines off you should show about 12 - 13 volts. With the charger off and engine(s) on if charge is going to house battery you should see 13-14.4 volts depending on battery charge and engine rpm. The voltage should move towards the 14.4 if you increase rpm.

[tomschauer]

PS. when the genny runs it is powering up your battery charger to charge the house and start batteries, it doesn't directly charge any battery other than its own.

[Samuel]

DC ELECTRICAL SYSTEM SECTION 2
DC Electrical System
Your boat is equipped with a 12-volt DC (Direct Current) electrical system.
Th is is a comprehensive system that is designed to meet your present and future
12-volt electrical needs. Wire-runs and connections are positioned to prevent
abrasion and exposure to moisture, as well as to remain accessible for inspection,
repairs, and the addition of aftermarket electrical accessories.
Wires used throughout the DC electrical system are plastic-coated and colorcoded.
Connections are made using crimped connector points. Th e electrical
system is virtually maintenance free, with only the batteries requiring periodic
inspection and maintenance.
Batteries
Th e DC electrical system is divided into three areas, each powered by one or
more 12-volt batteries:
• Engines (two batteries - one for each engine)
• “House” (one battery)
• Generator (one battery)
Engine Batteries
Each propulsion engine has its own dedicated battery. Th ese batteries are
located in the aft bilge: the port engine battery is directly beneath the port
cockpit hatch; the starboard engine battery is directly beneath the starboard
cockpit hatch.
Electricity from each battery to its engine is controlled by a master disconnect
switch. Th ese switches are located in the engine room on a horizontal panel
on the aft centerline. To provide electricity to the engines, turn the master
disconnect switches to the “ON” position.
Refer to Section 9 - Hatches and/or Engine Room for the exact location of the
engine batteries and their master disconnect switches.
“House” Battery
Th e equipment controlled by the three DC circuit breaker panels (Safety
Breaker Panel, DC Control Center and Bridge Breaker Panel) is powered by
a single battery. Th is battery is located in the aft bilge, directly beneath the
starboard cockpit hatch.
Electricity from the battery to the boat’s various DC circuit breaker panels
is controlled by a master disconnect switch. Th is switch is located on the
Safety Breaker Panel, which is located in a cabinet in the inboard end of the
galley counter. To provide electricity to these breaker panels, turn the master
disconnect switch to the “ON” position.
Refer to Section 9 - Hatches and Section 2 - Safety Breaker Panel for the exact
locations of the “house” battery and its master disconnect switch.
16 3327 • 33 Super Sport 9/05
DC ELECTRICAL SYSTEM SECTION 2
Generator Battery
Th e generator has its own dedicated battery. Th is battery is located in the aft
bilge, directly beneath the port cockpit hatch.
Electricity from the battery to the generator starter is controlled by a master
disconnect switch. Th is switch is located next to the port forward corner of
the generator. To provide electricity to the generator starter, turn the master
disconnect switch to the “ON” position.
Refer to Section 9 - Hatches for the exact location of the generator battery and
its master disconnect switch.
Monitoring Battery Voltage Levels
You can determine the voltage level of each engine battery by activating the
battery’s dedicated voltmeter. Th e voltmeters are located with the other engine
gauges at the helm. To activate each engine’s voltmeter, turn the engine’s ignition
key one position to the right.
Carefully follow the procedures described in Section 5 before
starting your boat’s engines. Improper starting procedures can create
hazardous situations.
NOTE: You do not need to start the engine to activate its voltmeter. Refer to the
OEM information for details on operating the engines.
A fully charged battery that has not been charged or discharged for at least two
hours should indicate between 12.3 and 12.6 volts. A reading below this level
indicates a partly discharged battery.
Charging the Batteries While the engines are running, their alternators generally supply enough power
to replace the power used by the boat’s 12-volt equipment.
Without an engine running, however, the 12-volt equipment will eventually
drain the batteries they are using. If this occurs, either start the engines or use
the onboard battery charger to recharge the batteries.
Never allow the boat’s batteries to become completely discharged.
Completely discharging a battery can damage it to the point that it
can no longer be recharged. The battery chargers should always be
operating when your boat is connected to shore power. If you leave
your boat for an extended period of time and the boat is not connected
to shore power, turn all battery master disconnect switches to the
“OFF” position.
Your boat is equipped with two battery chargers: one for the engine and “house”
batteries and one for the generator battery.
3327 • 33 Super Sport 9/05 17
DC ELECTRICAL SYSTEM SECTION 2
Engine / “House” Battery Charger
Th e voltage levels of both the engine and “house” batteries are monitored and
maintained by a single battery charger.
To operate the battery charger:
1. Provide AC power to the boat, from either a shore power source or the
generator. Refer to Section 3 - Shore Power and/or Generator Power for
more information.
2. On the AC Control Center, switch the Battery Charger 1 circuit breaker
“ON.” Refer to Section 3 - Battery Charger for more information. Th e engine
/ “house” battery charger now automatically charges the engine and “house”
batteries when their voltage drops below a predetermined level.
Th e engine / “house” battery charger is located in the engine room on the port
forward bulkhead. Refer to Section 9 - Engine Room for the exact location of
this battery charger.
Generator Battery Charger
Th e voltage level of the generator battery is monitored and maintained by
a single battery charger. Th e voltage level of the generator battery is also
maintained by the generator’s alternator whenever the generator is operating.
To operate the battery charger:
1. Provide AC power to the boat, from either a shore power source or the
generator. Refer to Section 3 - Shore Power and/or Generator Power for
more information.
2. On the AC Control Center, switch the Battery Charger 2 circuit breaker
“ON.” Refer to Section 3 - Battery Charger for more information. Th e
generator battery charger now automatically charges the generator battery
when its voltage drops below a predetermined level.
Th e generator battery charger is located in the engine room on the port forward
bulkhead. Refer to Section 9 - Engine Room for the exact location of this
battery charger.
Battery Maintenance
If you spill electrolyte:
1. Ventilate the area of the spill.
2. Neutralize the acid in the electrolyte by pouring baking soda on the spill.
3. Remove the neutralized electrolyte using a disposable rag or paper towel.
The batteries contain electrolyte which is an acid. Wear gloves and
protective eyewear when working on and around the batteries.
When servicing the batteries avoid spilling electrolyte into the
engine room or bilge. Also, avoid getting any salt water in or on the
battery. Either of these conditions can create a poisonous gas that is
harmful if inhaled.
18 3327 • 33 Super Sport 9/05
DC ELECTRICAL SYSTEM SECTION 2
While the batteries are relatively maintenance-free, there are a few things you
can do to increase their eff ectiveness and life:
• Keep your batteries fully charged. Batteries that are kept fully or near fully
charged last longer than batteries stored with a partial charge. Th e charge
level of the batteries can be monitored using the voltmeters on the helm
instrument panel.
• Inspect the batteries at least once every 30 days.
Disconnect the batteries before cleaning them.
• Periodically clean the battery terminals and cable connections. Remove any
accumulation of dirt on the top of the battery case. Use a wire brush to clean
the terminals. Coating the terminals with a terminal protecting product will
help reduce corrosion that can form in these areas.
• Check that the battery cables are securely attached to the terminal posts.
Tighten the terminal nuts ¼ turn beyond fi nger-tight using a wrench.
• Check the level of electrolyte in each cell of each battery. Th e correct level
is just above the plates. If the fl uid level is low, add DISTILLED water only
until the electrolyte is at the correct level. DO NOT OVERFILL the cells.
• Remove the batteries from the boat during periods of extended storage. Store
your batteries in a cool (above freezing temperature), dry area. All batteries
lose some charge during storage, but the lower the temperature the less charge
is lost. Avoid storing the batteries in a humid place. Humidity causes the
terminals to corrode.
• Check the battery charge level every three months using a hydrometer or
voltmeter. If the specifi c gravity of the battery is less than 1.225 or the voltage
is less than 12.4 volts, charge the battery. Avoid overcharging the batteries.
Operating the 12-Volt Equipment Power to your boat’s 12-volt equipment is controlled by circuit breakers and, in
most cases, individual controls for each piece of equipment.
Your boat contains three 12-volt circuit breaker panels:
• Safety Breaker Panel
• DC Control Center
• Bridge Breaker Panel.
Th e circuit breakers on these panels enable you to control the electricity to
either the equipment itself or to the equipment’s controls by switching
the breakers “ON” or “OFF.” Th ey also protect the electrical system by
automatically disconnecting the circuit from the power source in the event of
a short or overload. Power is supplied to these circuit breaker panels by the
“house” battery.
Th ere are also thermal circuit breakers installed in many circuits to provide
added protection for components in those circuits. Th ese circuit breakers are
located near the master disconnect switches.

