Misbehaving charging system

[vicafloat]

Hi folks.

A friend has a BMC 1.5 engine in his Liverpool boats 55 ft. Cruiser stern Narrowboat. There are two alternators;the

55amp one serving the starter battery behaves normally ie. the ignition light goes out immediately the engine starts and

the ammeter shows a charge. However, the alternator (90amp) for the auxiliary bank of 4 110amp batteries refuses to kick

in and start charging unless the engine is on maximum revs;this happens every time,not just on initial start-up.

Once charging commences all is well. We suspected a fault in the alternator itself,but replacement with a reconditioned

unit made no difference. We would be grateful for some advice from the electronics experts on the Forum! Incidentally,there

was a battery management system fitted but this became faulty and has been disconnected.

[Chris Pink]

it is generally possible to excite a reluctant alternator by bypassing the warning light with a momentary switch.

 

I don't know whether this is bad for the alternator or not but i know it works.

[nicknorman]

Could it be that the indicator lamp is too small a wattage or has been replaced with an LED? Try a higher wattage bulb or add a resistor in parallel. The alternator uses the current flowing through the lamp to get it started, so if the lamp is not passing enough current this could delay the alternator coming on line. However, needing max revs seems a bit extreme!

Edited February 5, 2013 by nicknorman

[ditchcrawler]

Hi folks.

A friend has a BMC 1.5 engine in his Liverpool boats 55 ft. Cruiser stern Narrowboat. There are two alternators;the

55amp one serving the starter battery behaves normally ie. the ignition light goes out immediately the engine starts and

the ammeter shows a charge. However, the alternator (90amp) for the auxiliary bank of 4 110amp batteries refuses to kick

in and start charging unless the engine is on maximum revs;this happens every time,not just on initial start-up.

Once charging commences all is well. We suspected a fault in the alternator itself,but replacement with a reconditioned

unit made no difference. We would be grateful for some advice from the electronics experts on the Forum! Incidentally,there

was a battery management system fitted but this became faulty and has been disconnected.

When the "Battery Management unit" (I am assuming by this you mean charge controller of some sort) was removed was it replaced by anything to supply a feed to the field connection of the alternator?

[Arthur Brown]

"Once charging commences all is well."

Therefore the alternator works!

 

IMO the issue is that the house alternator doesn't have the required ALT lamp. This may be caused by the lamp being lost when the mystery controller was disconnected or the lamp being faulty or badly connected.

[Chris Pink]

Good point does the domestic alternator have an IND light?

[vicafloat]

When the "Battery Management unit" (I am assuming by this you mean charge controller of some sort) was removed was it replaced by anything to supply a feed to the field connection of the alternator?

 

 

I have checked withe the owner and the Kestrel has not been removed,just switched off;he will test with the unit switched on.

Sorry if my original post was misleading! He will also try a higher wattage bulb; though this has not been changed from new.

Will not be able to relate the findings until Thursday because my friend is on an IWA working party on that day,looking after

those lovely visitor moorings we have on the Shroppie(well I think they are the best in the country!)

 

Good point does the domestic alternator have an IND light?

 

Yes,the domestic alternator has it's own indicator light which refuses to go out unless he revs the whatsits off the engine!

I have been next to his boat when this happens and it does nothing for the pollution control of this country!

[by'eck]

Following suggestions above try soldering a 47 ohm resistor across the existing warning lamp. This will simulate the normal 3 watt indicator lamp which needs to be present to excite the alternator. It may be that a higher wattage one has been installed, but in any case allows normal alternator startup if bulb blows.

 

 

Suggest a 10 watt wirewound one which can be obtained above or you could try Maplins.

[Chris Pink]

Is a resistor required? Would a momentary switch do any harm? My alternator on a hand cranked engine just had a switch and no light.

[by'eck]

Is a resistor required? Would a momentary switch do any harm? My alternator on a hand cranked engine just had a switch and no light.

 

No but read above again

[Chris Pink]

Ok, and...?

[by'eck]

Ok, and...?

 

Either will do but a resistor is cheaper and easier to fit (and forget).

[bizzard]

The alternators drive belt might be slack and slipping, especially as the 90amp alternator on that engine is probably driven by a single V belt instead of a multi-V belt, which is about on the limit with a 90amp alt, belts don't always screech when slipping.

[vicafloat]

Following suggestions above try soldering a 47 ohm resistor across the existing warning lamp. This will simulate the normal 3 watt indicator lamp which needs to be present to excite the alternator. It may be that a higher wattage one has been installed, but in any case allows normal alternator startup if bulb blows.

 

 

Suggest a 10 watt wirewound one which can be obtained above or you could try Maplins.

Went to the boat today,armed with the resistor as suggested.Wired it into the circuit and the alternator kicked in

immediately on start up! Problem solved we thought,but the plot thickens;the engine continues to run even when

the ignition is turned off and continues to do so until the resistor is removed.We are therefore back to the

head-scratching because we cannot understand how the introduction of the resistor could affect the solenoid which

stops the engine. There must be a wiring problem somewhere but we would appreciate your views

[Tony Brooks]

Went to the boat today,armed with the resistor as suggested.Wired it into the circuit and the alternator kicked in

immediately on start up! Problem solved we thought,but the plot thickens;the engine continues to run even when

the ignition is turned off and continues to do so until the resistor is removed.We are therefore back to the

head-scratching because we cannot understand how the introduction of the resistor could affect the solenoid which

stops the engine. There must be a wiring problem somewhere but we would appreciate your views

 

 

I assume that your engine has an electric stop control although this is rare for a 1.5 - are you sure it is not a 1.8 because later automotive ones had electric stops.

