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14 minutes ago, peterboat said:

It shows that an alternator goes into a float mode ie its not charging, and will only start charging when their is a demand for more power rather than what others and yourself say, which is that it runs at a fairly constant voltage. 

You aren’t really making any sense. Float mode means that the regulated voltage reduces once the absorption charge is finished. So for example a charger might be at 14.4v during the absorption phase. Once it detects a low current demand because the battery is fully charged, it will reduce the voltage to say 13.5v. That is float mode.

 

But a normal alternator fitted to a boat, without any extra gizmos such as Adverc or Sterling boxes, doesn’t do that. The voltage will remain at 14.4v until the engine is stopped.

 

If you are refuting that last para, then sorry but you are wrong. And this is why a bog standard alternator isn’t suitable for charging a Li battery whilst also being used to propel the boat (unless you are prepared to stop the cruise as soon as the batteries are charged). It would keep the Li battery at 14.4v indefinitely, and I think we all agree that is a bad idea.

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1 minute ago, nicknorman said:

You aren’t really making any sense. Float mode means that the regulated voltage reduces once the absorption charge is finished. So for example a charger might be at 14.4v during the absorption phase. Once it detects a low current demand because the battery is fully charged, it will reduce the voltage to say 13.5v. That is float mode.

 

But a normal alternator fitted to a boat, without any extra gizmos such as Adverc or Sterling boxes, doesn’t do that. The voltage will remain at 14.4v until the engine is stopped.

 

If you are refuting that last para, then sorry but you are wrong. And this is why a bog standard alternator isn’t suitable for charging a Li battery whilst also being used to propel the boat (unless you are prepared to stop the cruise as soon as the batteries are charged). It would keep the Li battery at 14.4v indefinitely, and I think we all agree that is a bad idea.

Clearly you know better than the people that make alternators nick? because that's where some of the quoted text has come from, and they say that once batteries hit 14.4 the alternator stops charging until the voltage drops below 13.5. And in checking alternators we see similar 

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33 minutes ago, nicknorman said:

You aren’t really making any sense. Float mode means that the regulated voltage reduces once the absorption charge is finished. So for example a charger might be at 14.4v during the absorption phase. Once it detects a low current demand because the battery is fully charged, it will reduce the voltage to say 13.5v. That is float mode.

 

But a normal alternator fitted to a boat, without any extra gizmos such as Adverc or Sterling boxes, doesn’t do that. The voltage will remain at 14.4v until the engine is stopped.

 

If you are refuting that last para, then sorry but you are wrong. And this is why a bog standard alternator isn’t suitable for charging a Li battery whilst also being used to propel the boat (unless you are prepared to stop the cruise as soon as the batteries are charged). It would keep the Li battery at 14.4v indefinitely, and I think we all agree that is a bad idea.

 

I agree.

 

This is easily proven by leaving the engine running and measuring the battery voltage at the end of a reasonable days cruising. It will be 14.4 volts or whatever  voltage the regulator is set to regulate at.

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54 minutes ago, peterboat said:

they say that once batteries hit 14.4 the alternator stops charging until the voltage drops below 13.5. 

 

This makes no sense to me at all. On my A127 the battery voltage definitely climbs towards 14.4v and stays there for hours on end once 14.4v is achieved. At 14.4v the alternator definitely continues charging i.e. does NOT stop charging. Why would it? 

 

 

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1 hour ago, peterboat said:

...they say that once batteries hit 14.4 the alternator stops charging until the voltage drops below 13.5. And in checking alternators we see similar 

And do ‘they’ make conventional (as in not ECU controlled) alternators as found on 99.99% of inland boats?  Because if they do then they don’t know what they’re talking about. 

10 minutes ago, Mike the Boilerman said:

This makes no sense to me at all. On my A127 the battery voltage definitely climbs towards 14.4v and stays there for hours on end once 14.4v is achieved. At 14.4v the alternator definitely continues charging i.e. does NOT stop charging. Why would it?

Of course that’s what you see, because that’s what alternators do. 
 

