Alternator Paralleler Circuit

[Smelly]

I have ordered both a spare reg and some of the 25V 470uF capacitors... We will see what we will see.

[smileypete]

I've come to the conclusion that the push switch paralleled to the latching relay it is in the wrong place. I will try it tomorrow. I appreciate help, PM and otherwise but having invested so much time into this I can't make one change and wait for a response, my time is limited.

The best I can do from now, is give a little help each weekend, first to get the contactor manually switched, and then to slowly build and test the circuit in post #168 bit by bit, and nothing else.

 

This would also give plenty of time to discuss and source any extra things that may be needed.

 

If you'd rather get it done asap, or for me to help during the week, or try anything else, then I have to call it a day. Maybe Gibbo/ChrisW/Sir Nibble can then help, either with that circuit or their alternatives.

 

I think part of the problem is down rushing things, even just reconnecting something quickly to save a few seconds, can then take hours to sort out if it's wrong.

 

Another part of the problem is not having the right stuff and then having to make do, this makes things more risky and can then take much longer too.

 

cheers,

Pete.

Edited May 22, 2009 by smileypete

[Smelly]

I've sussed it... I'd used the wrong connection off the illuminated switch. having been over everything with sone time and patience, there's a circuit through the aforementioned switch but there's hardly any volts, hence relays weren't closing so... If you're still playing... how does that capacitor connect?

 

It's not arrived yet mind but if W's going to work at all I'd rather try it that way.

 

Sorry for throwing my dummy out on Thursday but I nearly broke Last time i got that wound up I endedd uo off work with a letter from my GP confirming I was a nutter...

[Smelly]

It works!

[smileypete]

It works!

From W with engine running? Without a capacitor?

 

Does the latch relay switch off and Lamp 1 go out when the domestic alternator takes over?

 

cheers,

Pete.

Edited May 25, 2009 by smileypete

[Smelly]

From W with engine running? Without a capacitor?

 

Does the latch relay switch off and Lamp 1 go out when the domestic alternator takes over?

 

cheers,

Pete.

 

Well that's the next bit... For the time being I'm happy that the latch relay closes and opens on demand... the capacitor will be here around Wednesday I'd reckon.

 

edit... There's a different rant about Mr Sterling's dubious instructions behind the fact that I've not got to the domestic alt taking over bit, but that's quickly resolved, however housework has taken a low priority this week so I need to do some laundry before I clamber back below...

Edited May 25, 2009 by Smelly

[smileypete]

Well that's the next bit... For the time being I'm happy that the latch relay closes and opens on demand... the capacitor will be here around Wednesday I'd reckon.

OK, the capacitor goes across the latch relay coil as shown in this diagram:

 

 

Bear in mind the capacitor is very much polarity sensitive, the positive end goes towards 'W'. Have a careful close look at the capacitor and the web page for it on the Maplin website.

 

I'd recommend waiting 'til next weekend to try it.

 

cheers,

Pete.

[chris w]

What will prevent the electrolytic capacitor's being distroyed by the reverse voltage across the relay when the coil is switched off? The negative end is clamped by D1, but the positive end can go very negative when the relay switches off, heavily reverse-biasing the capacitor.

 

Chris

[Gibbo]

What will prevent the electrolytic capacitor's being distroyed by the reverse voltage across the relay when the coil is switched off? The negative end is clamped by D1, but the positive end can go very negative when the relay switches off, heavily reverse-biasing the capacitor.

 

Chris

 

No it won't.

 

1. When the relay opens the bottom end is only clamped to B+ because the relay is now open so there's no path to ground. It could be argued that the reverse voltage will start before the contacts actually open which is probably true. But either way it is irrelevant because.......

 

2. Even assuming the W voltage drops instantly to a minus value (which it can't), the relay coil can only provide the same current during its back emf period as it was previously conducting and only for a period until its stored magnetic energy has been dissipated. That will be about 200mA max which that 470uF capacitor, starting from 12 volts, will eat for breakfast.

 

Gibbo

[Smelly]

No it won't.

 

1. When the relay opens the bottom end is only clamped to B+ because the relay is now open so there's no path to ground. It could be argued that the reverse voltage will start before the contacts actually open which is probably true. But either way it is irrelevant because.......

 

2. Even assuming the W voltage drops instantly to a minus value (which it can't), the relay coil can only provide the same current during its back emf period as it was previously conducting and only for a period until its stored magnetic energy has been dissipated. That will be about 200mA max which that 470uF capacitor, starting from 12 volts, will eat for breakfast.

 

Gibbo

 

Well I hope so, I've got an extra stat day so the capacitor having arrived I'm going to have another brew then try it...

