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Go Back   SailNet Community > On Board > Gear & Maintenance > Volvo MD7A Alternator
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Thread: Volvo MD7A Alternator Reply to Thread
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Topic Review (Newest First)
12-15-2008 08:45 PM
dem45133
"50 degree heel"

cardiacpaul,

Yea, I too was concerned about the line and deck forces when it happened. It actually was exhilerating and I thought about pulling out down wind... but that would have brought me full broadside to the wind for a bit as I was still into it some and there was another boat coming along that way... parralel but oposite direction, and he too was heeled quite well. Caught us both off guard I think. So just had to go with it for a bit. It was all the rudder could do to maintain my course. I'd have had to release the jib and maybe let out the main if it kept up much longer or heeled any farther. It actually was a low wind day... just freak gust... didn't figure it would last very long. I was watching like a hawk though. Never had a chance to see what the knotmeter said, but she was moving right along. Spilled out stuff from the cabinets and my wife (still in the cockpit on the high side...) was hollering my name in that tone we all know. Spooked her a bit. Its going to take a bit to get her used to heeling at any degree.

My wife's back can't deal with the lines or pull - lift anything... so I have to sail her basically without help which means nothing happens real fast as I only have two hands. Since I got all the hardware from the salvage boat... I'm going to mount the lock wedge type line holds behind the capstans for the jib... instead of tying off on the standard type it came with. That way I can release it faster when I need to. The boom line is already set up that way.

I did pull apart three of the little yokes (yea, they have a name, but I can't think of it at the moment) that attach the sail from its eyes to the slide in the mast. But I do not know if it was then or not. I plan to replace all the slides and attachment yokes before spring.

Thanks, Dave
12-15-2008 04:47 PM
dem45133 cardiacpaul,

Thank you. I wondered about the Delcos. There is a single wire internally regulated one that is often installed on antique tractors (I have three) that were originally generator equipped.

So the regulators are different types. OK, I'll buy that I think before I buy anything, I'm going to take this Marchel unit into our local re-builder and have it tested. Its only an assumption that its really bad... but considering it was submerged and also subjected to battery acid when the boat this engine came out of broke up... I assume its been damaged. The starter was.

I believe its regulator is an external unit that was designed to mate to the case (real similar to the delcos).

Well, ok, your not the first one to say the Buccs did not sail well. Since this is the first and only boat I've ever sailed... I have no way to compare. I settled on it for cost vs completeness , and the shoal draft-trailerability reasons. We can not afford marina storage. When we are not using it, it has to live here at home. Basically I have to control when and even IF its allowed to eat money. Sitting in the shed on its trailer, it eats nothing.

Ugly is in the eye of the beholder... and for a 30 year old boat... complete and ready to sail with a good gelcoat and interior, including a running sailor 280 outboard for $800, I think I did well. One person told me I stole it. I didn't think her all that bad a looking boat. What is it that people think is ugly about her. There nothing about it that is anything appreciably different than any other.

Its not, nor was it designed to be a racer... its a cruiser that will sleep six, with 6'2 head room that my 5'11 inch tall wife needs, yet its only 27 ft... so what they all expect? Besides, I come from the power boat planing hull world... ALL sail is SLOW. So I get 4.5 to 5 knots instead 5 to 5.5 for the "racer".... I've always gotten a chuckle out of this.

SO rather than attack the old gal, how about some suggestions as to what realistic mods could be done to make her sail better. From my experience this summer... I think more rudder might be handy. When she heeled over a good 50 degrees on a unexpected gust and wind direction change with the jib full out and both sails reefed as tight as they could go for heading up wind... she heeled WAY over. I was happy it had the high free board and the extra 330 lbs of ballast someone before me added. But the rudder could just barely offset the forces on the bow from the jib. Full over on the rudder, but at that angle I doubt any center mounted aft rudder would be all that effective anyway. I'm serious on this question.... there isn't anything I won't at least consider modifying... Do it all the time.


mitiempo,

Thank you. I'll be using a pair of standard wet battery (deep cycle) batteries. This alt wasn't even hooked up when I salvaged this engine. The batteries evidently were being charged by the 110 system and the solar charger system, or he swapped out a bigger alt and put the little one back in. Who knows?

