Alternators for M-40

What size and make alternator are you folks using on your Universal M-40s? I am planning to upgrade the older unit I have now and am looking for some feedback. I will probably go with a Balmar and shoot for the 100-125amp range. Not sure if I can get a 3/8" belt model that big yet... I just picked up a new Xantrex regulator with decent charging profiles and a temp sensor. I guess I'm a bit of a whore for Xantrex products... Going for first weekend cruise this weekend. Have yet to really test my new electrical/battery setup for an extended period with refridge and all other stuff running. Been out for a lot of daysails and night sails but no full weekends yet. Really need to get a decent battery monitor like the Link 10 or new units. Right now I just have volt meters for both battery banks.

Thanks,

Alternator Setup

I am in the process of installing the Balmar Type 7 80 amp on the 35II M-30-4
The largest on a 3/8 belt is 80A. Will work fine with (4) 6V Cart Batteries-
House and (1) 12V-Start System. Also installing (24) Breaker 12V Panel and
(4) Breaker 120V Panel with Mains and Digital Amp/Volt Guages.

Good Luck on your New Alternator System !

Excess power

Hi Ted,

I don't know what the original electrical system on the 38-200 is like but there are a few key questions you should consider. It sounds like you spent this past weekend evaluating your current system? I have the benefit of several conversations with the electrical engineer, who I bought the boat from, about the electrical system he installed. Below seems to be the essence of the initial thought process.

1. How many batteries are you planning to carry around?
2. How often do you want to have to run the engine for charging? (or, How fast do your batteries get down to 50% charge when your do your normal "cruise stuff?")
3. How long do you want to run the engine to charge your batteries?

Actually, he may have started with "Darling, what modern conveniences do we have to install to make you happy on an extended cruise?" That would have changed question one above to "Where am I going to put all those batteries?"

I have happily inherited a pretty good, but complex, electrical system. The engine battery is a gel cell and it charges through an Alpha regulator off the standard 50+ amp alternator. Mine is a Prestolite 51 amp replacement. The house system has four 100 amp-hr AGM batteries in two banks. They charge from a 190 amp alternator (see the lower alternator in the picture) and a second Alpha regulator. I think this one is a Delco, but it has no external marks on it. Normally, the large alternator is de-energized. When I need to charge the house batteries while away from shore power, I have a power switch for the second regulator and a switch for the alternator (field current switch, I think).

With an Adler-Barbour refridgerator, 12v incandescent and fluorescent lighting at night, the instruments running when anchored, anchor light at night, it takes about 2 days to get into the 50% discharged state on the house batteries. It takes two hours of engine running to charge the batteries back to full. I've seen the house banks take 80 amps initial charge from the 50% state.

I have an out of production three-bank battery monitor that counts amp-hr cumulative consumption, which is very useful. It also has charge and discharge current readings in addition to voltage. I carry a Xantrex regulator for a spare.

P.S. The water heater peeking over the motor is 12 gallons.

On my M-25XP I have been runniing a 100 amp Balmar alternator using a 1/2" Gates Green frational HP belt that sits a little proud on the engine pulleys, but is the right size for the alternator. My thinking is that the crankshaft pulley is twice the diameter of the alternator pulley so there should be no problem if the crankshaft pulley isn't fully seated. [There is more belt contact area on the engine than the alternator]. The side angles on a 3/8" and !/2" are the same which I have verifyed with the manufacturer. The NAPA # is 4L410W-FHP and is made by Gates. The length of yours would be different. Size does matter.

I do not get 100 amps from my alternator as I only have a 210 ah house bank.

Tom Metzger
E-34 Xanthus

All those batteries

Craig- where did you put all those batteries (or rather- where did the PO put them). I have two series 31's for the house and one 27 for the engine and even then I can't get the covers on the 31's.

Battery Locations

Geoff,

The engine start battery is in the nav station seat, inboard. Probably the normal location for it. My nav station is to port at the base of the companionway stairs. The battery switches are there, too.

One house bank is at the forward end of the aft double berth, which is part of the port aft "stateroom" which includes the nav station. I think this is the normal location for the house batteries on the older E-38s, between the engine and the electrical panels.

The second house bank is under the aft dinette bench, at the inboard side. The fit is very tight. He also put the 35 amp AC charger there, which has a user-adjustable charge profile he set specifically for the AGMs. The Heart Interface inverter/backup charger (50 amp) is also located under there. Gave up a lot of storage, though.

The AGM house battery dimensions are about 13" x 6-1/2". Not sure how tall they are, or what their Group number is. I'll be out there today; might take a couple pictures for my records. If you would like to see them I'll post them or send them to you directly.

I do not have any battery trays or boxes which is a no-no by today's AYBC(?) standards, I guess. There may not be room for the aftermarket trays available today, by my measurements. I am thinking about a single custom tray for the dinette pair. I have covered the exposed terminals with a piece of plexiglass sheet, attached with cable ties.

Battery locations

Craig,

Thanks. I have the same set up (E381) in the nav station area. Aft seat of the dinette is a good place to put them to keep them close but yeah- that is alot of storage. I also currently have my fluxgate compass there for the autohelm but as that whole unit is currently posessed and draws way too much power I may remove and consider the additional battery option.

If you get a pic I'd appreciate seeing it.

Thanks,

G-