Aaaaaaaaaaaaaaaaaaaaaaaaargh!!!!!

[Bob18]

And don't forget the to label the cables.....

 

 

Sometimes the only solution is to start afresh.

Work out what SHOULD be done.

Work out what is needed to do it.

Work out what's available.

Work out what needs to be got and get it.

Generate two heaps, one for the bin, and one to be re-used

Do it right.

[sebrof]

Gentlemen,

 

Sometimes I have to work, and today was one of those days, so I have missed this discussion until now.

 

Whilst I am no expert, I am quite certain that the "HD" cables are the ones carrying the heavy loads, and that J and E are carrying the charging current from the VSR to the MS and from the MS to the batteries respectively.

 

I follow what Sir Nibs is saying, and I think that the man might just be a genius. When the batteries are connected in series, the charge cable is effectively attached to a single 24V battery. Thank God for the fuse.

 

What is most interesting is that the batteries bear a label which refers to the year 2005, which is when the previous owner - a DIY man of great enthusiasm and rather less electrical expertise - bought the boat.

 

It is more than possible that while changing the batteries he switched the charging cable from Bat2 to Bat1, thinking it would do no harm.

 

One question continues to trouble me. How come the whole system didn't explode before the fitting of the 100 amp fuse? It was the previous owner's practice to have all batteries connected together through the old black 1-2-Both battery switch. This would have meant 5 110AH batteries in parallel, plus the alternator, trying to fight two 190AH batteries in series. Of course, it would usually have been only for a few seconds at a time. And the five batteries WERE knackered. Also, I don't think he used the BT very much.

 

I shall try switching the cable tomorrow. There are two fuses left.

 

I do hope this works. It does sound very much like the right answer.

 

ETA: Tony, although I have not been able to trace the run of charging cable F definitely to the VSR, all the evidence points that way. The 100 amp fuse connects the VSR to what I believe is the start of cable F.

 

Your diagram is spot on except for the unimportant point that J comes from the vicinity of the VSR (or possibly the BT switch, along with the small black cables), and is attached to the MS at the same point as Earth cable K.

Edited October 11, 2011 by sebrof

[sebrof]

Damn. There seems to be a flaw in the Nibble prescription. Whilst it sorts out the problem of the fuse, it removes the ability to charge Bat1.

[smileypete]

I shall try switching the cable tomorrow. There are two fuses left.

 

I do hope this works. It does sound very much like the right answer.

I would leave well alone for the time being .... too late to explain for now.

 

ETA: NB Willawaw's earlier advice (that you took offence to) may well have been spot on.

 

cheers,

Pete.

Edited October 12, 2011 by smileypete

[Sir Nibble]

Damn. There seems to be a flaw in the Nibble prescription. Whilst it sorts out the problem of the fuse, it removes the ability to charge Bat1.

No it doesn't. In 12V mode both B+ve terminals are connected through the relay "magic box"

[WotEver]

No it doesn't. In 12V mode both B+ve terminals are connected through the relay "magic box"

But the only connection from batt 1 to the magic box is cable E...

 

One would assume that within the magic box there is a relay that connects E to C (and B to K) while BT is unpowered, and disconnects E when BT is switched on. (And simultaneously also disconnects B from K and connects it to C.)

 

Tony

[Sir Nibble]

But the only connection from batt 1 to the magic box is cable E...

 

One would assume that within the magic box there is a relay that connects E to C (and B to K) while BT is unpowered, and disconnects E when BT is switched on. (And simultaneously also disconnects B from K and connects it to C.)

 

Tony

You're quite right and you may well have put your finger on the problem. Looks like the top wants to come off that magic box then.

[sebrof]

No it doesn't. In 12V mode both B+ve terminals are connected through the relay "magic box"

 

Sadly, they are not. If Cable E is connected to Bat2+, Bat1+ is connected only to the BT; it has no connection to the MS and to the charging system at all.

 

I think that the only way this can work is if the MS isolates Cable E or Cable F when the BT is on.

 

I am moderately confident that neither my electrician nor the previous owner made any alteration to where the various wires are attached to the MS. The former was not asked to do anything with the BT, and the latter would have had no reason to. He might however have mis-wired the batteries, but despite racking my brains I can't see how different wiring would change things while still allowing the BT to work and the batteries to be charged.

