Alternator Paralleler Circuit

[Gibbo]

How can the float voltage (say 13.4v) shut the W terminal down? If you are correct about the relationship between the output voltage and the W terminal, then the W terminal should be at around at least 13.4v + 2 diode drops = 14.6v minimum if the regulator goes into float. But when the battery is discharged to say 12.2v, your W voltage would only be 12.2 + 1.2v = 13.4v. But that works!!!!!

 

When charging at say 14.4v, your output voltage would be 14.4 + (at least) 1.2v = 15.6v.

 

There is an anomaly somewhere.

 

Chris

 

In float the reg switches on, the battery voltage rises, when it exceeds the regulation voltage the reg switches off, the rotor current ramps down. Once it reaches zero rotor current the stator is producing no output. It can take some considerable time for the battery voltage to fall back below the regulation voltage. During that time, the tacho doesn't work.

 

Note that this is a very random effect. Some alternators don't do it because there is enough remnant magnetism in the rotor to keep enough stator voltage going for the tacho.

 

Anyway...........

 

1. How can you get 60 volts on the W terminal when it is clamped to the battery voltage plus 2 diode drops?

2. How come no one else has measured this apart from you.

3. Why have you not put the voltages and waveforms on the diagram as requested?

 

 

Gibbo

[smileypete]

There will be!

 

Dan is doing an excellent job with the current one, should it not work exactly as intended, I have a good alternative with a minimum of modification.

OK here is my modified and much simplified alternative:

 

(Dan you have permission to kill me!!! )

 

 

It works because a relay/contactor's holding voltage/current (in order to hold it closed) is usually much lower than the closing voltage/current (in order to close it from being open).

 

To close and latch the relay the pushbutton is pressed which puts the full battery voltage across the contactor coil.

 

Once the push button is released, Lamp 1 will allow enough current to hold the contactor closed.

 

But before the push button is pressed, Lamp 1 does not allow enough current to close the contactor from being open.

 

cheers,

Pete.

Edited May 18, 2009 by smileypete

[Guest]

That looks very businesslike Pete, and if it works good on yer. Even I understand how that works.

[smileypete]

That looks very businesslike Pete, and if it works good on yer. Even I understand how that works.

Thanks, I measured the cut in and cut out voltage on an 12V auto relay last night and got:

 

Cut out voltage 2.5V - 3.0V

Cut in voltage 6.3V - 6.7V

 

There's a fair amount of 'hysteresis' - the difference between highest cut out voltage and lowest cut in voltage and I suspect the SW180 contactor is much the same.

 

This got me thinking that the best way to guarantee a relay connected to W closes, is to 'flash' it with 12V.

 

Then once it's closed it doesn't need much to keep it closed, the voltage from W should be plenty enough, and a lamp can help regulate the voltage so it's not far above the highest cut out voltage.

 

As long as this level is some way below the lowest cut in voltage, then the relay can be permanently connected to W, and does not need a latching contact in series.

 

If the relay doesn't need a latching contact in series, then the SW180/contactor itself can be used.

 

The need to press the push button switch to get it started is a 'feature' . And depending on the feed used for the switch, it can also be used for a parallel starting capability.

 

cheers,

Pete.

Edited May 18, 2009 by smileypete

[Smelly]

Dan is doing an excellent job with the current one, should it not work exactly as intended, I have a good alternative with a minimum of modification.

 

cheers,

Pete.

 

Pete, feel free to stick to Smelly, as a nom de plume it has been with me for years and i'm quite happy with it!

 

 

OK here is my modified and much simplified alternative:

 

(Dan you have permission to kill me!!! )

 

cheers,

Pete.

 

I am preparing a slow and painful demise...

 

I'd've had that in place yesterday if it were that simple, but now I've nearly run out of leuchars and am skint 'til at least Friday. I wonder whether I can cannibalise what's already in place... However I would imagine the 24 volt bulbs I bought would be no good for lamp 1 now would they?

