Adding an alternator to an old engine

[MarkJohnson12345]

There was an article in one of the sailing mags several years ago about adding an alternator to an old engine with a dynostart. I am sure it was the PBO.

I have searched for it, but have had no luck.

Any ideas of how to do a better search , or indeed the mechanics of adding an alternator to and old Bukh engine.

Regards

 

[aztec]

apart from the brackets, which you'll have to make, or source from a breakers... the wiring is peasey!

only two, the thick one from the alt goes to the positive supply on the battery (or you may be able to add it to the feed to the dyna start.. not familiar wiv them)

the little one (signal) runs fron the alt, to a bulb (tells you if it's on/off/broke) and to a swith which supplies it with a positive from the battery (probably ign switch if fitted)

the alt needs earthing, but that should be achieved thu' the alt bracket (unless you've pinched it off an old vauxhall, then you'll need the earth bracket as well)

"proper" marine altanators are special, as they are spark proofed, but with diesel the problem is vastly reduced.

i have used cheapo 18 ACR lucas units (mini/meastro/all the old stuff) you can source them easily, and if you get stuck with a "handed one" all you have to do is undo the 3 main bolts and turn the mount to form the adjustment bracket to suit.(later four bolt one don't do this.

if you don't have an ignition switch you'll have to turn on the alt switch separately, don't run it disconected or you'll glaze the slip rings and it won't work no more!

just remember to turn on before and after starting/stopping engine.

good luck.... now wait until the proper boaties give you the proper/expensive version!

regards, steve.

 

[roger]

Had good advice from my engineer. Make up a wooden bracket for the alternator you are going to fit which uses existing studs etc on the engine. Hand this over to the engineer and he will re make it steel. Dont forget to allow for tension adjustment. On an MD2 engine I had him make up a pulley wheel for the other end of the belt. I used a 2-1 pulley ratio i.e the alternator runs twice as fast as the engine. You will probably have to remake the engine box/companion way steps as well.

 

[john_morris_uk]

You might want to check the speed of the alternator. Alternators need to be rotated at the correct rpm. Find out what your alternator of choice needs and choose the pulley sizes appropriately.

Don't get too hung up; there is a little latitude. Its worth checking though as marine (and other) diesels are slower reving than car petrol engines, and if you get your alternator off a petrol car at the scrap/recycle dealer you might wonder why it doesn't work very well on your marine diesel...

 

[brianrunyard]

Hi Steve.
Happy New Year.
How's your boat?

 

[mark_turner]

Not a Bukh but a Vire alternator installation can be found at http://gofree.indigo.ie/~vire7/index.htm. Might be of some use.

 

[Guest]

funny that my perkins supplied with bog standard Lucas alternator same as the bus uses ...... no problem and I just thinking that engines are run at varying speeds - so as long as speed gets above idle - alternator charges .... or light wouldn't go out .... and my beer cooler wouldn't work !!

 

[Guest]

just remember to turn on .......

<<just remember to turn on before and after starting/stopping engine.>>

Simple to sort that one ..... the power to the starter switch / press button can be supplied via the alternator switch also ..... so if you forget to switch on alternator before starting - starter wont work anyway ... and the red light annoys me when on - so reminds me to switch off when engine stopped. Simple init. /forums/images/graemlins/tongue.gif

 

[john_morris_uk]

Of course the same alternator can be used on different engines. Its just the the manufacturer will usually fit different pulleys.

It doesn't take much to check the revs. Alternators have maximum design speeds of rotation as well as the reccomended for their design output.

I did say that there was some latitude. I know that car engines are at different rpm a lot of the time, but I could also point out that the car alternator is not doing exactly the same job as the average yacht alternator. Doesn't alter my suggestion to check the rpm that your new/second hand alternator is going to run at.

 

[MarkJohnson12345]

Many thanks to all for contributions.

Regards /forums/images/graemlins/smirk.gif

 

[ytd]

I would be careful about adding a second alternator to the existing belt. I added one to a landrover diesel engine many years ago and the belt lasted only 1 hour. Eventually sourced a double crankshaft pully and ran a separate belt for the second alternator wired as suggested. Even so, there was a definite rubber smell after a couple of hours of charging.