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B2B chargers: isolated or non-isolated?


Tony1

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Hi folks, I'm hoping the electrical wizards might be able to advise on this question.

I currently use two Sterling BB1260 units, capable of delivering a bit over 45 amps each- but they are permanently set to half power, because my alternators are not that great.

I'm considering replacing these BB1260s with a pair of these 30 amp Victron units, which will give the same output, but which are more compact, and have the benefit of bluetooth control, which is handy if I'm at the tiller all day:

 

https://www.amazon.co.uk/Victron-Energy-Orion-Tr-Isolated-charger/dp/B07YMQ4GTQ/ref=sr_1_5?crid=1Q5GWL281ZEXX&keywords=victron+orion-tr+smart+12%2F12-30a+isolated+dc-dc+charger&qid=1676627609&sprefix=orion+TR+smart+%2Caps%2C510&sr=8-5

 

But here's my query- I'm not sure if I need to pay the extra £50 or so for the 'isolated' version, or on a narrowboat, can you use the 'non-isolated' version of the unit? 

This is the non-isolated version:

 

https://www.amazon.co.uk/Victron-Energy-Orion-Tr-Non-isolated-Charger/dp/B087CZC211/ref=sr_1_6?crid=14P01MU2I4YMP&keywords=victron+orion-tr+smart+12%2F12-30a+non-isolated+dc-dc+charger&qid=1676629112&sprefix=victron+orion-tr+smart+12%2F12-30a+isolated+dc-dc+charger%2Caps%2C484&sr=8-6

 

The only difference seems to be the isolated model has negative in and out connections, whereas the non-isolated has connection marked 'ground' 

Once again, many thanks in advance for any advice/info you are able to offer.

 

Oh, and there might be a brace of Sterling BB1260s (plus a BB1230) up for sale in a week or two (at about half the price of a new unit),  if anyone is interested.

 

 

Edited by Tony1
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I suspect that the non-isolated ones are designed for automotive use with an earth return wiring, while the isolated ones are for things like metal boats with insulated return wiring. I suspect (again, suspect) that is you mounted a non-isolated return on thick insulating material, so no mounting screws could go right through and touch any metal they should be fine. Just consider the grounds as negative connections.

 

Usual caveats - check with the Victron and await more knowledgeable confirmation, or not.

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3 minutes ago, Tony Brooks said:

I suspect that the non-isolated ones are designed for automotive use with an earth return wiring, while the isolated ones are for things like metal boats with insulated return wiring. I suspect (again, suspect) that is you mounted a non-isolated return on thick insulating material, so no mounting screws could go right through and touch any metal they should be fine. Just consider the grounds as negative connections.

 

Usual caveats - check with the Victron and await more knowledgeable confirmation, or not.

 

Thanks Tony, that's much appreciated.

I do struggle with some of the manuals because I don't know all of the electrical terminology they use. 

In this case if I end up getting two units, there is almost £100 price difference between the different versions, so this time its worth some extra hassle to get to grips with it and use the cheaper model, as long as I can confirm its ok on a boat, and its simple to wire in.

 

 

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4 hours ago, Tony1 said:

 

Thanks Tony, that's much appreciated.

I do struggle with some of the manuals because I don't know all of the electrical terminology they use. 

In this case if I end up getting two units, there is almost £100 price difference between the different versions, so this time its worth some extra hassle to get to grips with it and use the cheaper model, as long as I can confirm its ok on a boat, and its simple to wire in.

 

 

Is it worth the hassle and expense of changing at all. Apart from looking at your phone while trying to steer and dropping it in the cut, what are you going to gain. Does what you have work?

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1 minute ago, ditchcrawler said:

Is it worth the hassle and expense of changing at all. Apart from looking at your phone while trying to steer and dropping it in the cut, what are you going to gain. Does what you have work?

 

You make a good point Brian, and I have thought about whether its worth the cost of changing over, and whether its more because I just really like the Victron gear and I'm looking for an excuse to change out the Sterling B2Bs.

The victron bluetooth function is very handy, I will say that. If I'm cruising in the summer I'll have two MPPTs throwing loads of current in, plus two B2Bs, so being able to switch each of them on or off without pulling over is handy.  And the victron units are more compact, so they'll fit better in the electrics cupboard.

But does that extra convenience justify spending about £200? (and that's assuming I get a decent price for the Sterling units on ebay or on here). 

 

I have my BSS in November this year, and I want to tidy up the wiring and make sure it all looks neat and properly supported.

Plus I heard there is a new rule that the examiners are not allowed to fail your electrics if you have victron stuff, because its all so lovely and sleek looking. 

