Alternator working or not?

How things work, what's hot and what's not
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aquaplane
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Re: Alternator working or not?

Postby aquaplane » Tue Apr 07, 2009 11:09 pm

D- goes to somewhere, I don't know, but I may be able to say where when I have looked later.

The thing is, when you buy a boat you assume that it worked before, naieve I know but it's not that unreasonable. It may have worked as it is but with good connections.

It may not have worked at all and the price I paid is a reflection, but I don't think so.

I'm still hopeing that it's a duff connection but I'll print all this and take it with me to help with the diagnosis.

cheers.
Seminole.
Cheers Bob.

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sahona
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Re: Alternator working or not?

Postby sahona » Wed Apr 08, 2009 9:53 am

SEV - marchal that's the chappie!
I've still got the old one in my shed somewhere if you need one for spares.
I think I had diode problems with it, I'll look it out.
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ash
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Re: Alternator working or not?

Postby ash » Wed Apr 08, 2009 10:35 am

sahona wrote:SEV - marchal that's the chappie!


From my searches - "70229002" seems to be the relevent code no.

Alternator at £280.

I also found suggestions that the alternator was found on 2CVs and Renault 4s.

Want to race your 2CV? - Alternator at £55

May also be known as Valeo. They do appear mto be brushless.

These guys are Oop North.

Anyway - it's not the alternator - it's the wiring.... :wink:

Best of luck.

Enjoy your Easter Weekend.

Ash
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aquaplane
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Re: Alternator working or not?

Postby aquaplane » Wed Apr 08, 2009 12:32 pm

Ash, you are a star, you all are.

The 2CV option is worth trying, if it comes to that, even if it don't work. I could even put a couple on, I'm sure I have seen folks refer to dual alternators on boats! Don't go drawing a wireing diagram just yet, I'm going to fix my current problems with emery paper and maybe WD40.
Seminole.
Cheers Bob.

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Re: Alternator working or not?

Postby Gordonmc » Wed Apr 08, 2009 1:18 pm

ash wrote:Need to check alternator D- to engine block visually and for DavS's volt drop test. I think that this alternator will have the chassis isolated.

I think that the problem is with the wiring to connection 61. This supply will excite the alternator to get it producing volts. An alternator might self excite but not reliable.




This is familiar. It took me several months to realise the alternator on Flap was not doing anything. The battery charge was being maintained by the solar panel and occasional shore-charges. That's why after an extended period of motoring the batteries were flat!
I found the alternator was earth-isolated although the manual (Thorneycroft T90) showed a normal chassis earth type. I bought a 70 amp alternator off Ebay and rewired the installation to suit the manual specification. On starting the engine the volts to the battery at tick-over were nowhere near what I was expecting. I got on the phone to the supplier who told me to blip the engine until the charging light went out. Bingo - the ammeter jumped into life and I had 13.75 v at the terminals. The light acts and exciter for the alternator field coils.

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Re: Alternator working or not?

Postby sahona » Wed Apr 08, 2009 5:18 pm

At the risk of repeating what has gone before, I have dissected my old one just to refresh memory, and can offer the following:
B+ is connected to Battery Plus, probably via the start solenoid
D- is connected to alternator chassis, engine chassis, battery negative.
There are no brushes in this alternator. There is a static field coil, physically in beside the main stator.
The rotor has magnetic sectors that become energised when the field coil is powered - firstly by the small current through the ignition lamp, therefore this HAS TO BE the correct wattage. If in doubt, short it out with the engine running, that may start the alternator.
As the voltage rises at terminal 61, it becomes equal to the battery voltage and the ign lamp goes out (voltage same at both sides) the Field coil is now being energised by the voltage at term61 and it's current to ground (neg) controlled by the regulator via term DF.
The voltage measured between terminal DF and chassis, will vary depending on the current the alternator is trying to supply: If it is low, about 2volts, the alternator is pumping hard. If it is high, 8 -12 volts, the regulator thinks the batteries are charged and is just trickle charging.
Put your neg meter lead on battery post (not engine etc.) and make measurements with engine running at a fast tickover:
Pos lead to B-, 0volts or just a few millivolts. If more remake connections and tighten mounting bolts etc.
Pos lead to B+, >14v if charging, battery voltage if not.
Pos lead to T61, battery voltage or greater. Switch off ign with engine running, does reading drop?
Pos lead to DF, 2 - 10volts as above.
The only useful spares I can offer is the regulator and coils, as the main lump has seized and I had to repair the diode block previously.
Good luck!
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aquaplane
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Re: Alternator working or not?

