Alternator Replacement - VP MD17C

[cmoffatnc1]

Not getting the charging output we need, looks like we need to replace alternator. 1976 A 25. Any recommendations? Thanks.

[DesertAlbin736]

What is the chrarging output you're looking for? Voltage output (14.1 V for FLA batteries)? Amperage? Assume you've checked every thing, fan belt tension, wire & battery cable connections. WillieC is your go to guy for all things MD17C.

[WillieC]

I went nuts and installed a hunnert amp Balmar and 618 external regulator. It has the belt saver feature that basically detunes the alternator. The puny VP belt is good for maybe 70 amps, but since you have to remove the starter to swap it, you treat it gently and take your time getting the alt in perfect alignment.

It was a bit overkill but I had just installed true deep cycle batts and hoped to keep them properly charged. Sold the boat after just one season on the new setup. Prepare for learning curves if you are moving from stock parts. And bring sacks full of cash.

Will be doing the same exercise on our new(er) boat. It all starts with an honest load calc of your intended, yea, actual use. This new to us boat was a dock queen so the stock Hitachi(Yanmar) plus a solid 120v Shore charger worked well for the PO. Other than they really should have set it up right and regularly checked the electrolyte levels. Easy with the auto fill squeeze bulb somebody installed in the Trojans.

I’ll be upgrading to fit our intended use of longer distance cruising and prolonged hook hanging with little access to shore power. I’ll need a better alternator and regulator. I was given the name of a good alternator shop in Bellingham that can provide a suitable unit much cheaper than the Balmar. (Not looking for cheap Chinese knock off. You shouldn’t either.)

The latest greatest thing in regulators is the Wakespeed, but I’ll likely stick with Balmar because I figured it out. Not aware of others still in business.

Start with a true load calc and how you plan to use the boat. Winter storage will also require a good 3 stage shore charger, whether it’s on the boat or in the shop if you remove the batts over winter. As I said, a weekender may get by with much less than the full Balmar deal. I’ll also be looking at solar since the Lois Anne will be hanging on a mooring ball. No dock queen she! (If I ever get her back in the Canal…maybe she’s a Backyard Queen. For now.)

[dkirsop]

My boat is equipped with a standard 100A, two wire, Motorola alternator, with a Balmar ARS-5, three stage, external regulator. The regulator is key to getting maximum performance from the alternator and with this setup I could have actually used a 60A alternator and lessened the load on my engine. The Balmar regulator can be adjusted to meet the battery manufacturer's recommendations for bulk, absorption and float rates of charge.

I recommend you take your existing alternator with you to an alternator shop so they can match the pulley size and mounting system to your present set up. This will save time and effort on installation and belt alignment.

The dock at which I keep my boat does not have power. I use a 100W solar panel to meet my requirements when the engine is not running and I have had no problems with this arrangement. This also meets my needs at anchor when cruising.

For batteries I have a 12 V starting battery and two 6V 200A golf cart batteries wired in series for house loads.

In winter I use a 120V 3 Stage marine battery charger to maintain the batteries while the boat is on the hard under its winter cover.

[WillieC]

Once again, Mr. K nails it!

I prefer the 618 regulator because you can program it from a cell phone instead of the clunky reed switch. I think it has a few more handy features. Compare and contrast, reports due Friday, end of class.

[SalishAire]

After our first long A25 trip (Yanmar 3GM with stock alternator) we decided the stock alternator was not meeting our needs as even with solar we were needing to top off on shore power every several days. We have since gone with a Balmar alternator and external regulator and believe we are on the right track. We are still working on getting the belt fully tensioned (I finally realized that I needed to use a different adjustment hole in the brace) as I want to see if I can use its full capacity before I use the regulator to detune the alternator. The nice thing was that the 3GM is common enough that Balmar makes a kit to fit it.

[DesertAlbin736]

As long as we're into compare & contrast, like Norman & Clarice I have a Yanmar 3GM30F engine that came with stock 30 Amp Hitachi alternator & internal reg. In a one thing leads to another project a few years back I upsized the marine toilet holding tank from from 9 gallons to 20, which required moving batteries from the normal location to the storage locker under the starboard bench seat to make room for the larger tank. Because the space under the bench seat is restricted & difficult to get at to check electrolyte levels on conventional FLA batteries I switched to three Group 27 dual purpose AGM batteries, ie one for start & the other two wired in parallel for house bank. That required a different charging regime, which meant using a "smart" external regulator. The stock alternator did not play well with the external reg & was not able to prevent the stock alternator's internal regulator from overriding the external reg and kept charging at 14.1V without ability to step down to 13.4V "float" charge. And so that led to replacing the alternator with a 100 Amp Mark Grasser alternator (similar to Balmar). I'm on a second upgraded version of the digital external reg. Also meant upgrading the onboard shore power charger to a "smart" charger with AGM mode.

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