STERLING ALTERNATOR TO BATTERY CHARGER

[blackrose]

Gibbo, I read your article on external alternator controllers on your website and accepted what you were saying. I'm trying to keep up with the discussion here & take it you are saying more or less the same thing, that with modern alternators, external regulators are unnecessary.

 

How then do you account for the Professor's positive experience? Is it all in his mind?

 

Our boat is two and a half years old, fitted with an Isuzu 4BL33 with two 70 amp alternators.

Within a month on delivery I fitted a Stirling alternator to battery charger and a Sterling 1.8 Kw inverter. The setup works brilliantly! I have never in 43 years of boating had a boat with such well charged batteries, I check the 3 x 135ah domestic + 1 x 110ah engine battery for electrolyte level regularly but find they use no more than usual (very little!).

 

By the way Prof, I have exactly the same setup as you (but with an Izusu 55), two 70amp alternators and 3 x 135a/h domestic + a 110a/h starter and a 1.8 Kw inverter. I also have a VSR which switches charge from my starter battery when it reaches 13.6v to the 2 x 110a/h bowthruster batteries. I guess it switches back when the BT batteries reach 13.6v. Not sure what happens when they're both at 13.6v?

 

I don't yet have an external alternator regulator for my domestic system.

Edited November 14, 2006 by blackrose

[Gibbo]

Gibbo, I read your article on external alternator controllers on your website and accepted what you were saying. I'm trying to keep up with the discussion here & take it you are saying more or less the same thing, that with modern alternators, external regulators are unnecessary.

 

How then do you account for the Professor's positive experience? Is it all in his mind?

By the way Prof, I have exactly the same setup as you (but with an Izusu 55), two 70amp alternators and 3 x 135a/h domestic + a 110a/h starter and a 1.8 Kw inverter. I also have a VSR which switches charge from my starter battery when it reaches 13.6v to the 2 x 110a/h bowthruster batteries. I guess it switches back when the BT batteries reach 13.6v. Not sure what happens when they're both at 13.6v?

 

I don't yet have an external alternator regulator for my domestic system.

 

Maybe his alternator was charging at 13.8 volts in which case fitting an Adverc (that charges at 14.25 volts with periodic cycles up to 14.8 volts) will make a huge difference.

 

The article does make it very clear that *most* (but not all) modern alternators charge at much higher voltages than they used to. If the alternator charges at 13.8 volts then fitting an external controller will make a *big* difference.

 

If the existing alternator charges at:-

 

14.0 volts it will make a considerable difference.

14.2 volts it will make a tiny bit of a difference. (this is where it starts becoming an expensive useless device)

14.4 volts it might make a marginal difference.

14.6 volts it will probably do nothing or next to nothing.

14.8 volts it will almost certainly do nothing.

 

Note that these voltages are for wet cell batteries. With gels or AGMs the voltages are lower.

 

Gibbo

 

PS. There's a lot more to it than that in the case of the alternator to battery charger but this really isn't the place to get into it.

 

Gibbo

[whammy]

Can I at this point thank everybody for the contributions to my original question particularily from the boaters that have this piece of equipment fitted, I know I asked for replies to be kept simple for me but I can now see that I have opened a right can of worms, why oh why cant things in life be simple for simple folk like me, I have spoken to other boaters re this matter since posting this question and to be honest I am as confused now as I was at the start. I tried downloading the instruction manual from the Sterling website but the download fails half way through it, I dont think its a fault on my side so I emailed sterling but had no reply to date. Does anyone know how complicated the wiring in of this unit is.

[blackrose]

Maybe his alternator was charging at 13.8 volts in which case fitting an Adverc (that charges at 14.25 volts with periodic cycles up to 14.8 volts) will make a huge difference.

 

The article does make it very clear that *most* (but not all) modern alternators charge at much higher voltages than they used to. If the alternator charges at 13.8 volts then fitting an external controller will make a *big* difference.

 

If the existing alternator charges at:-

 

14.0 volts it will make a considerable difference.

14.2 volts it will make a tiny bit of a difference. (this is where it starts becoming an expensive useless device)

14.4 volts it might make a marginal difference.

