• Untitled Document

    Join us on March 29rd, 7pm EST

    for the CBEC Virtual Meeting

    All EYO members and followers are welcome to join the fun and get to know the guest speaker!

    See the link below for login credentials and join us!

    March Meeting Info

    (dismiss this notice by hitting 'X', upper right)

More AMPS

Randy Rutledge

Sustaining Member
Has anyone installed of the single wire Delco marine alternators on an Atomic 4. it will fit on the bracket, only question is will the V pulley match A4 aux drive?

This alternator has the coastguard end cover. Thoughts and experience needed. I just want a little more than the 37 amp that is on it now.
 

Glyn Judson

Moderator
Moderator
On the subject of alternators.

On the subject of alternators but not directly to Randy's question, I want to offer a thought to stimulate conversation. Years ago and I mean YEARS ago I read a piece in one of the old sailing mags about a fellow who provided himself with a high output alternator and paid a budget price for it. He fitted a rebuilt bus alternator which supposedly had a far higher output than what originally came with his marine diesel engine. Has anyone heard of or done this and can you please share your experience on the subject? how would it compare to a high output Balmar or equivalent? Thanks, Glyn Judson, E31 hull #55, Marina del Rey CA
 

Randy Rutledge

Sustaining Member
Glenn, I must have read that same article, it was a diesel school bus alternator, single wire Delco. Remembering this is what made me Google Delco marine and there they were. I think the one I am looking at is the same unit with a marine end plate with flame arrestor screen vents it looks just like the Moyer marine 120 amp unit that is over $300 and the 105 amp unit I am looking at is coast guard approved and is $65 with free shipping. If you have a diesel the Delco bus unit should work but on a gas engine you need the marine unit.

I have test fit a Delco on the A4 and it fits fine.
 

Glyn Judson

Moderator
Moderator
Alternator, small world.

Randy and all, What a coincidence that you and I would have read the same article so many years ago. Of interest, several years ago I had my original Yanmar 30 amp alternator rebuilt locally for around $90.00. I did do because I worried about power loss with using a rebuilt, larger output alternator. Granted, my alternator was from my Yanmar diesel engine so I didn't expect to see any spark suppression baffles or whatever but when I asked the guys in the shop if it looked any different from an automotive one, they declared it was identical. I want to say that they recognized it as a Mitsubishi part. So this begs the question, why are we all not buying automotive alternators at a fraction of the cost of a "marine" unit??? Also the question of load created from a large alternator came up the other day with Greg Ulrich, Christian Williams and me while we were having lunch and visiting each others boats. Christian offered that there was a 1 hp loss per 10 amps (did I get that right Christian) and that his 150 amp Balmar seems to be serving him well fitted to his M25. Comments anyone else? Now all of a sudden I'm very interested in trying a bigger alternator along the lines of a bus unit. Thanks, Glyn
 

Christian Williams

E381 - Los Angeles
Senior Moderator
Blogs Author
1 HP per 25 amps. My Balmar 100 puts out initially (briefly) about 80 amps if the batteries are down to 70 percent.

The real strain when a bigger alternator is working hard is on the belt, but I haven't seen any dust or problems.
 
Last edited:

footrope

Contributing Partner
Blogs Author
Cars don't have the confined space issue

For one, the engine compartment/cabin on a car can't be made into a gasoline vapor bomb quite like a boat engine compartment and cabin. Both of my alternators are automotive types.

The diameter of the larger alternator could be a problem, too.

I have a second alternator, an old 190 amp (Delco I think), added just for the house batteries. It noticeably loads down (~100 rpm) and heats up the engine, but it'll put out all juice the four AGMs in my house banks can handle.

Belt dust does collect, mainly when the belt is new. If the batteries are low, it is a good idea to let the engine run a few minutes to warm up the belt before engaging a large alternator. My 190 amp is manually controlled so that it doesn't run loaded all the time, and that takes care of the belt warm-up.
 
Last edited:

Randy Rutledge

Sustaining Member
Think I will order the 105 amp Delco @ $65 and keep the 35 as a spare. The Delco is ignition protected, a must for my application. I may have to change the pulley on the accessory drive to 1/2".
 

adam

Member III
Last edited:

Randy Rutledge

Sustaining Member
Adam, the 105 will fit under the engine cover on the E29 the sound proofing will need to be cut above to provide clearance. I got a reply today from the seller of the 105 and has a 3/8 V pulley. Remember as the voltage/resistance of the battery rises the amperage will drop on any alternator. I am going for the higher charge rate, installed a Guest 30 amp 2 bank charger for when at dock and may install a pair of group 29s to go with my pair of 27s. I plan to do some extended time on anchor with TV and comfort. Will need a Honda inverter 2000 to run air conditioner. Also looking at icebox conversion to Frig and that will be a demand on the battery bank.
 

Vagabond39

Member III
Vehicle Alternators

There are plenty of high amperage alternators available. If you don't ming arcing and sparking in a confined space with fule fumes, and oily bildges. Just look at the ones in th emergency vehicles that resopnd.
 

