Switchable alternator? 50/150 amp

Skipper

Skipper

.
Oct 9, 2008
1,742
Bristol 29.9 Dana Point
Is there a switchable alternator?
Would be nice to have (example) 150 amp capacity to quickly recharge at anchor if solar can't keep up, etc. while being able to tone it down to say 50 amps, or "normal" mode, when motoring.
I googled. Found nothing.

I'd even like to switch it off altogether for max engine power, without damaging diodes.
Universal diesel 14hp.
 
Maine Sail

Maine Sail

.
Feb 6, 1998
11,759
Canadian Sailcraft 36T Casco Bay, ME
External regulation..

A Balmar MC-614 or ARS-5 with two toggle switches.

Toggle #1 Small Engine Mode (50% field cut)
Toggle #2 Turns off regulator altogether

Although you'll not be able to drive anywhere near 150A on a 3/8" / 10mm belt.... You'd need a serpentine pulley kit for that...
 
Skipper

Skipper

.
Oct 9, 2008
1,742
Bristol 29.9 Dana Point
Maine Sail said:
External regulation..

A Balmar MC-614 or ARS-5 with two toggle switches.

Toggle #1 Small Engine Mode (50% field cut)
Toggle #2 Turns off regulator altogether

Although you'll not be able to drive anywhere near 150A on a 3/8" / 10mm belt.... You'd need a serpentine pulley kit for that...
Click to expand
That's fantastic. Thank you.
 
B

Benny17441

.
May 24, 2004
7,213
CC 30 South Florida
Quick charging is relative; the acceptance rate of the batteries is what determines the charge time. Although a high output alternator can be used to drive appliances while the engine is running as far as charging it would require properly sizing battery bank to alternator output or vice versa for maximum efficiency. Upgrading the alternator requires some planning, first we understand there are pros and cons to the upgrade and the sole reason that would drive the conversion should be to fulfill a real need. This is not a case where bigger is always better. I'm sure you are familiar with the negatives but let me list some for you;
1) Cost, HO alternator, drive belt and pulleys, external regulator, additional batteries to upgrade bank. It adds up.
2) Engine power, it takes horsepower to drive an alternator and our auxiliary engines have a very limited supply of it. Wear and tear.
3) Batteries, additional batteries cost $, add weight and take up space. If there is no use for the added capacity they will not have a deep enough discharge cycles to promote their longevity. The majority of time saved in battery charging is done in the bulk charging cycle and if the bank never reaches a discharge level under 75% of capacity it will make very little use of the bulk rate and strong de-sulfating current.
4) Reliability, most HO alternators in the market for boats are after market units. Most are not as reliable as the OEM units. The good ones are priced accordingly. Although most come with full replacement warranties that does nothing for being stranded or the ruining of the lifetime trip you have been saving for.

There are indeed benefits to upgrading the alternator as you can have topped up batteries and drive boat appliances and instruments while the engine is running. In deep bulk charging cycles the charging process will be faster as battery rate of acceptance will be at its highest. For a full time cruiser it will likely be a necessity, for a boat heavily equipped with electrical fixtures it may also be a necessity but for the regular Joe like me who day sails, overnights and takes a few trips a year it will likely be unwarranted. Let the need drive the decision.
 
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Maine Sail

Maine Sail

.
Feb 6, 1998
11,759
Canadian Sailcraft 36T Casco Bay, ME
Benny17441 said:
4) Reliability, most HO alternators in the market for boats are after market units. Most are not as reliable as the OEM units.
Click to expand
This is not at all what I see. I see factory alternators, usually just basic automotive alternators intended to charge an SLI battery not 400+ Ah's, fail at a considerably higher rate, perhaps 8:1 or 10:1 over aftermarket HO alternators.

My world cruising customers, about 40% of my clientele, are extremely demanding on gear. They are the ones who split the wheat from the chaff when it comes to gear such as alternators.

I have a rather interesting full time cruising customer who went through 4 Cummins factory alts in 2 years on his Defever trawler. Cummins was charging him over $750.00 for each alternator. They were so cooked each time they were not worth rebuilding so he just purchased new ones. In-between the third and fourth he tried a cheap $200.00 aftermarket Chinese knock off from an on-line source, it lasted three weeks. Finally after the fourth factory alternator, I was called in to help out.

He's now had a Balmar that has been to Labrador, Newfoundland and back three times and is now at least 7 years old. It has at least 3000 hours on it or the equivalent of 30 years of 100 hours per year coastal cruising. He also goes to the BVI each winter so that is a lot of charging time. The Balmar alt, regulator and temp sensors cost a fraction of what he spent on factory replacement alternators and it has already outlasted them by about 6X..to him the HO alternator and regulator were a steal. His batteries are also lasting considerably longer so he's saved even more because he is getting proper charging to them not just a "close enough"..

I can point to the same with the piles of Hitachi / Yanmar alternators in my bin full of dead ones. The thermal compensation circuits simply can't keep up with a large bank deeply discharged and they fry themselves.

All alternators can die but a well built heavy duty alternator, properly installed, should last as long as any 100 hour per year coastal cruiser keeps his or her boat.

All that said, most coastal cruisers who tie to a dock after each sail and re-charge, won't really need a high performance alternator system..
 
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