Voltage Sensitive Relay

[Moke]

For a long while now the bow thruster hasn’t worked. I’ve finally decided to investigate and it seems the thruster batteries are not getting charged so, after some checking .

 It’s a durite VSR

 There’s no red light showing on it

 With the engine running the starter battery is 14+ volts

 With the engine running the VSR is showing 13.7 volts at the starter battery terminal  

  Regardless of whether the engine is running or not the “leisure” terminal is reading about 2 to 3 volts

 

  Does this suggest the VSR is faulty? 

 

[jonathanA]

I'm a bit suspicious of why the voltage at the relay is only 13.7 with no current flowing. Makes me think thre is a bad connection somewhere. 

 

Assuming its one of these 

then as you can see it shold be cutting in at 13.3v 

 

is the lesiure terminal showing 2 or 3 v when connected to the BT battery ? 

whats the volts on the BT battery ?

 

 

[BEngo]

If the bow thruster batteries have not been charging for a while they will perhaps  have come to no good and will certainly be sulphated.  What is the voltage of the BT battery  with nothing connected to its terminals?

 

If the BT battery is really low, and heavily sulphated the alternator may not be able to charge it enough to raise the terminal voltage above 2-3 V.

 

 

[Moke]

18 minutes ago, jonathanA said:

I'm a bit suspicious of why the voltage at the relay is only 13.7 with no current flowing. Makes me think thre is a bad connection somewhere. 

 

Assuming its one of these 

then as you can see it shold be cutting in at 13.3v 

 

is the lesiure terminal showing 2 or 3 v when connected to the BT battery ? 

whats the volts on the BT battery ?

 

 

  Yes, it’s one of those. After investigating further while waiting for replies I found that the VSR is powered from the leisure batteries which are lithium. However, the thin black wire from the VSR goes to the starter battery terminal. 
  It seems odd to me that there one alternator charging the leisure and the BT when they have different charging profiles. 
  Wouldn’t it be better if the starter battery fed the VSR ?  At least that way all the charging profiles would match up. 
 

[David Mack]

The thin black wire is the negative connection, which should be connected directly (other than perhaps via a shunt) to the negative terminals of the engine, domestic and  bow thruster batteries, and also grounded to the shell. So it shouldn't matter where it is connected.

Connecting a lithium domestic battery to a lead acid thruster battery via the VSR will probably work as the long charging lead to the bow thruster battery will probably meet the requirements of the 'long wire' method. But this method is not acceptable to all insurers and may be outlawed by emerging standards. So probably better to feed from the lead acid engine battery.

[Tony Brooks]

Singe alternators are often connected to the engine battery and if this is an older mono-directional VSR then I can see why it would not work if sensed from the domestic battery - irrespective of it being an Li.

 

Mono-directional VSRs must sense from the battery being charged from the alternator. How is the OPs alternator connected to the domestic bank and/or engine battery?

[Moke]

So. Two alternators, one charging the starter battery only. The other alternator is charging the leisure bank plus, it seems, the BT batteries. The sensor wire for the VSR is connected to the starter battery.  This says to me that there’s no connection between the sensor wire and the charging “wire”. 
  In order to test this I’ve dug out an old leisure battery that’s been kept charged from a spare solar panel. I intend to connect this up to the BT so that I can check the VSR. 

PS. The VSR is a Durite one as shown in the picture further up the page,it’s no more than 6 years old. 

[Tony Brooks]

2 minutes ago, Moke said:

So. Two alternators, one charging the starter battery only. The other alternator is charging the leisure bank plus, it seems, the BT batteries. The sensor wire for the VSR is connected to the starter battery.  This says to me that there’s no connection between the sensor wire and the charging “wire”. 
  In order to test this I’ve dug out an old leisure battery that’s been kept charged from a spare solar panel. I intend to connect this up to the BT so that I can check the VSR. 

 

VSRs do not have sense wires a such, only a negative or ground wire. The "sense" wire is the main terminal(s). On a mono-directional, only one terminal, on a bidirectional both. I suspect yours may be a mono-directional with am alternator fault that supplies the sense side. You said it sensed or the domestic bank (ignore the thin black neg. wire) and as you also say they are Lis and do not mention maximum charge control I wonder if you have cooked it by prolonged operation at maximum output. We need to know the running voltage at about 1500 rpm on whichever VSR terminal is the sense one, i think that one often has a little red or green spot by it.

