Alternator Paralleler Circuit

[smileypete]

Pete that's quite nifty.

 

So you can do a few more calcs:-

 

The SW180-2 (the continuously rated one) has a coil resistance at room temperature of 13 Ohms

 

Once closed the relay opens when the current through the coil drops to around 225mA

 

The coil resistance (obviously) increases as the coil heats up.

 

The tolerance on drop out current is quite wide and measured values show anything between about 175mA and 275mA

Thanks for that,

 

So using the above, the lowest contactor drop out voltage is just over 2v.

 

I'd use a 24V lamp for Lamp 2 as it will last a lot longer than a 12v lamp. Also it should heat up a bit more slowly which will help keep the contactor closed for longer.

 

I've done some measurements on running lamps at half voltage, and their resistance when cold, which suggest a 24v 6w lamp could be best.

 

At the instant the latch relay opens, the resistance of the cold lamp filament should be about 13 ohms, which should hold the contactor relay coil voltage above dropout for a short while.

 

It could also be done with 2 x 24v 3w lamps in parallel, or 2 x 12v 3w lamps in series.

 

 

I suspect you will still get the same problem as I got, viz: the regulator switches at very high speed, far faster than the switch-off times of the relay and/or contactor, thius preventing the relay's dropping out.

I suspect it will work as the voltage at D+ depends on the alternator's field current, not the field voltage as it's switched by the regulator.

 

The field current and so the voltage at D+ will not change the instant the regulator switches on, because the field coils are inductive.

 

Also the lamp between contactor coil and 0v will help ensure the contactor drops out slightly after the latch relay opens anyway.

 

cheers,

Pete.

[Smelly]

Hi,

 

For auto switch-off of the alternator parallel connection I'd try the following circuit:

 

 

 

 

cheers,

Pete.

 

Now that LOOKS straightforward enough, but wouldn't the connection to D+ need to go through the switching? Otherwise the latch relay would close when D+ energised surely. Scuse my numptiness... Also, would 0volts be ground?

 

On a different note, those toolbox types seem a bit tardy at delivering things... I was hoping to have a crack at this today but the Albright's not arrived yet!

Edited May 10, 2009 by Smelly

[Gibbo]

I don't think it's a sound method if it relies on precise timings of the relay's interacting with the snubber network.

 

EH???????

 

Better throw all your electronic stuff out. It all relies on precise timing between things, precise voltage differences between things, precise current differences between things. It's the nature of the science.

 

It's too much "Select-on-Test".

 

It's not even close to "select on test". It is precisely "put a snubber on the big one but not the little one and if the rest of the circuit operates as you say it does then it will work"

 

With regard to the PDAR, the PDAR IS seeing 12v on the D+. There is a monitor wire from the PDAR to the D+ which is still in place. As I said, I'll bounce it off Mr Sterling tomorrow.

 

D+ should start at nothing then go up to 12 volts when the alternator fires up. At the moment (with the reg disconnected) how is the alternator firing up to produce 12 volts on D+ with no reg attached?

 

I'm still sure there is something about the PDAR with regard to internal regs if they are disconnected or brokn.

 

Gibbo

 

Now that LOOKS straightforward enough, but wouldn't the connection to D+ need to go through the switching? Otherwise the latch relay would close when D+ energised surely.

 

No. Not until the switch is pressed. It has no ground (and yes 0 volts is ground) until the switch is pressed.

 

Gibbo

[Smelly]

No. Not until the switch is pressed. It has no ground (and yes 0 volts is ground) until the switch is pressed.

EH???????

 

Better throw all your electronic stuff out. It all relies on precise timing between things, precise voltage differences between things, precise current differences between things. It's the nature of the science.

 

 

 

It's not even close to "select on test". It is precisely "put a snubber on the big one but not the little one and if the rest of the circuit operates as you say it does then it will work"

 

 

 

D+ should start at nothing then go up to 12 volts when the alternator fires up. At the moment (with the reg disconnected) how is the alternator firing up to produce 12 volts on D+ with no reg attached?

 

I'm still sure there is something about the PDAR with regard to internal regs if they are disconnected or brokn.

 

Gibbo

Gibbo

 

Hmm, I'm veering away from this due to my lack of understanding... Feel free to recommend I stick to a timer if this is tedious...

 

Looking to the contactor side, it looks to me as though when the ign (ignition?) is switched on it'd close the contactor as it seems to run straight to ground. How does the latching relay open the contractor?