[Viper]

There are a few possibilities but it sounds like you have three separate banks;1 per engine, and 1 house, and if that's the case and each bank has an ON/OFF switch rather than a multi selector switch (1/2/ALL/OFF), the two alternators on their own can only charge two banks and still maintain bank isolation. To charge an additional bank, there would have to be an isolator or ACR. It could be that it has failed. Easy enough to check with a volt meter. Of course check all your connections and make sure they are tight and free of corrosion.

[tomschauer]

From the owners manual description, it sounds like the house battery is only charged by the battery charger and receives no charge from either alternator. Maybe Carver figured the genny would be running when underway?
A voltage test as I mentioned above will confirm this.
As viper mentioned you could add an isolator to one or both engine banks to allow the house battery to charge from the alternator(s)

[Midnightsun]

My 1 year younger Carver has the same setup. No combine switches only on/off for each battery. Not exactly sure how it is wired or functions but I know there are at least 2 big factory isolators in the system and yes it charges fine while under way. I would agree with the isolation failure possibility.

[Helmsman]

All good suggestions! My understanding is that it is supposed to charge from the alternators while underway along with the engines. Tomorrow afternoon I will head down to the boat with the voltmeter to check the voltage at the battery with shore power off, engines off vs. engines on. Before that I will trace the wires for a loose connection. As a note, the galvanic isolator was replaced two years ago. Hope that isn’t it!

[Helmsman]

Tom, in Samuels post of the procedures above it indicates that the alternators charge the house battery.

“ Charging the Batteries While the engines are running, their alternators generally supply enough power to replace the power used by the boat’s 12-volt equipment.
Without an engine running, however, the 12-volt equipment will eventually
drain the batteries they are using“

I already have an isolator. One question I still have is does the alternator directly feed the isolator (and on to the three batteries) or does it have an external voltage regulator first. I will have to check that when I attempt to trace wires.

Source of the post From the owners manual description, it sounds like the house battery is only charged by the battery charger and receives no charge from either alternator. Maybe Carver figured the genny would be running when underway?
A voltage test as I mentioned above will confirm this.
As viper mentioned you could add an isolator to one or both engine banks to allow the house battery to charge from the alternator(s)

[tomschauer]

Most isolators have a terminal for the alternator(s) input (to the isolator) and terminals for the battery connections (separate terminal for each battery or bank of batteries). The voltage regulator is built into your alternator.
If you find the make and model of your isolator, you should be able to locate a diagram.