 

 

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The isolated version is for use where the two circuits have separate grounds, e.g. if one side was grounded on the bank this would be needed to prevent galvanic corrosion.

 

On a narrowboat, all the 12V negatives should be earthed to a single point anyway so the non-isolated version will be fine.

 

For what it's worth I'm rather unimpressed by my Orion Tr. It has no ability to ramp its output current up and down or adapt smoothly to the input voltage, only a very sharp cut-in/out that tends to cause momentary belt slip. It also overheats and fails to maintain its rated output installed in the engine bay, admittedly a high ambient temperature but within the specified range.

Edited by Francis Herne
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3 minutes ago, Francis Herne said:

The isolated version is for use where the two circuits have separate grounds, e.g. if one side was grounded on the bank this would be needed to prevent galvanic corrosion.

 

On a narrowboat, all the 12V negatives should be earthed to a single point anyway so the non-isolated version will be fine.

 

The negative 12V DC side of things in automotive or marine use should never be connected to the soil as far as I know, but it may get a bit more complex when 240V AC or higher is involved, but that would be for the AC, not the DC.

 

There should ideally be just one hull bond point for 12V DC negative, so fuses will blow or breakers trip in the event of a positive short to the hull. All other negatives from the circuits should end up back on the battery negative posts. What you should not do is connect any circuit negative to the hull. If you do, currant will/may pass through the hull back to the battery negative via the bond, and that MIGHT cause hull corrosion. Fixing the non-isolated version to any metal part of the hull may well provide a negative return path via the hull, hence my suggestion that they would need to be mounted on insulating material so they are isolated from the hull.

 

I fear there may be a bit of muddled thinking here, confusing AC and DC practice.

 

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2 minutes ago, Francis Herne said:

The isolated version is for use where the two circuits have separate grounds, e.g. if one side was grounded on the bank this would be needed to prevent galvanic corrosion.

 

On a narrowboat, all the 12V negatives should be earthed to a single point anyway so the non-isolated version will be fine.

 

For what it's worth I'm rather unimpressed by my Orion Tr. It has no ability to ramp its output current up and down or adapt smoothly to the input voltage, only a very sharp cut-in/out that tends to cause momentary belt slip. It also overheats and fails to maintain its rated output installed in the engine bay, admittedly a high ambient temperature but within the specified range.

 

Thanks Francis, its good to know the cheaper non isolated version would work ok. 

I have the 18 amp Orion B2B at the moment, and it certainly isn't as sophisticated or as configurable as the Sterling BB1260.

But that said, it does work well for me. Mine is in a cupboard, and it stays cool and maintains it current delivery very well.

I've found that increasing its charging voltage seems to result in a slight increase in charging current. So if increase the bulk charge voltage from 14.4v to say 14.6v, the current output will increase to 20 amps or more.

I dont know enough to comment on the smoothness of its switching into operation, although I haven't noticed any belt slip.  

But I'm not impressed by the Sterling units. 

I dont like that they name the units by the input current, so my BB1260 unit doesn't put out 60 amps as I expected, but only 46 or 47 amps. It feels a bit misleading to name them that way. 

I also dont like that if you run them at the full 47 amps, the very noisy cooling fan is on almost all of the time, and the unit overheats every 5 minutes and throttles itself down to 29 amps for a minute or so. The heat they chuck out is ridiculous. 

I dont think they are particularly well made either. I was testing the current output of my two BB1260s earlier (to make sure they were ok in case I decided to sell them), and I'm now finding that one of them wont stay at full power for more than a few minutes. Instead it throttles down and the current output wanders between 18 and 20 amps. I restarted it and it went up to full power initially, and then dropped to 20 amps again in a few minutes.  

So that's a £300 unit that's no longer working as it should, after little more than a year of very light use. 

Its just very disappointing, and I feel that the victron kit will be more durable, even if it isnt as configurable. 

 

 

 

 

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1 hour ago, Tony Brooks said:

The negative 12V DC side of things in automotive or marine use should never be connected to the soil as far as I know, but it may get a bit more complex when 240V AC or higher is involved, but that would be for the AC, not the DC.

 

There should ideally be just one hull bond point for 12V DC negative, so fuses will blow or breakers trip in the event of a positive short to the hull. All other negatives from the circuits should end up back on the battery negative posts. What you should not do is connect any circuit negative to the hull. If you do, currant will/may pass through the hull back to the battery negative via the bond, and that MIGHT cause hull corrosion. Fixing the non-isolated version to any metal part of the hull may well provide a negative return path via the hull, hence my suggestion that they would need to be mounted on insulating material so they are isolated from the hull.