At least initially, since my boat has none of the typical full live-aboard systems... it is an outboard version with an alcohol stove, an icebox, storage and beds being converted to an inboard. I just need to keep a single starting battery and a single house battery going. No real demand... at least as yet.

I did salvage all the "live-aboard systems" from the salvage Bucc... all rigging, mast, safety rail, windows, front hatch, 1250 watt 110 inverter, 110 12vt permanent install battery charger, all 110 hardware, hot water heater and all water system, reversible heat pump heat/AC, solar charging system, the entire fuel and fuel management system, and obviously the inboard and drive line/shaft/prop and related systems. Thought I did well...I paid a entire $1.50 for the salvage boat, cost about $60 to dispose of the hull pieces, $40 to the marina for miscellaneous things like lifting the 1650 lb block of lead, and that lead paid for the trip's fuel to FL and back. Took six days to demo and salvage.

I think before I buy anything, I'll clean up and take this Marchel unit into our local re-builder and have it tested. Its only an assumption that its really bad... but considering it was submerged and also subjected to battery acid when the boat this engine came out of broke up... its likely a safe assumption. The starter is directly under it... took a bad hit to the solenoid and the armature windings. So I'm not expecting much when I open up this alt.

Thanks again. Dave


PS, wile I was posting this, your pm message (cardiacpaul) notification came but I haven't found it yet. If you addressed any of the above it it, please disregard. I have to go find the PM section on this site... not sure where that is. later...

Oh and at the moment it is basically lights and radio, and starting... yes, it still a simple boat yet. That may change later.. but right know its still a simple boat. Hey, I'm just glad it still had sails!
12-15-2008 02:48 PM
Rockter If your batteries are deeply discharged, your automotive alternator is going to go flat out to hold 14.2 V across the battery.
Standby for alternator currents that are going to be fierce.... I have seen close to 100A on mine, dropping promptly but still high.
I hope that the alternator you plan will take it.

Volvo Penta are incorrigible.
The product is greater than the company, and should be far cheaper.
Avoid.
12-15-2008 02:30 PM
mitiempo Take your alternator with you and the rebuilder should be able to match the mount with one that he has. I bought a 90 amp Hitachi this way for less thgan $100 a couple of yrs ago. The rebuilder will also make sure that the reg is matched as well.
12-15-2008 02:25 PM
mitiempo In the price range you are looking, your best bet is probably a good rebuilt alternator. Look up rebuilders in your local yellow pages - I think you are better off with a good alternator rebuilt as good as new rather than a new one built to be low priced. Your alternator probably has a built-in regulator but check and look for the same. An external 3 stage regulator would be better but that will add to the price considerably. How big is your battery bank? Flooded type? A flooded battery will only accept about 20% of capacity so a large alternator would be a waste of money unless your bank is larger.
12-15-2008 02:15 PM
dem45133 I don't know what you are talkng about. I'm not off topic... I need a low cost solution to my alternator.

What exactly is the difference in the regulator? This little Marchel unit appears to be internally-on unit regulated, although I really do not know. This is the type of information I need.
12-15-2008 11:54 AM
dem45133
Alt research...

Thanks gentleman and keep it coming... still haven't figured out a low cost solution.

I researched a little on Ample and a couple of the other marine specialty alternators manufacturers. Yes, on a large cruiser's with many systems those 100 amp are necessary... but they generally have a lot more hp... so losing 4 hp to the alt is a non-consequence. I, on the other hand, only have a total of 13.4 hp at full rpm. Something lest than that at cruise rpm. So I am limited really to about 50 amp. Original was 35 amp. The tired Marchel unit I need to replace is only 35 amp. Supposedly its takes 1 hp for each 25 amps. so 2 hp is really all I should be giving up.

In think a proven automotive type will work fine. Its actually a nastier environment... trust me. Here in SW Ohio its wet and salty all winter... and I've have to retire several totally cancered vehicles over the years that still ran fine... and so did their alternators. We won't go here since I'm from WI and MN... just learn to drive and I wouldn't have to kill vehicles before their time! Oh, I said we wont go here didn't I? Hummpt!.

