Hi Amp Alternators

I put in the Balmar 100A with external regulator this summer, and it is working perfectly and usually has my batteries back in "float" within two hours of firing up and moving out. Two 4D batteries, no inverter, and mostly the refrigerator and stereo (no heater either). After two days on the hook, it was topped off in less than two hours. They are available discounted if you do a little searching. I love my little Honda, but hate to make noise to make coffee (electric range top) every morning. I bought a little Coleman single burner for coffee and use the leftovers from my propane grill once the bottles get too low to cook a whole meal. Still waiting for my new Dickinson propane stove and oven to show up...

On a work truck with a 3 ton capacity electric crane that ran off the truck battery and a battery on the crane, truck grp 31 AutoCrane grp 27. I had the standard Delco 55 amp alternator rebuilt several times over the years, at one time the shop I used boosted the output to 105 amps. The crane was used almost every day pulling or replacing components on excavating equipment and the truck engine would usually be running. Now to where this is going on a boat, I've thought about having the output of the alternator on my Hino that charges the house bank boosted to what the shop thinks it can reliably put out. Has anyone else tried this with your stock alternators? I believe mine are Nippon Denso and the output ramps down pretty quickly, it may be best to leave well enough alone as it has worked without any problem. What are your thoughts on this as a choice for faster charging vs going with the much more expensive Balmar units?

Ron: that's exactly what you would achieve by getting an external regulator and having the local alt shop pull out the internal regulator. That will both increase the output and safely hold it at the higher output rate for long enough to be really useful.

Aquabelle said:

Ron: that's exactly what you would achieve by getting an external regulator and having the local alt shop pull out the internal regulator. That will both increase the output and safely hold it at the higher output rate for long enough to be really useful.

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I agree!

There's nothing unique about the Balmar alternators except Balmar badging. My understanding is that most, if not all, of them are really Leece-Neville alternators inside with Balmar labels on the outside. If I had not received friend pricing on the Balmar 621-120, I'd have looked into buying a Leece-Neville at a fraction of the cost new.

I think any alternator can be modified to defeat the internal regulator and accept an external regulator. This might help.

Leece-Neville 8MR Series Alternator External Regulation Conversion Photo Gallery by Compass Marine How To at pbase.com

Thank you for very much for clearing that up, I know what I'll do if I update the alternator.

Here's a very good discussion of high output alternators and external regulators. There's a video that demonstrates the principles of smart charging very well.

He even brings into the discussion the differences between trawlers and sailors when it comes to the need for the float charge that a smart-regulator provides.

Great info in a clearly delivered format.

RC, there are some who have had their alternators rewound to increase the output significantly. It's certainly worth a try, especially is you're going to regulate externally with an alternator temp sensor.

FlyWright said:

Here's a very good discussion of high output alternators and external regulators. There's a video that demonstrates the principles of smart charging very well.

He even brings into the discussion the differences between trawlers and sailors when it comes to the need for the float charge that a smart-regulator provides.

Great info in a clearly delivered format.

Click to expand...

Excellent information I bookmarked it for future reference.

Hello. Congrats on the new boat, and being in the PNW. There is a LOT to do up in the islands! You mentioned Crusaders so that really limits you a lot - being gas engines. You really need to make sure you get proper marine alternators that have the needed explosion protection.

One thing you might do is consider your usage. Cruising the San Juan's you likely are just an hour or two between stops (or more if you slow it down). Even at our slow pace a 4-hour trip was unusual unless we were repositioning the boat. If you mostly do weekend cruising the engine alternators will not help you while at the dock/anchorage, and are not really needed on the return trip to home port (as the shore power charger will top off the batteries). Perhaps just try things a bit and see how it goes? After you understand your cruising pattern a bit you can decide where the weaknesses and opportunities are, alternators, battery size, generators, solar, etc.

It seems a lot of these posts have talked about other options, many of which are applicable only to Diesels. FWIW, we have been using large frame Leece Neville alternators for several years now. At this point I have a 270A/12v LN4870 alternator on the main. It is able to put out 120A+ at idle for hours on end, and we get upwards of 220A underway (Limited due to slow cruise RPMs).

I purchased it off Ebay for around $200; new ones are available for under $400. A cover plate can replace the existing regulator to allow an external regulator to be attached (part number: 39-5204, 100265, or A038100265S). I originally used a Balmar external regulator, but had issues with it exiting Acceptance Mode early - well before the battery was recharged. Perhaps the newer ones are different, but after a trip up the Columbia/Snake where I had to stop and restart the engine to get the regulator to continue Bulk/acceptance charging I pulled it for a fixed voltage truck regulator. Last summer I started using an Arduino based multi-step regulator I developed and posted in public domain.

I have been reading some good things about later model 'hair-pin' alternators, ala the Desno units that many Chryslers and some GM cars have been using for the past few years. Thinking about picking one up for our DC generator and see if it is indeed more efficient. If you have a Diesel I think there are lots of options out there. Gas is another story.

Best of luck deciding which way to go. Remember, if you upgrade the existing alternator to look also at the wire to the battery, don’t just reuse the existing wiring harness w/o verifying it is heavy enough for the current. And looked at some of the boats you build, wow. What a great life to have!

-al-

If your SOC meter and experience show low or dead batteries there are low buck cures.

Simplest would be a JC Whitney style windings kit to bring the amp output up.

I would go online and find a suitable kit and bring it with the alt to a local shop.

Perhaps just the paperwork , and let him find a source.

I would ask to have the internal V regulator replaced with an external field wire.This is the most important step.

The stock auto brain V reg is really lousy at recharging heavily discharged batts , a 3 or 4 stage marine unit will be far far better.Any extra output from the amp kit will help the better regulator.

Before pulling the alt draw its direction of rotation on the unit , so the rebuilder cam make sure the cooling fins are the proper ones.

IF the re-builder can also stick on a cast iron pulley , it may help belt life over the stamped steel ones.

All of the above should NOT be expensive as its the same work for the shop as a std rebuild.

I say just go try spending the weekend. Your start batteries are likely isolated from the house batteries, so go enjoy a weekend and see how it goes, knowing you can always start the engines. My house set up is a mere 2 golf cart batteries and I stay out for 2 to 4 nights without a problem. You will be leaving the dock with your batteries fully charged up from shore power, so the only time your alternator will matter to you (based on your question) is when you are out for multi nights (2 or more) and moving between anchorages.
You can save a ton of guessing and over thinking by grabbing the small Honda gennie and taking it along and forgetting alternators altogether. I have one and almost never use it. I also have a two year old who likes to open the fridge and look inside on hot days.