Postby aquaplane » Thu Sep 27, 2012 12:49 pm

It's dead now! :(

I hope it hasn't broken my 3yr old domestic battery, it went flat, wouldn't light a bulb flat, at the weekend. I have charged the battery up but I haven't had chance to put some load on it to see how much capacity it has yet.

Anyway, time to see what to do about an alternator.
Seminole.
Cheers Bob.

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Re: Alternator working or not?

Postby DaveS » Thu Sep 27, 2012 6:30 pm

aquaplane wrote:It's dead now! :(

I hope it hasn't broken my 3yr old domestic battery, it went flat, wouldn't light a bulb flat, at the weekend. I have charged the battery up but I haven't had chance to put some load on it to see how much capacity it has yet.

Anyway, time to see what to do about an alternator.


Er, what happened in the intervening 3.5 years?
Image

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ash
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Re: Alternator working or not?

Postby ash » Thu Sep 27, 2012 10:22 pm

DaveS wrote:
aquaplane wrote:It's dead now! :(

I hope it hasn't broken my 3yr old domestic battery, it went flat, wouldn't light a bulb flat, at the weekend. I have charged the battery up but I haven't had chance to put some load on it to see how much capacity it has yet.

Anyway, time to see what to do about an alternator.


Er, what happened in the intervening 3.5 years?

Looking into my crystal ball - sometimes it charged - sometimes it didn't - mostly it charged so if it ain't broke then leave it alone!!

I would still bet my money on a fault in the excitation wiring - might be easier to find if it's completely broken now.

I would be tempted to make up a cable which ran from the battery positive through a bulb holder with a suitable wattage bulb and connected to the alternator connection 61 - as a test to see if the alternator then produces charging voltage.

If this works then take the feed from the ignition switch instead of the battery so that it is only live when the ignition is switched on.

Keep us informed.

Are you going to use your KPost to tell us how you completely rewired Chiron? LoL

Ash
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Re: Alternator working or not?

Postby Clyde_Wanderer » Thu Sep 27, 2012 10:56 pm

Pardon me for crashing in on Aquaplane's post.
Someone mentioned something about giving the throttle a blast in order to extinguish the red charge light.
Why is this and what has the red light wattage to do with the alternater been excited>
Reason I ask is this, I turn on my ignition switch, charge and oil lights come on, I start engine and Have to give it at least halve revs before charge light goes out and alt charges, the two aforementioned light units are ones I bought and fitted in the home made ign pannel, what wattage should the bulb be?
C_W

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Re: Alternator working or not?

Postby sahona » Fri Sep 28, 2012 12:51 am

First -Bob have you fixed the problem? Was it the regulator?
I have refurbished (but not tested) my Sev do you want it?

Now,
Eamonn -The alternator needs a whizz to generate magnetic flux needed to become self-sustaining.
(don't read this if you're yawning already...) The current in the field coil creates a magnetic field in the rotating bit of the alternator (the rotor, oddly enough) The magnetic fieldstrength depends on the size of the current in the coil, initially this is provided through the 'ignition' lamp circuit.
The current generated by the alternator stator (the output we use) is proportional to the current in the field coil AND the speed of rotation of the rotor poles past the stator poles. A little of the current from the stator is fed back to the field coil
under control of the regulator.
It's late and I'm not explaining this as well as I would in a two-way conversation, sorry.