 

41 minutes ago, cuthound said:

This is easily proven by leaving the engine running and measuring the battery voltage at the end of a reasonable days cruising. It will be 14.4 volts or whatever  voltage the regulator is set to regulate at.

Absolutely this. 

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My battery monitor always shows 14. something at the end of a days cruising, I never see it dropping to 13. something.

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8 hours ago, peterboat said:

As the battery reaches a state of full charge, the electromotive force becomes strong enough to oppose the current flow from the alternator, the amperage output from the alternator will drop to close to zero, while the voltage will remain at 13.5 to 14.5.

Which simply reinforces what I, Nick and everyone else has said. The current will drop to close to zero but the voltage will remain at the regulated level. 

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1 minute ago, cuthound said:

In my opinion, any article which says "amperage" instead of "current" is best ignored.

 

My opinion too.

 

Although paradoxically, I have no problem with 'voltage' instead of 'potential difference'. Like. 

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2 minutes ago, Mike the Boilerman said:

 

My opinion too.

 

Although paradoxically, I have no problem with 'voltage' instead of 'potential difference'. Like. 

 

Same for me. I guess it comes from my Electrical Principles tutor hurling his blackboard rubber at anyone who said "amperage"! ?

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Just now, cuthound said:

 

Same for me. I guess it comes from my Electrical Principles tutor hurling his blackboard rubber at anyone who said "amperage"! ?

 

And quite right too!! 

 

"Amperage" is an abomination rivalling the use of 'less' when 'fewer' is meant.... 

 

I blame the teachers. Mutter mutter. 

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39 minutes ago, cuthound said:

In my opinion, any article which says "amperage" instead of "current" is best ignored.

I hate the word, probably because my tutor would have marked me down heavily if I’d ever used it. Unfortunately, it’s now an accepted word in the USA as I understand matters. Several years ago I took a UK company to task for using it and they emailed me back with a very friendly response which included references to a number of American regulations which use the horrid word. 
 

So I’ll continue to say ‘current handling capacity’ or similar myself but I’ve stopped railing against seeing ‘amperage’ used elsewhere as it’s pointless. 

32 minutes ago, Mike the Boilerman said:

I blame the teachers. Mutter mutter. 

Blame the Yanks. It’s far more satisfying ;)

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3 hours ago, peterboat said:

Clearly you know better than the people that make alternators nick? because that's where some of the quoted text has come from, and they say that once batteries hit 14.4 the alternator stops charging until the voltage drops below 13.5. And in checking alternators we see similar 

Well I may or may not know better than people who make alternators. But that isn’t relevant. What is relevant is that I do know more than people who are employed by companies to write pseudo tech-speak to be absorbed by folk who don’t really understand.

 

Do you really imagine that the person who wrote that is the same person who designed the regulator? Have you never realised that the sales literature produced by a company doesn’t actually bear much relation to the hard facts as designed into a product?

 

i had a lot of dealings with the manufacturers of a very expensive helicopters - €20 million a pop. It was amazing how little communication existed between those who wrote the training material, and those who actually designed it. The latter were a bit trainsetish, the former therefore had to make it up, according to what they thought it ought to be like. The reality was often very different.

 

The bottom line is that a basic alternator as found in canal boat engines, doesn’t have a float mode. If you think otherwise, you are sadly wrong and at risk of misleading people who might think you know what you are talking about. Which, as Donald Trump would say, is bad. Very bad.

Edited by nicknorman

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Swerving slightly to the related topic of "does charging lithium batteries blow up your alternator", I have to report that I've just had to do a transplant of the stator and diode pack in my A127 alternator. I've not done a post-mortem, but clearly one or more diodes have failed. Our cruising pattern over the last month or so means that the alternator has been turned up to 11 for pretty much the whole time the engine has been running.

 

 

MP.

  

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If it were possible to buy an alternator that would charge at say, 13.8V, and float at say, 13.2V for lithiums, or 14.4V and 13.6V float for LA batteries, it would good to know where, and how much.

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11 hours ago, nicknorman said:

Well I may or may not know better than people who make alternators. But that isn’t relevant. What is relevant is that I do know more than people who are employed by companies to write pseudo tech-speak to be absorbed by folk who don’t really understand.