[jonathanA]

I think folks are over complicating things, IF (big if) its the VSR i linked to earlier then its dual direction/auto sensing.  

 

extract from the spec:

 

• Dual sensing operation - charges from starter battery to leisure battery when alternator is running and charges from leisure battery to starter battery when mains charger is connected.
• Relay connects when sensed voltage reaches 13.3V or higher
• Relay disconnects when sensed voltage drops to 12.65V or lower

its only got 3 connections, 2 batteries and neg, so no sense wires, so David might be right and the black wire could be the neg connection, so not relevant where its connected so long as it is the Neg !  if it has sense wires its not the same Durite VSR pictured above and we need the OP to be really clear about whats connected where and what model of VSR it is. 

 

13.7V off the lithium domestics seems quite possible, even if one of both alternators are putting out 14v+ as we don't know how the lithiums are being charged (B2B/Long wire or smart alternator controller).  There is even a possibility of the domestic alternator being fried and the OP hasn't noticed yet (doubtful but possible) 

 

The OPs idea to use a spare battery to test the VSR seems like a good idea. it could simply be the BT battery is cream crackered... 

[Tony Brooks]

5 minutes ago, jonathanA said:

David might be right and the black wire could be the neg connection

 

He is, and it is, so as the engine and domestic battery negs should be linked it won't matter which bank it is linked to as David says.

 

Once again we are working from incomplete information. The OP needs to identify the VSR he has, and Durite did not always retail bidirectional ones. We need the charging voltages on BOTH main terminals with the engine revving at the very least.

 

Unless whatever battery the sense is connected to has a short circuit, a working alternator should produce in excess of 13.3 volts so that suggests either an alternator is faulty or it is not a bidirectional VSR. I don't think a totally flat and sulphated bow thruster battery could pull the voltage down to below 13.3V. I await more info from the OP.

[nicknorman]

Charging a lead acid battery from a LiFePO4 battery via (more or less) direct connection is never going to work properly. A Li battery when being charged will sit at around mid 13s voltage most of the time, only spending a very short amount of time above say 13.8v. This will not charge a lead acid battery properly. And this of course is why you are seeing only 13.7v at the VSR.

 

You should charge the BT from another lead acid battery ie the starter battery. Although of course first, you will need to replace the BT battery as it will be knackered having sat at 2 or 3 volts for a while.

[Moke]

38 minutes ago, nicknorman said:

Charging a lead acid battery from a LiFePO4 battery via (more or less) direct connection is never going to work properly. A Li battery when being charged will sit at around mid 13s voltage most of the time, only spending a very short amount of time above say 13.8v. This will not charge a lead acid battery properly. And this of course is why you are seeing only 13.7v at the VSR.

 

You should charge the BT from another lead acid battery ie the starter battery. Although of course first, you will need to replace the BT battery as it will be knackered having sat at 2 or 3 volts for a while.

That was what my thoughts were and the test so far seem to support that theory. 

[Tony Brooks]

But 13.7 volts should trigger the VSR and as you say the red light does not come on it seems to me that it is not being triggered.

 

Quote

 

There’s no red light showing on it

 With the engine running the starter battery is 14+ volts

 With the engine running the VSR is showing 13.7 volts at the starter battery terminal  

 

 

This is why I think we need the voltage on the other main terminal. IF it is only 2 to 3 volts as here:-

 

Quote

Regardless of whether the engine is running or not the “leisure” terminal is reading about 2 to 3 volts

 

and by leisure battery terminal you mean the bow thruster battery terminal, then that suggest either a faulty VSR or, as I suggested, a mono-directional one with the sense terminal connected to the bow thruster battery.

 

Will you post a photo of the back of the VSR with indication of what cable is fitted to what terminal.

[Moke]

To answer Tony,

two alternators. One charging the LA starter battery, output is 14.06 volts at the battery

        The second alternator charging the leisure bank of Li batteries through a Sterling “Alternator direct output power Linearisation Device” and a Sterling BB1270. Output is13.62 volts at the battery

  The VSR is a Durite 0-727-33. It is connected to the leisure battery alternator and the BT batteries. The ground wire for the VSR is connected to the starter battery negative. The red led light does not come on at any time

  Voltage readings were taken at circa 1400 rpm. 
 