Randy Rutledge

Sustaining Member
Oh but I do mind arcing and sparking, I like to go fast but not in all directions at once i.e. and explosion. ignition protected and C G approved is a must for me and the 105 Delco is both.
 

Christian Williams

E381 - Los Angeles
Senior Moderator
Blogs Author
HOw are these powerful inexpensive alternators regulated? Or do you just turn them off before they boil the bath water?
 

Bill Sanborn

Member III
Hi Output Alternators on A4

Be skeptical of the advertised rated amps. Often the detailed specs show this high output only with the alternator spinning 7,000 to 8,000 rpm. You will never achieve this from an A4 which I doubt is ever run at even 3,000 rpm, 1800 to 2200 is more like it.

Furthermore the "pulley" rpms are less than engine rpms by about 1/3. I hand cranked my A4 counting the revs. The pulley turned at 2/3 of the engine, and there
is no room to change pulley diameter. With a single 3/8" pulley, 100 amps is about the max a single belt will handle.

I am using a "Silver Bullet" alternator advertised at 102 amps with a smart regulator. The max output I have ever seen on the gauge is 60 amps and that was after 2 nites at anchor and using the anchor windless.

You might think about using a shunt type ammeter rather than running the alt output to the cockpit gauge and back to your batts.

To get the most amps from the A4 find the alternator with the highest output at low rpms.
 

Randy Rutledge

Sustaining Member
Thanks Bill. I know max and real in amps or any thing else can be far from the same. I run the alternator output to the battery cable lug on the starter to feed the output to a heavy cable with as short a run as possible. I have a volt meter rather than an amp meter.
 

tenders

Innocent Bystander
I remember reading that school bus alternator article too! I think it was in an early 2000s issue of Good Old Boat, is that possible?

This general topic has been discussed at length at moyermarine.com. Here's what I've taken away from it:
- 1HP is theoretically about 750 watts, which at 12V is 62.5 amps. At 14V it's 53.5 amps. Considering the effects of energy loss, figure 3.2HP to create 100 amps or 1200-1400 watts of actual output. The A4 has enough juice to do this, even underway, but since the engine doesn't run at close to 30HP output you're going to feel it if you're underway.
- Single belts start slipping around 100 amps; you could outfit the aux drive and the alternator with double pulleys to transfer more power, and it is not too difficult to get a custom pulley made for the aux drive, but...
- The alternator has to be spun at an insane speed (by A4 standards) to put out anything close to max output. The pulley on the alternator would have to be so small to achieve that speed that there would be very little surface area and belts would start to slip, so...
- Alternators are rarely able to put out much more than half their rated output

I installed a pretty good-sized inverter to provide power at my mooring for tools including a heat stripper and a Shop Vac. My takeaway from this discussion was that to get a meaningful amount of juice out of my A4 for this project, a pretty big alternator would be necessary, and that there was no easy way to get 1500 watts out of the inverter without tapping some of the battery reserve.

I ended up getting a good deal on a used-and-turned-out-to-be-broken 120-amp Moyer alternator, had it rebuilt, and it's worked quite well. Single belt, I think I had the pulley replaced to fit the stock A4 aux drive, it doesn't slip, but probably never puts out more than 60 amps even when the heat gun and Shop Vac on the inverter are dragging down the battery voltage and the engine is spinning at 2300 RPM.

So Randy, if you're thinking what I was thinking, I would encourage you to go big with your next alternator or stick with the status quo. I don't think a "slightly" larger alternator is going to do anything for you.
 

Randy Rutledge

Sustaining Member
Thanks Tenders, I don't expect miracles, just a bridge between long motoring's and stops at shore power. Mostly will use the inverter for a movie or two and minimal other power drain unless I do the frig conversion to the ice box. I am lining the icebox with 2" foam and glassing over that for a finished liner. This boat just keeps asking for MORE. I hope I enjoy the thing when I get it finished, I will have 5 hours travel each way to the boat. Current travel is just less than and hour and a half to the sailing club.
 

footrope

Contributing Partner
Blogs Author
HOw are these powerful inexpensive alternators regulated? Or do you just turn them off before they boil the bath water?

The large alternators should use the same external regulators as a smaller one. The regulators do not carry the high current, they just monitor the battery voltage and apply the correct voltage to the alternator field which in turn controls the alternator output. I have a pair of Cruising Club of America regulators (? - need to check on that, but I'm pretty sure) that are identical except for their max voltage and duration of charge settings. One is for the 50 amp start battery alternator and the other for the 190 amp house alternator.

My start battery charges for about 40 minutes and the house banks for about 2.5 hours.

When I describe the two charging systems I inherited when I bought my boat, I am not advocating for people to add a second alternator, especially to a small engine. The electrical engineer PO of my boat did a pretty good job of adding it and the second house battery bank. He and his admiral had certain requirements for Pacific NW cruising and this is one example of how he carried it out. After we figured out exactly how the system worked (and after I got the 190-amp refurbished) it has been reliable and logical to operate the second alternator.
 
Top