802.589.0911 Live Chat With Us

Finish Selecting Your Vehicle to Shop For Your Alternator

Choose a Year for your Ford Freestar 's Alternator

  • 2007
  • 2006
  • 2005
  • 2004

Shop By Brand

The Following brands are available based on your search.

  • BBB Industries
    BBB Industries
  • Denso
    Denso
  • MPA
    MPA
  • Remy
    Remy
  • WAI Global
    WAI Global

Shop By Related Alternator Parts

Shop below for all Alternator related parts for your Ford Freestar


Shop for Top Selling Genuine Ford Freestar Alternators

  • We Stock the following top leading brands, including WAI Global, BBB Industries, Denso, MPA, Remy
  • Constantly Updated Inventory of Ford Freestar Replacement Alternator Parts

WAI Global
2007 Ford Freestar Alternator WAI Global

P311-0B75C6C    8408N  New

Qty:
118.79
  • ; 135 Amp (Originally Equipped)
Brand: WAI Global
Additional Fitment Information:
Vehicle
2007 - Ford Freestar
BBB Industries
2005 Ford Freestar Alternator 6 Cyl 3.9L BBB Industries - REMAN ALTERNATOR

P311-1B81090    8408  New

Qty:
$40.00 107.58
BBB Industries Alternator
  • ; Originally Equipped 135 Amps
  • REMAN ALTERNATOR
Brand: BBB Industries
Additional Fitment Information:
Vehicle Block Engine CID CC
2005 - Ford Freestar V 6 Cyl 3.9L 238 -
Denso
2007 Ford Freestar Alternator 6 Cyl 3.9L Denso - Reman Alternator

P311-3626430    210-5361  Remanufactured

15450 , 8310610 , 8310 , 213-3179K , A08408 , 8408 , 3F2U-AA , N8408 , 3F2U-10300-AA , 4F23-AA , 90-02-5157 , 1N-3179K , AL7617X , 4F23AA , 6F2Z-10346-BA , 6F2T-10300-BB , 3F2Z-10346-AA , 23773

Qty:
$34.00 146.95
Denso Alternator
  • Remanufactured DENSO First Time Fit Alternator
  • ; 135 Amp First Time Fit
  • Reman Alternator
  • Product Attributes:
    • Amperage Rating: 135
    • Family: Ford Oe
    • Fan Type: Internal
    • Plug Type: 337
    • Regulator Type: Internal
    • Rotation Direction: Clockwise
    • Voltage: 12.0
  • DENSO alternators are not only original equipment on many of the world's top production cars; they are a favorite in motorsports as well, where their light weight, high efficiency, and durability under the most demanding conditions make them the natural choice. Remanufactured DENSO alternators go through a grueling process. Stators and rectifiers are tested to 300 volts, while rotors are submitted to 600 volts, all to ensure reliable performance. Rotor slip rings are buffed to an 8 micron surface finish, with runout limited to 20 microns, minimizing brush wear and abrasion. Bearings are validated to OE standards and loaded with premium OE standard lubricants. New or remanufactured, a DENSO alternator is a quality component. Offered in versions from 40 to 160 amperes and beyond for hundreds of specific vehicle applications, all alternators meet DENSO's rigorous First Time Fit standards. Contemporary cars employ dozens of sophisticated electronic systems from bumper to bumper, placing heavy demands on the charging system. The alternator is no place to cut corners. DENSO First Time Fit alternators meet or exceed all manufacturer standards, mount properly with a minimum of installation issues, and provide years of reliable service. Features. Premium cores and precise OE assembly benchmarks; Design to meet the grueling heat and electrical requirements; First Time Fit provides perfect mounting with no belt/pulley alignment issues; Benefits. Service professionals preferred DENSO's alternators for a trouble free solution; OE quality fit, appearance, and durability; Full compatibility with sensitive electronics systems; Compact and lightweight design
Brand: Denso
Additional Fitment Information:
Vehicle Block Engine CID CC
2007 - Ford Freestar V 6 Cyl 3.9L 238 -
MPA
2004 Ford Freestar Alternator 6 Cyl 3.9L MPA - Remanufactured

