Unbranded battery isolator switches

[nicknorman]

10 minutes ago, cheesegas said:

The Chief Bodger on one of the 12v Facebook groups recommends wiring the inverter directly to the battery via a fuse, no isolator, because he seems to think that every isolator switch will fail with the current draw. In reality, he's admitted to using only cheap isolators as he thinks the Blue Seas etc are a waster of money...

 

There's a lot of misinformation out there! A 200a fuse will happily pass 250a for a good few minutes, so in the event of an internal failure with the inverter you potentially get 3kw of heating power without the fuse blowing and no way to easily isolate it.

Looking at it from the BSS perspective, although an inverter should have an isolator switch, a Combi doesn’t. We have a Combi with only a fuse for protection. I think you have to look at probabilities. The probability of the scenario you propose (inverter taking a high fault current above the fuse rating by a modest margin) seems to me highly unlikely verging on impossible. And if that highly unlikely scenario does occur, there is only any point in having a switch if there is a sensible human present in close proximity who notices the issue before it becomes catastrophic. Our Combi is on 24/7 and most of the time we aren’t there.

 

The chief bodger you mention is of course incorrect, because it is or should be a BSS fail if it is just an inverter.

Edited January 10, 2025 by nicknorman

[cheesegas]

1 minute ago, nicknorman said:

Looking at it from the BSS perspective, although an inverter should have an isolator switch, a Combi doesn’t. We have a Combi with only a fuse for protection. I think you have to look at probabilities. The probability of the scenario you propose (inverter taking a high fault current above the fuse rating by a modest margin) seems to me highly unlikely verging on impossible. And if that highly unlikely scenario does occur, there is only any point in having a switch if there is a sensible human present in close proximity who notices the issue before it becomes catastrophic. Our Combi is on 24/7 and most of the time we aren’t there.

Inverters, MPPTs and bilge pumps are all exempt under BSS, as are a few other things. You can still get a good 2.6kw continuous through a 200a fuse, which is enough to cause a mild amount of chaos.

 

I'm basing all this off one incident mind, and that was a Sterling 3kw which is no surprise. Flames firing out of both ends, enough to scorch the top of the cupboard it was in, only died down when the owner turned the isolator. This was when it was under heavy load, which I'd assume is the most likely time to fail - and being under heavy load usually means that someone's on board.

[nicknorman]

50 minutes ago, magnetman said:

Thats interesting. I've never had an isolator between alternator and batteries. 

 

 

Well you are very naughty! BSS requires starter battery to be isolated from the alternator by the isolator switch. Apart from anything else on modern engines the starter alternator, and the starter motor positive feed, are connected together within the engine wiring harness making it difficult to isolate the starter without isolating the alternator.

[IanD]

54 minutes ago, magnetman said:

Thats interesting. I've never had an isolator between alternator and batteries. 

 

Did you mean starter motor and batteries? 

 

 

As mentioned above putting cheap switches in the line to the starter motor very often causes problems because of the enormous current draw. 

 

Current is like water. It will find the flaws. 

 

 

I'm going to be getting a battery switch for one of the launches. 

 

I came across that one but it just looks wrong to me. Its not the price its just that the actual article to me looks tinny and puts me off. 

 

 

 

 

 

I prefer this one as it looks better. Might still be crap inside to be fair. I think it is a copy not a real Blue Sea as they are more expensive. 

 

These copy things are interesting. I use Anderson SB50 (type) connectors on the floating electric beer drinking platform. I have had failures with the cheap copies because the pieces of spring steel used to hold the terminals in place are not proper spring steel. They lose their grip and provide a bad contact leading to overheating. 

 

Cost cutting has interesting effects. 

 

Blue Sea are a reputable brand -- assuming that's the genuine article and not a cheap Chinese copy. Which it is, see here...

 

https://marinehowto.com/counterfeit-electrical-components-just-say-no/

 

 

[nicknorman]

5 minutes ago, cheesegas said:

Inverters, MPPTs and bilge pumps are all exempt under BSS, as are a few other things. 