[Gibbo]

I hope sove got an extra stat day so the capacitor having arrived I'm going to have another brew then try it...

 

Dot worry. I absolutely know so

 

I don't know wether the idea will work. ButI do know for certain that the cap cannot be damaged (unless you put it in the wrong way round).

 

Gibbo

[Smelly]

With the capacitor definitely facing the right way it doesn't work. It's still working with ign+ve connected but from W nowt.

 

I've reconnected lamp 1 and it's lighting when the button is pressed, although not as brightly as when using the ign+ve...

 

I'm yet to get a question as to whether I can suppress the residual voltage from D when the alt shuts down... Any ideas?

 

i will commence surgery on the new reg in the meantime.

Edited May 26, 2009 by Smelly

[Smelly]

however I can't find the socket set with the socket I butchered to get the reg off when I fitted the Sterling. Looking down on the brush holder can anyone remember which is the negative, closest to or further from the main body of the reg?

[Smelly]

Using W for all the lives, with a capacitor across the contactor as well as the latch relay it engages!

 

 

just got to see whether it shuts down again now!

 

edit, to make a bit more sense; I hope. The two relays are, I believe, effectively in parallel, with the contactor connecting to the latching side of the small relay then to ground.

 

There are capacitors across both relays and it engages and disengages on the switch, now I'm waiting to get enough charge into my batteries.

 

There is a second question behind this now...

 

When I fitted the Sterling DAR a couple of years ago, the instructions in the book contradicted the case as to where the jumpers need to be set for open lead acid batteries. Having checked them today it's much the same. the multi colour LED also is red whereas it should be yellow. I phoned Mr Sterling when i fitted it and he told me that it was just a problem with the LED which evidently it isnt as the voltage is too low.

 

Mr Sterling was so dismissive I gave up and have lived with it since, but now it's relevant.

 

Has anyone any idea how the jumpers should be set, or is it trial and error until I make 14.8?

 

I should explain that when I fitted the DAR i was trying to save knackered batteries and have only now come to test voltages against a decent bank.

Edited May 26, 2009 by Smelly

[chris w]

Looking down on the brush holder can anyone remember which is the negative, closest to or further from the main body of the reg?

Measure the continuity (resistance) between the D+ connection on the regulator and the brushes. You want the brush that is NOT connected to D+. This is known as the "field brush".

 

I would swap out the regulator bolts for M3.5 screws of about 25-30mm length. They are so much easier to remove as compared to the very thin walled socket needed to remove the dstandard bolts.

 

Chris

[Smelly]

Measure the continuity (resistance) between the D+ connection on the regulator and the brushes. You want the brush that is NOT connected to D+. This is known as the "field brush".

 

I would swap out the regulator bolts for M3.5 screws of about 25-30mm length. They are so much easier to remove as compared to the very thin walled socket needed to remove the dstandard bolts.

 

Chris

 

That's a very good idea but I'll need to get the bolts out first if I get that far. As it stand I think I just need to ramp up the Sterling voltage as discussed above to finish my testing.

 

[Gibbo]

Aren't those bolts the same size head as a snap on scredriver bit?

 

I'm sure I remember removing them with a magnetic bit screwdriver with no bit in it. Might be a failed memory though.

 

Gibbo

[Sir Nibble]

The screw threads should be M4. The hex size should be 5.5mm (7/32af will fit) sometimes they have phillips heads and sometimes 6mm (which is how come Gibbo can remember shifting them with a 1/4" driver). Field brush is closest to the reg, the small rectangular aperture 'tween reg and alternator is there for access to ground this brush for test purposes.

[Smelly]

The screw threads should be M4. The hex size should be 5.5mm (7/32af will fit) sometimes they have phillips heads and sometimes 6mm (which is how come Gibbo can remember shifting them with a 1/4" driver). Field brush is closest to the reg, the small rectangular aperture 'tween reg and alternator is there for access to ground this brush for test purposes.

 

Thank you Sir! You've just saved me a job! However as the switching side is now working, at least to switch it on from W (so I assume as and when the alt shuts down the W supply will stop and hence the relays will open) then I may not need the surgery after all.

 

edit. As I'm using the same alt the tacho's connected to I suppose I'll need to swap it to the other alt...

Edited May 27, 2009 by Smelly

[Gibbo]

Thank you Sir! You've just saved me a job! However as the switching side is now working, at least to switch it on from W (so I assume as and when the alt shuts down the W supply will stop and hence the relays will open) then I may not need the surgery after all.

 

edit. As I'm using the same alt the tacho's connected to I suppose I'll need to swap it to the other alt...

 

Yes. And recalibrate it unless both alternators have the same number of poles and the same pulley ratios.