 

Ah, I think I've figured it out but I'll leave the question as I'd value comments... The lamp's in series, so with only 12v available the contactor won't open(it'd need 24v with the lamp in series) until the latching relay is activated to give the full 12v the run to ground. Close the relay and the lamp absorbs some of the current as the coil current dissipates so it will flicker a tad but that's it...

 

My A-level physics is awakening somewhere in the background!

[Gibbo]

Hmm, I'm veering away from this due to my lack of understanding... Feel free to recommend I stick to a timer if this is tedious...

 

Looking to the contactor side, it looks to me as though when the ign (ignition?) is switched on it'd close the contactor as it seems to run straight to ground. How does the latching relay open the contractor?

 

Ah, I think I've figured it out but I'll leave the question as I'd value comments... The lamp's in series, so with only 12v available the contactor won't open(it'd need 24v with the lamp in series) until the latching relay is activated to give the full 12v the run to ground. Close the relay and the lamp absorbs some of the current as the coil current dissipates so it will flicker a tad but that's it...

 

Sort of but not quite.

 

The relay won't close because there isn't enough current through it. That is limited by the lamp in series.

 

When the push button is pressed that gives both relays a proper ground, they both close, the latching relay then provides it's own power feed to keep itself closed. The closed relay (the small one) effectively shorts out the bottom lamp so it will be completely off.

 

Gibbo

[niloc]

This started as a really interesting thread. Detail of a drawing that was simple to follow. Want went wrong? Seemed to veer into a heated debate which tended to confuse the matter. Have we yet reached a final version or is there still some r&d to contemplate? Perhaps i need to read it all again.,using my limited powers of concentration.

[Gibbo]

This started as a really interesting thread. Detail of a drawing that was simple to follow. Want went wrong?

 

Seems extremely simple to me.

 

The original circuit didn't do exactly what Chris wanted. It's been modified and different ideas are being proposed that will do what is wanted.

 

I can give you a diagram of a piece of wire if you want. That's nice and simple. But that won't do what is wanted either.

 

Gibbo

Edited May 10, 2009 by Gibbo

[niloc]

Seems extremely simple to me.

 

The original circuit didn't do exactly what Chris wanted. It's been modified and different ideas are being proposed that will do what is wanted.

 

I can give you a diagram of a piece of wire if you want. That's nice and simple. But that won't do what is wanted either.

 

Gibbo

Oh dear sarcasm,the lowest form of wit. Perhaps it would be better for you precious techy types to just pm each other. You can fool some of the people some of the time, but you cannot fool all of the people all of the time. Your right it is simple.

[smileypete]

Hi,

 

I've altered the circuit that I posted yesterday to include fuses on the feeds from D+ and ignition:

 

 

They will give protection if the circuit is miswired or a connection comes adrift at any point. A 3 amp or 5 amp fuse will be plenty enough.

 

 

Also here is a circuit that uses a 2 pole relay for the latching relay. This may be a bit easier to understand:

 

 

The dotted line between the two relay contacts indicates they are part of a 2 pole relay and so switch at the same time. However they are electrically isolated from each other.

 

cheers,

Pete.

Edited May 10, 2009 by smileypete

[chris w]

Seems extremely simple to me.

 

The original circuit didn't do exactly what Chris wanted. It's been modified and different ideas are being proposed that will do what is wanted.

 

 

Gibbo

Actually that's not correct. The original circuit does EXACTLY what I wanted. ie: parallels the alternators and doubles the charge rate. You can manually cancel it at any time and it will cancel automatically if you turn the engine off.

 

The mod is only to add an auto switch-off which wasn't in the original circuit. I don't want members thinking the original circuit doesn't work - it does.

 

It's just that it would be neat to have it switch off automatically (as well as manually if desired). The auto switch-off is only worth adding if you have an alternator controller fitted on the domestic alternator AND you have wet cell lead acid batteries. The alternator controller will, in this case, take the wet lead acids up to 14.8v which could overcharge the starter battery if the alternators are paralled for 8 hours.

 

If you have no alternator controller or you only have sealed gel batteries which charge at around 14.2-14.4v then the auto switch off is not necessary because the start battery will be charged at the voltage at which it is charged anyway, paralleler or no paralleler. The debate is about a fesible, reliable and repeatable way of achieving auto switch-off.

 

At the end of the day, a 90 timer switch-off will work perfectly.

 

Chris

 

 

 

EH???????

 

Better throw all your electronic stuff out. It all relies on precise timing between things, precise voltage differences between things, precise current differences between things. It's the nature of the science.