14.6 volts it will probably do nothing or next to nothing.

14.8 volts it will almost certainly do nothing.

 

Note that these voltages are for wet cell batteries. With gels or AGMs the voltages are lower.

 

Gibbo

 

PS. There's a lot more to it than that in the case of the alternator to battery charger but this really isn't the place to get into it.

 

Gibbo

 

Thanks. I checked mine at the domestic batteries the other day with the engine running and I think it read 14.2v (It was definately over 14 but I'll have to check again to be sure).

 

However, I thought the point of external devices was that they held the charge up above 14v, while alternators without any form of external regulation would soon drop down below that. As I said, I don't have an external regulator, so when should I test? Am I doing it correctly with my multimeter on the + & - battery terminals?

[Gibbo]

Thanks. I checked mine at the domestic batteries the other day with the engine running and I think it read 14.2v (It was definately over 14 but I'll have to check again to be sure).

 

However, I thought the point of external devices was that they held the charge up above 14v, while alternators without any form of external regulation would soon drop down below that. As I said, I don't have an external regulator, so when should I test? Am I doing it correctly with my multimeter on the + & - battery terminals?

 

I don't know where that's come from.

 

If your alternator is currently charging at 14.2 volts then fitting an external controller will do almost nothing.

 

The existing alternator will stay at 14.2 volt indefinitely. They do not go to a lower voltage.

 

An external controller will not increase the maximum available current from the alternator.

 

Run your engine until you feel your batteries are getting pretty well charged. Then measure the battery voltage. Then measure it again on the back of the alternator. Any difference indicates some serious losses in cabling, connectors etc.

 

If you want to *really* test the charging system then measure for these losses when the batteries are flat and therefore the alternator is producing full output.

 

The voltage you measure will remain the same. The alternator will not reduce that charge voltage.

 

It may fall under heavy load conditions, but it would with an external controller as well.

 

Gibbo

[chris w]

Whammy

 

I just tried the Sterling site and the document you are after downloaded OK for me. If you still get a problem downloading, PM me with an email address and I'll email it to you.

 

Chris

[JohnO]

supposed to be working so just a quick one.....

Another point alot of people are not aware of is the alternator needs to spin at at least 4000 RPM for the digital amplifer to "kick in"

SO

a engine ticking over

a slow revvin vintage engine

or

a pulley ratio of less than 3:1

means the active part of charger will not work

 

 

basically

with a 3:1 pulley ratio your engine would need to be turning over at least 1333.3333333333 RPM for the charging unit to produce the managed fast charge

[chris w]

John

 

To whose alternator controller are you referring? The Sterling one doesn't need a "kick".

 

Alternators themselves only need a high rev "kick" if the alternator charging light becomes disconnected or blows. This light provides some initial current to the alternator rotor in order to magnetise it and thereby allow it to start producing output. Once the engine starts the alternator then provides its own rotor feed.

 

If the light fails then some alternators will start producing output at high revs due to some residual magnetism in the rotor. Once "kicked in" like this the alternator will then run normally at all revs until stopped again.

 

Chris

Edited November 14, 2006 by chris w

[blackrose]

Can I at this point thank everybody for the contributions to my original question particularily from the boaters that have this piece of equipment fitted, I know I asked for replies to be kept simple for me but I can now see that I have opened a right can of worms, why oh why cant things in life be simple for simple folk like me, I have spoken to other boaters re this matter since posting this question and to be honest I am as confused now as I was at the start. I tried downloading the instruction manual from the Sterling website but the download fails half way through it, I dont think its a fault on my side so I emailed sterling but had no reply to date. Does anyone know how complicated the wiring in of this unit is.

 

Whammy, before you go look Gibbo's words of widom again:

 

*most* (but not all) modern alternators charge at much higher voltages than they used to. If the alternator charges at 13.8 volts then fitting an external controller will make a *big* difference.

 

If the existing alternator charges at:-

 

14.0 volts it will make a considerable difference.

14.2 volts it will make a tiny bit of a difference. (this is where it starts becoming an expensive useless device)

14.4 volts it might make a marginal difference.

