Date: Thu Oct 18, 2001 7:11 am

I'm in the process of upgrading my electrical system to dual banks of golf cart batteries. Should I upgrade to a high output alternator with either single or dual outputs? The Balmar most suitable for my Bukh would put out about 70 amps. My current alternator is rated at 35 amps. What do you think?

Date: Thu Oct 18, 2001 7:48 am

Considering that the result in increasing the ampere capacity is essentially the amount of time needed to recover a percentage of lost charge you will appreciate higher output alternators.

If you are living aboard and dockside the Freedom 10 with the 2000 monitor will do a great and silent job of keeping the batteries constantly topped up and precisely monitored. Even weekend cruises take a toll on the batteries. By being able to understand what makes batteries happy (by the numbers) your alternator charging cycles will be dictated as much by how you use your electrical system and how efficient you charging system is. Read up as much as you can about how batteries discharge and recharge. The regulator is at least as important to the system as is your choice of alternators. Recently the newer generations of smart regulators have become far more reliable that their predecessors. You may find a basic system just fine for local jaunts as well as extended cruising as long as you completely understand the predictable nature and the care and feeding of batteries in relationship to your intended usage.

Unless your engine crank pulley is capable of providing two belt grooves you'll find that the 70 amp is about all you will be able to use at maximum. The load co-efficient for a single belt drive is maxed and you tend to replace and adjust belts frequently. When installing the higher amp alternator be absolutely certain that the drive pulley and all of the driven pulleys are precisely aligned to prevent uneven wear at the V belt sides.

Date: Thu Oct 18, 2001 8:23 am

My boat came with a Heart multi-stage regulator. I'm not sure how effective it is at this time since the factory alternator already has an internal regulator.

Date: Thu Oct 18, 2001 8:52 am

PS's mailport (5/15/00 issue) had an artical on inexpensive alternators. The author was happy with a Delco-Remy part #A1358 (a school bus alternator) which had an internal regulator. He said the output at 1000 rpm's was just over 100 amps. At 2500 rpm's it put out 135 amps. PS didn't comment on the unit however.....FYI

Date: Thu Oct 18, 2001 10:54 am

We have two banks of golf cart batteries under the locker on the starboard side of the cockpit. They are kept charged by

  1. a engine driven 55 amp alternator with a 65 alternator spare.
  2. a 60 watt solar panel mounted on the bimini.
  3. a 65 amp alternator, driven by a towed line and propeller.
  4. a Redwing wind generator that's hung in the rigging at anchor.

We believe in multiple ways to generate power and therefor have not ever been without adequate power. I might add that our refrigeration unit draws 27 amps per hour.

We also believe in simple systems, because once outside the U.S. in many areas of the world even getting parts for the simple systems can be difficult if not impossible.

We also believe that if you have a system on board you should have the skills necessary to remove the unit, dis-assemble it, repair it, and re-assemble it to a like new operating condition. This limits us to simple technology as I'm not of the genius catagory.


1517 Feb 11, 2002

I will also be installing a Hehr Proline 120 amp alternator on my engine in a couple of weeks. It has an external regulator that you can set so that the alternator is turned off until you get your engine started in order to reduce the load during cranking. Iíll let you know how it perfoms.

James, Niko 91

1518 Feb 11, 2002

James, Iíve been watching your questions (and the corresponding answers) with considerable interest. By the time you have completed all of these tasks, there may be a number of us that want to hire you to rebuild our Seawinds as well (Iím only half joking).

Tom Lix, Pequod

1526 Feb 11, 2002


I may caution you that most of us have found that single pulley, high output, alternators will have a difficult time with drive belts. The friction surface ratio is well below all recommendations from almost all manufacturers.

Drive belts for alternators on the W-30 in the stock configuration offer only about 160 degrees of contact with the alternator pulley. Friction increases substantially after the contact increases beyond 190 degrees.

I will be trying to adapt a "continuous" belt tensioned, used by General Motors to continually tension their serpentine belts on V-8 engines to not only supply constant tension but increase the belt contact surface. Even my Delco 65 amp can get very testy under high initial loads. Iíll report this spring on failure of success.

Paul Sea Quill # 29K

1546 Feb 13, 2002


In our previous boat, we lived mostly on the hook for five years with a Powerline 110 amp alternator driven by a single, skinny, belt on the Universal. It was a challenge. First, go to NAPA and get the best quality belt you can get, preferably one with "teeth". Next, and I might get an argument on this, but keep it tighter than you think it should be. The greatest wear occurs when the belt slips - and it will slip if it is not really tight. Check the tension soon after installing a new belt as it will stretch. Finally, carry extra spares and check the belt often. Running the belt tight may have put a strain on bearings, but it was still working fine when we sold the boat last April. We owned the boat for a total of 11 years, with the last five full-time live-aboard.

Our Westerbekes have a wider belt and the raw water pump has its own belt, so I really feel it will not be a problem. I have a Balmar 110, which only just fits in the space for the old alternator. I had to change the adjuster arm. Have not been on the hook much since we bought DAYBREAK, so canít report on performance, but I see very little belt dust.

Good luck,

Gil Steinfort, KP2U

1533 Feb 12, 2002


I appreciate your input on this subject as well as the others.

I contacted the folks at Crinan Marine in to inquire about installing a higher output alternator and the Hehr 120 was recommended. I too questioned the use of only one pulley on an alternator of that amperage. One of the technicians assured me that a single pulley would work, because the relationship of the Bukh flywheel pulley to the alternator mount allows for a high degree of belt contact on the alternator.

James, Niko (91)