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micky1010

Electrical engineer required

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Hi all,

I have been having an issue for the past few months with high voltage from the alternator.

The boat has a sterling alternator to battery regulator and this had a warning light on for high alternator volts, so I measured the voltage it was putting out at the batteries and it is 14.75 which I believe is too high. I was advised it would be the voltage regulator on the alternator that had failed and so have had a new alternator fitter by RCR as it is covered by their parts replacement, however after the engineer left the warning light came back on and it was back to overcharging again. RCR came back, fitted another new alternator, still over volts, tested all wiring and connections, all were fine even wired the alternator direct to the batteries cutting out the sterling alternator controller and it was still high voltage and so they said they couldn't help anymore as it would require deeper investigation. They arranged another engineer to come out and investigate further, he has checked the alternator and confirmed it as fine, checked all the batteries and confirmed they are fine, check all connections and they are fine. He believes it must be the sterling alternator controller that is causing the issue but did not attempt to disconnect it or tell me what I would need to buy to replace it which is what I want doing as I just want it fixed. I am not 100% convinced this has failed as the unit has a unit fail warning light that is supposed to come on if it has failed and should shut down if it does fail which has not happened, and the original RCR bloke wired the alternator direct to the battery and it was giving out high volts.

I need to find an electrical engineer in the midlands who could come out and strip out the sterling controller and replace it with a new one or a split charge system of some sort, I cannot take the boat to a boat yard as I do not want to run the engine as it will damage the batteries and there is nothing in our marina, does anyone know of someone who will be able to come out and not just check what needs doing bet also replace anything that needs it?

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I am sure our sterling alternator controller outputs 14.8 volts into wet cell batteries during absorption. 

What controller is it and what warning light is on? 

May help someone diagnose the problem. 

FWIW the over voltage alarm on our unit doesn't trigger until 15.5V

Edited by rusty69

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Why do you think 14.75V is too high? As far as I can tell, it's actually fine for many batteries as an absorbtion phase voltage.

What happens when the batteries are "full"? Does it revert to something around 13.5V, or remain at 14.75V? 

 

 

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Not a question for the OP but for you other clever electric bods out there.

If there is a sterling alternator to battery regulator in circuit do the batteries ever see the alternator voltage?

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I can't comment on the alternator controller but I have a sterling pro charge mains battery charger and the output voltages for flooded lead acid batteries are:

High Charge 14.8 Float 13.6 and Maintenance  12.8

 

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44 minutes ago, ditchcrawler said:

Not a question for the OP but for you other clever electric bods out there.

If there is a sterling alternator to battery regulator in circuit do the batteries ever see the alternator voltage?

For an alternator to battery CHARGER A to B you are correct. Any voltage seen by the battery is produced by the charger.

For the Sterling advanced external regulator then the battery always sees the alternator output voltage. The regulate just shorts out the alternator's own regulator and makes the alternator produce a higher voltage - much like all the other brands of similar equipment.

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The controller is a sterling ab12160 and the warning light is the 'high alternator voltage' light, according to the manual when this is on:

LED 7 - HIGH ALT VOLTS (red)

This LED indicates that the unit has tripped because of high voltage (>15.5V) on the alternator. It usually means that the alternator’s own regulator has failed.Check the voltage and, if necessary, stop your

engine as soon as possible and disconnect the alternator input cable, or you will boil and destroy your batteries!

The batteries are taking 14.4v from the mains charger/inverter which is correct as per the engineers who have been out but it goes up to 14.7 when charging from the alternator, the voltage on the back of the alternator was at 15.15v. They should be more or less fully charged as I do not use too much 12v being in the marina on shore power, it is only lights that are drawing 12v power. 

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5 minutes ago, micky1010 said:

... it goes up to 14.7 when charging from the alternator, the voltage on the back of the alternator was at 15.15v. 

When the alternator was connected directly to the battery what was the voltage, 14.8 or 15.1?

if the former (14.8) then that's what I'd expect from a modern alternator and therefore the problem is either the alternator controller or its wiring. 

If the latter (15.1) then the alternator is faulty. That's unlikely (although not impossible) with a new alternator. 

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Not sure as I did not do this it was the engineer, but I believe it was 14.8 on the batteries when it was connected directly.

So it does look like the sterling controller that is at fault?

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3 minutes ago, micky1010 said:

Not sure as I did not do this it was the engineer, but I believe it was 14.8 on the batteries when it was connected directly.

So it does look like the sterling controller that is at fault?

Yes, to me it does. I'll be interested in what Tony B thinks as he know more about those controllers than me.

14.7/14.8 with the alternator connected directly to the batteries sounds spot on for a modern alternator, but let's see what others think first. 

What alternator is it?

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It is an A460 they said, 70A I do not know the make I'm afraid.

