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Inverter charger


Chrisgriff

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3 hours ago, Mike the Boilerman said:

 

13.9 is an odd voltage. I'm fairly sure when I had an alternator with an expired diode it was giving me 12.9v on the DVM.

16 minutes ago, cuthound said:

Only then can we decide if the alternator is faulty. 

 

On my last 2 boats, the alternators gave out 13.9V when in absorption. The first one was a brand new volvo penta engine (2005). The second, my current boat - a 2002 beta43. Gibbo talks about 'poor' alternators designed for cars giving this sort of voltage. Maybe some examples are blown diodes but my volvo experience says that 13.9v charging does exist.

It would be good if we understood Mike's question of what a goosed alternator gives out.

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28 minutes ago, cuthound said:

When was the 13.9 volts measured? If the batteries were very flat, the alternator may not have come out of current limitation, and thus only be giving 13.9 volts.

 

In post 6, the OP said

 

"

Shore power off : 13.2

Shore power off & engine on : 13.9"

 

That sounds to me like the shore power had been on....as it was when the OP posted the thread. He then turned shore power off. He then started the engine. (OP please confirm).

Also, the combi was in float so the unit must have thought the batteries were near full. Ok, the 13.2V isnt an 'at rest' voltage. More than likely the 13.9V was the charge voltage from the alternator with a full ish battery. (OP, can you tell us the battery size...it may be relevant).

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5 minutes ago, Dr Bob said:

In post 6, the OP said

 

"

Shore power off : 13.2

Shore power off & engine on : 13.9"

 

That sounds to me like the shore power had been on....as it was when the OP posted the thread. He then turned shore power off. He then started the engine. (OP please confirm).

Also, the combi was in float so the unit must have thought the batteries were near full. Ok, the 13.2V isnt an 'at rest' voltage. More than likely the 13.9V was the charge voltage from the alternator with a full ish battery. (OP, can you tell us the battery size...it may be relevant).

 

However Stirling Combi's are well known for going into float too early (see post #14), so we don't know whether the battery was fully charged or not.

 

The other thing the OP cold ones s compare voltages at the alternator output and battery terminals. If significantly different he can look for poor connections.

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2 minutes ago, cuthound said:

 

However Stirling Combi's are well known for going into float too early (see post #14), so we don't know whether the battery was fully charged or not.

 

 

Agreed, but it should at least get it to 90% if not 95% SoC before going to float. That's why I keep using the term  'full ish'.?

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36 minutes ago, Dr Bob said:

On my last 2 boats, the alternators gave out 13.9V when in absorption.

 

That's interesting. None of my alternators has discrete stages like a battery charger (bulk, absorp, float). The current from all mine just progressively decays as the terminal voltage rises. What alternator do you have?

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4 minutes ago, Mike the Boilerman said:

 

That's interesting. None of my alternators has discrete stages like a battery charger (bulk, absorp, float). The current from all mine just progressively decays as the terminal voltage rises. What alternator do you have?

 

Yes, same with mine.

 

Except on the very latest automotive alternators, there are no active regulators delivering discrete charging voltages on automotive alternators. The voltage regulator reacts to the rising alternator output voltage and changes the magnetic field to limit the alternators output current.

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22 minutes ago, Mike the Boilerman said:

 

That's interesting. None of my alternators has discrete stages like a battery charger (bulk, absorp, float). The current from all mine just progressively decays as the terminal voltage rises. What alternator do you have?

No of course it doesnt have discrete stages. I was refering to the charging between 80 and 90% full which if using a decent charger, AtoB etc would be in the absorption stage. I used the term absorption to indicate how full the battery was so that I wasnt accused of charging a nearly empty battery so the 13.9v would be meaningless. Apologies to all who thought I was a muppet.

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1 hour ago, Dr Bob said:

Agreed, but it should at least get it to 90% if not 95% SoC before going to float. That's why I keep using the term  'full ish'.?

No... they dont! The term you should be using is "nowhere near full'ish" :(

 

They have an algorithm which measures how long the unit is charging at constant current, (bulk charging), multiplies it by ten, and that is the period it sets for absorption before reverting to float, (except that absorption is a minimum of 1 hour).