Edited May 18, 2009 by Smelly

[smileypete]

I'd've had that in place yesterday if it were that simple, but now I've nearly run out of leuchars and am skint 'til at least Friday. I wonder whether I can cannibalise what's already in place... However I would imagine the 24 volt bulbs I bought would be no good for lamp 1 now would they?

 

The 24V lamps will almost certainly be too low a power rating for driving the SW180, but would be ideal in conjunction with a higher rated lamp for fine tuning things.

 

How far have you got with the previous circuit?

 

Edit: I'd just build and test the previous circuit as is.

 

cheers,

Pete.

Edited May 18, 2009 by smileypete

[Smelly]

The 24V lamps will almost certainly be too low a power rating for driving the SW180, but would be ideal in conjunction with a higher rated lamp for fine tuning things.

 

How far have you got with the previous circuit?

 

Edit: I'd just build and test the previous circuit as is.

 

cheers,

Pete.

 

Apart from moving one of the lamps and giving it a live feed it's just about done now, I plan tp play with it, weather permitting when I get back from work which will be soon.

[smileypete]

Apart from moving one of the lamps and giving it a live feed it's just about done now, I plan tp play with it, weather permitting when I get back from work which will be soon.

 

Good stuff, if it's nearly there might as well finish it.

 

For testing it I'd work through the steps in post #168 (clicky).

 

cheers,

Pete.

[carlt]

Pete, feel free to stick to Smelly, as a nom de plume it has been with me for years and i'm quite happy with it!

Were you the 8th dwarf, they kept locked in the attic?

[Smelly]

Were you the 8th dwarf, they kept locked in the attic?

 

Nearly, they kept me in an airtight room and fed me nothing but oats... Anything else and the rumbling started... Saddam Hussain sent me home, hence no WMD were discovered...

[chris w]

OK here is my modified and much simplified alternative:

 

(Dan you have permission to kill me!!! )

 

 

It works because a relay/contactor's holding voltage/current (in order to hold it closed) is usually much lower than the closing voltage/current (in order to close it from being open).

 

To close and latch the relay the pushbutton is pressed which puts the full battery voltage across the contactor coil.

 

Once the push button is released, Lamp 1 will allow enough current to hold the contactor closed.

 

But before the push button is pressed, Lamp 1 does not allow enough current to close the contactor from being open.

 

cheers,

Pete.

What is the mechanism by which the circuit will auto switch-off?

 

If you are counting on the regulator's switching off the rotor current, then you may have overlooked the excitation current through the charge lamp and any remanent magnetism in the rotor, both of which will excite the rotor and produce an output at the W connection. This may be more than enough to hold the contactor closed.

 

Chris

[Smelly]

The deed is done, but testing will have to wait as the need to charge my batteries far outweighs any other cause at this minute in time... I realised when I got home that I'd got the circuit completely wrong so have just re-built it.

 

It's amazing how much quicker jobs get done when I've not got a herd of friends howling at me to go for a pint from the pub balcony above our mooring

 

Edit... I should explain that as it's a cruiser stern I'll need to test it while straddling the engine which would soon warm the family jewels should it be running...

Edited May 18, 2009 by Smelly

[smileypete]

What is the mechanism by which the circuit will auto switch-off?

 

If you are counting on the regulator's switching off the rotor current, then you may have overlooked the excitation current through the charge lamp and any remanent magnetism in the rotor, both of which will excite the rotor and produce an output at the W connection. This may be more than enough to hold the contactor closed.

Chris,

 

Do you now, finally at last, fully accept that the voltage across an alternator's stator winding connections cannot be more than 2 diode drops greater than the battery voltage???

 

 

The deed is done, but testing will have to wait as the need to charge my batteries far outweighs any other cause at this minute in time... I realised when I got home that I'd got the circuit completely wrong so have just re-built it.

 

It's amazing how much quicker jobs get done when I've not got a herd of friends howling at me to go for a pint from the pub balcony above our mooring

 

Edit... I should explain that as it's a cruiser stern I'll need to test it while straddling the engine which would soon warm the family jewels should it be running...

 

Sounds good, nearly there!

