Advanced Alternater Regulator

[Sir Nibble]

1/ any recommendations for a vehicle sourced replacement alternator please?

 

This is probably my forte Bob, I have catalogues full of specifications and vehicle applications.

Are you tied to the lucas mountings? or are you happy to fabricate brackets to hang any shape unit?

What is it you are after, just maximum output?

Would you be able to drive with a "serpentine"* belt or fit a twin belt?

 

*the flat unes with lotsa little vees, "polyvee".

[RobinJ]

The A127 is an older design of Alternator, but is still widely available, and at 55 amps is a much lower output than many modern alternators, so whether that makes any difference, I do not know, but I am very happy with it.

Last time my A127 regulator failed (dazzling in the tunnel!) I was told that parts were no longer available.

I found the problem with the older Lucas alternators was cooling (but that depends on the engine compartment).

Now have a Bosch 70 amp with big fan, but does burn the belt more!

 

If you are cruising or spending time on the boat a lot or using loads of power, then they are probably worth the money (eventually). With leisure batteries, it is difficult to keep them at maximum capacity without a decent charger, and in the absence of shore power or a generator, the easiest way is probably a clever alternator controller.

 

(Not sure about finacially - red diesel versus electricity?)

[Sir Nibble]

Last time my A127 regulator failed (dazzling in the tunnel!) I was told that parts were no longer available.

Who on earth told you that!? A127 regulators? how many dozen do you want? rectifiers? rotors, stators, bearings, cases, the lot. All are I assure you readily and cheaply available through the trade.

[RobinJ]

Who on earth told you that!? A127 regulators? how many dozen do you want? rectifiers? rotors, stators, bearings, cases, the lot. All are I assure you readily and cheaply available through the trade.

The trade!I have a box of bits somewhere all without diodes I think?

External controllers increase the charge voltage. Quite simple really.

Actualy some maintain the charge current up to a voltage limit!But the trick is to keep the voltage below gassing point.

[Sir Nibble]

You bin fibbed to mate! There is NOTHING for A127 alternators I couldn't have in my hand by the dozen by this time tomorrow.

[Gibbo]

Last time my A127 regulator failed (dazzling in the tunnel!) I was told that parts were no longer available.

 

Eh?

 

They still make them.

 

The same reg is used on several different alternators from different suppliers.

 

It's one of the most common regs around and will probably remain so for many years to come.

 

I also know that all the other spares for that alternator are freely available. Did someone want to sell you a new alternator?

 

http://www.algaauto.com/vl_lu_01.htm

 

Gibbo

 

Actualy some maintain the charge current up to a voltage limit!But the trick is to keep the voltage below gassing point.

 

The alternator maintains the charge current. The regulator sets the voltage limit.

 

Gibbo

Edited July 17, 2007 by Gibbo

[RobinJ]

The alternator maintains the charge current. The regulator sets the voltage limit.

 

Argh! (gone bald) Now I know why everybody's so chummy.

 

I suppose technically the engine maintains the charge current!

[BobTidy]

This is probably my forte Bob, I have catalogues full of specifications and vehicle applications.

Are you tied to the lucas mountings? or are you happy to fabricate brackets to hang any shape unit?

What is it you are after, just maximum output?

Would you be able to drive with a "serpentine"* belt or fit a twin belt?

 

*the flat unes with lotsa little vees, "polyvee".

 

I think more output for not to much money I have 1 start and 2 leisure totalling 330 amp if my memory serves.

New mountings is not a problem the old ones are bolted to the oak engine bearers and look like they came out of a scrap box.

The existing pully is 7inch and behind the flywheel and not practical to change (and takes a 5/8 belt with a bit of oil compliments of the crankshaft oil seal!

Would a flat belt run on the flywheel? its 20i x4 inches and unlikly to ever exeed 1000rpm.

[chris w]

The alternator maintains the charge current. The regulator sets the voltage limit.

 

Gibbo

 

In essence, with an external multistage alternator controller, the controller is maintaining the charge current (in the bulk stage only) by allowing the controller voltage to increase in order to maintain a constant current against the rising battery voltage. In the absoption stage the voltage is held constant, so the increasing battery voltage means the current will decrease vs time.

 

Chris

[Gibbo]

In essence, with an external multistage alternator controller, the controller is maintaining the charge current (in the bulk stage only) by allowing the controller voltage to increase in order to maintain a constant current against the rising battery voltage. In the absoption stage the voltage is held constant, so the increasing battery voltage means the current will decrease vs time.