14.6 volts it will probably do nothing or next to nothing.

14.8 volts it will almost certainly do nothing.

 

Note that these voltages are for wet cell batteries. With gels or AGMs the voltages are lower.

 

So it's probably worth checking what you are getting out of your existing alternator. If you do decide to fit one, the sterling alternator to battery charger will be far simpler to fit than the sterling alternator regulator and it will do the same job.

Edited November 14, 2006 by blackrose

[Gibbo]

 

So it's probably worth checking what you are getting out of your existing alternator. If you do decide to fit one, the sterling alternator to battery charger will be far simpler to fit than the sterling alternator regulator and it will do the same job.

 

This I have to take slight issue with. A normal external controller will actually do a better job.

 

Where the alternator to battery charger scores is in two places.

 

A) It's easier to fit.

It can be fitted to installations that will not permit a "normal" alternator controller to be fitted.

 

It's performance is nowhere near as good as a "normal" external alternator controller.

 

And no I'm not prepared to go into why on here.

 

Gibbo

 

How silly that you can't write a capital letter B followed by a close bracket.

Edited November 14, 2006 by Gibbo

[bottle]

 

Well I can

 

Edit: no I can't, it shows the above smiley with glasses.

Edited November 14, 2006 by bottle

[chris w]

The alternator-to-battery controller also means that the warranty on a new alternator is not invalidated because there is no connection to the internals of the alternator needed. So this is the route of choice for many people when considering controllers. It's easier to fit from this viewpoint.

 

The alternator controller which does require adding one internal wire to the alternator's own regulator is significantly cheaper, much smaller, has more control and will charge the batteries faster. But its fitting will almost certainly invalidate the alternator warranty. One way around this is to buy another regulator for your alternator (mine was a brand new one for £6 from Ebay!) and modify that one and then you can always put the original one back on if there's ever an alternator failure.

 

Chris

 

 

(typo edit)

Edited November 14, 2006 by chris w

[Sir Nibble]

Oh, so you can't!

I've been watching this topic, but I'm keeping my fur dry for now!

Edited November 14, 2006 by snibble

[Lesd]

Do you guys see the logic in using Sterling alternator to battery charger to combine two alternaotor outputs together to increase charging speed ?

Im my case Im looking at the Barrus shire 65 which comes with 50a and 160a alternators. I've sized my domestic bank as 540Ah. Im unsure if I should just use the 160a alternator to charge the dmetic bank or use Sterlings product to combine the alterntors and charge at a combined max 210a. Your advice would be much appreciated.

Les

[Keeping Up]

Oh, so you can't!

I've been watching this topic, but I'm keeping my fur dry for now!

Just click on the little square at the bottom of the post you are writing, where it says "Enable Emoticons" so that the tick disappears. Then you can put in and anything else you like such as :-)

[chris w]

When you connect two alternators together, one will always have a slightly higher output voltage than the other. This will effectively cut-off the second alternator (it reverse biases the output diodes) until the first alternator's output drops due to the current demand. Then both alternators come into play. In the literature this is sometimes referred to as a "lazy alternator". So you will have one alternator providing the day-to-day charging needs but both alternators will cut in when demand is high.

 

For most people who have a second alternator charging only the starting battery that's a lot of potential power wasted as it's only going to used for about 15 mins each day after starting, so combining the two alternators makes a lot of sense.

 

One thing I haven't checked in practice is that if the two alternators are connected together and one is held-off by the other for a time as described above, it may be that your rev counter would stop functioning, if it were connected to the idling alternator, as most take their signal from one of the output stator windings. (usually marked "W" on the alternator case).

 

If this is the case in practice, and as I say, I haven't checked it out in reality, it's just a htought, you can't (usually) get round the problem by moving the rev counter lead to the dominant alternator because the two alternators are usually on different ratio pulleys and so the rev counter would read erroneously.

 

Maybe someone has direct experience of this?

 

Chris

Edited November 14, 2006 by chris w

[Gibbo]

Do you guys see the logic in using Sterling alternator to battery charger to combine two alternaotor outputs together to increase charging speed ?