P311-2A07BA9    15450  Remanufactured

334-2652A , 6F2Z-10346-BA , GL-599 , 3F2Z-10346-AA , 3F2U-10300-AA , 6F2Z-10346-BB , 88864873 , 8408

Qty:
$54.00 78.12
MPA Alternator
  • ALTERNATOR-RMFD STDRD
  • Remanufactured
  • Product Attributes:
    • Amps: 135 Amps
    • Clock: 2:30
    • Fan: Internal
    • Manufacturer: Ford
    • Pulley: 6 Groove Serpentine
    • Regulator: Internal
    • Rotation: Clockwise
    • Volts: 12 Volts
Brand: MPA
Additional Fitment Information:
Vehicle Block Engine CID CC
2004 - Ford Freestar V 6 Cyl 3.9L 238 -
MPA
2007 Ford Freestar Alternator 6 Cyl 3.9L MPA - New

P311-179E731    15450N  Remanufactured

88864873 , 8408 , 3F2U-10300-AA

Qty:
218.36
MPA Alternator
  • ALTERNATOR-RMFD STDRD
  • New
  • Product Attributes:
    • Amps: 135 Amps
    • Clock: 2:30
    • Fan: Internal
    • Manufacturer: Ford
    • Pulley: 6 Groove Serpentine
    • Regulator: Internal
    • Rotation: Clockwise
    • Volts: 12 Volts
Brand: MPA
Additional Fitment Information:
Vehicle Block Engine CID CC
2007 - Ford Freestar V 6 Cyl 3.9L 238 -
Remy
2007 Ford Freestar Alternator 6 Cyl 4.2L Remy - Premium; Remanufactured

P311-478E689    23773  Remanufactured

3F2Z-10346-AA , 6F2T-10300-BB , 6F2Z-10346-BA , 3F2U-10300-AA

Qty:
$40.00 101.27
Remy Alternator
  • Premium Remanufactured Alternator
  • ; 135 Amps
  • Premium; Remanufactured
  • Product Attributes:
    • : Remanufactured
    • Amperage Rating: 135
    • Fan Type: Internal
    • One Wire Capable: No
    • Plug Clock Rear View Main Mounting Ear at 6 O Clock: 2
    • Pulley Belt Type: Serpentine
    • Pulley Groove Quantity: 6
    • Pulley Included: Yes
    • Pulley Outside Diameter: 65.0
    • Regulator Type: Internal
    • Rotation Direction: Clockwise
    • Voltage: 12.0
Brand: Remy
Additional Fitment Information:
Vehicle Block Engine CID CC
2007 - Ford Freestar V 6 Cyl 4.2L 256 -
Remy
2005 Ford Freestar Alternator 6 Cyl 3.9L Remy - Premium Remanufactured

P311-478E689    23773  Remanufactured

3F2Z-10346-AA , 6F2T-10300-BB , 6F2Z-10346-BA , 3F2U-10300-AA

Qty:
$40.00 101.27
Remy Alternator
  • Premium Remanufactured Alternator
  • ; 135 Amps
  • Premium Remanufactured
  • Product Attributes:
    • : Remanufactured
    • Amperage Rating: 135
    • Fan Type: Internal
    • One Wire Capable: No
    • Plug Clock Rear View Main Mounting Ear at 6 O Clock: 2
    • Pulley Belt Type: Serpentine
    • Pulley Groove Quantity: 6
    • Pulley Included: Yes
    • Pulley Outside Diameter: 65.0
    • Regulator Type: Internal
    • Rotation Direction: Clockwise
    • Voltage: 12.0
Brand: Remy
Additional Fitment Information:
Vehicle Block Engine CID CC
2005 - Ford Freestar V 6 Cyl 3.9L 238 -

Latest Car Advice

CarJunky AutoAdvice

1994 Mazda 626 alternator problem

Showing 2 out of 2 Posts
Question From hrichard on 1994 Mazda 626 alternator problem

Had alternator replaced maybe 3 months ago (was rebuilt one probably). twice within last 2 weeks, lights start dimming and car just dies and won't start back up. Took back to alternator shop and they say alternator good. Had Advance Auto run diagnostic on battery, starter, & alternator and shows alternator producing only 12.1 volts and they say alternator bad. Had Autozone run test and they say battery good, and alternator good, but voltage regulator is bad. My question is: Is the regulator part of the alternator? If not, when alternator is replaced, do you normally check voltage reg. to make sure it's OK. Should the alternator shop have checked the regulator when I took it BACK to them (after car had died twice on me) to check the alternator? Wordy, I know, but thanks!

Response From Tom Greenleaf Top Rated Answer

If the 4 cyl the voltage regulator looks like this..........