 

Chris

 

That's what I said originally. All a controller does is increase the voltage. Nothing more, nothing less. All the other ideas that pop around people's heads (like controlling the voltage *and* current at the same time - clearly impossible) are a simple direct results of this, confused by muddy thinking.

 

Gibbo

[Sir Nibble]

Would a flat belt run on the flywheel? its 20i x4 inches and unlikly to ever exeed 1000rpm.

I have seen vee belts run on a flat flywheel, but I imagine their ability to transmit power would be seriously compromised. I have in mind a land rover 100A unit (I can supply part numbers and a list of vehicle applications for whatever you finally choose). This is a Marelli A127IR (no connection with "old faithful" A127 except the 127mm dimension) and is safe to 15000 rpm and I would be inclined to turn it as fast as you can. At any rate I would recommend not less than 4000 rpm at cruising speed. You may have to give serious thought to getting something engineered to provide a good solid drive for these sort of speeds. Would it be a great crime to have grooves machined on the flywheel? Or break the bank to have a rim machined up and dutch key it on?

[David Schweizer]

Last time my A127 regulator failed (dazzling in the tunnel!) I was told that parts were no longer available.

I always keep a re-conditioned spare on board £29.50 from these people:- http://www.vehicleelectrics.net Or they will recondition yours in a couple of houis for the same price, they will even solder a field wire on for the alternator controller at no extra cost.

Edited July 17, 2007 by David Schweizer

[BobTidy]

I have seen vee belts run on a flat flywheel, but I imagine their ability to transmit power would be seriously compromised. I have in mind a land rover 100A unit (I can supply part numbers and a list of vehicle applications for whatever you finally choose). This is a Marelli A127IR (no connection with "old faithful" A127 except the 127mm dimension) and is safe to 15000 rpm and I would be inclined to turn it as fast as you can. At any rate I would recommend not less than 4000 rpm at cruising speed. You may have to give serious thought to getting something engineered to provide a good solid drive for these sort of speeds. Would it be a great crime to have grooves machined on the flywheel? Or break the bank to have a rim machined up and dutch key it on?

Ok thats intresting, the current set up could get an alternator to 4200 revs with the motor at 1500 which it might have just managed 50 years ago but would probably self distruct just after everything in the rest of the boat jumped out of the cupboards!

Its a wonder I get any charge at all the curent alternator probably never betters 2000 revs and spends most of its time about 1400!!!

Ok time to own up I know a woodrough key when I see one (even if I cant spell it) but whats a Dutch key please?

It looks like the flywheel with or without a additional pully is required.

[chris w]

My alternator runs at only 1400-1600 rpm normally and I can get 45 amps out of a nominal 80 amp alternator at this speed. (engine running at half this speed)

 

Chris

[Sir Nibble]

Ok time to own up I know a woodrough key when I see one (even if I cant spell it) but whats a Dutch key please?

 

Dutch key, Imagine you have a close fitting sleeve around your flywheel, drill a hole straddling the joint line, tap it, fit a bolt. Dutch key.

 

Its a wonder I get any charge at all the curent alternator probably never betters 2000 revs and spends most of its time about 1400!!!

That's precisely why I converted diesel duck's alternator for slow speed output, how much current do you need?

[Chris Lingwood]

Hang on have I been dense? I was under the impression we were talking about something far cleverer than I think we are.

 

I though an alternator controller was a fancy bit of kit just like a mains battery charger that just uses the 12v ish supply instead of a AC supply. Whereas it seams they aren't, they are just external voltage regulators. So as you drag your batteries voltage up it won't do anything UNTIL you reach the limit set by the internal regulator. At this point the controller either starts lying to the internal regulator about the voltage or takes over the energising of the field windings (assuming it doesn't just do that anyway). At this point without the controller the internal regulator would be in effect limiting the charge current but in reality is limiting the voltage.

 

Couldn't roughly the same thing be achieved with an internal regulator that has its limit set at 14.4v or whatever? Which I'm pretty sure is exactly what Gibbo and others have been trying to say for 5 pages.

 

I think I reiterated a couple of other peoples posts here but I'd like to make sure I'm not thinking/talking bollocks.

