Automotive Style Alternator??

[Sleepy850]

I have heard a few bits here and ther about using an Automotive style Alternator (spark shielded 1-wire inboard alternator perhaps) but there was discussion about pulleys and side loading the top crankshaft bearing, so i started thinking about it, what if the alternator were mounted above the flywheel, on a motor like mine for example a '74 mercury 850 4cyl (S/N # 4100979), i think I could do that, and maybe even use a hood and cowl from a Inline 6 motor and have the whole thing covered so it looks nice too<br />I found this web page (http://www.angelfire.com/mo/bucketheadsgrotto/onewire.html) that has a low-rpm cut in self exciting alternator, so the fact that it would be turning at less rpms could be overcome., So I guess my questions are;Would this work with a battery driven CDI system (which is what I think I have) Is the feasible?, Is This a good Idea? Could it be reliable?<br />thanks in advance for

 

[Sleepy850]

Re: Automotive Style Alternator??

^that should read thanks in advance for any help

 

[SlowlySinking]

Re: Automotive Style Alternator??

Hi Sleepy850, interesting question. Wonder why you're trying this, doesn't your outboard engine<br />have a built in battery charging system? Mounting the alternator above the outboard and driving it directly from the flywheel would require a perfect axial alignment and some quality brackets, you might be able to use a flexible coupling similar to ones used on electric motors to compensate for any minor mis-alignment. Also check to see if the alternator is rated to turn at your outboards maximum RPM's, this is very important with side mounting depending on the pulley size ratio, seriously over-rev it and you might see shrapnel fly. Side mounting would work given that the electrical load on the alternator should be much less than in a car which has so many electric devices available to work simultaneously, so the side loading on the outboard engine crankshaft bearing would be minimal unless you run the battery way down, even then it would be short term until the battery is re-charged so I doubt that you would have a problem, however, with cage bearings I suggest you get a professional opinion on this. The side loading would be proportional to the current the alternator is producing. You also noted that your current CDI ignition runs from a battery, is this by design or due to your alternator being inoperative. I mention this since the battery puts out 12 volts, but with the alternator going the system voltage in a car will run up to 14-15 volts which may damage the CDI if its rated for 12 volts maximum. And, don't even think about doing this without having a battery connected to the alternator to help regulate the system voltage, alternators can easily produce about 20 volts DC without a battery connected. The alternator in my wifes Taurus developed an internal short which produced a system voltage measured at 19 volts, every idiot light blinked and the over<br />voltage fried many parts, fortunately under warranty, and I was also lucky, many Fords burned from this problem. In any case think this through carefully and good luck, Ken

 

[petryshyn]

Re: Automotive Style Alternator??

Sleepy<br /><br />The idea of mounting an alternator above the fly wheel would work if you are precision with the brackets and alignment. You will also need a marine alternator for its spark suppressed characteristics. The fan would also have to be changed to a omni directional style. (blades are straight out from the pulley axis).<br />A love-joy coupling would work for that application. <br />I would advise you to go with a three wire alternator, rather than a one wire. (minimal wiring required) They are by far better for voltage control....<br />

 

[Sleepy850]

Re: Automotive Style Alternator??

I suppose my reasons for wanting to try this come from liking to tinker with things, I like the idea of having a higher amperage regulated charging system and the ability to have an easily attainable replacement part, The stator went bad on my motor, well rotted wiring, etc....the new one is a bit pricey, especially for an extremely simple devince that puts out around a dozen amps and is unregulated, I'm starting to scrap the idea of the top mount in favor of side mount but I am considering a opposed pulley to counter the side load although I probably won't do that anyway. I guess i should clarify and i think i'm correct that it's an electrical system operated CDI system rather than Magneto (are all CDI's?)<br />but I have found web sites with side mount alternators on outboards but they aren't very detailed about how they accomplished it. <br />I'm looking at a self-energizing GM-style alternator that makes 22-amps @ 900 armature rpms this company modifies GM alternators for use on low speed goverened diesels for farm and industrial use. I'm a bit concerned about unbalancing the flywheel by mounting a pulley on it. If and when I do this, i don't intend to do it half way I mean to better the original design so I'm trying to take everything into account<br /><br />Thanks for the comments, suggestions, and thoughts<br /><br />-Sleepy850

 

[petryshyn]

Re: Automotive Style Alternator??

I've seen some small alternators (4"-5" diameter) from motor cycles that would do the job. 30 amps or so. There will be minimal side loading if you use a cogged belt....

 

[Sleepy850]

Re: Automotive Style Alternator??

Hey Schematic, <br /><br />how does one hook up all the wiring on a multi-wire alternator?

 

[clanton]

Re: Automotive Style Alternator??

If you look at a new Merc injected 2 stroke, it has an automotive style side mount alterntor.

 

[petryshyn]

Re: Automotive Style Alternator??

The wiring is simple to hook up. <br />>One large wire to battery<br />>One small wire to battery<br />>One small wire to acc. terminal on ignition switch<br />

 

[Sleepy850]

Re: Automotive Style Alternator??

I have seen one of these small alternators on a motorcycle, I can't remember what brand it was it just caught my attention that there was this little nippondenso-looking alternator sitting in the "V" I could be mistaken but I believe I have seen a similar alternator on a 20-something HP Kohler or Onan commercial engine (a welding machine or air compressor maybe)..<br /><br />Any suggestions on brackets and cogged pulleys and belts (specifically where to get them)?

 

[Sleepy850]

Re: Automotive Style Alternator??

I don't know if I have mentioned it, but I really appriciate all this help and info you guys are giving me, when I first thought of the notion I imagined getting laughed at, etc....and then I found out others had done this, so I figured I could too.<br /><br />Thanks<br /><br />Sleepy850

 

[ICEMAN]

Re: Automotive Style Alternator??

OMC had a motor called a saildrive. It was used in sailboats. It's basically an outboard motor, mounted in the boat, meeting inboard specs. This unit utilitized an MARINE automotive type alternator. It is mounted with brackets and driven off the flywheel with a Vee belt pully. There doesn't seem to be much of a problem with the set-up. I haven't seen an alternator wear out, but then again, it's on a sailboat, how long does it run for?