 

So I am now fairly sure that I have a malfunction in the MS, which should be isolating Cable E or F and is not doing so. I shall endeavour to take thew MS apart over the weekend. Heavy duty relays are sometimes designed to be repaired, though whether I will be able to get parts for something fitted to a Dutch barge in Holland perhaps thirty years or more ago is another matter.

 

If I can't, then some kind of switch will be needed.

 

Thanks again for all inputs.

 

ETA to correct cable refs. What was J is now F.

 

But the only connection from batt 1 to the magic box is cable E...

 

One would assume that within the magic box there is a relay that connects E to C (and B to K) while BT is unpowered, and disconnects E when BT is switched on. (And simultaneously also disconnects B from K and connects it to C.)

 

Tony

 

 

Exactly. And the E disconnect is not happening.

Edited October 12, 2011 by sebrof

[smileypete]

Exactly. And the E disconnect is not happening.

What makes you think that?

 

One way to tell for sure would be disconnect E from Bat1+ and put a 12V bulb in between, then operate the BT.

 

ETA: I suspect F may just go to C/Bat2+

 

cheers,

Pete.

Edited October 12, 2011 by smileypete

[sebrof]

I would leave well alone for the time being .... too late to explain for now.

 

Nothing will happen before the weekend. I hope you will explain further when you are rested.

 

ETA: NB Willawaw's earlier advice (that you took offence to) may well have been spot on.

 

cheers,

Pete.

 

It wasn't the advice that I took exception to. It was the imputation that I was being a cheapskate when the reality is that I want to understand how it all works. And of course, if it is something I can do myself, it is sensible to do so.

 

Hilaire Belloc wrote:

 

It is the duty of the gentleman

To give employment to the artisan

 

But when he wrote it, there was a much greater disparity between the incomes of gentlemen and artisans than there is now, and this particular "gentleman" might well earn less than many artisans. And since some artisans take pleasure in ripping off gentlemen who don't understand how their boats work, it is wise to keep oneself informed.

 

 

Just for clarity, this seems to be the situation.

 

Normal condition

 

BT off

 

Cable F connects to Cable E and Cable C.

Cable B connects to Cable K (Earth).

 

BT on

 

Cable F is disconnected.

Cable B connects to Cable C

 

Present condition

 

BT off

 

Cable F connects to Cable E and Cable C.

Cable B connects to Cable K (Earth).

 

BT on

 

Cable F is NOT disconnected

Cable B connects to Cable C

[Bob18]

A question (and don't worry if you can't remember what happens, or haven't looked to see what happens)

When you press the button, but before you select a direction do you hear any relays or contactors moving?

 

 

 

A more significant question:

 

Are we right in assuming that the 100A fuse is in cable "F"?

[sebrof]

A question (and don't worry if you can't remember what happens, or haven't looked to see what happens)

When you press the button, but before you select a direction do you hear any relays or contactors moving?

 

I have just, inspired by Pete, tried to see what happens when I try to operate the BT with E disconnected.

 

First, the On lamp lights up when the BT is switched On, but nothing else happens. Then I hear the relay operate when I press the toggle to operate the BT, but the BT doesn't work. Reconnect E, and it does.

 

So E has an additional purpose.

 

BTW, E, when disconnected and BT is off, is carrying 12V. So it must be connected to F, which is the only cable that could possibly be supplying the charging current (it's the only one that is the appropriate size, and the only one that goes to the control box with the VSR).

 

 

A more significant question:

 

Are we right in assuming that the 100A fuse is in cable "F"?

 

 

I am as certain as I can be that F carries the 100amp fuse. There are no other possibilities. I have accounted for all the HD cables. Cable A heads North towards the BT, and the others are all short and I can see both ends. F emerges just below the box containing the VSR and various busbars and fuses (inc 2 100amps attached to the VSR, of which one is presumed to attach to F, and blows when the BT is operated). The other 100amp fuse connects to the domestics. I know, because I blew it once, and the lights went out.

 

I am mystified as to why the BT doesn't work when E is disconnected. It suggests that things are more complex than I had thought. Perhaps there are two relays; the first is meant to disconnect F (but doesn't, though I can hear the relay working), and the second, powered by E (because F is or should be disconnected) connects B and C.

 

I have to go now, so will see any replies tonight.

Edited October 12, 2011 by sebrof

[Bob18]

Thanks for your responses.

Thinking aloud (dangerous habit) - It sounds as if battery B1 is used to supply power for the box, and by disconnecting "E" that supply is "lost". As you say it sounds as if that box is more complex than on the face of it. (I've got the box as being about "half a shoe box" cube in my mind - is that about right?)

