How Long Will Boat Battery Last Without Alternator?

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The word ‘boat’ and ‘alternator’ feels oddly placed, doesn’t it? It’s far more usual to see the word ‘alternator’ in the same sentence with the word ‘car’ compared to seeing ‘boat’ and ‘alternator’ together.

But regardless, cars are not the only machines that use alternators and a boat is one of those machines that rely on an alternator to function properly, now imagine your boat without an alternator, how long will the boat battery last without an alternator? 

 How long your boat battery will last without an alternator fully depends on the rating of the marine battery in terms of RC, you might be wondering ‘What is reserve capacity?’ 

Well, Reserve Capacity, (RC), is a battery industry rating, it defines a battery’s capacity to fuel a vehicle with a non-functioning alternator or fan belt.

Simply put, this rating is the number of seconds a battery at 80 degrees F can be ousted at 25 amps and retain a voltage of 10.5 volts for a 12-volt battery, and the higher the reserve rating on that battery, the longer your vehicle can run should your alternator or fan belt fail.

Table Of Contents

How does a boat alternator work?

Alternators use magnetism to produce electricity, and by moving current through a cable, it creates a magnetic field around the wire; Moving a wire through a magnetic field creates current flow in the wire.

The alternator produces electricity by swirling a magnetic field in the rotor around a circle of stationary copper windings called the stator. The amperage produced is selected by the power of the magnetic field.

The result produced by the alternator is curbed by the field wire that modifies the current to the magnetic field found inside the rotor. One amp of field current will about produce 30 amps of output current on the stator.(Read Also:Can A Bad Ground Cause An Alternator To Overcharge?)

What’s a boat stator?

A stator is just a generator on earlier model boats/outboards, or a stator could essentially just be the alternator on later models, it would play all roles modern-day alternators play in new boat models. 

What does a stator on a boat do?

A stator is a segment on an engine that is connected under the flywheel of the engine. A stator can also be the component that creates the charging power for your boat’s batteries.

If the stator fails, you should worry because then you won’t be able to be charging your boat’s batteries while you are running, yes, it’s that useful and very required. The only goal of the boat stator is to replenish the energy needed to run the ignition system on an outboard boat engine and if the stator can’t do that, then your battery is doomed.

What are the symptoms of a bad stator on an outboard?

 Now we know a battery’s stator is very essential, now how would you be able to tell if your battery stator is failing? Well, since the stator is the main power to generate the power needed by the engine to run, and the outboard has only one or two smaller cylinders.

If your stator fails, your boat fails too, it will not even be able to start and run! If your boat isn’t turning on, it might be a sign you’re dealing with a failed stator, do note; Larger engines have four, six, or eight cylinders.

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Can a stator be repaired?

 If your stator gets bad, you can always repair it, not personally, but a failed stator is repairable, but it is time-consuming because fixing a stator usually involves slowly unwinding, and cleaning the primary stator core, before rewinding it with a device or carefully by hand.

This process consumes a lot of time, and you have not even started yet, you start with looking at the coil heads for damaged or burned wires, then cutting out the protective rubber coating from damaged coils, it’s a very extensive process of trying to repair your failed stator.(Read Also:Will An Alternator Work Spinning Backward?)

What’s the difference between a sailboat and a car?

 We’ve talked a lot now about statues, and the rest, now let’s only talk about boats; Sailboats, what’s the difference between a sailboat and a car? Most sailboats have larger battery banks and a car has smaller battery banks because cars do not require as much energy as boats do. 

What’s the difference between a marine battery and a regular battery?

Car batteries are designed to only deliver concentrated bursts of power to crank over and start the engine… Marine (boat), batteries must not only have the starting power to crank over high compression engines, but they also provide the stored capacity needed to run onboard accessories.(Read Also:Can You Spray An Alternator With WD40?)

What is special about a marine battery?

Marine units are designed to have thicker internal lead plates than their automobile counterparts, which allow them to expel energy over a longer period…

Finally, you can identify a marine battery by its use of “marine cranking amps,” or MCA rating, instead of the basic automobile “cold cranking amps” (CCA)

Do you need a battery to start a boat?

 Yes you do, without a battery, your boat won’t function, and some boat engines do not need much power to start, some people use their car batteries to power their boats, and other boat batteries are fire-breathing monsters, they require the power of multiple batteries to turn over, most boats use the same battery that starts the engine to power accessories, like, showers, stereos, and other electrical accessories.

Do you really need a marine battery for your boat?

 Marine batteries are manufactured to crank over an engine, and they are also required to supply energy for lighting, pumps, sound systems, and anything else that might be essential for convenience or protection while out on the water, so yes you need a battery. (Read Also:How Much Voltage Is Too Much From An Alternator?)

What kind of battery should you put in your boat?

Most boats use 12-volt lead-acid batteries. But, if your boat uses 6-volt, 8-volt, or some other type of battery that isn’t 12-volt, you’re not on the wrong side of history.

Can you run a boat without an alternator?

Yes. Most outboards that have electric start, and that were built in the last 20 years, will have either an alternator or a stater that charges the battery when the engine is running. So if your boat lacks an alternator you’re good. (Read Also:Should The Alternator Get Hot?)

How long will a marine battery hold its charge?

How Long Do Boat Batteries Last? Most marine batteries can last anywhere from 2 to 5 years riding on the degree of maintenance you give them. Most batteries come with a one-year warranty, but more expensive batteries might come with up to three years of warranty.

How often should you change your boat battery?

The average life of a boat battery is around 3-4 years, although they can last up to 6 years in the right conditions. To ensure your battery lasts its full lifespan, keep your batteries connected to a maintenance charger to keep it fully charged.

Will outboard run without stator?

The stator coil generates the power for the spark plug and other accessories on small engines Without a stator there would be no spark at all, meaning the engine won’t run. (Read Also:Will A Battery Tender Charge A Low Battery?)


Should I take the batteries out of my boat for the winter?

In the winter, discharged batteries can freeze over. The water inside the battery expands when frozen, and damages the battery and this is the reason why you must remove your boat battery before you put the boat in storage; To prevent it from freezing over in the winter, keep the battery properly charged through the winter

Is it OK to leave batteries in the boat over winter?

A fully charged, the lead-acid battery will survive climates of 75 degrees below zero without freezing. 

If the batteries are removed from the boat, store them in a cool place that does not drop too far below freezing. A basement or garage is a good place to safely, and properly store your boat batteries.

How Long Will Boat Battery Last Without Alternator – Conclusion

How long will your boat battery last without an alternator depends on how fast you run your boat. The faster you drive, the quicker it dies. It also depends on the capacity of the battery. Batteries are like pails of electricity, and big pails hold more juice. The higher your battery capacity, the more energy it can hold and the longer your boat would last.

It also depends on how often you stop and restart your boat; Let’s say every ten minutes you switch off the boat and start it soon after, you’re reducing the time frame in which your battery would last and if you’re not careful enough, you might try to start the boat and it won’t even come on at all.

 Nonetheless, a “good” battery or a new one should run the engine a couple of hours with plenty of reserves given that no other accessories are running, no lights, no stopping and restarting and you apply moderate throttle while driving.

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