Volvo Penta 3.9 Sail - how to connect to the batterie?

jaxman

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Hi,

I've got a Volvo Penta 3.9 Sail outboard motor, it's a little two stroke. I've received this little nice thing just yesterday and now, I've got a big question: How to connect to the battery? There are a couple pages of a partial manual, telling me, that it should be possible to hook the motor up to a electric system or to a battery, but pages are missing, telling me where the connector / point to connect the wires is. I only know so much, tha tthe motor should have a rectifier and produces electricity, does anybody know this motor? Has anybody an idea?
Thank you for your info.
 

VicS

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[ QUOTE ]
Has anybody an idea?

[/ QUOTE ] Got the manual for the VP39 and VP51 (Still got the VP51 in fact) The standard model VP39 gives an AC output for 4 x 6volt 5watt bulbs in a series parallel circuit while the longshaft "sail" version (and the VP51) gives an AC output for 4 x 15watt 12 volt bulbs in a series parallel circuit. (That does meean they generate 12 and 24 volts respectively)

To connect to a battery you will need a suitable bridge rectifier eg from Maplin. It's a good idea to get one which has spade terminals to take push on connectors if you want to avoid soldering on leads. It can be bolted to small square of aluminium sheet to make a mounting bracket/heat sink... the VP51 has an output socket on the front obvious and marked.. I did not have the special plug but used a couple of banana plugs. The manual shows that but does not idicate where the connection is on the VP39.

Don't worry about the volts, but be careful not to power any voltage sensitive electronics directly from the motor without the battery in circuit (I did accidentally and fried my Autohelm!) and dont be under any illusions about the amount of power you'll get... minimal!

BTW although the engine is air cooled there is water cooling of sorts of the exhaust system and Neil-S who has a VP39 advised us not to run it without cooling for long or you'll cook the rubbers in the mounting

I have already scanned this manual for a forumite so I should have the result somewhere. Let me know if you need any more info.
 

VicS

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I have had a look at the beast to see if I can be more helpful on connecting up but I cant see very much without removing the lower casing (which the VP51 has). It sould not be difficult to ID the wires though. The plug lead is easy to spot, another wire goes to the stop button, the otherside of which is earthed. I cannot see if there are two others or just one but one side of the output at the socket seems to be earthed so probably only one. If it is earthed you will have to keep your DC boat system insulated from earth or just use a single diode instead if a bridge rectifier, but that will effectively halve the power you have available.
 

jaxman

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Hi, thanks for your posting, I can locate the wire going to the stop switch and the one plug for the spark. So, as I understand this, I can hook this up to my battery, I've got a device for charging it already in place. I can charge the battery from there via a power cord with 110V or the motor.

Thanks for the posting. I you could send me the manual, this would be great.
 

VicS

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Hi have now had a closer look at my engine. There are two wires sleeved together exiting the engine itself, apart from the HT lead to the spark plug. One is black and goes to the stop button the other is yellow and goes to one terminal of the AC ouput socket. The other terminal of this socket is connected to the engine casing (by another black wire)

So the AC output is between the yellow and the casing.

In order to charge the battery you need a rectifier to convert the AC to DC. There are two possible ways of doing this.
One is a single diode that is connected between the yellow lead and the battery positive while the battery negative is connected to the other socket connection, and hence to the engine casing. (its important to get the diode the right way round or it will be destroyed instantly)

The second way is to take both AC connections to the AC terminals of a bridge rectifier and then connect the battery to the DC connections. (again it is important that the polarity of the DC connections is correct..

I used a bridge rectifier but I do not know what the "charging lead" that was available as an accessory was precisely.

Make sure you incorporate a fuse in the positive connection to the battery!

I assume your reference to a "device" and 110volts means you have a battery chager that operates from a 110 volt mains supply, or do you mean that the motor is already fitted with a rectifier?

Regarding the manual. I do not seem to have it on the computer. I think I must have photocopied it and sent it by post. At the moment I am swapping over to a new computer but the old scanner does not work with the new one and I am not yet sure about the printer. Eventually I intend networking the two computers. When every thing is sorted out I will decide the best thing to do.
 
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