Battery doesn't seem to be charging

[hackenbush]

16 minutes ago, Tony Brooks said:

 

That's good news. Please put the voltmeter across the engine battery ad then the domestic battery while the engine is revving to ensure both batteries are charging.

That resistor will always be a weak link because of the solid single strand copper cable that will work harden and snap with vibration. If it were mine I would be looking for another warning lamps with a 2.2 watts or higher bulb in it. Then the resistor will not be required.

Note what I said about the relay being a caravan one. Again, if it were mine, I would be planning to change it for a higher amps one or more likely a bi-directional voltage sensitive relay. That way any solar or mains charging would do both battery banks. This is not  urgent but the relay is a weak link, especially if we are unsure of how it is wired, and is likely to fail sooner rather than later.

Also please now study the electrical notes, especially the charging system ones, on my website. They should help you to understand your electrical system. However be aware that any particular boat may differ slightly but achieve the same thing.

 

Yes, all working as it should be on batteries.

And yes, all points noted and will work on them all. Will start with some studying this eve

 

[chubby]

Happy days !! 

The forum at its best . Brilliant stuff 

Hackenbush ......Now get the hell out of Haggerston 

[hackenbush]

11 minutes ago, WotEver said:

Great news. Once you've studied Tony B's notes as he suggests, please do come back here and ask any questions. 

 

10 minutes ago, mross said:

This is good advice.  TB's website is the Open University for canal electrics and mechanics.  Click here www.tb-training.co.uk in case you missed the link in his signature.  He's too modest to promote it now that he has retired.

I will be studying tonight! Thanks again guys

[cuthound]

Great news, congratulations for sticking with the advice given and not giving up. 

This is another example of the forum helping out. Special thanks to Tony Brooks (again).

[bizzard]

Incidentally, did you note which way the alternator turns when the engine is running ?

 

 

 

 

 

 

 

 

[MtB]

On 23/03/2017 at 17:52, bizzard said:

Incidentally, did you note which way the alternator turns when the engine is running ?

 

And a related point the OP may be wondering about, an alternator generates the same power spinning in either direction. So the fact his alternator works is not proof the fan is the correct hand. 

(Good thing the OP didn't rush out and buy a new alternator too, his initial intention. The new one wouldn't have worked either!)

And credit too to the OP for sticking with it, answering the torrent of sometimes seemingly nit-picky and trivial questions coming from the board, posting all the photos, and finding the problem. 

Edited March 23, 2017 by Mike the Boilerman

[mross]

As an aside, can you buy a 12 VDC generator for a boat?  All cars had them years ago until these new-fangled alternators proved to be more effective.  DC is coming to the fore in power systems.

[cereal tiller]

2 minutes ago, mross said:

As an aside, can you buy a 12 VDC generator for a boat?  All cars had them years ago until these new-fangled alternators proved to be more effective.  DC is coming to the fore in power systems.

The reason 'Dynamo's were superceded was that all their output current went through the Brushes,40 AMPS. was about their limit

Shorter service life than an Alternator

[mross]

Another reason was their output was low at low revs.

[Tony Brooks]

Dynamos cannot rev as fast as alternators because of the construction of the revolving parts. Alternators use slip rings and rotor windings that run circumferentially (is that a word) so centrifugal (centripetal if you must) force simply ties to stretch the slip ring or rotor winding. They are very good at resisting that.

Dynamos have a built up/fabricated commutator made of loads of metal "bars" that lie along the axis of the spinning member and the armature windings also lie flat along the length of the armature. If the armature spins too fast centrifugal force will burst the commutator and also throw the armature windings out of the armature. The slower speed this demands ensures the output will ways be somewhat limited. The low maximum revs also means that the gearing has to be lower for a dynamo so it does not fly apart at high engine speed. This means at low engine speeds this means the dynamo will be turning far slower than an alternator.

Also the cooling of the current generating armature in the dynamo is poor with only one face open to are and most of the windings buried in the armature. The current generating stator in the alternator has two cooling surfaces and far more of the windings exposed. The better cooling allows it to generate a greater current before things get too hot.

