Volvo penta warning Lt unit

[Caldy]

Hi all,
My charging system is not working.
I've fitted a reconditioned alternator, the water and battery warning Lts are dim and oil fully bright
Before start up. Oil Lt extinguishes when engine runs, still no charge, I think all tests point to unit being goosed.
I appreciate all advice given.

 

[jrudge]

How are you determining that it is not charging.

If you say what boat / year someone may know its charging arrangement. Charging on a boat is usually not that complex. Does the exciter line have a voltage on it? Is the alternators outputting anything ? If so then it is a loose / corroded wire or faulty split charge unit.

Finding such things on a boat is sometimes the challenge

 

[Caldy]

Colvic sea worker, volvo penta instrument panel,
Possibly 1988. Alternator putting out zero v. You're right it is a challenge

 

[jrudge]

Is there an exciter voltage ? This often goes via the alternator fail bulb so maybe the issue

 

[Croftie]

Assuming normal system the warning lamp should have 12v to it then the other connector from the warning light goes to the alt. This provides 12v to excite the alt. Once the alt starts charging the wire from the alt to WL supplies voltage to the lamp instead of an earth so the lamp goes out (12v both sides = no lamp lit). You say the lamp is dim so as JR says check the 12v supply to the W/L first, it may be low (bad connection somewhere) The other alternative could be a bad earth at the alt assuming its the correct alternator, it has a good earth etc.

 

[Caldy]

Colvic sea worker, volvo penta instrument panel,
Possibly 1988. Alternator putting out zero v. You're right it is a challenge

Is there an exciter voltage ? This often goes via the alternator fail bulb so maybe the issue

That's what makes me think that it's the warning light unit. No volts at the alternator warning sensor

Is there an exciter voltage ? This often goes via the alternator fail bulb so maybe the issue

Is there an exciter voltage ? This often goes via the alternator fail bulb so maybe the issue

No volts at alternator 61 point which makes me think that the electronic warning light unit???

 

[jrudge]

So just put 12v to the exciter ( or 24 v it 24 v boat) and see if it comes to life. If so then just solve that problem

 

[julians]

So just put 12v to the exciter ( or 24 v it 24 v boat) and see if it comes to life. If so then just solve that problem

you cant just put 12v to the exciter, it needs to go through some kind of resistive load first, this is what the bulb provides - as well as being used to indicate a charging failure.

So if the battery bulb is only glowing weakly with the engine not running I suspect either the power to the bulb is failing - look for corroded connection somewhere on that circuit , or some other issue with the bulb/unit it lives in.

 

[jrudge]

I can’t see why but if it needs limiting then run if via a bulb ( which is what the fail light does anyway )

 

[Croftie]

Julians is correct, thats why you cannot use an LED bulb it needs that resistance usually a min/around 2 watt bulb

 

[jrudge]

I know you cant use an LED as there is in effect no exciter current.

I have looked this up and the bulb is required to limit current as if not when the ignition is on there is all current flow though the exciter circuit that stops as soon as it is turning as the volts are in balance. So just wire 12v via a bulb to test it

 

[julians]

I know you cant use an LED as there is in effect no exciter current.

I have looked this up and the bulb is required to limit current as if not when the ignition is on there is all current flow though the exciter circuit that stops as soon as it is turning as the volts are in balance. So just wire 12v via a bulb to test it

Yep, as long as any new wire is run through a 12v incandescent bulb it should be fine, can also use a 15ohm ish resister,but I'd guess a bulb is easier to come by .

Edit : I learnt all this when I replaced all the old fashioned bulbs on my caterham 7 with LEDs. Needed to wire a resister in parallel with the battery led otherwise the alternator wouldn't start generating any charge until the engine was revved past 5000 rpm.

 

[Caldy]

Yep, as long as any new wire is run through a 12v incandescent bulb it should be fine, can also use a 15ohm ish resister,but I'd guess a bulb is easier to come by .

Yep, as long as any new wire is run through a 12v incandescent bulb it should be fine, can also use a 15ohm ish resister,but I'd guess a bulb is easier to come by .

Edit : I learnt all this when I replaced all the old fashioned bulbs on my caterham 7 with LEDs. Needed to wire a resister in parallel with the battery led otherwise the alternator wouldn't start generating any charge until the engine was revived past 5000 rpm.

Yep, as long as any new wire is run through a 12v incandescent bulb it should be fine, can also use a 15ohm ish resister,but I'd guess a bulb is easier to come by .

Edit : I learnt all this when I replaced all the old fashioned bulbs on my caterham 7 with LEDs. Needed to wire a resister in parallel with the battery led otherwise the alternator wouldn't start generating any charge until the engine was revved past 5000 rpm.

Just discovered the problem, replacement was 24 volts. I didn't read the plate correctly, I feel really stupid but thanks for your input guys

 

[Caldy]

What 12volt alternator can be used for a boat old ford 2712e truck engine, my damaged one has no markings except valio, thanks in anticipation

 

[gordmac]

I would think one of the Lucas alternators used on almost everything 40 years ago would do.

 

[Caldy]

Cheers Gord