 

The reason I think this is happening is that when you turn off the ignition switch current from the alternator D+ terminal is back feeding up the warning lamp wire and back through the bulb and resistor, Because they are now in parallel this allows sufficient current to pass to keep the stop solenoid energised.

 

In my view (as I said) one warning lamp serving two alternators is bad practise and not only are you likley to get the problem you had but are also in line for all sorts of odd warning lamp "faults". Some faults you may not see and some you see may not be real faults. It would be far better to fit another warning lamp and energise it via a relay. See My diagram

Edited February 9, 2013 by Tony Brooks

[vicafloat]

I assume that your engine has an electric stop control although this is rare for a 1.5 - are you sure it is not a 1.8 because later automotive ones had electric stops.

 

The reason I think this is happening is that when you turn off the ignition switch current from the alternator D+ terminal is back feeding up the warning lamp wire and back through the bulb and resistor, Because they are now in parallel this allows sufficient current to pass to keep the stop solenoid energised.

 

In my view (as I said) one warning lamp serving two alternators is bad practise and not only are you likley to get the problem you had but are also in line for all sorts of odd warning lamp "faults". Some faults you may not see and some you see may not be real faults. It would be far better to fit another warning lamp and energise it via a relay. See My diagram

Hi Tony,

The domestic alternator has it's own light but you are correct in that it is fed from the ignition switch.We

will now consult your wiring diagrams but would appreciate your advice on what kind of relay and where would we

obtain same;you are talking to enthusiastic amateurs here!!

[Tony Brooks]

Hi Tony,

The domestic alternator has it's own light but you are correct in that it is fed from the ignition switch.We

will now consult your wiring diagrams but would appreciate your advice on what kind of relay and where would we

obtain same;you are talking to enthusiastic amateurs here!!

 

 

Any car relay would do. Preferably one with a mounting bracket so its easy to fix in place and also try for one with no internal diode. If there is a diode the relay coil connections have to be "the right way round" but in your case it would not matter because as soon as you connected it incorrectly and energised it the diode would burn out/shatter, then it would be the same as one without the diode. Maplin also sell small 12/24 volt relays.

 

My diagram shows the domestic alternator bulb energised by the relay but that is because it is a further step on from a single alternator as discussed earier in the notes. In your mind just change any label saying domestic to engine and engine to domestic and the diagram will be fine.

 

Please look into your exact engine because although many 1.5 and 1.8 parts are interchangeable some are not and if it is a 1.5 the injector pump is very non-standard. You would need to be aware of this when changing the pump and when asking for advice. Or did I misunderstand your original post?

[OldGoat]

I had exactly the same problem with my boat on build. Spin the engine up and the alternator kicked in for the rest of the day even after stopping at locks.

That's because a bit of "magnetism" is still retained in the yokes of the windings for the alternator to self excite. The true function of the "I" terminal was not explained anywhere (It was a "professional" Leece-Neville unit, and installers are supposed to know....)

Mine is a 24V unit so jiggling around with resistors was not appropriate, nor was a bulb connected to the battery as it would always be On. I fitted a relay to the igniotion switch setup and ewerything was "peachy".

 

I assume in your setup that the engine stops "on the key" and has a solenoid to shut the fuel off. so any voltage left in circuit holds the solenoid On. (Mine has a separate Off button) If the former is so, then the "I" wire is wired incorrectly.

[ditchcrawler]

I had exactly the same problem with my boat on build. Spin the engine up and the alternator kicked in for the rest of the day even after stopping at locks.

That's because a bit of "magnetism" is still retained in the yokes of the windings for the alternator to self excite. The true function of the "I" terminal was not explained anywhere (It was a "professional" Leece-Neville unit, and installers are supposed to know....)

Mine is a 24V unit so jiggling around with resistors was not appropriate, nor was a bulb connected to the battery as it would always be On. I fitted a relay to the igniotion switch setup and ewerything was "peachy".

 

I assume in your setup that the engine stops "on the key" and has a solenoid to shut the fuel off. so any voltage left in circuit holds the solenoid On. (Mine has a separate Off button) If the former is so, then the "I" wire is wired incorrectly.

I have a 24 volt alternator and have never bothered connecting a field wire to it, it kicks in first start of the day when the engine reves to 600 rpm and as soon as it starts for the rest of the day. Saved worrying about lamps relays and things.

[vicafloat]

Any car relay would do. Preferably one with a mounting bracket so its easy to fix in place and also try for one with no internal diode. If there is a diode the relay coil connections have to be "the right way round" but in your case it would not matter because as soon as you connected it incorrectly and energised it the diode would burn out/shatter, then it would be the same as one without the diode. Maplin also sell small 12/24 volt relays.

 

My diagram shows the domestic alternator bulb energised by the relay but that is because it is a further step on from a single alternator as discussed earier in the notes. In your mind just change any label saying domestic to engine and engine to domestic and the diagram will be fine.

 

Please look into your exact engine because although many 1.5 and 1.8 parts are interchangeable some are not and if it is a 1.5 the injector pump is very non-standard. You would need to be aware of this when changing the pump and when asking for advice. Or did I misunderstand your original post?

Hi Tony,

Thanks for your advice;by fitting a relay as shown in your wiring diagram,and the resistor as shown by "by'eck! we

now have a fully functioning system .The domestic alternator kicks in on start-up and the engine switches off as normal.

Thanks to both of you for your expert advice from Ray Moore (NB: Carmel Marie) & Vic Moses (NB:Lyndsey Jane)