/

Hard to know but by that pic my guess is it's part of the alternator and with the hole suggest it's at least part inside and should be covered by warranty still. Testing could be bypassing this whole thing and inconclusive. Only having 12.1 volts with a running engine isn't enough. If belt is tight enough and not just a disconnect alternator, burned plug, bad wiring my best guess is this alternator is bad.

Part was not available at two places I just checked so it would mean whole alternator,

T

alternator problem

Showing 6 out of 13 Posts | Show 7 Hidden Posts
Question From carss on alternator problem

Hello,,
grand prix, 3.1L, 1994, 130,000miles

car died and the alternator went bad, the mechanic told me to change the alternator. and i did and changed the battery too. two week later, the alternator reads about 8v, the mechanic did something and recharged the battery and the alternator reads 14v. one month later the alternator made the same problem and reads about 7-8v and the battery is totally dead. what to do? how i make sure that the alternator is bad or something else makes it bad?

Response From Tom Greenleaf Top Rated Answer

Have the alternator bench tested. Parts stores like AutoZone and others will test them for you.

Charge the battery with a charger. The two work together and greatly enable each other. Neither is very happy about working too hard - alt can burn out trying, and batteries don't like being undercharged.

The voltage regulator and diode trio inside the alternator can go like a flash,

T

Response From carss

No, my friend they said this alternator can't be opened.
But last time the mechanic charged the battery with a charger and every thing went good for couple of weeks, but why problem comes back.
thanks for your reply

Response From Loren Champlain Sr

Pardon my jumping in, here. It really sounds that you've got a defective alternator. It happens. As Tom suggested, you really should have it retested. There are different qualities of rebuilt units. Remember, you get what you pay for. We have switched to CarQuest reman. alternators and starters. They also have new ones available in increasing applications, but they can be considerably more money. And, it's not uncommon to get a whole lot number of bad units. Just because some el-cheapo parts stores have a lifetime warranty, that doesn't insure quality. Just that they'll replace it. GM alternators are about the easiest to open and replace the diode trio or regulator, but if it's still under warranty, you don't want to do that. Of course, make sure that all of your connections are clean and tight. And, that the battery is capable of accepting the charge. Again, as Tom mentioned, a defective battery can take out an alternator. And, discharging and re-charging the battery is really hard on it.

Response From Tom Greenleaf

>>Quote "No, my friend they said this alternator can't be opened." End Quote<<



They are opened all the time to replace common parts like this. Those parts can plain wear out or get destroyed from heat from overworking. The usual reason they say "alternator's can't be opened" is that voids warranties now as nobody knows how to do it. You used to have to "clock" an alternator so it was in the right position for a particular application.

Note: Rebuilts frequently only replace just the parts that will make it work again vs all new parts all over again. Many alts get sent back and just have new brushes, diodes or a bearing replaced and might check ok for a 2 second test, cleaned up to look new again and resold. Some have intermittent troubles and will test ok for a second but fail in real use too.

When you buy an alternator YOU aren't expected to open them up for anything and again - most places will void a warranty if you do,

T

Response From carss

Hello again guys.
thanks you Loren and Tom

1. if i want to bench test the alternator at home, it's easy to see if brushes are worn out or not, diode can be tested, i believe, by multimeter it's one way open and the other way closed or have some resistance is that right?, but how i test the voltage regulator?

2. suppose the alternator and battery are both ok, what other problems could prevent the alternator form charging the battery? wires that i can see from battery and alternator look fine (the red wire, the only wire come out of the alternator is always hot, is that normal)

3. has the diode ever come out side the alternator in early 80's model cars? as my friend said he had same problem with his 1980 saab long age and found that diode is in line with the cable out side alternator.

thans alot you all,,,

Response From Tom Greenleaf

Back to top you said this alternator was replaced just last month. Take it back as if you open it you'll void any warranty.

At home "bench" testing would be on the car as you would need to spin the thing. The parts stores have that machine and it either works when prompted or not - they (usually) won't be able to state just why just a go or no go.

I just searched around for simple ohms tests or what to ground for forcing it and nothing was good enough for me to post so I suggest taking it for testing.

All the parts are available but the trouble of late is the whole unit is available for about twice the price of each replaceable part one by one so not very cost effective.

Ok: Regulator and diodes are inside on any recent GMs that I've run across. If wiring looks perfect and YOU own this alt, you could open it and look for something burned. I don't know on this one what ohms should test what testing from what to what.