 

cheers,

Pete.

[chris w]

Chris,

 

Do you now, finally at last, fully accept that the voltage across an alternator's stator winding connections cannot be more than 2 diode drops greater than the battery voltage???

 

Pete.

Clearly not ,or else I should not be asking the question.

 

Chris

[Smelly]

I suspect I've gone wrong somewhere though... As it stands, with W connected to the latch relay and the engine running, but no feed to the contactor, then lamp 1 should light when i press the button but it doesn't... possibly a diode pointing the wrong way...

 

edit... nope found it, a no brainer as well... I've forgotten to connect the latch relay to ground... doh!

Edited May 18, 2009 by Smelly

[Guest]

I suspect I've gone wrong somewhere though... As it stands, with W connected to the latch relay and the engine running, but no feed to the contactor, then lamp 1 should light when i press the button but it doesn't... possibly a diode pointing the wrong way...

 

edit... nope found it, a no brainer as well... I've forgotten to connect the latch relay to ground... doh!

Ae we functional now?

[Smelly]

Ae we functional now?

 

No, and this time I suspect it's a bit more serious... I've connected the lug to the earth on the albright with a short length of cable and some croc clips. The lamp in the switch lights up... good but the relay doesn't seem to engage when I push the push switch... Bad. I'll play around and see what I come up with.

 

Dan

[smileypete]

No, and this time I suspect it's a bit more serious... I've connected the lug to the earth on the albright with a short length of cable and some croc clips. The lamp in the switch lights up... good but the relay doesn't seem to engage when I push the push switch... Bad. I'll play around and see what I come up with.

 

Looking at the steps in post #168 (clicky), which step are you on?

 

One thing to try, if you move the feed from W to B+, does the relay stay in then?

 

cheers,

Pete.

[Smelly]

I'm a bit baffled now... Having poked around, the lamp in the switch must be energising via the bulb to earth (lamp 2).

 

The relay is not closing when I press the momentary button. I've pulled the clip so as to connect the coil ground to the switched side but still the relay is not closing. I'm quite convinced it should be. I think I'm missing a bond to ground somewhere. Playtime once more...

 

edit.. no, it's tea time!

Edited May 18, 2009 by Smelly

[niloc]

I'm a bit baffled now... Having poked around, the lamp in the switch must be energising via the bulb to earth (lamp 2).

 

The relay is not closing when I press the momentary button. I've pulled the clip so as to connect the coil ground to the switched side but still the relay is not closing. I'm quite convinced it should be. I think I'm missing a bond to ground somewhere. Playtime once more...

 

edit.. no, it's tea time!

Hmm think perhaps i will stick with 2 alternators

[Smelly]

Looking at the steps in post #168 (clicky), which step are you on?

 

One thing to try, if you move the feed from W to B+, does the relay stay in then?

 

cheers,

Pete.

 

I'm testing whether the latch relay works and it doesn't. Using the diode test on my multimeter there's a circuit from the W+ connection on the coil through to the earthing stud on the engine when I press the button so with the engine running the relay should engage but it's not doing, well at least the lamp parelleled across the switching bits of the relay isn't lighting up. It's an earthing problem I'm sure, so long as there's enough of a push from W to close the relay. I'll try it properly connected tomorrow with a link direct to the battery. that's tell me for sure.

 

niloc... where's your sense of adventure? Don't be put off by my error laden woes... I'm rubbish at this kind of thing so am probably a good test bench...

[smileypete]

I'm testing whether the latch relay works and it doesn't. Using the diode test on my multimeter there's a circuit from the W+ connection on the coil through to the earthing stud on the engine when I press the button so with the engine running the relay should engage but it's not doing, well at least the lamp parelleled across the switching bits of the relay isn't lighting up. It's an earthing problem I'm sure, so long as there's enough of a push from W to close the relay. I'll try it properly connected tomorrow with a link direct to the battery. that's tell me for sure.

 

Have you done steps 1) and 2) in post #168?

