High output Alternator for Atomic 4

Question:

: [snip]….. : My question is: Does anyone have experience with putting a high output : alternator on the standard A4 mount?  Is the recommendation of a 30 amp : max alternator overly conservative?  I would rather live with my icebox : than burnout a bearing at an unopportune time. : I had a balmar on my A4 in a columbia 8.7.  The only problem I had with it was the regulator on the Alt. went out and was replaced under warranty.  I used it to charge 2 gel 8Ds and I had a small refer. It worked very well for many years and I had no signs of premature failure or wear on the A4.  I occasionally toasted a belt, but I sort of expected that would happen from the outset.  I kept my old alternator rig in case of failure.  I too used a solar panel. I would second the opinion of others on the list that your charge output should be matched to your batteries ability to take that charge.  That’s why I used gell betteries, my understanding is that they can handle high charging currents better.  I would correct an earlier statement made that the charge tapers off.  The charge level is a function of your regulator. Depending on what sort of regulator you have the charge may be at it’s highest for a while (This is the profile that most sailors desire) I believe that Spa Creek makes a regulator where you set the desired profile (in case you want all of your horse’s to push the boat).  I think Blamr does as well. If you replace your alt. you will also be replacing some big chunks of wireing harness.  The wire to the batteries has to be very large to handle 100 Amps without losing current etc. Send me email if you want more info. Good luck.

Response:

I have been thinking about putting refrigeration on my Pearson 35 which still has the original Atomic 4 engine.  The research I have done tells me that I should count on a battery drain of around 60 amp-hours/day.  I have a 60 watt solar panel which I believe provides about 20 amp-hrs/day in the summertime.  The mounting of 2 more panels would be crowding things, so I would like to look into a high output alternator/charging system.  The problem is that I remember reading in the A4 manual that the 30 amp standard alternator is the max recommended for that pulley and bearing.  Because of my engine installation, a flywheel pulley is out of the question. My question is: Does anyone have experience with putting a high output alternator on the standard A4 mount?  Is the recommendation of a 30 amp max alternator overly conservative?  I would rather live with my icebox than burnout a bearing at an unopportune time. Thanks, Mart D. — Mart Dismukes           Loral Data Systems      Fax   1-941-378-6773 Sarasota, FL, USA          Pearson 35′          Can’t speak for Loral

Response:

– Hide quoted text — Show quoted text -My question is: Does anyone have experience with putting a high output alternator on the standard A4 mount?  Is the recommendation of a 30 amp max alternator overly conservative?  I would rather live with my icebox than burnout a bearing at an unopportune time. Thanks, Mart D. — Mart Dismukes           Loral Data Systems      Fax   1-941-378-6773 Sarasota, FL, USA          Pearson 35′          Can’t speak for Loral

I don’t have information about limits of bearings or mounts but I wonder about horsepower left at the prop.  I know our atomic four, even newly rebuilt, does not have a lot of surplus power to push around our C&C 35. I would hate to lose a substantial amount of the little horsepower there is to driving a larger alternator. Peter Zarzecki

Response:

I would not worry too much about stealing power from the prop, as the alternater is only loading the engine when and if the batteries are taking a charge. Charged batteries do not present a load. Also the load tapers off quickly as the battery charge builds up. My concern would be the load on the engine shaft bearing. My Farryman 24 HP engine can drive a 65 Amp alternater, but not larger. Anything larger requires a double pulley, anyway. I would also be suspicious of the 60 Amp Hour daily estimate for refrigeration. I would expect that in the real world the requirement will be higher than that. Closer to 75.

Response:

Peter responded with: I don’t have information about limits of bearings or mounts but I wonder about horsepower left at the prop.  I know our atomic four, even newly rebuilt, does not have a lot of surplus power to push around our C&C 35. I would hate to lose a substantial amount of the little horsepower there is to driving a larger alternator.

The Balmar alternators come with instructions for a switch to cut out the alternator at the users discression – leaving all the engine power for the prop. But another question that should be asked – are the batteries big enough to take advantage of the big alternator’s output?  For example, my 8D’s in parallel only accept 80 amps or so for about 10 minutes in the morning.  Then they accept around 50 for about an hour, then fall off more until I reach my sick-of-the-noise limit.  The extra money spent for a 100 amp alternator may be wasted if you are charging smaller batteries. –Alan

Response:

[snip]….. My question is: Does anyone have experience with putting a high output alternator on the standard A4 mount?  Is the recommendation of a 30 amp max alternator overly conservative?  I would rather live with my icebox than burnout a bearing at an unopportune time.

I would recommend calling Don Moyer at Moyer Marine.  He specializes in A4s and knows all of the tricks.  If it’s been done, he more than likely seen it. His A4 newsletter is useful for anyone who owns one. He’s at 717 564-5748 in Pa. Steve Let us know what the outcome is, I’ve made similar considerations and would love more info too. (I have no business interest in Moyer Marine, I’m just a happy customer)

Response:

Haveing done research into this also, I found out that the A-4 had an optional 75 amp charger. This should work, without loading the engine too much      Carl

Response:

But another question that should be asked – are the batteries big enough to take advantage of the big alternator’s output?  For example, my 8D’s in parallel only accept 80 amps or so for about 10 minutes in the morning.  Then they accept around 50 for about an hour, then fall off more until I reach my sick-of-the-noise limit.  The extra money spent for a 100 amp alternator may be wasted if you are charging smaller batteries. –Alan

I did not mention it, but appropriate batteries and 3 step charger are part of the plan if I decide to do it.  However, before I throw that much cash at the problem I would like to resolve in my mind the question of a high power alternator on the A4.  The current batteries with the solar and standard alternator are adequate for non-refrigerated cruising. I agree with previous posts that robbing power to the prop is not a problem. Cheers, Mart D. — Mart Dismukes           Loral Data Systems      Fax   1-941-378-6773 Sarasota, FL, USA          Pearson 35′          Can’t speak for Loral

Response:

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