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Power Generation & Warning Light


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I'm new to boating, whilst also new to engines and electrical systems (which appears to be a common combination / problem). Whilst recently moving on board we have encountered a few issues with the starter motor and ignition switch, which now appear to be fixed, though we're now on to the next 2 challenges ...

 

1. When the engine is running the power management panel (Sterling) indicates that we are generating 11.8v, however I would have expected it to show increased power and therefore be reading 13.5v - 14.8v whilst the engine is running, and then to drop to ~12.6v once the engine is off and battery charged. Is my understanding correct, and we are therefore not generating the right amount of power from the engine / alternator? [I believe it could be caused by slippage of the alternator belt which will likely soon need replacing anyway]
 

2. Once the engine is turned on the battery light is consistently flickering on the engine control panel, probably 4-5x per second. After running for a few hours it then appeared to stop. We have a single leisure battery at present (in the process of sourcing new ones, but want the full system up and running appropriately first) and that didn't appear to hold any charge overnight despite 3 hours with the engine on. Then once again this morning the flickering occurred.

 

We have an Isuzu engine and a 12v alternator, connected to the starter and leisure with a split relay.

 

I'll be very grateful for any advice you can offer, this forum has already served as wealth of knowledge.

Thanks,

DooW

 

 

 

 

 

 

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2 minutes ago, DuckOutOfWater said:

I'm new to boating, whilst also new to engines and electrical systems (which appears to be a common combination / problem). Whilst recently moving on board we have encountered a few issues with the starter motor and ignition switch, which now appear to be fixed, though we're now on to the next 2 challenges ...

 

1. When the engine is running the power management panel (Sterling) indicates that we are generating 11.8v, however I would have expected it to show increased power and therefore be reading 13.5v - 14.8v whilst the engine is running, and then to drop to ~12.6v once the engine is off and battery charged. Is my understanding correct, and we are therefore not generating the right amount of power from the engine / alternator? [I believe it could be caused by slippage of the alternator belt which will likely soon need replacing anyway]
 

2. Once the engine is turned on the battery light is consistently flickering on the engine control panel, probably 4-5x per second. After running for a few hours it then appeared to stop. We have a single leisure battery at present (in the process of sourcing new ones, but want the full system up and running appropriately first) and that didn't appear to hold any charge overnight despite 3 hours with the engine on. Then once again this morning the flickering occurred.

 

We have an Isuzu engine and a 12v alternator, connected to the starter and leisure with a split relay.

 

I'll be very grateful for any advice you can offer, this forum has already served as wealth of knowledge.

Thanks,

DooW

 

 

 

 

 

 

The battery is holding charge OK but you are not charging it up, if the ign light is on and the output volts are under 12 volts your alternator is not doing anything, now it could be a slipping belt or it could be a knackered alternator 

 

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Don't source new leisure battrey/batteries until you have fixed the charging problem, or you will very quickly goose the new ones.

 

If voltages are being read correctly, your alternator isn't charging properly.  Expect at least 14 volts, unless the engine is only idling.

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Yes it sounds like the alternator isn’t working. Easy to check the belt tension- should be fairly firm and definitely not sloppy. However it sounds to me more like an alternator failure to me.

 

Just one question, when you first turn on the ignition does the alternator warning light (what you call the battery light) come on steady, or is it flickering? The correct behaviour would be for the light to be on solid when the ignition is on, then off once the engine has started.

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hmm - at what speed is the engine running - if at tickover the flickering siggests to me that it's not running very fast. It nees to be running at 1100-1500 rpm befor the alternator can do anything useful.

Actual engine rotational speed depends on the make and type of the engine.

Can you enlighten the assembled members?

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Thanks all for quick help. I'll review the belt tension first

 

Alan - that was our plan. We need a new leisure bank anyway as the single existing is old and we intend to extend the capacity, so will source but only install once confident setup working correctly.

 

Nicknorman - the alternator warning light flickers from the point then engine begins running

 

OldGoat - I'll check more closely. I had been running it in neutral with some additional revs. I'll test it specifically, however i'm confident we're generating less power than previously at similar speeds which from my limited understanding would indicate a loose / belt at the minimum, or dodgy alternator (I won't say at worst as sod's law would quickly prove that the situation could be, and is, worse!)

 

We're in Tottenham Hale, near Stonebridge Lock

 

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1 hour ago, DuckOutOfWater said:

Thanks all for quick help. I'll review the belt tension first

 

Alan - that was our plan. We need a new leisure bank anyway as the single existing is old and we intend to extend the capacity, so will source but only install once confident setup working correctly.

 

Nicknorman - the alternator warning light flickers from the point then engine begins running

 

OldGoat - I'll check more closely. I had been running it in neutral with some additional revs. I'll test it specifically, however i'm confident we're generating less power than previously at similar speeds which from my limited understanding would indicate a loose / belt at the minimum, or dodgy alternator (I won't say at worst as sod's law would quickly prove that the situation could be, and is, worse!)

 

We're in Tottenham Hale, near Stonebridge Lock

 

There are so many variations of boat / engine / hull / fit-out / additional equipment and so forth, that is can be quite a challenge to diagnose a problem with any degree of certainty.

On my boat I had to blip the throttle 'momentarily' to get the charging circuits to engage properly. The fact that you most-often do or do not do that doesn't mean that a third party suggestion is correct or not - it's something to try.

Your 'charge' light flickering could suggest the blip approach may return dividends (or even not). Worth a go!

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If the flickering is at 1000rpm+ then if the voltage is confirmed I would initially suspect very worn brushes. It may be just two or three screws to free the regulator and twist it out with attached brush assembly bit that very much depends upon the alternator make & model.

 

Before anything else make sure all the battery and alternator terminals are clean and tight.

 

 

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