Im my case Im looking at the Barrus shire 65 which comes with 50a and 160a alternators. I've sized my domestic bank as 540Ah. Im unsure if I should just use the 160a alternator to charge the dmetic bank or use Sterlings product to combine the alterntors and charge at a combined max 210a. Your advice would be much appreciated.

Les

 

This is a really complicated subject and comes up regularly on urw. A simple summary might go something like this..

 

The smaller the charger, the better the overall charge into the battery. i.e. the batteries will (eventually) be more fully charged. Weighed against this is "how long do you want to take to charge your batteries?". The bigger the charger the faster the recharge time.

 

Somewhere in the middle you have to reach a compromise.

 

Then others will say "keep 2 totally separate sytems - K.I.S.S". This is something I just cannot understand. The same people usually happily spend half their lives using mobile phones, the internet, PCs, Ipods, PDAs etc etc etc. Yet they think combining 2 alternators is too complicated? Odd argument that one.

 

10 minutes after the engine is started, the engine start alternator is doing next to nothing (starting a modern engine uses about 1 amp hour at the most). It's wasted capacity. And often the alternator feeding the domestic battery is too small. So in this ase it makes perfect sense to utilise this otherwise wasted capacity from the smaller alternator to increase the charge rate into the domestic bank. There are many ways of doing this.

 

However in your case you have 2 things to consider.

 

Firstly what is the output voltage of the alternator as it is? If it's already above 14.2 volts (and I'm pretty sure it will be 14.4 or 14.6 on that particular engine) then adding a controller (of any sort) is going to do *very* little.

 

Secondly, assuming the voltage is ok, 160 amps is a good size alternator and the batteries probably wouldn't accept much more than this anyway (unless they are AGMs) so increasing the alternator size wouldn't have any effect.

 

And finally, the 160 amp alternator fitted to that engine produces nothing like 160 amps once it's warmed up. More like 100 amps.

 

You have lot's to think about now.

 

And now 5 people will disagree

 

Gibbo

[Gibbo]

One thing I haven't checked in practice is that if the two alternators are connected together and one is held-off by the other for a time as described above, it may be that your rev counter would stop functioning, if it were connected to the idling alternator, as most take their signal from one of the output stator windings. (usually marked "W" on the alternator case).

 

If this is the case in practice, and as I say, I haven't checked it out in reality, it's just a htought, you can't (usually) get round the problem by moving the rev counter lead to the dominant alternator because the two alternators are usually on different ratio pulleys and so the rev counter would read erroneously.

 

Maybe someone has direct experience of this?

 

Chris

 

Yes it's common problem. Losing a charge warning light or the rev counter, or both. It's also not easy to cure!

 

In the past I've used various "solutions". Sometimes I've moved the rev counter to the other alternator (they have an adjustment screw for calibration). No big deal.

 

The charge warning light, well, some people don't care. Sometimes a cure can be got by putting a small light bulb on the D+ terminal down to ground. It has to be much lower wattage than the charge warning light. This can fool the internal reg into thinking the output voltage is lower than it actually is and it (just slightly) increases the output voltage. It doesn't always work. Sometimes the alternator doesn't measure the D+ terminal (some do, some don't) for reg purposes. Sometimes the voltage difference between the 2 alternators is too great for this trick to work.

 

I've never tried to look for any other solutions but it *is* something that happens.

 

Gibbo

[chris w]

And finally, the 160 amp alternator fitted to that engine produces nothing like 160 amps once it's warmed up. More like 100 amps.

Isn't this because the internal regulator has a temperature sensor and reduces the regulator's output voltage to compensate. Hence the advantage of an alternator controller.

 

Chris

[Gibbo]

 

Just checking

 

Isn't this because the internal regulator has a temperature sensor and reduces the regulator's output voltage to compensate. Hence the advantage of an alternator controller.

 

Chris

 

It would be nice to think so. It's actually because it runs so hot the stator resisitance rockets to a much higher level.

 

(tested by applying full battery power to the field until the alternator smoked)

 

And how would an alternator controller help in this instance? *Most* of them override the internal reg and don't have a temp sensor for the alternator. Same situation.