Yes - the red wire stays hot and should on this. The two wire connector should be for the gauge/warning light and with ign on will enable it to charge. There is a way to add ground or power to one of those to force output to max and I just don't know which so I'll suggest don't!

Perhaps Loren or another knows which you do what with on this - I don't and didn't just find anything credible to pass on for this Delco or possible Delphi alternator??

Again - less than a month - take it back,

T

Response From carss

thanks a million tom for replaying so fast, as a matter of fact my alternator had only three days warranty as it is used.
you mentioned the two wire connector, i remember that the battery sign inside tha dash board does not come on. i did see it long time age but now i don't see it on. any clue
as i also said, if i charge the battery out side the car and return back, the alternator gives me 14v. which sounds it charging, then 2-3 days the battary dies and the alternator does not charge it if i jump start it.

thanks again tom, and i will tell if the problem is solved.

Response From Tom Greenleaf

3 Day warr! I'm shocked! Used is used but usually for the lower price they'll still give at least 30 day on anything.

Some things don't add up. Charge the battery (new or is it used too?) while it's in the car. Start it and read the voltage with the engine running - what is it then without a charger on it?

Does this have a volt gauge or just a batt warning light icon on dash or both. Generally when you turn key to "run" but not start the car the bulbs will light as a bulb check for which are working and go out when running. If there's only a battery warning light some much older GMs would fail to charge because of that but never heard of that since the 60s!

Note: If for any reason the battery is run down too low to start engine then just jumped the alternator would be overworked if it worked trying to charge battery back up and that alone can kill an alternator with high heat.

NoteII: While running you should see over 13v about all the time and if less there's a problem as well as over 15v a problem. You can put a volt meter if you wish hooked up thru power port/cig lighter if you don't have or trust a volt gauge on instruments.

You said it would last three days if charged off car! How many miles or how much run time is that? I'd like to see what the volts read with it running and then with it running with headlights on and fan blower on high with a raised idle. Report that and I'll have a clue on what next would be best.

One more - How much did this used alternator cost? Diodes are about $40 bucks alone and whole unit rebuilt ~$120 or so,

T

Response From carss

Dear Tom
Battery is new... voltage on battery with charger on it 14v, charger away 9-10v
the warning light on dash stays on while engine is running even when charger on the battery
when battery charged off car to full it lasts about 30 miles with lights on and AC on
i checked the voltage between the wire connector while car is on on position and while it's running and voltage was zero and resistance was 36 ohms.
last, i bought that alternator for about $95 not from usa.
thanks all

Response From Tom Greenleaf

Back:

If this new battery shows as low as 9v when charged! No need to report what the reading is when the carger is on it as you are just reading the charger - we need to know what the battery is by itself. A bad battery can easily kill an alternator.

Make sure you are charging posts to the battery and not just on it's cables as they might not be making a great connection. Take readings from the battery itself and not the clamps as well.

Side note: You can take a good brand new battery with no help from a vehicle's alternator to maintain it and it will run for a period of time till it's charge runs too low to run the vehicle. It isn't a cell phone battery - taking the typical lead acid car battery down destroys them in just a few total run downs.

Side note II: The common battery is made to be at 100% almost all the time. When you draw from it to start the vehicle it takes away some percent - like 5% of it total available charge if the vehicle starts right up - then the alternator will quickly restore the battery to 100% and the alternator is running the electrical items while running.

If you drop a battery to 50% with multiple failed starts or leaving something on by mistake the alternator will blow it's brains out trying to get it back to 100% and usually will. When you get down to 10-20% and they can get dropped to zero you are killing the battery and the alternator will constantly overwork, get so hot it ruins it.

The two need each other and either can kill the other so when you get caught with one bad make haste to be sure both are restored to good or it's just ping pong of repeated failures,

T

Response From hashhead

with motor off, battery showing 12.45 volts

Response From Loren Champlain Sr

hashhead; 12.45V is okay. A fully charged 12V battery will have 13.2V. But, at this point, all you are doing is showing surface voltage. If the battery holds a 200A load for 15 seconds and stays above 9.6V, the battery is okay. Once the engine is started, charging voltage should be between 13.6V and 14.6V. You'll need an amp guage to check for amperage output as well.

alternator gets really hot

Showing 2 out of 11 Posts | Show 9 Hidden Posts
Question From jsti4 on alternator gets really hot

i have 2004 F350 6 liter powerstroke the alt gets hot and stops charging both batts and alternator are new i need some help please !!!!it shows its charging at 13.3 at the batteries and 13.6 at the alternator

Response From jsti4

does anyone know if the fuel injection control module and the alternator have anything to do with each other ?