Essentially you need a combination of speed and current to get started, the more you have of one, the less you need of the other. If you're worried about high starting revs, and want to experiment, wire another 12 bulb in parallel with the ign lamp and see if they go out at lower revs - but remember if you inadvertently leave the ign on with the engine stopped, you will be drawing more current, and may overheat the field coil as well as draining the battery.
I found the revs thing more obvious after I had fitted a higher power alternator from a car to the boat.
I can't find anything in the documentation for lamp wattage but can look next time I'm down (or look in your car!)
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Re: Alternator working or not?

Postby aquaplane » Fri Sep 28, 2012 9:42 am

DaveS, As Ash said, mostly it's worked, but occasionally it hasn't. It has worked since the belt broke about 2 months ago
,it didn't when there wasn't a belt on ;)

Ash, the alternator has been to a man who tested it and said it's not doing anything. Generally it's been behaving recently, untill it died that is. Before I took it off and got it tested I tested all the wireing for continuity and couldn't find any problems.

C_W, That is just how the new instalation on Seminole works, charging light on and no tacho until it gets a rev up and then it's all tickety boo.

Sahona, I don't know if it's the regulator yet. I'm going to see about geting it fixed before biting the bullet and buying a new one. I'll bear in mind that you have one that may be OK if it comes to that, cheers.

I have posted the following on the WOA forum for advice incase I have to replace the thing:

"My alternator has died. It's off a 1979 MD11C and it's the SAV Marchal 14V 35amp one.

I have been looking on the internet and Wood Autos (which is conveniently 2 miles from my work) list one for £376, god knows how much they want for them when they are in stock!

http://www.woodauto.com/Unit.aspx?Man=S ... f=70229702

Another site I found suggests that this 60amp alternator is suitable:

http://www.newstarteralternator.com/Sho ... arine.aspx

and at $141 it looks good value, not quite as good if you add on the $170 (or so) postage. There isn't a 35amp one listed for my engine and the numbers don't match up either so I'm a bit cautious about this source.

Since I'm replacing the alternator anyway I'm wondering about increasing the output so if I can source a bigger unit that will fit, localy and at a not too eye watering price, I'll probably do that.

What alternators have other folk fitted?
Where did you get it from?
How much should I expect to pay? Within £50 is close enough.

Numbers= SEV Marchal 14/35 70229702 28 8. Regulator markings: 72367802 28 8 "
Seminole.
Cheers Bob.

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Re: Alternator working or not?

Postby sahona » Fri Sep 28, 2012 10:56 am

Bob, just remember that you can fit a more modern and efficient alternator from a car.
As you don't have isolated return (the negative comes through the chassis) it's easy. What you need to look for is:
What wattage do you want - the SEV is 35amp, any more than 75amp will steal too many HP and make belts squeal. ( so anything between those values)
The mounting configuration. Measure the existing one using the front face of the big mounting lug as datum, the distance to the centre of pulley (Belt -line) and the orientation (like a clock-face SEV is about 6 o'clock) of the adjusting lug are what matter.
Now go to your local car scrapper and get a nice fat Bosche for about £15......
The wiring may be different physically, but electrically it'll be the same. We can help if you show us what you get!
The SEV requires a bit more field current due to the indirect way it works, brushes allow more instant oomph and won't wear out in our lifetime (when did you have to change them in the car that's done 150K?)
Bon chance mon brave, Le SEV est mort, vive la Bosche!
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Re: Alternator working or not?

Postby Clyde_Wanderer » Fri Sep 28, 2012 12:08 pm

Bill, it sounds as if there is more Poles in there than in Claymore's list of plumbers :lol:
I do follow exactly what you are saying and will investigate bulb wattage etc.
I use my ign (key) to stop engine just like a car so no worries about flattening batt.
Thanks again for the advice.
C_W

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Re: Alternator working or not?

Postby ash » Fri Sep 28, 2012 5:54 pm

Is this how your alternator is mounted? Should be 'relatively' easy to modify a replacement to line up the pulley. You would need to fit the bigger pulley from the old unit because the Vee drive is taken off the large diameter flywheel.

Image

Best of luck with it.

Ash
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