That’s interesting, I see you are right the exemption now includes inverters as well as Combis. Not sure when that changed, or what the justification for an inverter needing a continuous supply is!

[cheesegas]

4 minutes ago, IanD said:

 

Ooft. Nice bit of casual racism there. I did pick up on that previously in other parts of his site, at least now I know not to peruse or recommend it again. Shame, it's got some good info there.

[IanD]

3 minutes ago, cheesegas said:

Ooft. Nice bit of casual racism there. I did pick up on that previously in other parts of his site, at least now I know not to peruse or recommend it again. Shame, it's got some good info there.

I agree, but that doesn't change the fact that there's a lot of solid information on there which is difficult to find elsewhere. You don't have to take any notice of the comments, and other people can decide for themselves whether to be offended by them... 😉 

Edited January 10, 2025 by IanD

[cheesegas]

Just now, IanD said:

I agree, but that doesn't change the fact that there's a lot of solid information on there which is difficult to find elsewhere. You don't have to take any notice of the comments, and other people can decide for themselves whether to be offended by them... 😉 

Agreed, but as someone of half Chinese heritage, I choose to be offended by this. I expect comments like this are partially responsible for some nasty comments to me in the work environment in the past, and during covid too.

 

Yes, most of the fakes come from China, but I've also worked with Chinese suppliers before and they're capable of making some very high quality stuff - it's just not much cheaper than what comes from Europe, so naturally people go for the cheap copies.

[magnetman]

1 hour ago, magnetman said:

 

I prefer this one as it looks better. Might still be crap inside to be fair. I think it is a copy not a real Blue Sea as they are more expensive. 

 

 

 

28 minutes ago, IanD said:

. Which it is, see here...

 

 

yes

24 minutes ago, cheesegas said:

Ooft. Nice bit of casual racism there. I did pick up on that previously in other parts of his site, at least now I know not to peruse or recommend it again. Shame, it's got some good info there.

Well spotted. Bloody yanks. Over paid, over sexed and over here. 

Edited January 10, 2025 by magnetman

[nicknorman]

40 minutes ago, cheesegas said:

Agreed, but as someone of half Chinese heritage, I choose to be offended by this. I expect comments like this are partially responsible for some nasty comments to me in the work environment in the past, and during covid too.

 

Yes, most of the fakes come from China, but I've also worked with Chinese suppliers before and they're capable of making some very high quality stuff - it's just not much cheaper than what comes from Europe, so naturally people go for the cheap copies.

Obviously you are entitled to be offended if you wish! I would just mention that this is a bit like the antisemitism row. IMO one can criticise the Israeli state’s actions without that automatically making one antisemitic. If that were not the case then it gives the Israeli government the right to do absolutely anything with impunity.

 

Surely you can’t deny that Chinese business practices (within china, not the diaspora) tend to give little or no respect to intellectual property of other nations? That doesn’t mean that all Chinese people are bad, it is simply a reflection of the Chinese national business culture, and pointing that out isn’t racist IMO.

 

As we know, most things like iPhones are made in China to very high standards so it’s not as if everything Chinese is rubbish. And they make fantastic custom PCBs for me for a pittance so I am not complaining. I recently sent off a PCB design. 30 minutes later I realised I’d made a mistake but the PCB was already in production. Never mind, new design submitted and new fee paid. So that was a whole £3.46 wasted. Yes £3.46 for 5 boards including tax and shipping, and they arrived yesterday from China, 6 days after I ordered them. Astonishing!

Edited January 10, 2025 by nicknorman

[cheesegas]

Just now, nicknorman said:

Obviously you are entitled to be offended if you wish! I would just mention that this is a bit like the antisemitism row. IMO one can criticise the Israeli state’s actions without that automatically making one antisemitism. If that were not the case then it gives the Israeli government the right to do absolutely anything with impunity.

