Generator Head?

The problem with internally regulated automotive type alternators is they never seem to get the batts to full charge. They're fine on a car, where they dont have to work much. But on a boat, when you have to run the engine 2 hours more than neccessary just to get the batts to 80 % they just dont make since. Its that last 20 % they have trouble with. The regulator tapers the charge to much. A good external, temp compensated regulator will cut you recharge time significantly. Also, the hot rating on most auto type alternators is not even close to rated output. I'm guessing this is a 10SI Delco ? If so, you can do a lot with it, cheaply.

kulas44 said:

The problem with internally regulated automotive type alternators is they never seem to get the batts to full charge. They're fine on a car, where they dont have to work much. But on a boat, when you have to run the engine 2 hours more than neccessary just to get the batts to 80 % they just dont make since. Its that last 20 % they have trouble with. The regulator tapers the charge to much. A good external, temp compensated regulator will cut you recharge time significantly. Also, the hot rating on most auto type alternators is not even close to rated output. I'm guessing this is a 10SI Delco ? If so, you can do a lot with it, cheaply.

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Thank you Kulas44... perhaps my logic is off.

This is the plan and why I changed alternators after giving up the generator head idea as a bad one, complicated, etc.

The old alternator (from a Yanmar) was 55 amps. My a/c wall-banger used 45 of those amps. Actually it is 455 watts at 120. Give or take, 45 amps at 12 volts.

In my opinion running a 55 amp alternator at max (essentially) would have overheated the unit in a short time.

The theory was to upgrade the alternator to 120 amps. Now it won't be stressed giving me the power to run my a/c while underway or at anchor.

I have 455 watts of solar providing 150 amp hours daily. Topping off is not a problem. Without the a/c I top out and go into absorption charge by noon or one at the latest.

Seaweed also has an Air-Breeze though frank it's been a disappointment on this coast.

I cannot picture myself ever running the engine to charge the batteries. That's what my solar does.

In theory I believe this: The larger capacity alternator working less hard should be a better solution than stressing the older 55 amp unit. Maybe!

Is my logic correct?
I am interested in an external regulator and will be keeping my eyes opened for one. In the short-term though the a/c functions just fun while running Betsy.

I forgot to run the a/c when underway. Did not need it as it was a perfect day on the water. It's good to be back. Now if the storm system will just go by I want to take my Seaweed for a spin on Monday for a few hours.

Weekends here are fully of crazies. Even when underway I go no place on Saturday or Sunday, preferring to tuck myself into a nice deserted nook with Skipper, Algae and my Kindle.

Life is wonderful afloat.

The alternator has no label except Will's Starter & Alternator. It looks very much like the 55A I removed - same size. I had thought the larger capacity would have a bigger case. It does not.

Janice- Lots of amp ratings for alts in the same size casing. There are different stators and rotors and regs and diodes that make the higher ratings possible. If it came from a reputable alt shop, I'd trust it. Just keep an eye on the alternator case temperature, if it is being overworked it will be over 200F, then either reduce load or increase engine rev's, either will help it cool down.

Kulas is right, internal reg is not best for marine house batt service as it is not meant to completely top up batts, then reduce voltage. But in your case you have the solar to help in that regard. I think you will be ok as is.

Keep an eye on how hot the alt gets, otherwise enjoy being mobile with AC!!

Congrats!!

You can have the alternator changed from an internal regulator (it's removed) and wired for an external regulator. It's pretty simple and something Will's could do. I paid less than $100 for an older Ample Power 3 stage reg with temp sensor on EBay a few years ago, so not real big bucks. Maybe in the future.

By the way, Yahoo! You've had quite the journey.

It is so wonderful to be mobile again. Of course the winds have kicked up so any planning is definitely fluid. And now I don't/won't have to wait for a ride to the grocery store. If I want something I can take Seaweed over to Publix or WinnDixie, both of which have docks nearby.

I will keep an eye on the alternator temperature.

As for the external regulator, yes, I'll keep that on the list.

When I went for my three hour cruise that took seven (having fun, no problems)
I'd brought along the final mechanic and a friend. We had a pleasant time.

It was nice to have two helm-boys though I would prefer one autopilot. That's next on the agenda.

Oh, and I did not turn on the a/c while underway. It was so pleasant I did not even think about it. Plus it's fun to wave a folks as they pass by. Yes, I'm one of those!

Thanks again gents for steering me in away from the generator head. This solution was lots less costly and works. Thank you to one and all.

Have I mentioned lately how wonderful life is afloat?!?

janice142 said:

Final Update: Ski (and others) I did take your advice. I've upgraded to a 120A alternator -- same size as my 55A. It works. The a/c works a-okay from it.

My alternator is internally regulated. I won't be using the alternator at any place near top rating -- 60 amps or so would be about max output so hopefully this unit will last me for a long time. Life is wonderful afloat.

Click to expand...

Janice, did you mean 60 amps or so (out of the available 120) would be about the most you'd be using at any given time?

If so, and given your solar battery charging... sounds to me like you've got this phase of improvements sorted out pretty well.

-Chris

ranger42c said:

Janice, did you mean 60 amps or so (out of the available 120) would be about the most you'd be using at any given time?

If so, and given your solar battery charging... sounds to me like you've got this phase of improvements sorted out pretty well.

-Chris

Click to expand...

Yes, of the 120A the alternator is (maximum) capable of putting out, the most I'd ever use is 60. I believe (hope) being so much larger than required will give me a longer time before failure. That's the desire.

And too, I am woman and there might be more power required down the waterway. In the meantime I'm set.

Thanks for all the advice and commentary/suggestions provided on this thread. I believe I've got it right now. A BIG thank you for saving me from myself.

"The problem with internally regulated automotive type alternators is they never seem to get the batts to full charge"

This is NORMAL for any V regulator single wire or 4 stage marine.

Its the batteries that have a problem with that last 15% -20% and need to be charged at a modest rate .

The marine units are great at stuffing in lots of amperage ,,,untill 85% full ,,then must slow down.

A temp unit on the batteries can keep the marine V refg from overheating them.

Most cruisers just accept how a LA battery functions and go from 50% full to 85% full as a norm.
Any wind or solar can help preserve the life of the batts by getting to 100% full , at times.

Using AGM can partially help solve the charge hassle , but for most folks a bigger house set that does what you need with 50-85 is far less expensive than AGM,

Since much of the AGM majic is when the batts start being charged a larger alt is usually required for the full effect.

After reading this thread as a generator tech i have throw my 2c in.

the big problem with adding a generator off the main will be fabrication costs. then you have to ether find a 4 pole generator or figure out a pulley configuration that will allow you to get 60hz at a reasonable engine rpm. then you have to take into account it will always be turning and costing you a small amount of fuel. the other ideas about stepping the up the engines existing alternator will be the most cost effective but it will be the least efficient. the option for running it off a small honda eu. will work but as has been pointed out you have to contend with moving it, different fuel source and not being able to run it in the rain. imo i would be looking into getting a engine driven ac system and ditch the window shaker. it would allow you to run the engine at idle or damn near and still have ac as well as running it when cruising. the only thing is i am sure the cost will be greater as will the instillation complexity.