Response From Discretesignals Top Rated Answer

it shows its charging at 13.3 at the batteries and 13.6 at the alternator

Is that the voltage your getting when you think it it isn't charging?

The FICM has nothing to do with controlling the output of the alternator. The alternator has an internal regulator and sensing circuit that is used to control the field. The electromagnetic strength of the field determines how much the alternator puts out.

You need to make some power and ground voltage drop measurements at the alternator stator and regulator circuits to see if anything goes missing or wacky when it quits charging. It also would be nice to see how many amps the alternator is putting out. If the alternator is putting out max amps, it won't last long.

Another possibility is you could have an inferior alternator. Some of the aftermarket remans are junk.

Response From jsti4

found something on another forum about my abs system i removed the fuse for the abs system and everything works great now charging system is good alt doesnt get hot every thing seems to be good i will have the abs system checked out but atleast i can use the truck for now . Thanks for everyones help and your time on my problem i will be sure to return the favor when i can !!!!!!!

Response From Discretesignals

That's interesting. Which fuse did you pull? Was it the 60 amp? If so, something in the ABS system is using a lot of current and overworking the alternator.

Has the ABS light been on before removing the fuse?

We'll keep this thread open, so let us know what they find out about the ABS system.

Response From Tom Greenleaf

2004 - you should be on your third battery!

Tom

Response From Discretesignals

Is this vehicle used for snowplowing or does it have any aftermarket accessories that use a lot of current?

Response From jsti4

I do not have a snowplow or any aftermarket acc. on my truck it just started getting hot and shutting of so i replaced the alternator cleaned all connection and checked all plugs on the engine that i could find but after minutes of running the alt gets very very hot and shuts off.

Response From nickwarner

Have you checked the cable from the alternator to ensure it isn't shorting out somewhere? Thats a tight engine bay in there and things do rub.

Response From jsti4

thanks but i did follow the cables from alt to batteries no signs of broken wires or shorts all wires test good

Response From Discretesignals

Wonder if you could get your hands on an amp clamp and see how much current it is putting out.

sucky alternators or bigger problem?

Showing 2 out of 6 Posts | Show 4 Hidden Posts
Question From jackwashere on sucky alternators or bigger problem?

Over the past year and a half I have replaced the alternator on a Saturn Ion three times. The last one that was replaced about a week ago is going bad again. The electric auto shop claims that there must be a bigger problem. The problem is making the alternator work extra hard according to the owner and that is breaking the unit. Several people have told me that the shop is probably using cheap bottom of the line alternators that go bad. Who is right?

Response From Sidom

Double check the basics.....Make sure all the connections are clean & tight......Look for missing or broken body to engine ground straps....I won't go into the whole story but bad grounds can cause bearings, mounts & other things to fail prematurely.....Current gets home any way it can and it doesn't care what it goes thru to get there......just that it can go thru it....

I can't say for sure on yours but on some GMs the feed for the alt runs off the starter solenoid.....I've had some weird charging system problems on GMs that were traced back to a loose nut on the starter solenoid.......

At the rate you are going thru alternators.....It might not be a bad idea to let the electrial shop take a look at it.....

Response From Tom Greenleaf

Comments: Battery in trunk! OK - Some others are under a back seat or in closed quarters do need to attach to vent outside vehicle and the vent hoses should be right there waiting. If hard to find doesn't surprise me. WE ARE TALKING HYDROGEN GASSES that can not be allowed to accumulate in a closed area - disasters happen over that.

Eating up alternators. Tons of cheap junk that isn't really rebuilt but more like cleaned up and brushes perhaps. If a battery is weak or low it does really strain an alternator. Belt must be known properly tensioned.

Other: I don't know of a good bargain battery especially lately. This is not a place to save a buck. I'm not even sure what brand or place to suggest anymore as things change so fast as to who really makes what and just gets a name slapped on them. There's also a factor with how they are handled along the way. They don't do being dropped and bounced around well nor being tipped over. Gel cell ones made for wild extremes can handle that but cost a real fortune.