 

I would usually have to set an alarm for 55 minutes after starting the charger, so that I could reset it for another hour of absorption... and I would have to do it several times before reaching a suitable tail current.

 

If left to its own devices, the batteries could be drawing 25A when it goes into float, despite my ideal tail current being around 2 or 3 Amps.

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18 minutes ago, Richard10002 said:

No... they dont! The term you should be using is "nowhere near full'ish" :(

 

They have an algorithm which measures how long the unit is charging at constant current, (bulk charging), multiplies it by ten, and that is the period it sets for absorption before reverting to float, (except that absorption is a minimum of 1 hour).

 

I would usually have to set an alarm for 55 minutes after starting the charger, so that I could reset it for another hour of absorption... and I would have to do it several times before reaching a suitable tail current.

 

If left to its own devices, the batteries could be drawing 25A when it goes into float, despite my ideal tail current being around 2 or 3 Amps.

Ok,  that's bad.........and if the OP's Sterling unit performs the same, that could be a contributary cause of the batteries being shot if being used without a battery monitor. Lets see what we hear when the OP checks how quick the voltage drops with a bit of load and no charging.

We will need to know the size of the OPs domestic bank though!!!!

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2 hours ago, cuthound said:

 

Yes, same with mine.

 

Except on the very latest automotive alternators, there are no active regulators delivering discrete charging voltages on automotive alternators. The voltage regulator reacts to the rising alternator output voltage and changes the magnetic field to limit the alternators output current.

PENDANT ALERT

 

No it does not. It changes the magnetic field to alter/limit the charging VOLTAGE. Its the batteries that control the charging current as we have to keep pointing out.

 

I know that you know that but it might give newbys the wrong idea.

Edited by Tony Brooks
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4 minutes ago, Tony Brooks said:

PENDANT ALERT

 

No it does not. It changes the magnetic field to alter/limit the charging VOLTAGE. Its the batteries that control the charging current as we have to keep pointing out.

 

I know that you know that but it might give newbys the wrong idea.

Well if you want to be ultra pedantic, no.  It changes the magnetic field to alter the output current. The output current is adjusted so that the desired output voltage isn’t exceeded for whatever the required output demand is. So it actually controls the current, in order indirectly to control the voltage.

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Well http://www.bbc.co.uk/schools/gcsebitesize/science/add_ocr_pre_2011/electric_circuits/mainsproducedrev1.shtml

 

says near the bottom:

 

Increasing the induced voltage

To increase the induced voltage:

  • move the magnet faster
  • use a stronger magnet
  • increase the number of turns on the coil
  • increase the area of the coil

Now, the speed of the magnet is fixed by the engine speed. The number of turns and the area of coil is fixed by the design of the machine. That leaves strength of magnetic field and that is what is altered but pulse width modulation so I stand by my statement that its the voltage that is controlled and that any current control is, in part, a result of that voltage control. In other words the opposite of what you argue.

 

Current flowing in any circuit depends upon the voltage pushing it and the resistance of that circuit. Curreent does not determine the voltage trying to push it.

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SO.......

 

i I have turned the shore power off & engine is not running.

 

we are now running off 12.4v..... We have a fridge which is on & a laptop charging.

 

i have checked the batteries and they are at 12.7....... & the leads running to the alternator are running at 12.7. 

 

I have have added a picture of the batteries. We have 5 of them. I could only read the front one as I couldn't reach the back.....

 

with th the engine on the it goes up to 13.8. & also with the engine on I tested the wires connected to the alternator & that was at 14.8.....

 

hope we this all helps...... I will leave shore power off and let you know how long we last!

image.jpeg

image.jpeg

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Those screw down clamps look like a BSS failure waiting to happen and are also likely to cause volt drop. Please change them for the sort of clamp that has a stud stuck up to accept a heavy duty ring terminal.

 

Check the voltage at the back of the voltmeter you showed in a photo. If its the same or very similar then go looking for thin cables, poor/loose terminal crimps, loose dirty terminals and so on. 