Edited March 23, 2017 by Tony Brooks

[mross]

Surely someone must be making a DC generator with a permanent magnet rotor and no commutator?

[bizzard]

12V Dynamos, cut outs, control boxes and lots of older as well as current stuff is available from AES of Tutbury. I get stuff from them including the old 12v stand alone starter solenoids which make excellent heavy duty relays.   Google AES, their range of stuff is interesting.

[bizzard]

58 minutes ago, Mike the Boilerman said:

 

And a related point the OP may be wondering about, an alternator generates the same power spinning in either direction. So the fact his alternator works is not proof the fan is the correct hand. 

(Good thing the OP didn't rush out and buy a new alternator too, his initial intention. The new one wouldn't have worked either!)

And credit too to the OP for sticking with it, answering the torrent of sometimes seemingly nit-picky and trivial questions coming from the board, posting all the photos, and finding the problem. 

He might get away with it if the fan is the wrong hand. Being an air cooled engine the engine space is ventilated much better than most water cooled engine spaces, ''cruiser stern boats at any rate'' The engines cooling fan is constantly drawing in cool air from outside much of which doesn't pass through the engine at first to cool it but gently ventilates the area.

 

[bizzard]

36 minutes ago, Tony Brooks said:

Dynamos cannot rev as fast as alternators because of the construction of the revolving parts. Alternators use slip rings and rotor windings that run circumferentially (is that a word) so centrifugal (centripetal if you must) force simply ties to stretch the slip ring or rotor winding. They are very good at resisting that.

Dynamos have a built up/fabricated commutator made of loads of metal "bars" that lie along the axis of the spinning member and the armature windings also lie flat along the length of the armature. If the armature spins too fast centrifugal force will burst the commutator and also throw the armature windings out of the armature. The slower speed this demands ensures the output will ways be somewhat limited. The low maximum revs also means that the gearing has to be lower for a dynamo so it does not fly apart at high engine speed. This means at low engine speeds this means the dynamo will be turning far slower than an alternator.

Also the cooling of the current generating armature in the dynamo is poor with only one face open to are and most of the windings buried in the armature. The current generating stator in the alternator has two cooling surfaces and far more of the windings exposed. The better cooling allows it to generate a greater current before things get too hot.

Many car engines of years ago that were capable of revving to 5 or 6000 rpm, ''and were'', that used dynamos and must have run their dynamos up to around maybe 7,8 or even 10,000 rpm without exploding.

[hackenbush]

15 hours ago, bizzard said:

Incidentally, did you note which way the alternator turns when the engine is running ?

 

 

 

 

 

 

 

 

Clockwise, when looking from galley

Edited March 24, 2017 by hackenbush
More detail

[hackenbush]

And yes, I had that exact thought - if I'd followed my initial instinct I'd have bought a new alternator which ironically wouldn't have worked either

[Tony Brooks]

25 minutes ago, hackenbush said:

And yes, I had that exact thought - if I'd followed my initial instinct I'd have bought a new alternator which ironically wouldn't have worked either

and hopefully you understand far more about how the system works ready for the next time - an don boats there will be a next time!

[hackenbush]

12 minutes ago, Tony Brooks said:

and hopefully you understand far more about how the system works ready for the next time - an don boats there will be a next time!

Absolutely. It's great getting to know the workings of the boat a little more. Also, I've been reading your site and can't recommend it enough. Detailed and yet very easy to understand

[Tony Brooks]

There is an absolutely deliberate "mistake" on the schematic of the internal wiring of most alternators. This will not  be an issue for the majority of people like yourself but tends to get up the noses of a few "experts". The reason is that a number of my diagrams have been ripped off by non-English language websites. If anyone wants the correct diagram from the actual course notes document they only have to email and ask.

[WotEver]

4 minutes ago, Tony Brooks said:

... tends to get up the noses of a few "experts"...

I recall one who became most upset 

[Tony Brooks]

4 hours ago, WotEver said:

I recall one who became most upset 

Yes, but he thinks Smartgauges are inferiors to amp hour counters so he does not count.

[WotEver]

3 minutes ago, Tony Brooks said:

Yes, but he thinks Smartgauges are inferiors to amp hour counters so he does not count.