 

 

 

It's not even close to "select on test". It is precisely "put a snubber on the big one but not the little one and if the rest of the circuit operates as you say it does then it will work"

 

 

Gibbo

A circuit for forum members is no good to man and beast if it depends on selecting the right snubber network depending which regulator one has. That is never going to happen. It might be OK for you and me but not the average boater who won't have the technical knowledge in this area. I want to do it in a way that will always work regardless of alternator type and alternator controller type. The timer (time-out) method is looking more and more attractive.

 

Chris

[Gibbo]

A circuit for forum members is no good to man and beast if it depends on selecting the right snubber network depending which regulator one has. That is never going to happen. It might be OK for you and me but not the average boater who won't have the technical knowledge in this area. I want to do it in a way that will always work regardless of alternator type and alternator controller type. The timer (time-out) method is looking more and more attractive.

 

But that's the point. It doesn't depend on this that or the other. Snub the big relay with a diode, but not the little one. I reckon it will work.

 

Gibbo

 

............. Perhaps it would be better for you precious techy types to just pm each other.

 

Perhaps it would be better for people who don't understand a thread to just read a different one instead?

 

Gibbo

[chris w]

But that's the point. It doesn't depend on this that or the other. Snub the big relay with a diode, but not the little one. I reckon it will work.

 

Gibbo

But I said on here yesterday or the day before that I have already tried that since and it didn't affect anything. The relay would still not auto switch-off because of the "chattering" reg.

 

Chris

[Chris-B]

Perhaps it would be better for people who don't understand a thread to just read a different one instead?

 

Gibbo

 

 

That is without doubt one of the funniest replies I have ever seen on any forum !!

 

Chris

 

edited to add the ironic smiley

Edited May 10, 2009 by Baldock

[Gibbo]

But I said on here yesterday or the day before that I have already tried that since and it didn't affect anything. The relay would still not auto switch-off because of the "chattering" reg.

 

Chris

 

No you didn't. You removed the snubbers from BOTH relays. You need to KEEP the diode on the big relay but remove it from the small one. You very clearly said you removed the diodes form both relays.

 

Gibbo

 

PS. It's obviously a bit of a guess without having access to the smaller relay you're using but a typical auto cube relay opens in about 5mS with no snubbing. As opposed to the 50 or 60mS for the SW180 with a diode across it. That should be plenty of time.

Edited May 10, 2009 by Gibbo

[chris w]

No you didn't. You removed the snubbers from BOTH relays. You need to KEEP the diode on the big relay but remove it from the small one. You very clearly said you removed the diodes form both relays.

 

Gibbo

 

PS. It's obviously a bit of a guess without having access to the smaller relay you're using but a typical auto cube relay opens in about 5mS with no snubbing. As opposed to the 50 or 60mS for the SW180 with a diode across it. That should be plenty of time.

But, as I pointed out much earlier, the small relay will still have the rotor quench diode effectively across it which I can't remove!

 

Chris

[Gibbo]

But, as I pointed out much earlier, the small relay will still have the rotor quench diode effectively across it which I can't remove!

 

Chris

 

Not quite. If you go back to your original diagram one side of the smaller relay coil is connected to the ignition feed. It is now proposed that the other side is connected to the reg tranny collector (that would normally be connected to the field). So the top of the relay coil will have to go through the charge warning light before it reaches the field quenching diode. The charge warning light will massively reduce the coil current when it switches off. The switch off time will still be very quick.

 

Honest.

 

Gibbo

[chris w]

Not quite. If you go back to your original diagram one side of the smaller relay coil is connected to the ignition feed. It is now proposed that the other side is connected to the reg tranny collector (that would normally be connected to the field). So the top of the relay coil will have to go through the charge warning light before it reaches the field quenching diode. The charge warning light will massively reduce the coil current when it switches off. The switch off time will still be very quick.

 

Honest.

 

Gibbo

A 3W lamp in parallel with a 47R resistor is only about 24R overall. That's not going to reduce the current very much! I will try it but I am not at all hopeful - it's too hit and miss.

 

My timer idea is simpler, neater more reliable and utterly reproducible.

 

Chris

Edited May 10, 2009 by chris w

[chris w]

double posted in error

Edited May 10, 2009 by chris w

[Smelly]

Sort of but not quite.

 

The relay won't close because there isn't enough current through it. That is limited by the lamp in series.

 

Gibbo

 

I edited that twice yesterdayb ut my browser doesn't seem to like being in such a low signal area... Honest

[Smelly]

Hi,

 

I've altered the circuit that I posted yesterday to include fuses on the feeds from D+ and ignition:

 

 

The dotted line between the two relay contacts indicates they are part of a 2 pole relay and so switch at the same time. However they are electrically isolated from each other.

