Victron/battery isolator

[nickfryer]

Hi all.

I am very new to Combi chargers as my current boat is all 12V.when i normally leave the boat i would switch both battery isolators off.

 

In my new boat which is well on the way to being fitted out, advice is needed on where to connect the combi. I have read some various threads on connections, this is how i intend to connect mine.

Any comments would be appreciated.

 

Main battery bank to Megafuse. Megafuse to battery isolator. Battery isolator to 12v distribution unit. Combi connection taken from battery side of isolator.

 

smartgauge advanced fitted so relay will connect both banks when shoreline connected.

 

Comments or advice please.

 

Thanks. Nick

[nicknorman]

Hi all.

I am very new to Combi chargers as my current boat is all 12V.when i normally leave the boat i would switch both battery isolators off.

 

In my new boat which is well on the way to being fitted out, advice is needed on where to connect the combi. I have read some various threads on connections, this is how i intend to connect mine.

Any comments would be appreciated.

 

Main battery bank to Megafuse. Megafuse to battery isolator. Battery isolator to 12v distribution unit. Combi connection taken from battery side of isolator.

 

smartgauge advanced fitted so relay will connect both banks when shoreline connected.

 

Comments or advice please.

 

Thanks. Nick

This sort of question always produces lots of argument! Our boat is connected as you say, with the Combi bypassing the isolator. Provided this is adequately fused very near the batteries, I think that is fine. You just have to bear in mind that the Combi is live even with the isolator off.

 

The upside of this is that you can turn all other circuits off, but leave the Combi in charger-only mode to keep the batts topped up if you are on shore power. The downside is that if something dire happened to the Combi - it went on fire say, without drawing sufficient current to blow the fuse - it would be quite difficult to stop fire-feeding current from going into the Combi. At least make sure the fuse rating is no more than that specified for the Combi installation, or have an additional fuse just for the Combi (which is what we have).

 

Most Combis have an auxilliary charging output for the starter battery, therefore there is probably no need to have the SmartBank connecting the two banks together.

Edited February 19, 2013 by nicknorman

[by'eck]

As Nick suggests there are two camps on this issue. Connecting the Combi via a fuse and correctly gauged cables directly to the batteries gives the minimum of installation issues and is often manufacturer recommended.

 

I and others prefer to have the battery isolator do just that, particularly to allow safe working on an inverter. If properly engineered with short cable runs and over-rated isolator, the volt drop issues will be insignificant even at max current draw from the inverter.

[Chris Pink]

The thought of only being able to isolate a large inverter with a spanner or a fire axe gives me the willies.

Isolated side of the isolator please.

 

Or even better ( I recently did this) get a 0-1-2 isolator with the inverter on 2 and domestic on 1

[nicknorman]

The thought of only being able to isolate a large inverter with a spanner or a fire axe gives me the willies.

Isolated side of the isolator please.

 

Or even better ( I recently did this) get a 0-1-2 isolator with the inverter on 2 and domestic on 1

I understand your point, but as Richard says, the installation manuals show the device connected directly to the batteries (via a fuse). Presumably they wouldn't show that, with the inherent risk of liability, if they were not pretty sure it was adequately safe. Every connection, switch etc in the circuit between the inverter and batteries adds resistance - and it only takes a tiny bit of resistance for significant voltage drop at 200+ amps. From that point of view, connection to the battery side of the isolator is preferable - or even direct to the batteries via a dedicated fuse (fewer connections still). I also wonder how the devices would handle the isolator being opened in your preferred configuration, whilst charging at high rate?

[Chris Pink]

Much the same as poking a tiger with a big stick. You could but really better not.

[nicknorman]

Much the same as poking a tiger with a big stick. You could but really better not.

Anyway, the OP is now aware of the factors, he will have to make his own mind up!

Edited February 20, 2013 by nicknorman

[Keith M]

As Nick suggests there are two camps on this issue. Connecting the Combi via a fuse and correctly gauged cables directly to the batteries gives the minimum of installation issues and is often manufacturer recommended.