[hackenbush]

On 23 March 2017 at 11:23, Mike the Boilerman said:

Hmmm a brief google of what's written on it, suggests it is a high power resistor for vertical mounting...

 

On 23 March 2017 at 12:35, WotEver said:

Here's a guess...

Lamp has a wire going to a resistor (?) which then goes to a soggy bit of insulation tape. Has that insulated end fallen off the other side of the lamp?

What you've labelled "loose end" - has it fallen off the other side of the warning light?

 

On 23 March 2017 at 12:58, nicknorman said:

So just for clarity this is what the resistor is about:

The alternator needs a modest current through the warning light terminal to get it charging. This is supplied from the starter battery via the warning light. The current flowing to the alternator also of course illuminates the warning light. Once the alternator is charging, the voltage at the alternator terminal rises to be the same as the battery voltage and so current no longer flows through the light - it goes out!.

Now add the split charge relay that is connected between the warning light to alternator wire, and -ve. When the ignition is switched on, this relay "steals" some of the current flowing through the warning light to the alternator. So this can mean it is hard to get the alternator to start charging - lots of revs required. So the solution is either to fit a bigger wattage bulb (= more current) or to fit a resistor in parallel with the bulb (= more current). So the resistor should definitely be connected across the bulb. This will have the effect of dimming the bulb slightly, but that is not an issue.

If everything is working correctly, when you put on the ignition and before starting the engine, the voltage on the alternator to warning light wire should be a couple of volts or so relative to -ve. Not zero, and not 12v. If that is not the case, there is something wrong with the wiring.

 

On 23 March 2017 at 15:40, Tony Brooks said:

 Just back from the boat so not looked since about 7am.

1. Mike - now we have a better photo it is a ceramic resistor. These do not have bands but letters and numbers to show the value.

2. Mr H - as others have said one end of the  resistor should be connected to one warning lamp terminal and the other end to the other terminal. Don't worry about the whys or wherefores, just do it OR change the warning lamp assembly for one with a much higher wattage bulb.

Your description of where the wires run from the ignition switch make no sense to me. They shoudl be as follows (also in the electrical notes on my website): 

one thickish from the engine battery master switch (the thing with the black "butterfly" knob) TO the ignition switch.

one from the ignition switch to the warning lamp PLUS any other instruments and warning lamps.

one from the ignition switch to the small terminal on the starter motor.

That's it for the ignition switch.

Now the warning lamp. One wire from the warning lamp to the small alternator terminal that may be marked Ind or D+ or have no marking at all.

One of the small blades on the spilt charge relay might be fed from the wire between warning lamp and alternator OR another feed from the ignition switch. You seem to show some sort of 1 in to 2 out junction on the warning lamp to alternator wire. This may be the wire in question.

The other small blade on the relay shoudl be connected to any negative point.

The relay has two other larger terminals. These shoudl be connected by thick wire between the positives on the two battery banks but perhaps not directly. For instance they could connect between the engine and domestic battery master switches or between the main large starter terminal and the domestic battery positive.

Finally that relay is a low power caravan type. Once you get the system sorted I would change it for the highest rated one I could find. This  will have nut and stud terminals instead of the two large blades.

 

The same problem has reappeared and in attempting to solve it I discovered an kindergarten error I made last time.

i connected the resistor incorrectly - not from one terminal on bulb to another but from terminal on bulb to ignition (so basically I did nothing).

After connecting it correctly and running the engine the light remains on and the resistor gets very hot.

i went to Halfords and Maplins for a light with higher wattage but could not find one. What do I ask for as the guys there didn't know either?

[WotEver]

5 minutes ago, hackenbush said:

After connecting it correctly and running the engine the light remains on and the resistor gets very hot.

Then either the alternator is faulty or there is a wiring fault. Based on previous posts my bet is on the latter. Have you traced the wire from the lamp to the alternator?

For now, disconnect the split charge relay. 

[Tony Brooks]

I agree, probably a short to metal.

I would suggest running a new temporary cable between the warning lamps and alternator but note what Snibs says in other topics. We are all assuming this is a conventional 9 diode alternator (I am not wading through all the posts in case it has been identified).