 

Gibbo

[chris w]

you forgot to switch your emoticons back on

 

My Sterling one has a battery AND an alternator temperature sensor.

Edited November 14, 2006 by chris w

[Lesd]

This is a really complicated subject and comes up regularly on urw. A simple summary might go something like this..

 

The smaller the charger, the better the overall charge into the battery. i.e. the batteries will (eventually) be more fully charged. Weighed against this is "how long do you want to take to charge your batteries?". The bigger the charger the faster the recharge time.

 

Somewhere in the middle you have to reach a compromise.

 

Then others will say "keep 2 totally separate sytems - K.I.S.S". This is something I just cannot understand. The same people usually happily spend half their lives using mobile phones, the internet, PCs, Ipods, PDAs etc etc etc. Yet they think combining 2 alternators is too complicated? Odd argument that one.

 

10 minutes after the engine is started, the engine start alternator is doing next to nothing (starting a modern engine uses about 1 amp hour at the most). It's wasted capacity. And often the alternator feeding the domestic battery is too small. So in this ase it makes perfect sense to utilise this otherwise wasted capacity from the smaller alternator to increase the charge rate into the domestic bank. There are many ways of doing this.

 

However in your case you have 2 things to consider.

 

Firstly what is the output voltage of the alternator as it is? If it's already above 14.2 volts (and I'm pretty sure it will be 14.4 or 14.6 on that particular engine) then adding a controller (of any sort) is going to do *very* little.

 

Secondly, assuming the voltage is ok, 160 amps is a good size alternator and the batteries probably wouldn't accept much more than this anyway (unless they are AGMs) so increasing the alternator size wouldn't have any effect.

 

And finally, the 160 amp alternator fitted to that engine produces nothing like 160 amps once it's warmed up. More like 100 amps.

 

You have lot's to think about now.

 

And now 5 people will disagree

 

Gibbo

 

Gibbo,

Thanks for that, it does sound like (in my specific case) sticking to the 160a on my domestic bank and the 50 on my starter/bow thruster will be the way to go. Will save me a few bob and keep things simple.

Les

[chris w]

Gibbo

 

Your assertion that internal alternator regulators don't have temperature compensation is certainly not correct for my regulator. I just took a spare regulator for an Isuzu 80A alternator (A127 type) and connected an indicator bulb across the brushes. I then applied an increasing voltage from a power supply and monitored the voltage at which the indicator just extinguished. I also monitored the temperature of the regulator.

 

At room temperature the cut-out voltage was 14.6 volts. I then applied a hot air gun until the regulator case temperature was 60degC. In between this temperature and room temperature the regulator cut-out voltage dropped until at around 60degC it was down to 13.4v.

 

The A127 type alternator is one of the most ubiquitous around so this is not some kind of esoteric regulator. Certainly this internal regulator would never charge the batteries like an external controller despite its having a high nominal charge voltage at room temperature

 

Chris

[smileypete]

Do you guys see the logic in using Sterling alternator to battery charger to combine two alternaotor outputs together to increase charging speed ?

Im my case Im looking at the Barrus shire 65 which comes with 50a and 160a alternators. I've sized my domestic bank as 540Ah. Im unsure if I should just use the 160a alternator to charge the dmetic bank or use Sterlings product to combine the alterntors and charge at a combined max 210a. Your advice would be much appreciated.

Les

 

Hi,

 

I'd wait and first see whether the default setup charges your domestic batteries adequately in normal use.

 

If not then the next step is to see if the Sterling ABC would give a worthwhile improvement.

 

If you can measure much voltage the alternators generate at typical cruising speed, that will greatly help others to give good advice on the above.

 

cheers,

Pete.

Edited November 14, 2006 by smileypete

[Lesd]

Hi Pete,

Good advice I think. My boat is on order but not due to be delivered till next Aug so can't measure anything !! I'm just trying to finalise the electrical spec for the fit out currently.

Not sure if anyone out there has a Shire 65 that could measure the aternator output ? (I know Ledgard have sold some of these engines)

Les