No domestic power unless the engine is running :(

[Richard10002]

Got to the boat about 8.30pm, turned the lights on, and nothing happened. All the domestic power is off, with no lights at the switch panel which is must be fed from the domestic batteries via the domestic isolator. The domestic batteries are showing 13.4V at the batteries and on the NASA BM2 battery monitor, and the Smartgauge is showing 100%, so reasonably sure the charging circuits are fine, and the batteries are fully charged.

 

Anyway - not to be defeated... I fitted my new alternator V belt, (result!), started up the engine, and the domestic power came on.... it actually comes on with the key turned to the glow plugs position, without actually starting the engine. The engine is running now so I've got power.... but I'm going to post this, shut things down, and go home. Hopefully there will be a solution for tomorrow

 

Given that starting the engine, (or merely engaging the engine electric circuit), connects the domestics, I'm wondering if it's related to the relay. I also wondered if attaching both of the thick positives on the relay to each other would be a temporary bodge - but I'm not risking it until I have a bit more knowledge

 

With the engine off, connecting the right hand relay terminal to the hull shows 13V, and connecting the left hand one shows 0V. I havent tested them with the engine running.

 

HopefullY, I have attached pics of the relay, and the adjacent domestic and starter battery isolators.

 

Off home now.....Any assistance welcome.

[WotEver]

Sounds like the domestic isolator isn’t working. Switch it off and on a few times. 

[ditchcrawler]

The split charge relay is connecting the 2 systems together I would say.

Edit

Thinking on, probably supplying the domestic power from the starter battery

Edited August 2, 2018 by ditchcrawler

[nicknorman]

Yes it must be the domestic isolator or the wiring / connections in the vicinity of it. I would guess that when you turn the key on, the relay is activated which passes starter battery current to the domestic system.

[Richard10002]

1 hour ago, WotEver said:

Sounds like the domestic isolator isn’t working. Switch it off and on a few times. 

Makes sense now you and Nick mention it. I did turn it on and off a few times and the first time it clicked as normal but, after that it spun loosely. Strange that I could have left the boat this afternoon and all was well, and something failed over the next 8 hours

 

Given that I’d like to fix it tomorrow, is there a shop I could go to to buy one - surface mounted?

 

I could drive the 50 mile round trip to Midland Chandlers at Preston Brook, where they have this:

 

https://www.midlandchandlers.co.uk/store/category/1939/product/vs-259.aspx

 

they also have a Durite one but it’s about seventy quid!!

 

I’m guessing the space will be about 7cm x 7cm, so the 12cm ones from Screwfix are too big, and Halfords have one that isn’t surface mounted.

 

So is there somewhere like a motor factors or similar which might be nearer, (Manchester), that might sell them over the counter?

 

Thanks for the help!

 

 

[nicknorman]

17 minutes ago, Richard10002 said:

Makes sense now you and Nick mention it. I did turn it on and off a few times and the first time it clicked as normal but, after that it spun loosely. Strange that I could have left the boat this afternoon and all was well, and something failed over the next 8 hours

 

Given that I’d like to fix it tomorrow, is there a shop I could go to to buy one - surface mounted?

 

I could drive the 50 mile round trip to Midland Chandlers at Preston Brook, where they have this:

 

https://www.midlandchandlers.co.uk/store/category/1939/product/vs-259.aspx

 

they also have a Durite one but it’s about seventy quid!!

 

I’m guessing the space will be about 7cm x 7cm, so the 12cm ones from Screwfix are too big, and Halfords have one that isn’t surface mounted.

 

So is there somewhere like a motor factors or similar which might be nearer, (Manchester), that might sell them over the counter?

 

Thanks for the help!

 

 

I would doubt you’d get one in a motor factors - not the sort of thing you find in a car. I would just say that a 50 mile drive is not an insignificant cost, not to mention the time and inconvenience, and if you buy el cheapo isolator, how long will it be before the next 50 mile drive / 1/2 day wasted? There are some rubbish isolator around. Not saying that one is necessarily, but looking at the price it’s not going to be the bees knees either. And it does look a bit “cheap”!