If it is the controller then what is best to replace it, I have read elsewhere a lot of people saying just go with a straight forward split charge diode but I would prefer something to control the charge to each bank safely, would a sterling pro r split charge be a straight replacement ?

1 minute ago, rusty69 said:

Are the batteries in good, condition? 

The engineer today said they are fine when he tested the voltage with everything disconnected. the house bank is a year and a half old now and the engine bat only half a year old.

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A lot of "engineer" visits and nothing sorted out, a bit worrying.

It looks like an "A to B" type converter. This type of controller sucks the power out of the alternator and then totally generates the charging voltage itself.. 14.8 is reasonable but possibly a bit high for sealed batteries though Im not sure of this. There is most likely a temperature correction so as its still quite cold even 15.1 might be ok.

You could change the battery type settings if you feel happier with a lower voltage. The 15.1 volts measured at the alternator is not right, was this with the first or replacement alternator?. However as the AtoB totally controls the voltage this MIGHT not be a problem. You could remove the AtoB and just use the Alternator directly though the AtoB is a good thing to have.

It is possible that the AtoB is working correctly and just showing the warning light because it has correctly set a quite high voltage due to the cold???? Mr Sterling is very fond of his flashing lights.

..............Dave

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Thanks all but I'm no wiser as some are saying these volts are all fine and other saying the controller is at fault.

I still really need an electrical person who would come out and not just investigate the issue but replace what needs replacing as I cannot use the engine until this is fixed. Does anyone know someone who would cover the Lichfield area they can recommend?

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1 hour ago, micky1010 said:

Does anyone know someone who would cover the Lichfield area they can recommend?

We have a location!

Try PMing Tony Brooks. 

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There seems to be a lot of confusion here, with people confusing the "alternator voltage" and the "battery voltage".

 

Firstly, let's be clear here. With this type of Sterling A-B unit, these two voltages are completely independent. The alternator output voltage goes into the A-B unit, and the output from the unit charges the batteries. The two are not connected.

 

Secondly there is the matter of the warning light. As micky1010 quotes from the manual,   "This LED indicates that the unit has tripped because of high voltage (>15.5V) on the alternator". Thus it is clear that the A-B unit THINKS that the alternator is presenting it with more than 15.5 volts. If the reading at the back of the alternator is indeed 15.15 volts, then EITHER the A-B unit is faulty OR there is a higher voltage at its input than there is at the output of the alternator. This shouldn't be hard to test with a meter - remembering to measure with BOTH the probes near to the A-B unit's input terminals (to eliminate odd effects that may be caused by voltage drops in the negative wiring).

 

Thirdly there is the matter of what is the correct voltage at the batteries. 14.8 doesn't sound unreasonable for bulk charge, perhaps the A-B unit's manual could clarify this? Does it reduce once the batteries are full? I don't know the A-B's operation in enough detail to comment, but I'm fairly sure that the A-B unit I saw last year did that - although of course if it's faulty anyway, its behaviour would be unpredictable.

 

ETA the unit I saw last year behaved oddly because it had been installed incorrectly by the boat-builder. Although the A-B unit itself had been correctly connected, the builder had left the original alternator to battery connection in place as well; he said he had done so in order that the batteries would still charge if the A-B unit should fail, but this was totally wrong and instead it caused the unit to behave rather erratically. Removing the unwanted connection fixed all the problems immediately Could there be a similar problem here?

Edited by Keeping Up
To add an afterthought
  • Greenie 2

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5 minutes ago, Keeping Up said:

There seems to be a lot of confusion here, with people confusing the "alternator voltage" and the "battery voltage".

 

Firstly, let's be clear here. With this type of Sterling A-B unit, these two voltages are completely independent. The alternator output voltage goes into the A-B unit, and the output from the unit charges the batteries. The two are not connected.

 

Secondly there is the matter of the warning light. As micky1010 quotes from the manual,   "This LED indicates that the unit has tripped because of high voltage (>15.5V) on the alternator". Thus it is clear that the A-B unit THINKS that the alternator is presenting it with more than 15.5 volts. If the reading at the back of the alternator is indeed 15.15 volts, then EITHER the A-B unit is faulty OR there is a higher voltage at its input than there is at the output of the alternator. This shouldn't be hard to test with a meter - remembering to measure with BOTH the probes near to the A-B unit's input terminals (to eliminate odd effects that may be caused by voltage drops in the negative wiring).

 

Thirdly there is the matter of what is the correct voltage at the batteries. 14.8 doesn't sound unreasonable for bulk charge, perhaps the A-B unit's manual could clarify this? Does it reduce once the batteries are full? I don't know the A-B's operation in enough detail to comment, but I'm fairly sure that the A-B unit I saw last year did that - although of course if it's faulty anyway, its behaviour would be unpredictable

Well said

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