 

What I don't quite understand it how the battery responds to applied voltages. I've tried and failed to find a graph showing this. As I understand it (perhaps wrongly) presuming we start with a discharged battery:

 

The battery voltage starts low (when disconnected)

We then connect charger

This slowly brings the voltage up to a set limit (bulk charge?) 11-14.4-.8v

Then it sits at this limit (absorption?) 14.4-.8v

Then drops down (float?) 13.?v

 

What I know I don't understand is at absorption the voltage is around 14.4-.8v but if you switch it off the voltage would go down to 13v ish (same as float?). Does the voltage drop on the battery if you turn off the charger in the bulk stage? Why can't you get the voltage of the battery higher during the bulk stage? I guess its down to the chemistry. If I'm not talking bollocks the first 2 stages are down to the nature of batteries and the voltage limit.

 

What is the purpose of float? To avoid damage to the batteries? Do the alternator controllers have a float stage? This could be an advantage but admittedly wouldn't charge it any faster.

 

Also with lower current battery chargers/alternators does the bulk stage just last longer as the charger can't raise the voltage up to the absorption level without trying to supply more current than it is capable of?

 

I think with some of this I've attempted to treat a battery as a ohmic conductor which its not.

[RobinJ]

I always keep a re-conditioned spare on board

 

I always carry at least one spare (hence the box of bits). Since I upgraded to the Bosch I haven't had to use the only working one I have left!

The first failure was as a result of the starter battery going short in a lock. Other failures were probably related to staying overnight close to tunnels (I believe more drain than charge - the other reason I upgraded).

Here the external controller saved the day (always a bank holiday!), as I was able to continue running without the internal alternator controller working! (hence no spare diodes!)

Incidentally, as a result, I now start with my external controller switched off, allow the starter to recover at least before switching it on to boost the domestic and inverter batteries. Normally it only takes about fifteen minutes running to fully charge, but after a heavy inverter session it can take hours.

[chris w]

The easist way to think of a regulator is its being a voltage-controlled switch. It's not strictly this but thinking of it as such is an easy way, IMHO, to visualise how the regulator and the alternator controller function. This switch is in series with the alternator rotor and the more current flowing through the rotor the more volts that appears at the output of the alternator.

 

Let's look at the regulator first. At the instant the alternator starts up the regulator's "switch" is closed so a lot of current can flow through the rotor hence the alternator's output climbs steeply. At a preset voltage (around 13.8v - 14.4v depending on the regulator) the regulator's "switch" opens so no current flows through the rotor so the alternator output drops. Because the output drops, the regulator immediately detects a low output and closes its "switch" again so the output rises once more and so on ad infinitum. This cycle repeats at a very fast speed so the output is effectively held constant at the regulator voltage.

 

Just like a multicylinder engine, the alternator has 3 output coils (like 3 pistons in an engine) which gives a smoother output. However, although the output is DC (ie: unidirectional) it is not a constant 14v or so. If you were to look on an oscilloscope, you would see 3 positive half sinewaves . These sinewaves are "smoothed" by the battery which acts as a bloody huge capacitor (tens of farads for the engineers).

 

Because the battery voltage will keep rising but the applied voltage won't go over say 14.2v the charge current will decrease automatically. The charge current, (to a first approximation) being determined by (regulator voltage - battery voltage) divided by the battery's internal resistance.

 

One of the issues with internal regulator's is that as they get hot they reduce the charge voltage to maybe only 13.4v instead of 14.4v (example of my alternators) so the batteries never get properly charged.

 

Now to the alternator controller:

 

The alternator controller is wired in parallel with the regulator and also can be envisaged as a "switch". So when the regulator's "switch" opens at say 14.2v the alternator contoller's switch is still closed, thus allowing rotor current to continue to flow and allowing the output to rise to a maximum of 14.8v for wet lead acid batteries.

 

However, once the battery voltage reaches 14.8v, the same process of decreasing charge current takes place as for the regulator above.

 

The main advantages of the alternator controller are that the battery is charged at a higher voltage so it fully charges and charges much quicker. Further the various stages of charging are timed and run from a sophisticated software controlled microprocessor which, in good versions, will take battery capacity etc into account. They will also monitor battery temperature and alternator temperature and halt the process if either go over a pre-set limit. Standard regulators can do none of these functions.

 

One can adapt a standard regulator to give a higher voltage fairly easily (at least, easy for those with some electronic knowledge), but the problem still remains of the regulator's voltage decreasing with temperature. The reason they do this is that if the alternator is hot, the regulator is hot and the assumption is that (under a car bonnet) the battery must be just as hot. So, to protect the "hot" battery the charge voltage is decreased. This situation does not obtain on a boat so instead when the alternator gets hot, the battery gets undercharged. A standard regulator has no timed functions either nor the ability to detect the battery capacity nor the ability to detect battery or alternator temperature anomalies.