[Momac]

The durite 0-727-18 relay is a make or break relay.

It is not a split charge relay.

It appears the relay is   used to link the two battery banks together . 

In your case it seems the Durite relay may be activated by the ignition switch . So when the engine is on all of the batteries are linked together .

 

This is not the usual split charge relay arrangement . A spit charge relay charges the starter battery first and when that reaches a  set voltage the charge is  sent to the domestic bank.

This would explain why the domestic batteries  were fully charged  and why the lights work with the ignition on.

 

Anyway it does help confirm also the domestic isolator is not working. 

 

 

 

[WotEver]

8 minutes ago, MartynG said:

In your case it seems the Durite relay may be activated by the ignition switch. So when the engine is on all of the batteries are linked together.

 

This is not the usual split charge relay arrangement...

I guess it depends on what you mean by ‘usual’. It’s a very common arrangement. Vetus use it all the time. 

[Flyboy]

8 hours ago, Richard10002 said:

Makes sense now you and Nick mention it. I did turn it on and off a few times and the first time it clicked as normal but, after that it spun loosely. Strange that I could have left the boat this afternoon and all was well, and something failed over the next 8 hours

 

Given that I’d like to fix it tomorrow, is there a shop I could go to to buy one - surface mounted?

 

I could drive the 50 mile round trip to Midland Chandlers at Preston Brook, where they have this:

 

https://www.midlandchandlers.co.uk/store/category/1939/product/vs-259.aspx

 

they also have a Durite one but it’s about seventy quid!!

 

I’m guessing the space will be about 7cm x 7cm, so the 12cm ones from Screwfix are too big, and Halfords have one that isn’t surface mounted.

 

So is there somewhere like a motor factors or similar which might be nearer, (Manchester), that might sell them over the counter?

 

Thanks for the help!

 

 

Don't skimp on price, you get what you pay for. I would go for a BlueSea isolator which are high quality. If you decide to go to Midland make sure they have what you need in stock before making the journey.

https://www.cclcomponents.com/blue-sea-system-m-series-mini-on-off-battery-switch-with-knob-red

[Richard10002]

OK....

 

Agreed on quality... the existing look like Durite switches, and will have lasted 18 years. Is Durite an OK brand?

 

Could I do a temporary bodge with a fuse holder and fuse?

 

Given that I would like to be on the boat over the weekend, and I won’t get anything mail order until probably Monday, is there any reason not to remove the failed isolator and fit a midi fuse holder to connect the cables for a few days?

 

 If I need to isolate I can remove the fuse, and if current is excessive, the fuse will do the isolating. I think I have a 50A midi fuse and holder, and I rarely see more than about 12-15A flowing.

[nicknorman]

Durite is mid range. Probably do another 18 years! Yes you could bypass with a fuse in the short term, strictly against the BSS so leave it like that for the minimum time.

[Momac]

9 hours ago, WotEver said:

I guess it depends on what you mean by ‘usual’. It’s a very common arrangement. Vetus use it all the time. 

I refer to boats within my limited experience a they are sea boats not narrow boats.

A split charge relay directs the alternator charge to the starter battery and only when when that gets to a set voltage the domestic bank receives a charge .

The arrangement shown charges all of the batteries together as if the starter battery and the domestics are a single bank.

I have the same relay but controlled by  a  switch and not by the ignition key .

 

[Richard10002]

7 hours ago, nicknorman said:

Durite is mid range. Probably do another 18 years! Yes you could bypass with a fuse in the short term, strictly against the BSS so leave it like that for the minimum time.

Correct - the isolator had failed in a kind of catastrophic way

 

All bodged up now, and working fine  Blue Sea Isolator ordered from RJS Marine - £39 inc. postage. CCL have a slightly lower price, but take the mickey with £10 postage, (presumably plus VAT once you get to checkout), so I gave them a swerve.

 

On the isolator, thre are 4 little screws that hold two connectors on the switch bit. The locators for all 4 screws had failed, such that the spring forced the connectors away from the switch part, thus losing the connection, and allowing the switch to spin freely.