One of the things "marine" are touting is heavier bearings... thats likely a good idea... but let me express my experience. I used to kill Chrysler's alt bearings rather routinely back in my hot rod days... BUT that wasn't due to a failure of the alt design... it was because I routinely revved up the engine to 5 or 5,500 rpm... now and then 6k, running stock diameter pulleys. No, the 60s style (pre high rev 4 banger/V6 days) alts were not designed to be routinely taken up to 18-20,000 rpm. They were designed to be charging at about 3500 rom with an engine lugging along at about 1200. Todays alts are a bit better in this regard, with these little engines routinely revving 4k in normal operation. So I'm not worried about the bearings. Belt over tension will effect this too BTW. Since I out grew my young and dumb days... I no longer have that problem, there are 3 of them outside with better than 200k miles on them. Besides, just how many hours do the industry think I'm going to put on this old gal... its a pleasure craft and a sailboat to boot...maybe it'll get 50 hours of runtime in a season. My vehicles get that in less than a month... routinely, all year long.

SO... the question still stands... which $50 to 75 automotive alternator will work with the engine control and monitoring systems on this VP MD7A? Oh, BTW, Volvo Penta dealers have been no help. I suspect they know but aren't saying. I've explained that its not their fault... and that they need to tell VP to become more reasonable... but it is what it is. The only part they'll get to sell me is an $85 head gasket (that shouldn't be over $20 to start with... its a real simple gasket!). Actually VP doesn't want to mess with anything over 10 years old... let alone 30.

Also, do any of you know where I can find on-line information on the various alternator electrical designs? I might be able to deduce from them.

Thanks again... Dave
12-13-2008 09:22 PM
Rockter Jt :

I have the Volvo MD17C, from 1977.

I can recommend highly the 100 A "small frame" alternator from the American-supplied Ample Power together with their (separate) 3-step regulator. I bought that set-up in 1992, and it's still going strong. It is, apparently, capable of 100 A continuous output when the temperature is 93 degC. I trust that is the air temperature. That is very hot indeed. Even in the tropics, your engine room, properly ventilated, will not reach that. Here in Scotland, I always leave the engine room wooden panels off the motor, such that the engine an alternator breathe cold.

Jt, everything hinges on the "continuous output" rating. I bought a rival's 100 A alternator. It lasted one half of an afternoon. I kid you not.

The Ample is not cheap, but it just keeps rolling....

Ample Power Alternators

.... I think mine is the 4023.

Of all things, at heavy alternator loadings, spin the engine fast. Keep those revs up. The big centrifugal fan on the front of the alternator must be kept spinning fast. The alternator cooling thrives on revs. Cooling is everything to the alternator. When you first begin a re-charge, rev the motor and hold the revs up until the charge current drops off. When it drops off, you can drop your revs a bit, and given time, you can drop to idle again if you wish.

I have no other interest in Ample Power.
12-13-2008 03:20 PM
mitiempo Volvo is notorious for their extreme parts prices. I agree that a marine installation can be dryer and cleaner than automotive use. Could it be that Volvo uses a generic alternator before their logo goes on? What is the difference between a marine alternator and an automotive one? I think not too much, but would like the experts to chime in with their .02 worth.
12-13-2008 02:48 PM
dem45133
MD7A Alternator

I know this thread is old, but Thought I'd revive it with my own MD7A alternator need. Does anyone know if the original DEV Marchel A14/35 alternator is actually intrinsic? I am in the process of rebuild the starter... nothing is really intrinsic about it since the drive end is wide open to the atmosphere. Intrisic to me mean fire/ignition proof... meaning 100%. Its a deisel so maybe its not as important when compare to gas.

I am looking for for a generic LOW cost... yea <$50 or 75 automotive alternator that can be wired in. Mount up can be built to suit (professionally.. I have the equipment). There is nothing really magic about an alternator to ever make a 35 amp alt worth $350 or 400 and whatever. Oh and don't tell me about marine environments... ever run in the salt laden roads and rain in you car or truck... they hold up just fine even if the outside gets a bit corroded. Actually the inside of my boat is much dryer than anything under the hood.

Sorry, I guess I'm just too practical and know a little bit too much about mechanical systems. I am really getting tired of the Marine industry thinking that Everyone who happens to own a boat is independently wealthy. My ready to sail 30 year old 27 footer cost $800. If it had cost 8k or 80k I couldn't own it.

Any ideas? Thanks.
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