Why is my battery indicator light showing?

[Medskipper]

My battery indicator light on the flybridge has started to come on now with the engine running. At first I thought it was a bit of corrosion behind the panel after the winter, so I took panel off and cleaned all the terminals to the light and it still came on. Next I checked and cleaned all terminals to the alternator,
and it still came on, next I checked all terminals to the battery bank, cleaned tightened etc and still the light shows a battery problem yet my amp meter indicates that I am charging at 14v and I am not getting any flat batteries!

Any ideas chaps? have I missed anything?
All help gratefully received

Barry

 

[Peanuts]

Its going to be a series of questions to assist in your problem,apart from your statement of your 'ammeter reading 14v!!'
Apart from your battery light on the flybridge coming on do you have any other indications,eg battery volts,(I know you said 14v) ammeter reading etc that are available to you if so what are they doing. You said the light is on the flybridge so is the same happening at the lower helm? I appreciate you cleaning all the connections but has any other work been done on the electrical system recently before the time the problem started. Is the boat single or twin and what make of alternator do you have?
Once again sorry for all the questions just trying to get all the facts.
Look forward to your reply

 

[Medskipper]

Hi Steve,

I have not had any work done or added anything electrical since last year. All batteries were new last year and have good readings on a meter. Twin engine with both ameters reading 14v when engines running, as they always have done. The alternaters are the oringinal ones on Volvo engines, not sure of the make as I'm a hour away from the boat. both were taken off and serviced year before last and appear to be running correctly. I don't have a light on the lower helm as that is where the ammeter is.

Many Thanks

Barry

 

[Peanuts]

Not so many questions this time.
You state that you have 14v on both gauges, (lower helm)what are the ammeters reading? I assume that the light coming on is for one engine and that the other is OK.
What Volvo engines do you have, should be able to work out what alternators are fitted.
Look forward to reply and probably more questions.

 

[William_H]

Run the engine with the light showing and note the voltage and amps being generated. Now apply as much load to the electrical circuit as you can. ie all lights fridge radios etc. If you can get a decent load in the order of 30 amps then check the amps out of the alternator and the volts.
It is conceivable that the generator will not provide anything like its rated current.
Next remove the lamp or the wire after the engine has been started and the alternator is charging. If the charge and voltage drop then you have the answer.

The generator (alternator) gets current for excitation (field current) from the battery via the light this current gets the alternator giving output part of which is rectified to provide its own current for excitation. This is usually via additional diodes. These may have died.
The excitation from the battery will not give enough for full power output.
If in fact you are sure the alternator is capable of doing its job then ignore the light. If it is not capable then take the alternator off for repairs. If it has a separate regulator take that off for checks too. good luck olewill

 

[Guest]

[ QUOTE ]

My battery indicator light on the flybridge has started to come on now with the engine running. At first I thought it was a bit of corrosion behind the panel after the winter, so I took panel off and cleaned all the terminals to the light and it still came on. Next I checked and cleaned all terminals to the alternator,
and it still came on, next I checked all terminals to the battery bank, cleaned tightened etc and still the light shows a battery problem yet my amp meter indicates that I am charging at 14v and I am not getting any flat batteries!

Any ideas chaps? have I missed anything?
All help gratefully received

Barry

[/ QUOTE ]

Batt Ind. light .... do you mean Ignition red light ?

If so that normally means a problem in the excite circuit. The light goes out after starting engine by alternator supplying current in reverse to excite current making a zero nett - = light out. If a break in the wiring to alternator occurs you can still get a light but it won't be fed the opposing alternator bit to put it out.

If its another light - then I have no idea !

 

[Peanuts]

I don't know how electrically minded you are, so sorry if I am preaching a bit to you.
The previous (good) replies explain exactly what should be happening, but to explain in easy terms (one I understand!).

The charging light is a simple way of monitoring the electrical system. It is connected between the alternator (usually terminal D+ or 61) and the operating current terminal on the starting switch (usually 15). The light will go out when the alternator provides more voltage then is present in the battery. That is why William_H told you to load up the system and to check the volts/amps and if OK to basically ignore the problem.
However I always like to find out why and after checking all the cables and connections the next thing I would do would be to swop the alternators over, run them up and see if the problem has moved as well, if it has then you know it's the alternator, any good electrical auto repair shop will be able to fault find eg diode pack or regulator. If however it remains on the same side then its in the wiring. I hope this is of some help.

As always please let us all know how you get on.

 

[pampas]

Warning light diode kaput.

 

[Medskipper]

Hi Steve,

Both ammeters read approx 14v with engines running. Light is only lit on the port engine. The engines are Volvo TAMD40Bs

I was thinking it might be a stray earth, or perhaps the exitor circuit creating too much current? I think I will try a slightly higher wattage bulb? what do do think?

Barry

 

[Medskipper]

Hi Nigel,

Yes, I thought it may be the exciter, the light is amber actually and is labelled "battery" on the panel, but yes its really an ignition light and should go out with engines running.
Many Thanks

Barry

 

[Medskipper]

Yes many thanks, I will try that!

Barry

 

[Medskipper]

Yes many thanks, excellent advice!

I will let you know how I get on,

Barry

 

[William_H]

Barry we have to get this Ampmeter sorted out. It may be a meter unit which will read voltage however the most important part (and as well) is current ( by a switch). In amps (ampmeter) this hopefully will indicate either how much current is going into the battery and often in the reverse sense how much current is going out of the battery.
If you can load up the electrics with everything turned on and engine running you may get a net current that is fairly low. That may be good. Certainly if the net current with a large load is negative amps then the alternator is not working very well.
In any case when the battery is low and has just started the engine you should get 10 or 20 amps at least for ashort period into the battery.
But like I said we need to know you are measuring amps.
If you can only measure volts,(and you have the name of the meter confused) 14 volts indicates that the alternator is apparently adequate but again if you hit it with a big load the voltage after a while may decay towards 12. That would be a sign that alternator is not working well. All testing with only the doubtfull engine alternator running. good luck olewill

 

[Guest]

[ QUOTE ]
Warning light diode kaput.

[/ QUOTE ]

Not necessarily ... I can use a normal bulb or diode on my panel and have light out when alternator works.

I used to have similar to original post and was due to a poor regulator on alternator. I was only getting very poor output and battery was basically feeding more to keep light on - simple terms of course.
£20 and my alternator had new diodes fitted etc. - and bingo..... light went out.

 

[Guest]

Now we know its the Ignition light and only on one engine ...

I would honestly not play around ... I would take of that alternator and give it to a local Auto Electrics guy to check out ... While he has it for a day - go back to boat and check carefully all connections especially on the excite lead that lights the light and feeds the alternator field.
No need for extensive "pre-flight" checks etc. /forums/images/graemlins/wink.gif

 

[pampas]

you answerd my statement by havind new diodes fitted, yes it will work with a diode instead of a lamp if correctly fitted.

 

[Guest]

[ QUOTE ]
you answerd my statement by havind new diodes fitted, yes it will work with a diode instead of a lamp if correctly fitted.

[/ QUOTE ]

Hi ... my panel lamp works either way round and is therefore not an LED ... but a grain of wheat red bulb. The diodes I had fitted were to the alternator regulator itself ...

/forums/images/graemlins/wink.gif