Other issues are they are not in full state of charge when first made new. Some will charge them but near know most don't. Batteries don't like being at part charge or low and worse they can sit unsold for many months but are marked when they were made new. You can end up with a year old new battery but the aging starts when it was made.

It is a problem and you can end up playing ping-pong with batteries and alternators each dependent on the other being good. Unsure of this popular free battery testing too. Better than not doing anythng but I don't think it is perfect to know if one is really good or not?? - T

Response From Discretesignals Top Rated Answer

Does this have an aftermarket sound system or any after market equipment that may put extra load on the alternator?

Could be cheap alternators or something is causing them too fail because they are overworked. It is also important to be sure your battery tests good and has the rated amount of capacity. Important to make sure nothing is leaking all over the alternator. Washing an engine and getting chemicals or thermal shocking the alternator can cause failure also.

Probably wouldn't be a bad idea to amp clamp the alternator output and see what the alternator is actually doing.

Response From jackwashere

No aftermarket sound system. Regular standard GM Delco radio that came with the car.

I thank you for the idea to check the battery. The battery was replaced under warranty one month ago. It went bad after about 35 months. Now I have a new battery. I replaced the alternator a week ago because a new battery did not fix the problem. New battery new alternator. The battery light on the dashboard still intermittently occasionally flashes to indicate the alternator is not charging. I'm wondering what are the implications for battery performance if it needs to be vented and I got a regular old battery from Pep Boys? After you mentioned checking the battery I did some research and found out I need a vented battery for the Ion because it is housed in the trunk. I will also check the amps rating on the battery they gave me. Three years ago I walked into Pep Boys and asked for a battery. They looked it up in their computer system and gave me one. I'm wondering if perhaps they did not give me the wrong battery and that is the source of all of these problems with the alternator and battery going bad? Either this venting feature not being present on the battery I bought kills batteries or they gave me a battery that was too small for the job?

Response From Hammer Time

Several people have told me that the shop is probably using cheap bottom of the line alternators that go bad.


That's what I would guess. It's pretty hard to find any quality these days and competition pushes them into the cheapest thing they can find.

alternator kill switch

Showing 2 out of 4 Posts | Show 2 Hidden Posts
Question From flaviobonzer on alternator kill switch

Hi everyone,
I am wanting to install a kill switch or something to enable me to control when the alternator charges the battery. This is actually for a diesel engine in a yacht and I need to cut the load that the alternator puts on the engine every now and again.
I have tried putting a switch in the field/ exciter wire. with this I can start the engine with the alternator off and then flick the switch and the alternator starts charging but then when I turn the switch off doesn't turn off the alternator as now the regulator is supplying voltage to the field circuit. Is there any way I can install a switch somewhere to achieve what I want? Was thinking maybe adding another batt in series to the sense wire so regulator thinks batt is full charged and cuts alternator output. Would this work?
Any suggestions greatly appreciated
cheers
Tim

Response From Discretesignals

Would help if we knew what kind of alternator you have.

Response From flaviobonzer Top Rated Answer

Alternator is a Mitsubishi. not sure of amperage or model etc. Alternator only has field/sense/tach connections on back of alternator. Apart from main batt + of course.

cheers

Response From Tom Greenleaf

You won't save a thing - forget that idea completely. Did a ton of pretty large yacht misc stuff over many years.

OK - just because the engine may not need electricity for anything to run there are a zillion things still using some power all over a typical yacht unless it's an empty shell.

Alternator is almost just a nothing pulley for power loss if not powering something anyway. Even the best deep cycle battery(s) w starting amps enough for a diesel engine doesn't like going low just tolerates it lots better and when you do enable it it would just make up drag to recharge them later.

Do you really want to risk it not starting because you let it get too low?

Last yacht I did a lot on had power for water for 3 sinks, ice maker, six bilge pumps, TV, radios, gauge lighting and 100 more things I can't think of right now and guess you could do without blowers for heat and A/C if equipped underway.

Even sail boats of size need power for pumps. Yes - most charge battery(s) slowly with just a little wind generator usually at the top of the mast.

The other problem is when you ask an alternator to charge hard with low battery(s) is you are really stressing it out and can kill it. Much bigger bucks than automotive as it must be designed not to make sparks.

In short - you save nothing and risk a lot. Last one I deal with a lot had SIX deep cycle batteries and could choose 3 at a time, all or either set such that a failure still left you with at least starting power if one set failed in any way.

Enough crap is always going wrong in a real yacht all the time and you want to mess it up even worse?

T