 

Thinking about it, it might have been a good idea to build it on a small piece of plywood etc as a 'baseboard', with the three feed connections W, Ign/Acc, 0v and the contactor coil output connections.

 

Then it could be tested away from the engine using a 12v supply, and then tested in situ with the feeds.

 

Still you've done a sterling job to get this far, I'm well impressed.

 

cheers,

Pete.

[Smelly]

Have you done steps 1) and 2) in post #168?

 

Thinking about it, it might have been a good idea to build it on a small piece of plywood etc as a 'baseboard', with the three feed connections W, Ign/Acc, 0v and the contactor coil output connections.

 

Then it could be tested away from the engine using a 12v supply, and then tested in situ with the feeds.

 

Still you've done a sterling job to get this far, I'm well impressed.

 

cheers,

Pete.

 

I've not done step 1 but thought, while the engine was running that I could have a run at step 2. Step 1's for the morrow.

 

Edit... I was meaning to say that fixing it all to a board first is an extremely good idea, especially for those not electronically minded such as I．Ｒｅｍｏｖｉｎｇ　ｄｉｓｔｒａｃｔｉｏｎｓ　ｓｕｃｈ　ａｓ　ｔｈｅ　ｈｅａｄｓｔａｎｄｓ　ｉｎ　ｔｈｅ　ｅｎｇｉｎｅ　’ｏｌｅ　ａｎｄ　ｂｅｉｎｇ　ａｂｌｅ　ｔｏ　ｓｅｅ　ｅｖｅｒｙｔｈｉｎｇ　ｅａｓｉｌｙ　ｗｏｕｌｄ　ｍａｋｅ　ａ　ｂｉｇ　ｄｉｆｆｅｒｅｎｃｅ．

 

Thank you!

 

Ｈｏｗ　ｄｉｄ　ｔｅｈ　ｆｏｎｔ　ｃｈａｎｇｅ？

Edited May 18, 2009 by Smelly

[smileypete]

Edit... I was meaning to say that fixing it all to a board first is an extremely good idea, especially for those not electronically minded such as I

Also it's then possible to fix a length of terminal strip to the board, connect the diodes on one side of the strip, then connect stranded wire to the other side.

 

Not the most perfect way to do it, but easy to set up (and change <cough>!)

 

 

Clearly not ,or else I should not be asking the question.

Why not take a 'scope to your boat, attach it to 0v and W, run the engine and photograph the scopes display and settings.

 

I bet you won't

 

cheers,

Pete.

Edited May 19, 2009 by smileypete

[chris w]

Why not take a 'scope to your boat, attach it to 0v and W, run the engine and photograph the scopes display and settings.

 

I bet you won't

 

cheers,

Pete.

Funnily enough, even before you wrote this, I did just that and took a scope up to the boat this morning and also had a good look through my star/delta file on board which contains all the data from that experiment of a few months ago.

 

I owe you and Gibbo an apology as you are quite right. The W connection is indeed about 2v above the B+ connection.

 

The voltages to which I was referring yesterday and before (eg: 60v peak to peak), I now realise are the internal voltages generated within the stator windings in order to be able to drive the charge current through the battery.

 

These voltages are not accesible to the outside world (unless the alternator is open-circuited) because of the voltage drop across the stator windings. This is analogous to an actual battery voltage not being accessible to the real world (unless the battery is open-circuited) because any currents drawn off cause a voltage drop across its internal resistance.

 

So, if the charge current is say 50A, the battery to be charged is at 12.4v say and the stator windings have a resistance of 0.3 ohms, then the internally generated alternator voltage is 12.4v + 2v + 0.3Rx50A = 29.4v peak (58v peak to peak or 21v rms).

 

By the way, putting the W waveform on a scope, the W connection waveform is NOT a half-wave rectified output as I did say yesterday and contrary to the "Amplepower.com primer" which appeared yesterday. It is in fact a square wave of 50% duty cycle. It's lower end is one diode drop below ground and its upper end at the battery voltage plus one diode drop.

 

So apologies again for my dogmatic, but incorrect, view which clearly shows that Saga moments are for real.

 

Chris