 

Do you really imagine that the person who wrote that is the same person who designed the regulator? Have you never realised that the sales literature produced by a company doesn’t actually bear much relation to the hard facts as designed into a product?

 

i had a lot of dealings with the manufacturers of a very expensive helicopters - €20 million a pop. It was amazing how little communication existed between those who wrote the training material, and those who actually designed it. The latter were a bit trainsetish, the former therefore had to make it up, according to what they thought it ought to be like. The reality was often very different.

 

The bottom line is that a basic alternator as found in canal boat engines, doesn’t have a float mode. If you think otherwise, you are sadly wrong and at risk of misleading people who might think you know what you are talking about. Which, as Donald Trump would say, is bad. Very bad.

 

pstree-swing-s-hogh.jpg

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11 hours ago, WotEver said:

 

Blame the Yanks. It’s far more satisfying ;)

those pseudotechs can't even distinguish between a meter and a metre.  sad innit?

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8 hours ago, Richard10002 said:

If it were possible to buy an alternator that would charge at say, 13.8V, and float at say, 13.2V for lithiums, or 14.4V and 13.6V float for LA batteries, it would good to know where, and how much.

 

Keep up at the back there.The last few days' posts have been discussing the fact that alternator regulators don't come with a float setting!

 

But yes I agree there would be a latent demand for what you describe. There is also a latent demand for unicorns...

 

:hug:

 

 

 

 

 

 

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9 hours ago, MoominPapa said:

Swerving slightly to the related topic of "does charging lithium batteries blow up your alternator", I have to report that I've just had to do a transplant of the stator and diode pack in my A127 alternator. I've not done a post-mortem, but clearly one or more diodes have failed. Our cruising pattern over the last month or so means that the alternator has been turned up to 11 for pretty much the whole time the engine has been running.

 

 

MP.

  

Eeek!

'turned up to 11'. Does that mean you've not run the engine much in the last month and turned up the output to high?

I've been keeping my output around 40A constant to avoid high temps and will order a bilge blower as Peter recommended as soon as we get to civilization. What Amps have you been putting out and any idea of temps? 

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13 minutes ago, Dr Bob said:

Eeek!

'turned up to 11'. Does that mean you've not run the engine much in the last month and turned up the output to high?

I've been keeping my output around 40A constant to avoid high temps and will order a bilge blower as Peter recommended as soon as we get to civilization. What Amps have you been putting out and any idea of temps? 

We've very rarely seen the batteries full, so whenever the engine has run, the alternator has been on maximum output. 

 

The large amounts of fluff in the cooling-air path around the diodes probably didn't help either.

 

I think my spare alt now has a sufficiently large fraction of U/S bits that it's time to Ebay a brand new spare, 55 of your earth pounds.

 

MP.

 

ETA The dead alt was bought as a 70A job, but it seems to max out at more like 60A

Edited by MoominPapa

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17 minutes ago, MoominPapa said:

We've very rarely seen the batteries full, so whenever the engine has run, the alternator has been on maximum output. 

 

The large amounts of fluff in the cooling-air path around the diodes probably didn't help either.

 

I think my spare alt now has a sufficiently large fraction of U/S bits that it's time to Ebay a brand new spare, 55 of your earth pounds.

 

MP.

 

ETA The dead alt was bought as a 70A job, but it seems to max out at more like 60A

 

Seeing as @WotEver thinks we should capitulate to American electrical phraseology, shouldn't those be "ground pounds"? ?

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13 hours ago, cuthound said:

 

Same for me. I guess it comes from my Electrical Principles tutor hurling his blackboard rubber at anyone who said "amperage"! ?

What about amperage per hour? ?

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4 minutes ago, Jen-in-Wellies said:

What about amperage per hour? ?

 

That would have him turning in his grave. ?

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26 minutes ago, Mike the Boilerman said:

 

If he was dead!!

 

 

 

 

He must be, either that or in the Guinness book of records, he was approaching 60 back in 1970!

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