 

cheers,

Pete.

 

Cheers Pete

 

My one concern with this is that I've not seen a double pole relay at Maplins... I like your earlier version as everything's off the shelf and I hopefully won't need to start doctoring alternators to any significant degree.

 

I wonder Gibbo and Chris, when you're talking about the system you seem to be talking about now, I assume that that's the doctored alt system, as opposed to Pete's circuit above. Having stretched my brain yesterday I can understand why it should work so I am off to Maplins for bulb & fuse holders after work, unless someone can compel me not to by about 4pm.

[Gibbo]

A 3W lamp in parallel with a 47R resistor is only about 24R overall. That's not going to reduce the current very much! I will try it but I am not at all hopeful - it's too hit and miss.

 

My timer idea is simpler, neater more reliable and utterly reproducible.

 

Chris

 

1. Why on earth have you got a 3 watt lamp in parallel with a 47R resistor connected to an alternator that has the reguilator disconnected? You don't need it.

 

2. In any event, a typical auto cube relay pulling 200mA on 12 volts with a diode snubber in series with 24R will open in less than 7mS

 

3. Your SW180 will be taking at least 50mS

 

That's simpler than a timer.

 

Gibbo

[chris w]

Well....... In post #52 I did say...........

 

"You could be right but there's something telling me that the PDAR doesn't bark up until it sees 12 volts on the D+ terminal, which it will never see if the internal reg isn't working. I'm not certain on this, I could well be wrong which is why I asked it as a question."

 

and was wholeheartedly slagged off and told I was talking cr*p.

 

There is something telling me (again) that for some reason the PDAR has to have something different done with it if there is no working internal reg.

 

Gibbo

I have just spoken to Sterling re the PDAR alternator controller and they say that, categorically, the PDAR does NOT need the alternator's internal regulator to be present. So long as the field brush is still connected to the PDAR's field wire, the PDAR will work (all other connections remaining the same). It has a similar output circuit to the A127 output circuit, viz: a transistor switching the rotor current which is (normally) in parallel to the internal reg's output transistor.

 

The alternator should still "excite" in the same way as before, viz: through the charge lamp.

 

Now I'm puzzled as to why it didn't work for me - I shall be investigating!

 

Chris

[Gibbo]

I have just spoken to Sterling re the PDAR alternator controller and they say that, categorically, the PDAR does NOT need the alternator's internal regulator to be present. So long as the field brush is still connected to the PDAR's field wire, the PDAR will work (all other connections remaining the same). It has a similar output circuit to the A127 output circuit, viz: a transistor switching the rotor current which is (normally) in parallel to the internal reg's output transistor.

 

The alternator should still "excite" in the same way as before, viz: through the charge lamp.

 

Now I'm puzzled as to why it didn't work for me - I shall be investigating!

 

Chris

 

Yeah there's something odd here. A few years ago a colleague of mine removed the internal reg from a working system with a PDAR and afterwards it didn't work. He put the internal reg back, and it worked again. But he wanted the internal reg gone - I can't remember why. I also can't, for the life of me, remember what he did to get it working again. But there was definately something he had to do.

 

Gibbo

[chris w]

D+ should start at nothing then go up to 12 volts when the alternator fires up. At the moment (with the reg disconnected) how is the alternator firing up to produce 12 volts on D+ with no reg attached?

 

I'm still sure there is something about the PDAR with regard to internal regs if they are disconnected or brokn.

 

Gibbo

D+ will still go through the same sequence with or without the internal regulator if the PDAR is still attached. ie: the charge lamp excitation current will pass throught the rotor (which will be grounded through the PDAR output stage) which will energise the stator which will produce an output which will be fed back to D+.

 

Chris

[smileypete]

Cheers Pete

 

My one concern with this is that I've not seen a double pole relay at Maplins... I like your earlier version as everything's off the shelf and I hopefully won't need to start doctoring alternators to any significant degree.

 

I wonder Gibbo and Chris, when you're talking about the system you seem to be talking about now, I assume that that's the doctored alt system, as opposed to Pete's circuit above. Having stretched my brain yesterday I can understand why it should work so I am off to Maplins for bulb & fuse holders after work, unless someone can compel me not to by about 4pm.

Hi,

 

The double pole relay version was just for reference really.

 

Read post #101 carefully with regard to the voltage and power rating of Lamp 2

 

A motor factors should also be able to supply the fuseholders, fuses, lamps and relay.

 

They should have a 24V 5w sidelight lamp which will be a good try for Lamp 2.

 

cheers,

Pete.