Battery doesn't seem to be charging

[hackenbush]

12 minutes ago, 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.

It's the "across the bulb" bit that baffles me slightly. Sorry to be so dim. Should the loose end out of the resistor go in a loop and fit back to the same wire its connected to or should it go to the wire that leads to the ignition? I did try both although there is an outside chance that I didn't do it properly either time

11 minutes ago, WotEver said:

We already know you don't need to replace the alternator. It works fine when energised by the piece of wire, just not with the lamp. 

So... connect that soggy end to the other side of the lamp and see what happens. It can't possibly damage anything to try. 

AS Mike the Bolierman said, I did try but maybe incorrectly but yes, I did rev engine every time.

[WotEver]

1 minute ago, hackenbush said:

It's the "across the bulb" bit that baffles me slightly. Sorry to be so dim. Should the loose end out of the resistor go in a loop and fit back to the same wire its connected to or should it go to the wire that leads to the ignition? 

The latter. So that one end of the resistor connects to one side of the lamp and the other end connects to the other side. 

1 minute ago, hackenbush said:

AS Mike the Bolierman said, I did try but maybe incorrectly but yes, I did rev engine every time.

Next time you do it disconnect the wire to the split charge relay. Does the lamp still glow?

[hackenbush]

9 minutes ago, nicknorman said:

Most likely there is just a bad connection or broken wire between the warning light and the alternator. The warning light is illuminating because it is seeing the resistance to -ve of the split charge relay coil.

Connect everything up, ignition off, then use a multimeter on ohms / resistance range to check that the alternator warning light terminal is connected to the warning light. You should find that the resistance is less than 1 ohm. I'm pretty sure you'll find it isn't

What is the "-ve"? Also, to test this where am I placing the prongs, exactly?

 

[hackenbush]

4 minutes ago, WotEver said:

The latter. So that one end of the resistor connects to one side of the lamp and the other end connects to the other side. 

Next time you do it disconnect the wire to the split charge relay. Does the lamp still glow?

I need some clarification on this. There are 3 wires that come from the light+IGN. 1- to right nut on switch connected to relay (but not relay itself) 2- directly to starter motor on engine 3 - directly to alternator (negative). 

There are 4 wires coming from relay box itself. 1- to switch 2- alt (pos) 3- alt (neg) 4- batt (neg)

[WotEver]

23 minutes ago, hackenbush said:

I need some clarification on this. There are 3 wires that come from the light+IGN. 1- to right nut on switch connected to relay (but not relay itself) 2- directly to starter motor on engine 3 - directly to alternator (negative). 

There are 4 wires coming from relay box itself. 1- to switch 2- alt (pos) 3- alt (neg) 4- batt (neg)

I'm lost. 

Can you draw out the circuit as it is right now? Just expand your previous drawing if you like to include the split charge relay. 

[hackenbush]

2 minutes ago, WotEver said:

I'm lost. 

Can you draw out the circuit as it is right now? Just expand your previous drawing if you like to include the split charge relay. 

ok, give me a few mins to get back to the boat

[WotEver]

24 minutes ago, hackenbush said:

There are 4 wires coming from relay box itself. 1- to switch 2- alt (pos) 3- alt (neg) 4- batt (neg)

That sounds incorrect, so you've misunderstood something. What are you referring to as "alt (neg)"?

[hackenbush]

3 minutes ago, WotEver said:

That sounds incorrect, so you've misunderstood something. What are you referring to as "alt (neg)"?

the thin wire I disconnected

there is a chance I've got it wrong, yes!

Edited March 23, 2017 by hackenbush

[WotEver]

Just now, hackenbush said:

the thin wire I disconnected

That's the excitation terminal, often labelled "Ind" (for indication I guess). 

And that's the wire I suggest you disconnect. 

The wire from there to the relay. 

[nicknorman]

46 minutes ago, hackenbush said:

What is the "-ve"? Also, to test this where am I placing the prongs, exactly?

 

Sorry, -ve is short hand for negative. Place one prong on the alternator terminal that goes to the warning light, the other on the wire that comes out of the warning light going to the alternator.

However it might be easier to do as I said later, ie put one prong on the battery negative and the other on the alternator terminal that goes to warning light, meter set to volts, ignition on engine not running.

[hackenbush]

33 minutes ago, WotEver said:

That's the excitation terminal, often labelled "Ind" (for indication I guess). 

And that's the wire I suggest you disconnect. 

The wire from there to the relay. 

Disconnected it and light goes out

[WotEver]

Just now, hackenbush said:

Disconnected it and light goes out

We're getting somewhere!