 

I and others prefer to have the battery isolator do just that, particularly to allow safe working on an inverter. If properly engineered with short cable runs and over-rated isolator, the volt drop issues will be insignificant even at max current draw from the inverter.

 

If the installation is just an Inverter this would be fine but what if the unit were a combi there is no way to isolated the installation

Plus there is also the issue of the BSS

Personally I fit a separate isolator to the combi positive

 

Keith

[nicknorman]

 

Plus there is also the issue of the BSS

 

Here we go again! What is "the issue of the BSS"?

[Keith M]

Here we go again! What is "the issue of the BSS"?

 

 

I suggest that you read 3.6.2 of the boat safety scheme?

 

Keith

[nicknorman]

I suggest that you read 3.6.2 of the boat safety scheme?

 

Keith

 

Here it is. Inverters, Combis and Chargers are specifically mentioned as not having to go via the isolator provided they are fused.

 

Identify any d.c. electrical circuits bypassing the battery isolator.

Check that any electrical circuits bypassing the battery isolator supply the following equipment:

· automatic bilge pumps;

· security alarms (including marine radios);

· fire pumps;

· electronic navigation equipment with memories;

· any other equipment where the manufacturer’s instructions indicate or specifically require direct connection to a battery, such as diesel-fired central heating boilers;

· battery charger outputs;

· inverters or combination inverter/chargers;

· solar panels and wind turbines.

Check electrical circuits supplying any equipment on the specified list, and which bypass a battery isolator, for the presence of a fuse or circuit-breaker, where the circuit can be seen.

 

So I still don't get your point.

[Keith M]

Here it is. Inverters, Combis and Chargers are specifically mentioned as not having to go via the isolator provided they are fused.

 

Identify any d.c. electrical circuits bypassing the battery isolator.

Check that any electrical circuits bypassing the battery isolator supply the following equipment:

· automatic bilge pumps;

· security alarms (including marine radios);

· fire pumps;

· electronic navigation equipment with memories;

· any other equipment where the manufacturer’s instructions indicate or specifically require direct connection to a battery, such as diesel-fired central heating boilers;

· battery charger outputs;

· inverters or combination inverter/chargers;

· solar panels and wind turbines.

Check electrical circuits supplying any equipment on the specified list, and which bypass a battery isolator, for the presence of a fuse or circuit-breaker, where the circuit can be seen.

 

So I still don't get your point.

 

 

So if the combi is on the load side how do isolator the system?

When connected to the grid.

Have a look at post 3

Edited February 20, 2013 by Keith M

[nicknorman]

So if the combi is on the load side how do isolator the system?

When connected to the grid.

Have a look at post 3

Ah I think we were talking at cross purposes! You are saying that the Combi shouldn't be on the load side of the isolator (I agree! - although not sure it would be against BSS). You are saying that you would fit it to the batt side, but with its own isolator. Nothing wrong with that except that its additional cost and resistance and not required by BSS nor the manufacturer. However if you are of nervous disposition, it wouldn't be "wrong"!

 

If the above is correct, we can go in peace!

[pearley]

If the installation is just an Inverter this would be fine but what if the unit were a combi there is no way to isolated the installation

Plus there is also the issue of the BSS

Personally I fit a separate isolator to the combi positive

 

Keith

This is how Joanie M is wired. One isolator for the feed to the domestic fuse box and a separate one, and dedicated Megafuse, for the Combi.

 

Regards

Pete

[Keith M]

Ah I think we were talking at cross purposes! You are saying that the Combi shouldn't be on the load side of the isolator (I agree! - although not sure it would be against BSS). You are saying that you would fit it to the batt side, but with its own isolator. Nothing wrong with that except that its additional cost and resistance and not required by BSS nor the manufacturer. However if you are of nervous disposition, it wouldn't be "wrong"!

 

If the above is correct, we can go in peace!

 

Yes we can go in peace

 

But many boat builders install combi's with the positive of the combi via a fuse on the load side of the isolator

Turn isolator off

Plug combi into the grid all 12 or 24 volt circuits are all live again also batteries are not charged

No way of isolating the system when connected to the grid.