 

It could well be that something in the box has broken, which would add to the external confusion. (Relays and contactors both have a habit of failing when you least want them to fail)

 

 

 

Enjoy your afternoon.

[Sir Nibble]

The games's afoot!

[sebrof]

Thanks for your responses.

Thinking aloud (dangerous habit) - It sounds as if battery B1 is used to supply power for the box, and by disconnecting "E" that supply is "lost". As you say it sounds as if that box is more complex than on the face of it. (I've got the box as being about "half a shoe box" cube in my mind - is that about right?)

 

It could well be that something in the box has broken, which would add to the external confusion. (Relays and contactors both have a habit of failing when you least want them to fail)

 

 

 

Enjoy your afternoon.

 

The box is just a bit smaller than a shoe box. I reckon that you could wrap two generously in bubble-wrap and get them into a show box.

[by'eck]

Just for clarity, this seems to be the situation.

 

Normal condition

 

BT off

 

Cable F connects to Cable E and Cable C.

Cable B connects to Cable K (Earth).

 

BT on

 

Cable F is disconnected.

Cable B connects to Cable C

 

Present condition

 

BT off

 

Cable F connects to Cable E and Cable C.

Cable B connects to Cable K (Earth).

 

BT on

 

Cable F is NOT disconnected

Cable B connects to Cable C

 

Taking the statement in red. Can I assume the double negative means cable F is still connected? If so AND its still feeding both battery positives (cables E & C) for re-charging purposes then its providing a direct short on B1, because B1 neg is connected to B2 positive

 

If this is the case then maybe that fuse blowing was a blessing

 

Although feasible with the use of contactors, just to show how complex this system is, here is a list of what needs to happen when switching BT on/off in this order.

 

BT OFF

+ve supply to bowthruster isolated

B1 -ve isolated from B2 +ve

B1 -ve connected to common -ve & ground

B1 +ve connected to B2 +ve connected to positive charge feed

 

BT ON

B1 +ve isolated from B2 +ve & both isolated from positive charge feed

B1 -ve isolated from common -ve

B1 -ve connected to B2 +ve

B1 +ve connected to feed 24 volts to bowthruster

 

Surely time to junk this over complex system & get dedicated 24 volt battery & charging system.

Edited October 13, 2011 by richardhula

[WotEver]

If this is the case...

It probably is, but the whole problem with this thread is that we don't actually know...

 

Tony

[Bob18]

Some people just love to make simple things complex, and who ever designed and wired this bit of the boat up had developed complexity into a work of art - sadly for the current owner.

 

I'm with Tony - we don't actually know what is in that Magic Box.

We know what we think it should do, and there's probably a couple of sensible alternatives for that.

Until the lid is prised off the box, and its guts exposed to the air we don't know what is in there, how its wired up, or if anything in there has failed.

 

For pure "simplicity" with on a 12v boat with a 24v bow thruster the separate battery with its own dedicated charger has got to be a "good stater for ten".

[WotEver]

For even greater simplicity on a 12V boat, fit a 12V BT

 

Simples

[Bob18]

Now that would be the simplest provided there is a 12v version of the 24v motor available.

Probably more expensive than putting a 12/24 charger in, that might be a consideration.

[WotEver]

Oh it's probably too late now, but fitting a 24V BT in a 12V boat simply so you can have smaller cables and remote batteries seems a most odd decision to me.

 

Tony

[Bob18]

And me - as I said a few posts ago, this is a prime example of how to make something more complex than it needs to be...

[by'eck]

Maybe I was a little harsh in my condemnation of OP's present system. Here is diagram of the simplest solution I can come up with to his current setup using a single three pole two way contactor capable of taking the full current demand of the bowthruster.

 

 

This is hopefully what should be inside the box marked MS

[Bob18]

Nice, but there are nine wires into the magic box. One of the extras appears to be a "control negative", but the others??

 

The description of the box size does suggest that there is only one contactor in there, and maybe an arm/disarm relay, but not much else.

[by'eck]

Nice, but there are nine wires into the magic box. One of the extras appears to be a "control negative", but the others??

 

The description of the box size does suggest that there is only one contactor in there, and maybe an arm/disarm relay, but not much else.

 

I was assuming cables G,H,I were the actual bowthruster controls so not directly relevant to the battery switching.