 

Surely you can’t deny that Chinese business practices (within china, not the diaspora) tend to give little or no respect to intellectual property of other nations? That doesn’t mean that all Chinese people are bad, it is simply a reflection of the Chinese national business culture, and pointing that out isn’t racist IMO.

Without derailing this thread too much...

 

Just to clarify, the only bit I have a problem with is the last line, 'sadly the sleazy Chinese could care less', which doesn't criticise sleazy Chinese business practices, it's aimed at the wider diaspora. 

 

Pointing out that there's dodgy business practices within China when it comes to human rights, copyright infringement etc is totally fine and I don't have a problem with it, it's just comments which brand everyone from that region with the same brush. Calling everyone from China 'sleazy' isn't good.

 

I was on a boat a few months ago to look at a Multiplus dropping shore power under heavy load. Nice new-ish narrowboat on a mooring. Diagnosed a dry joint on the output breaker (the little black internal one with a red button) on the isolation transformer, something multiple people before me had missed. Mentioned it would need a new breaker and he said 'I don't want any Chinese fakes, I know what you lot are like'. Normalising comments like this doesn't do the wider community any good.

 

Replaced the cover, packed up my tools and left without a word. Never mind that the OEM Victron part is actually Chinese designed and made...

[nicknorman]

3 minutes ago, cheesegas said:

Without derailing this thread too much...

 

Just to clarify, the only bit I have a problem with is the last line, 'sadly the sleazy Chinese could care less', which doesn't criticise sleazy Chinese business practices, it's aimed at the wider diaspora. 

 

Pointing out that there's dodgy business practices within China when it comes to human rights, copyright infringement etc is totally fine and I don't have a problem with it, it's just comments which brand everyone from that region with the same brush. Calling everyone from China 'sleazy' isn't good.

 

I was on a boat a few months ago to look at a Multiplus dropping shore power under heavy load. Nice new-ish narrowboat on a mooring. Diagnosed a dry joint on the output breaker (the little black internal one with a red button) on the isolation transformer, something multiple people before me had missed. Mentioned it would need a new breaker and he said 'I don't want any Chinese fakes, I know what you lot are like'. Normalising comments like this doesn't do the wider community any good.

 

Replaced the cover, packed up my tools and left without a word. Never mind that the OEM Victron part is actually Chinese designed and made...

Yes ok but I think it was just lazy writing rather than the type of overt nastiness you mention above. If that had been me I might have rammed a screwdriver into the board whilst it was on. Or do what a friend of mine genuinely did with his BMW 7 series electronic Pcb-dashboard that was playing up - took a wire brush to the back of it to ”clean it up” whilst it was powered, and then wondered why there were sparks and it never worked again. But then he was French and we all know what the French are like.

[IanD]

1 hour ago, cheesegas said:

Agreed, but as someone of half Chinese heritage, I choose to be offended by this. I expect comments like this are partially responsible for some nasty comments to me in the work environment in the past, and during covid too.

 

Yes, most of the fakes come from China, but I've also worked with Chinese suppliers before and they're capable of making some very high quality stuff - it's just not much cheaper than what comes from Europe, so naturally people go for the cheap copies.

Like many electronics companies we use the Far East/China for manufacturing, and as you say they *can* make high quality gear that's as good as anywhere else in the world, but more cheaply -- there are many reasons for this including lower wages than the West, economies of scale, cheaper power, lower factory costs, cheaper raw materials, complete local supply chain, and a massive number of local component suppliers.

 

You do need to use manufacturers with good QC (and sometimes inhouse monitoring staff from us) who are not the cheapest, but even then (and allowing for shipping etc) the manufacturing costs are considerably lower than in the West, typically 30%-50% cheaper depending on component costs.