With a single, spare, battery connected to the BT (LA @ 13.6 volts) the BT works as it should but does not charge………this could be because the battery doesn’t need any charge yet 

As it’s too dark to see now any pictures will have to be taken in the morning. 

[Tony Brooks]

Thanks. I have googled the number you give for the relay and I can't find any talk of mono, or bi direction, but more modern ones tend to be bidirectional. The drawn diagrams give no indication either.

 

If it is bidirectional I can't see why it won't supply charge to the bow thruster battery unless that is shorting and tries to pull close to maximum output or more from the alternator so it pulls the alternator voltage to below 13.3V. Because it has a few seconds delay before it disconnects on low voltage you should see the voltmeter on the input rise as the alternator energises and then drop for a few seconds before it disconnects if that is what is happening

 

 

[GUMPY]

The Durite relay like that I had was not bidirectional.

Best to wire it as if it's not bidirectional that will eliminate that.

[Tony Brooks]

Just now, GUMPY said:

The Durite relay like that I had was not bidirectional.

Best to wire it as if it's not bidirectional that will eliminate that.

 

Ah, but if the terminals are not suitably marked, how do you know which one is the sense. All the OP can do is try it both ways. 

[GUMPY]

6 minutes ago, Tony Brooks said:

 

Ah, but if the terminals are not suitably marked, how do you know which one is the sense. All the OP can do is try it both ways. 

 

They are:

 

https://webshop.durite.co.uk/WebResources/Common/Docs/Technical Information/701-800/0-727-33 spec.pdf

 

I'll say no more.

 

[Tony Brooks]

32 minutes ago, GUMPY said:

 

They are:

 

https://webshop.durite.co.uk/WebResources/Common/Docs/Technical Information/701-800/0-727-33 spec.pdf

 

I'll say no more.

 

 

Yes, I read that hours ago ad it does not say if it is mono or bi directional, although it seems to imply mono by the talk of primary and secondary battery. That in turn implies the 6mm terminal closest to the earth lead is the sense terminal. but that is all implication and inference, nothing is clearly stated.

 

I agree, the OP should try with the 6mm terminal coses to the earth lead connected to the start battery and see what happens.

[Moke]

I shall have a look tomorrow. 

[GUMPY]

1 minute ago, Tony Brooks said:

 

Yes, I read that hours ago ad it does not say if it is mono or bi directional, although it seems to imply mono by the talk of primary and secondary battery. That in turn implies the 6mm terminal closest to the earth lead is the sense terminal. but that is all implication and inference, nothing is clearly stated.

 

I agree, the OP should try with the 6mm terminal coses to the earth lead connected to the start battery and see what happens.

Trust me the one I had was mono.

No if ands and buts.

 

[jonathanA]

interestingly (or confusingly !) 12V planet claim that this VSR is bidirectional but the Durite website very much reads as a uni directional unit.  I can't see a bidirectional durite version so suspect 12V planet have it wrong.   Which agrees with what Tony found when he googled.   Since it must have worked at some time then its reasonable that the op has the 'input' battery connected to the right terminal. But if he wants to check its the one next to the black GND/Neg wire as per Gumpys PDF.   ( I don't think its actually marked).  

 

I wonder if the "hasn't worked for some time" coincides with the Lithium install...

 

I see we are all saying the same thing now. 

Edited February 10 by jonathanA
x post with Gumpy/TB

[Tony Brooks]

7 minutes ago, jonathanA said:

I don't think its actually marked

 

Mine had a little red spot of paint by the sense terminal, and the insulation instruction were more explicit than the website, but who knows if they all have the spot.

Edited February 10 by Tony Brooks

[MtB]

14 hours ago, GUMPY said:

Trust me the one I had was mono.

No if ands and buts.

 

 

One of my personal maxims is: Never trust anyone who says "Trust me".

 

Has stood me in good stead, many times over  

 

 

 

 

[Moke]

That what’s on the back of it. Not much chance of getting that the wrong way round I’d say.