 

Gibbo

[Smelly]

Yes. And recalibrate it unless both alternators have the same number of poles and the same pulley ratios.

 

Gibbo

 

Fair to say the pulley ratios etc are identical so that's not a worry.

 

OTH the fact that I seem to be charging at 13.4 (according to B on the domestic alt) is a worry, that should be float voltage but with only 2 hours's running, with the yellow timer LED still alive on the DAR it's only 13.4... I'm still testing it's fair to say and it'll probably need to wait 'til next weekend for more asserted testing, but with the timer on even if it's on a sealed AGM setting it should be higher than that shouldn't it? the manual agrees with me...

 

I wonder about my new meter as we've no probs with the batteries running down quicker than we'd expect so I'm on a mission to borrow another and see. The combi meter i fitted in the midst of this was a duffer so I'm going to order another, fit it immediately and this time, if it's a knacker I can send it back!

[WotEver]

Using W for all the lives, with a capacitor across the contactor as well as the latch relay it engages!

 

Finally (by using a new email address) I'm able to post. Probably a good thing or I might have stepped into the middle of a punch-up a few days ago.

 

Smelly - it works like that because you've effectively parallelled the capacitors and ended up with a large enough capacitance to sufficiently smooth the square wave (or heavily clipped sine wave, let's not get into that again) to raise the equivalent DC voltage just enough to bring the relay in.

 

If you measure the voltage at the w terminal now you'll see it's probably a volt or so higher than it was.

 

You should be able to put the contactor's live feed back to V+ if you just parallel the two capacitors on the w side.

 

Good luck - I'm letting you test this before I try it

 

Regards,

Tone

[Smelly]

Smelly - it works like that because you've effectively parallelled the capacitors and ended up with a large enough capacitance to sufficiently smooth the square wave (or heavily clipped sine wave, let's not get into that again) to raise the equivalent DC voltage just enough to bring the relay in.

 

 

Good luck - I'm letting you test this before I try it

 

Regards,

Tone

 

Tony, with one capacitor on the latching relay the latch relay engaged; Lamp 1 was staying on, but there wasn't enough clout to close the contactor. Using Pete's original circuit, with the latch relay in the negative side, a capacitor across it and the contactor being fed from ign +ve I'd imagine it would have worked as well, it was just more convenient for me to do it this way and I fluked it.

 

I think I may be testing for some time as my Sterling might be dodgy and struggling to get the charge voltage high enough to shut down the engine alt. As Chris has said, the paralleler side of things works really well, and there's a surprising lack of arcs when the contactor closes.

[WotEver]

Using Pete's original circuit, with the latch relay in the negative side, a capacitor across it and the contactor being fed from ign +ve I'd imagine it would have worked as well

 

Hmmm, if it's not the two capacitors doubling-up on the W side that did it for you (the 940uF being just enough to 'smooth' the wave to raise the voltage sufficiently) then there must have been a slight problem with your original wiring.

 

Taking Pete's circuit, if the latching relay is operating then there's a straight path from V+ to earth through the contactor coil. It's a simple switched circuit (battery, coil, switch).

 

As you say the switching relay was latching with one capacitor you could probably leave everything as it is right now and remove the second capacitor. But hey, if it's working leave it alone ;-)

 

Note that electrolytic capacitors have a habit of drying out over time, so keep the circuit as far from engine heat as possible.

 

Good luck with the Sterling - I'll let others speculate on where the problem may lie with that.

 

Cheers,

Tone

Edited May 28, 2009 by tony@hdheaven.co.uk

[Smelly]

Hmmm, if it's not the two capacitors doubling-up on the W side that did it for you (the 940uF being just enough to 'smooth' the wave to raise the voltage sufficiently) then there must have been a slight problem with your original wiring.

 

Taking Pete's circuit, if the latching relay is operating then there's a straight path from V+ to earth through the contactor coil. It's a simple switched circuit (battery, coil, switch).

 

As you say the switching relay was latching with one capacitor you could probably leave everything as it is right now and remove the second capacitor. But hey, if it's working leave it alone ;-)

 

Note that electrolytic capacitors have a habit of drying out over time, so keep the circuit as far from engine heat as possible.

 

Good luck with the Sterling - I'll let others speculate on where the problem may lie with that.

 

Cheers,

Tone

 

The initial problem was with the illuminated switch, I didn't know which contact to use for live to the circuit and when i tested the one I used I could see continuity, but when I finally calmed down and checked the voltage as well there was only about 2 volts. Swap it around, earth it all from the correct place (having sorted the short that killed my engine panel) and it fell into place.

 

Useful info about the capacitors, if they're vulerable I might swap to using ign+ve for the contactor and moving the latch relay as currently it's very much staring at the engine. Ta.