There is a break or bad connection between the lamp and the ind terminal of the alternator. 

[WotEver]

Either the cable is broken somewhere along its length or perhaps it's at one or other of the crimps.

None of the electrics looks good and it would be worth getting someone with the kit (and knowledge) to remake all the terminations. 

[nicknorman]

6 minutes ago, WotEver said:

We're getting somewhere!

There is a break or bad connection between the lamp and the ind terminal of the alternator. 

That's what I said! 

 

[WotEver]

1 minute ago, nicknorman said:

That's what I said! 

 

Yeah, but you said loads and it got lost. Anyway, I proved it

[hackenbush]

2 minutes ago, nicknorman said:

That's what I said! 

 

Off to get kid from school but the wires look fine so I reckon it's at one of the crimps

3 minutes ago, WotEver said:

Yeah, but you said loads and it got lost. Anyway, I proved it

Hopefully have it running by dusk!

[nicknorman]

43 minutes ago, hackenbush said:

Off to get kid from school but the wires look fine so I reckon it's at one of the crimps

Hopefully have it running by dusk!

Just as aside on "bad connections" whilst you are doing the school run, I fitted a new battery to the gliding club's tug end of last year. It is a car sized battery with flat terminal posts with a hole, so you simply bolt the ring crimp connector onto the flat terminal post. The bolts have washers and spring washers. Battery was brand new so obviously the terminals were clean. There was no obvious corrosion on the ring crimps. So I bolted it all up and everything was fine. That was until a couple of weeks ago. It started perfectly from cold (it's a 6 litre engine so takes a fair bit from the 32AH battery!). It started perfectly formthe next 5 or so launches. Then suddenly, it was virtually dead. As you operated the starter, everything went off and only slowly came back over a minute or so after you released the starter switch. I wiggled the battery leads, they were tight. Eventually got the meter out and found 8v or so between the battery post and the ring crimp, just powering the warning lights, despite the post and crimp seeming to be firmly held together by the tight bolt. I seperated the parts and there was some very thin black dirt (not really corrosion) on the ring crimp, which I cleaned off, reassembled and then it started happily ever after. So just goes to show that a tiny bit of dirt or corrosion goes a long way!

[Tony Brooks]

 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.

 

[hackenbush]

1 hour ago, 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.

 

Yes, my written list was confusing

 

[hackenbush]

SUCCESS! it was indeed the wire in question. I snipped off the end, re-crimped, reconnected all cables, hit ignition, revved engine and light went out

Massive thank you to you guys for all your help and patience.

ps. I've reconnected resistor as instructed too

[Tony Brooks]

Please stop referring what I think is the alternator warning lamp connection on the alternator as alternator negative - its the alternator warning lamp terminal, exciter termina,l D+ or ind depending upon the alternation and what you choose. It is in no way a negative. According to your photos the alternator negative is the metal alternator case.

The thin cable by the alternator that you showed in a photo where two cables go into a 6mm female blade crimp terminal and a single cable  in a 6mm male crimp terminal would   be expected to be 2feed"  that energises the split charge relay. If this is the case then the other thin wire on the relay should be a true negative.

If that bodged connection you showed is NOT providing a feed to the relay coil then you may be correct in that the feed to the coil comes from the ignition switch BUT it would have the relay closed as you start the engine. This stands a very good chance of burning the relay contacts out. I do not think this is what is going on. I suspect there is something you have not understood.

 

Anyway, if it works with the resistor connected you can get your battery charged and worry about what else may be non-typical later.

 

Edited March 23, 2017 by Tony Brooks

[hackenbush]

9 hours ago, chubby said:

Reading thru this thread has given me horrifying flashbacks to my alternator probs two years ago which i referred to in a previous post

Though i had to work thru similar issues , i wasn t stuck in Haggerston & so this situation is now even more urgent . Broken down in Haggerston ..... my god it doesn t bear thinking about . What a toilet ! 

Hackenbush , you're doing admirably so things will be fixed soon and all will be well ...... but you 'll still be in Haggerston ..... 

Good luck with the fault tracing & fixing  

Chubby, thanks. This forum is truly invaluable 

[Tony Brooks]

3 minutes ago, hackenbush said:

SUCCESS! it was indeed the wire in question. I snipped off the end, re-crimped, reconnected all cables, hit ignition, revved engine and light went out

Massive thank you to you guys for all your help and patience.

ps. I've reconnected resistor as instructed too

 

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.

 

[WotEver]

23 minutes ago, hackenbush said:

SUCCESS! it was indeed the wire in question. I snipped off the end, re-crimped, reconnected all cables, hit ignition, revved engine and light went out

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

[mross]

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.