Put your voltmeter across the domestic master switch with a fair electrical load running. It should read all but zero, if it reads more than about 0.1V suspect burned contacts or a worn out switch.

 

Do the same for the large terminals on the split charge diode and expect similar results but this time with the engine revving first thing in the day

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23 minutes ago, Chrisgriff said:

with th the engine on the it goes up to 13.8. & also with the engine on I tested the wires connected to the alternator & that was at 14.8.....

That’s a heck of a big voltage drop down a couple of metres of cable. It suggests you have a very poor connection somewhere between the alternator and the batteries. It also suggests that your alternator is fine. 

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15 minutes ago, Richard10002 said:

What do you mean by "we are now running at 12.4V", then you say "I have checked the batteries and they are at 12.7V"?

 

Are these readings taken at the same time, but in different places? or what?

 

A photo early in this topic shows what looks suspiciously like a far eastern bargain voltmeter. I would not trust it without checking it with a known voltmeter so I think one is that meter and one is at the batteries but I agree we can not be sure. I am not even sure that the OP has confirmed he has a multimeter and knows hot to set it and use it.. This is why I am trying to encourage him to do some basic voltmeter checks.

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So in summary you are losing 1v or so between alternator and batteries. This is bad! Probable cause is a bad connection between a wire and a terminal, or possibly in the battery isolator switch. You need to work through the circuit with a multimeter whilst the engine is running (be careful of belts) to see what point has a big voltage drop. Until that is fixed, don’t even think about new batteries!

4 hours ago, Tony Brooks said:

Well http://www.bbc.co.uk/schools/gcsebitesize/science/add_ocr_pre_2011/electric_circuits/mainsproducedrev1.shtml

 

says near the bottom:

 

Increasing the induced voltage

To increase the induced voltage:

  • move the magnet faster
  • use a stronger magnet
  • increase the number of turns on the coil
  • increase the area of the coil

Now, the speed of the magnet is fixed by the engine speed. The number of turns and the area of coil is fixed by the design of the machine. That leaves strength of magnetic field and that is what is altered but pulse width modulation so I stand by my statement that its the voltage that is controlled and that any current control is, in part, a result of that voltage control. In other words the opposite of what you argue.

 

Current flowing in any circuit depends upon the voltage pushing it and the resistance of that circuit. Curreent does not determine the voltage trying to push it.

I’ve asked for this to be moved to a new thread so I can argue with you without disrupting this thread.

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Looks as if batteries are also not secured to me though id be glad to be wrong. If the are not any movement ( hitting cill or gates ) can move them. That at best puts strain on connections which may induce resistance or corrosion as the loosen. Not to mention no cover and a hot exhaust boiling off electrolyte.

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19 minutes ago, nicknorman said:

So in summary you are losing 1v or so between alternator and batteries. This is bad!

 

Indeed it is! Half of that volt could be getting lost in a split charging diode though, if the OP has one.

 

The four domestic batteries look like 6v open cell batteries to me with proper stud terminals. I'm wondering if the OP measured the easy battery to get at, the starter battery at the front, and if he stuck the probes on the lead posts or on the wires entering the dodgy terminals. Those terminals could account for the other half a volt. 

 

And if he was measuring the starter battery we are no further forward.

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Mike and Tony are right. I think we are all guessing as we haven't a clue where the voltages are being measured or what the measurement was done with. It is no use to compare the volt meter shown in an earlier photo with a multimeter reading unless you know what readings they give when measuring the same point. Is the meter connected to the domestic circuit or the start battery? It would be great if the OP could specify the point in each circuit where he measures a voltage and what meter he is using plus whether the engine is running etc etc.

Mike is right that we are totally in the dark if some of the numbers are from the start battery.

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6 hours ago, Tony Brooks said:

PENDANT ALERT

 

No it does not. It changes the magnetic field to alter/limit the charging VOLTAGE. Its the batteries that control the charging current as we have to keep pointing out.

 

I know that you know that but it might give newbys the wrong idea.

Yes, very dodgy wearing a necklace near batteries. 

Edited by nb Innisfree
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