 

That's why even most high-quality equipment (e.g. telecomms, Victron) is made there -- of course it would be great to help support Western economies and workers, but the simple fact is that almost nobody will pay 50%-100% more for a "Made in the UK" or "Made in USA" sticker... 😞 

 

Once you take away the quality controls and allow the cost to drop then it absolutely plummets, it can end up as low as 10%-20% of Western manufacture -- which is where the "cheap Chinese junk" accusation comes in, because it's basically true. Saying that all this stuff comes from China is not racist -- unless you start using racist language... 😞 

Edited January 10, 2025 by IanD

[jonathanA]

4 hours ago, Ray T said:

My observations from the boating world, various disciplines,  "Buy cheap - get cheap."

I always go for the best branded equipment I can afford.

True but equally the "marine" premium pisses me off. 

I believe in value for money which is not the same as buying cheap. I just struggle to see how the blue sea switch at £60 is a fair price. To me someone, either blue sea or their distributor is making a large markup. 

 

I think its always worth shopping around for non marine alternatives and making an assessment on risk/quality/cost in light of the intended use. 

 

Just as blackrose has done.

[cheesegas]

1 minute ago, jonathanA said:

True but equally the "marine" premium pisses me off. 

I believe in value for money which is not the same as buying cheap. I just struggle to see how the blue sea switch at £60 is a fair price. To me someone, either blue sea or their distributor is making a large markup. 

 

I think its always worth shopping around for non marine alternatives and making an assessment on risk/quality/cost in light of the intended use. 

 

Just as blackrose has done.

Isolators often sold as 'marine' are also used on Bruno gensets, which never go near a boat or the water. These are around the same price or more than the Blue Sea ones. They're a quality product which can be used in any application, there's no premium attached to this particular item. I agree that some things do have a premium however.

 

Prices are relative too; if the Blue Sea was £120 and the cheap switches were £60, you'd be commenting that £60 is very reasonable and the Blue Sea is a rip off.

 

Blackrose hasn't pulled one apart to see how it's made, and nor have they done any testing - it's just an assessment based on the look and feel. £60 is a reasonable figure for something expected to work in a humid environment, passing high currents without heating itself up, and being able to break the circuit under high current too.

[IanD]

14 minutes ago, cheesegas said:

Isolators often sold as 'marine' are also used on Bruno gensets, which never go near a boat or the water. These are around the same price or more than the Blue Sea ones. They're a quality product which can be used in any application, there's no premium attached to this particular item. I agree that some things do have a premium however.

 

Prices are relative too; if the Blue Sea was £120 and the cheap switches were £60, you'd be commenting that £60 is very reasonable and the Blue Sea is a rip off.

 

Blackrose hasn't pulled one apart to see how it's made, and nor have they done any testing - it's just an assessment based on the look and feel. £60 is a reasonable figure for something expected to work in a humid environment, passing high currents without heating itself up, and being able to break the circuit under high current too.

The inside of the burned cheap copy of the BEP switch, which from the pictures looks identical to Blackrose's...

 

 

Edited January 10, 2025 by IanD

[magnetman]

Yes. I was going to re-post that image as I think it is relevant. 

[cuthound]

6 hours ago, nicknorman said:

Looking at it from the BSS perspective, although an inverter should have an isolator switch, a Combi doesn’t. We have a Combi with only a fuse for protection. I think you have to look at probabilities. The probability of the scenario you propose (inverter taking a high fault current above the fuse rating by a modest margin) seems to me highly unlikely verging on impossible. And if that highly unlikely scenario does occur, there is only any point in having a switch if there is a sensible human present in close proximity who notices the issue before it becomes catastrophic. Our Combi is on 24/7 and most of the time we aren’t there.

 

The chief bodger you mention is of course incorrect, because it is or should be a BSS fail if it is just an inverter.

 

I agree. An isolator is a device to allow you to depower equipment whilst you work on it safely, It is not part of the electrical protection.

[magnetman]

Given the fact an isolator switch can fail in closed circuit by welding the contacts I feel an emergency disconnect is better performed by one of these 

 

 

 

Fuses ? Yeah whatever.