 

I guess, if it's a plastic failure after 18 years, the chances are that the Starter battery isolator will be on the way out, so i'll get the Domestic one fitted, then get another for the Starter circuit.

 

Thanks again for all the help!

[ditchcrawler]

8 hours ago, nicknorman said:

Durite is mid range. Probably do another 18 years! Yes you could bypass with a fuse in the short term, strictly against the BSS so leave it like that for the minimum time.

I am not 100% sure you are correct, haven't read the BSS since reading your post but does in mention switch or just a means of isolating, which pulling a fuse is. 

[Sir Nibble]

11 hours ago, MartynG said:

The durite 0-727-18 relay is a make or break relay.

It is not a split charge relay.

It appears the relay is   used to link the two battery banks together . 

In your case it seems the Durite relay may be activated by the ignition switch . So when the engine is on all of the batteries are linked together .

 

This is not the usual split charge relay arrangement . A spit charge relay charges the starter battery first and when that reaches a  set voltage the charge is  sent to the domestic bank.

This would explain why the domestic batteries  were fully charged  and why the lights work with the ignition on.

 

Anyway it does help confirm also the domestic isolator is not working. 

 

 

 

It's a split charge relay if it's wired as a split charge relay. The notion that a split charge system charges the engine battery first is one of the most persistent fallacies in the whole subject. A normally connected split charge relay charges both battery banks in parallel from the word go.

[Tony Brooks]

59 minutes ago, MartynG said:

I refer to boats within my limited experience a they are sea boats not narrow boats.

A split charge relay directs the alternator charge to the starter battery and only when when that gets to a set voltage the domestic bank receives a charge .

The arrangement shown charges all of the batteries together as if the starter battery and the domestics are a single bank.

I have the same relay but controlled by  a  switch and not by the ignition key .

 

 

Unless someone has installed some fancy device to automatically do what you describe then even on sea boats id far from usual if a split charge relay is in use but if you wire a Voltage Sensitive Relay in the wrong way (in mine and sever other opinion) that is what happens.

 

Boat fitters are by and large profit driven and after an easy install so on a single alternator boat that is to have twin battery banks fitted they tend to leave the alternator connected to the engine battery and use the relay to parallel the domestic bank when it is energised. This is (again in my opinion, far from best practice because it can and does lead to relay failure. It is not helped by the diagrams supplied with the relays that seem to be concerned with a caravan install where the domestic bank is often not  present or connected.

 

On 9 diode alternators the relay is more often than not energised by the D+ terminal so in theory (although practice does not always bare this out) te relay can only energise once the alternator is producing some charge. There are alternative methods, but this is the most common.

 

If you wire the alternator to the engine battery then upon start up the relatively flat domestic bank is libel to draw more or less full alternator output, plus more current from the engine battery, through the relay contacts making it much more likely to burn then out.

 

Wiring the alternator to the domestic bank ensures the only current that passes through the relay contacts is the relatively small charging current for the engine battery and as the engine battery is only discharged by a very few Ah upon starting there is no anger of leaving the engine battery discharged. In any case once the relay has paralleled the banks each bank will draw current proportional to its depth of discharge so within half an hour or so the starting discharge will have been replaced.

 

In my view anything more is a waste of money, time and will tend to introduce more components and thus more unreliability. If seem to me certain vendors are spouting bull shine when they try to make charging the engine battery first a good thing to do.

 

Anyway as long as you can get one to suit your charging current I think a VSR is the way to go today because it will automatically parallel the banks when a shore power charger or solar charging makes doing so advantageous BUT sensed form the domestic bank and with the alternator charging the domestic bank.

 

 

 

s

 

 

[WotEver]

^^^^^ This

[Richard10002]

Blue Sea switch arrived and fitted, so all is well. The failed one was a BEP, not a Durite. ETA In fact, now I've uploaded the big pic, you can see the starter isolator has BEP Marine printed on the picture of a battery

 

Thanks to all for the help... saved me going off down a relay testing dead end for a while.... and I now know how my relay works, and where a few more of the myriad of wires go

 

 

Edited August 10, 2018 by Richard10002