How is a Marine Alternator different from Automobile Alternator??

[MrCramp]

Wanting to fit an alternator to a Volvo MD2B to charge batteries and to not use chargeing off the Dinostart. Can sort out the mounting brackets but wonder whether a normal car alternator (off a Peugeot 306) can be used or is there something special about a "Marine" one.

I can see I will probably need a smaller pulley on the car alternator as the Volvo runs at 750 to 2000 revs and the Peugeot runs at 1000 to 3000/3500 revs.

What happens if there is a load on the alternator but it is running too slow to produce enough current, does it end up getting hot?

Any advice appreciated. Thanks.

 

[Andrew_Fanner]

Marine could be double insulated. The standard car one will use its attachment to the engine as the earth return. If you are stonkingly lucky it will be battery sensed as opposed to machine sensed, that will charge your batteries more effectively.

marine is also more expensive because boaters are gullible and rich.

Allegedly

 

[VicS]

Check out the earthing arrangemnt but an MD2B wont be insulated although I believe Bosch Dynastarts have an earth terminal.
Not likely to be battery sensed I'd think .. never are on cars are they?

Possible that the car one will have an earth connection.. not always earthed through their mountings.

If you don't change the pulley it probably won't generate at low speeds but it's not going to cause overheating. Just wont supply the current to the load ( battery)

 

[oldsaltoz]

Also note, many alternators also supply the feed for the rev counter. so look for three terminals.

 

[BGW]

Are marinised alternators not also designed to be sealed - so there are no sparks to ignite any flammable fumes?

 

[alan17]

Marine/automobile alternators

Probably the price!

 

[oldharry]

I was told by the local alt repair shop that 'Marine' alternators use more in the way of non-corroding materials, such as brass. However, car type seem to survive well enough with a modicum of care in a fully enclosed engine compartment. Guess its more important in an open launch where spray can reach the engine.

 

[Marsupial]

Marinising Alternators

If you can find a copy of the Yanmar manual for 4JH series of engines it describes within in minute detail how to marinise a Hitachi alternator for marine use on a yanmar marine engine, I wont recount the minute detail here because most (as usual) wont believe me, its better that you find out for yourself.

 

[MrCramp]

If you can find a copy of the Yanmar manual for 4JH series of engines it describes within in minute detail how to marinise a Hitachi alternator for marine use on a yanmar marine engine, I wont recount the minute detail here because most (as usual) wont believe me, its better that you find out for yourself.

Thanks rof all the info. The standard 4JH doesn't have the Alternator manuel included but I found the following link to the Cruisers Forum which contains the conversion info. It is a bit above my head but I will print it off and study it. Posted the link in case it is of use to anyone.

http://www.cruisersforum.com/forums/f14/smart-regulator-for-yanmar-alternator-7620.html

 

[VicS]

I dont know why you would want to "convert internally regulated or "N" field alternators into the "P" field externally regulated type allowing them to be regulated by external regulators."

Take the unit off the Peugeot and use it as it is ( except for the pulley) You'll need connect a warning light, fed via the "ignition switch" to the appropriate terminal and if it is a negative regulated type I think you'll need to connect a supply from the switch to another terminal, but whatever wire it up as it was on the car. Dont forget the main output from an alternator goes directly to the battery ( or isolator).

Standard internal positive regulated job on my Peugeot as far as I can see from the WShop manual. Its either a Bosch one or a Valeo one never looked at to to discover which!

Got a wiring diagram for a Hitachi negative regulated job if needed though.

 

[charles_reed]

Marine alternators (Lucas do a 90 amp one), are always double-insulated and have ss bearings. I replaced the 35-amp Hitachi on my Yanmar with one, and had to earth it to the engine to get it to charge properly (the field was fed through an Adverc regulator).
The Valeo alternator from a Peugeot, will work, but its output will not suit a marine diesel's much lower rpm than a petrol-engined car.

 

[TrueBlue]

You may have a challenge with sourcing the pulley.
Boats use industrial size and type of belts.

If I'm right in your case, take measurements and contact www.bearingboys.co.uk and they can supply both pulleys and belts by post.
If the pulley required to get the correct revs: is small, I suggest you buy a toothed belt as they last a lot longer than the standard variety.

Taperlock bushes and pulleys can work out a lot cheaper than a one piece pulley

BBs are very helpful if you phone or email them.

Usual disclaimers - satisfied customer

 

[Tropic Cat]

Marine alternators have a spark arrestor missing from the automotive equivalent. This arrestor sort of looks like a piece of screening.

Here in America, Auto electric shops have this material and can add it to any alternator they are reworking.

 

[MrCramp]

I dont know why you would want to "convert internally regulated or "N" field alternators into the "P" field externally regulated type allowing them to be regulated by external regulators."

.

Thanks for that comment Vic. I did not know why that info. might be required, (unless used with Advarc/Sterling unit maybe) and I certainly did not understand the detail.

I understand the pulley problem, (Peugeot was a diesel) and the differing normal revs, and I will make sure the unit has proper earth and other wires as suggested.

Thanks to all for replies.

 

[Stu Jackson]

You might be interested in Reply #16 in this thread. While not an "automotive vs. marine" issue, it does point out the differences in cost for marine material even when from the same vendor!

http://c34.org/bbs/index.php/topic,5686.15.html

 

[Marsupial]

The Difference between Automotive and Marine Alternators

PAINT! yes thats all PAINT, and the Yanmar repair manual tells you where to put it!