 

Chris

Edited July 18, 2007 by chris w

[Gibbo]

In reality an external controller simply wacks the charge voltage up to a higher level. This charges the batteries faster. All the "complex software algorithms" is marketing hype. I know this. I'm not guessing. I've designed and built commercial ones.

 

There are a few little tricks that can be pulled like cycling the voltage either side of the gassing point. They make at best a couple of percentage points increase in performance.

 

Mr Lingwood. Your description of what happens is spot on. Your understanding is correct. I did try to reply to each separate part individually but got an error about having too many quotes and it then threw it in the trash.

 

Gibbo

Edited July 18, 2007 by Gibbo

[chris w]

Ah Mr Gibbo - it's you and I again in mortal combat. The bottom line is that one WILL get faster charging with am alternator controller vs a standard regulator, plus the additional temperature monitoring of the battery and alternator and no decrease in charge current due to normal alternator heating.

 

Those of us who have fitted one know there is a difference because we can see it on the volts and amps.

 

Incidentally, to respond to one of Robin's points, my alternator controller (Sterling) has an "automatic soft start" which means it does not activate for the first minute after starting the engine to reduce the load on the alternator belt.

 

Chris

[Sir Nibble]

The only thing I would add, is to say that the thermal compensation in the regulator is responsive to the ambient air temperature rather than alternator temperature. If you look at almost any design of alternator the thermal connection to the regulator is next to non existant. There is invariably however, a "heatsink" usually finned in the direct path of the cooling airflow upstream of all other components, meeting the ambient air and possibly dropping charge voltage back if it's a hot day in equatorial regions. Proper ventilation should deal with any problems that arise with this.

[Gibbo]

Ah Mr Gibbo - it's you and I again in mortal combat. The bottom line is that one WILL get faster charging with am alternator controller vs a standard regulator, plus the additional temperature monitoring of the battery and alternator and no decrease in charge current due to normal alternator heating.

 

If you use a bog standard internal reg at 14.4 volts and compare the results with an external controller, and do the tests properly, you will find almost *no* difference.

 

Honest.

 

I spent 3 entire years doing almost nothing but charging and discharging batteries and measuring the results. It isn't speculation.

 

If you analyse the results properly you will see *why* there is almost no difference.

 

The internal regulator is thermally isolated from the alternator. It measures the air temperature not the alternator temperature. It is *partially* thermally coupled so if the alternator gets too hot it protects it by reducing the charge current. I still giggle when I remember you heating up the reg with a hot air gun

 

The battery temperature sensing is a red herring anyway unless the batteries are at the north pole or in the desert. The very act of charging them warms them up to roughly the same temperature irrespective of ambient

 

Gibbo

[Sir Nibble]

The bottom line is that one WILL get faster charging with am alternator controller vs a standard regulator

IF the standard regulator is holding the charge rate down, but not of course if it is being limited by the stator output limit being reached, or the rotational speed being too low. A charge controller is a proposed solution to one particular problem and cannot be a panacea for all ills. Like I've said before, identify your problem and then select a solution to suit.

[chris w]

All I can say is that there is a significant difference on my set up and also it appears from others who have actually fitted them if you recall previous threads.

 

Chris

 

IF the standard regulator is holding the charge rate down, but not of course if it is being limited by the stator output limit being reached, or the rotational speed being too low. A charge controller is a proposed solution to one particular problem and cannot be a panacea for all ills. Like I've said before, identify your problem and then select a solution to suit.

 

Although neither Gibbo nor I explicitly stated it, I think it can be taken as read that we are assuming we never get close to the limit of the stator. My nominal 80A alternator will deliver 45A at idle speed (700rpm engine; 1400 rpm alternator)

 

Chris

Edited July 18, 2007 by chris w

[Gibbo]

IF the standard regulator is holding the charge rate down, but not of course if it is being limited by the stator output limit being reached, or the rotational speed being too low. A charge controller is a proposed solution to one particular problem and cannot be a panacea for all ills. Like I've said before, identify your problem and then select a solution to suit.

 

Well said.

 

The ONLY time an external controller will increase the charge rate is if the alternator IS being spun fast enough AND the internal regulator voltage is too low AND the cabling is up to spec. If any of these conditions are not met then the external controller will either do nothing or next to nothing. It's cheaper and easier to sort the duff cabling out and replace the internal reg with a higher voltage one.

 

Unless, of course, there is a split charge diode in the system (spits).

 

Gibbo