 

I feel it should fail the BSS

Edited February 20, 2013 by Keith M

[nicknorman]

Yes we can go in peace

 

But many boat builders install combi's with the positive of the combi via a fuse on the load side of the isolator

Turn isolator off

Plug combi into the grid all 12 or 24 volt circuits are all live again also batteries are not charged

No way of isolating the system when connected to the grid.

 

I feel it should fail the BSS

Well when "on grid" the circuits can be isolated by turning off the Combi / charger. This will isolate the DC circuits (assuming battery isolator also turned off). I can see nothing in the BSS that requires a separate isolator for services. It's only the battery that has to be isolate-able. Presumably this is because they store a huge amount of energy and can release it rapidly.

 

Certainly the boats built by my builder (5-10 a year) seem to pass like this.

Edited February 20, 2013 by nicknorman

[Chris Pink]

Yes we can go in peace

 

But many boat builders install combi's with the positive of the combi via a fuse on the load side of the isolator

Turn isolator off

Plug combi into the grid all 12 or 24 volt circuits are all live again also batteries are not charged

No way of isolating the system when connected to the grid.

 

I feel it should fail the BSS

 

A good argument for a 0-1-2 switch. I used one with an inverter simply because it was knocking around but it safeguards against exactly that eventuality with a combo unit. The BSS list is getting ridiculous. Might as well just say isolate lights and water pumps. I feel somewhere there should be a means of isolating the battery. The word is a clue. There are too many potential for working accidents if you can allow live systems with no override. So all isolated or none.

Edited February 20, 2013 by Chris Pink

[smileypete]

Would have thought any decent combi has internal fuse protection in case a transistor shorts or something like that. There must be loads of them idling away on boats in marinas, a much bigger risk is that a batt shorts or goes into thermal runaway.

 

 

The thought of only being able to isolate a large inverter with a spanner or a fire axe gives me the willies.

Isolated side of the isolator please.

As long as it's fused, in an emergency if you really want you could just short the fused side to the hull, fuse blows and it's isolated, no problem. Isolating from the mains side is just a matter of switching it off.

 

Anyway, most combis, inverters, solar controllers are in a fairly sealed metal box, it's the external wiring that really needs protection.

 

cheers, Pete.

~smpt~

Edited February 20, 2013 by smileypete

[Chris Pink]

You are worrying me even more now ;-)

 

Most power units I've seen don't have internal fuses though they may have varistors or some such. I think they all should have being brought up on amplifiers with internal fuses.

 

300A is a very good welding current

 

And fairly sealed boxes that live in close proximity to wet things.

[nicknorman]

You are worrying me even more now ;-)

 

Most power units I've seen don't have internal fuses though they may have varistors or some such. I think they all should have being brought up on amplifiers with internal fuses.

 

300A is a very good welding current

 

And fairly sealed boxes that live in close proximity to wet things.

However, assuming these devices are installed in accordance with the manufacturers instructions in the main (though, listening to the people on this forum, by no means all!) one would imagine that if a lot of expensive boats were written off by fire caused by a faulty Combi, that would be untenable for the manufacturer. So it probably doesn't happen!

 

The other thing to bear in mind is that there is no point in having an isolator if someone is not there to turn it off when the box goes on fire etc. To say that you will only leave the Combi on when you are awake, on the boat, is to me getting just a bit too paranoid!

[nickfryer]

However, assuming these devices are installed in accordance with the manufacturers instructions in the main (though, listening to the people on this forum, by no means all!) one would imagine that if a lot of expensive boats were written off by fire caused by a faulty Combi, that would be untenable for the manufacturer. So it probably doesn't happen!

 

The other thing to bear in mind is that there is no point in having an isolator if someone is not there to turn it off when the box goes on fire etc. To say that you will only leave the Combi on when you are awake, on the boat, is to me getting just a bit too paranoid!

Thanks for all replies, as was said in post 2 a very emotive subject with lots of differing opinions.

 

Thanks all.

 

Nick