 

I fear there may be a bit of muddled thinking here, confusing AC and DC practice.

 

The muddle is more on Victron's part with labelling the "GND" terminal than anyone else's, I think.

 

The only difference between the isolated and non-isolated versions is that the two negatives of the former are electrically separate from each other.

 

The metal heatsink part of the chassis is not electrically bonded to the GND terminal on the non-isolated version - I've just been out in the engine bay with a meter to double-check that - nor if I recall correctly to either negative terminal of the isolated version.

Edited by Francis Herne
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You don’t need an isolated negative. You would use the isolated version if you wanted to charge a battery whose negative is not at the same voltage as the negative of the source battery, for example if it was the second 12v battery in a 24v string - ie its negative at around 12v and it’s positive at around 24v. It is unrelated to the concept of using the hull as a negative return.

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16 minutes ago, Francis Herne said:

 

The muddle is more on Victron's part with labelling the "GND" terminal than anyone else's, I think.

 

The only difference between the isolated and non-isolated versions is that the two negatives of the former are electrically separate from each other.

 

The metal heatsink part of the chassis is not electrically bonded to the GND terminal on the non-isolated version - I've just been out in the engine bay with a meter to double-check that - nor if I recall correctly to either negative terminal of the isolated version.

 

Thanks, I stand corrected, that is good info,

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18 minutes ago, Francis Herne said:

 

The muddle is more on Victron's part with labelling the "GND" terminal than anyone else's, I think.

 

The only difference between the isolated and non-isolated versions is that the two negatives of the former are electrically separate from each other.

 

The metal heatsink part of the chassis is not electrically bonded to the GND terminal on the non-isolated version - I've just been out in the engine bay with a meter to double-check that - nor if I recall correctly to either negative terminal of the isolated version.

 

I installed my Orion 18 amp B2B over a year ago, and I bought the isolated version- but for some reason I can no longer remember, I joined the two negatives together just below the unit itself. 

Reading your post here, I can see that I did the right thing in joining the negatives.

But my ongoing problem with electrics, and with these units, is that I installed them essentially as a chimp would, either by copying the wiring setup of the first B2B, or by following Nick's very kind advice- but it was done without having a true understanding of the electrical theory behind it, and at times that does come back to bite.   

 

 

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26 minutes ago, Tony1 said:

 

I installed my Orion 18 amp B2B over a year ago, and I bought the isolated version- but for some reason I can no longer remember, I joined the two negatives together just below the unit itself. 

Reading your post here, I can see that I did the right thing in joining the negatives.

But my ongoing problem with electrics, and with these units, is that I installed them essentially as a chimp would, either by copying the wiring setup of the first B2B, or by following Nick's very kind advice- but it was done without having a true understanding of the electrical theory behind it, and at times that does come back to bite.   

 

 

 

I think that is the point. I bet there is no documentation easily available to the public that clearly states that the Gnd terminal and all internal negatives are insulated from the case/backplate. Francis kindly tested it so can confirm the Gnd terminal  is isolated from the case.

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14 hours ago, Tony1 said:

So that's a £300 unit that's no longer working as it should, after little more than a year of very light use. 

 

If it's not working correctly, contact Sterling.  They are excellent at diagnosing and repairing/replacing stuff. 

 

If it's overheating because it's in a cupboard, open the door when running your engine!

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41 minutes ago, TheBiscuits said:

 

If it's not working correctly, contact Sterling.  They are excellent at diagnosing and repairing/replacing stuff. 

 

If it's overheating because it's in a cupboard, open the door when running your engine!

 

I have large vents in the top and bottom of the cupboard door, and I fitted an extractor fan into the top of it, so there's no cooling issue- and out of habit I leave that door open anyway whenever the B2Bs are running. 

 

But you are right, its worth a try with Sterling- there is a chance it'll be an easy fix. But it wont be any kind of user setup/config issue.

Both of the BB1260s are set up identically for every parameter, and they are running from very similar alternators and lead acids that are in decent nick, and yet only one of them is now working. 

I've never been over the moon with the products tbh. They made them super configurable and versatile, but even when working, neither of mine two units will run at full power for more than about 10 minutes before they throttle down to about 30 amps for a few minutes, presumably to cool off.

I admire what they tried to do with these units, but in my view they didnt quite pull it off in terms of managing the heat output, and I always felt happier running them at half power, which still yields 30 amps but they behave much more consistently. 

 

I did try talking to them about the heat issue a long time ago, and I explained that after about 10 minutes, the cooling fan would come on, and at that exact moment, the current output would be reduced to about 30 amps. The guy ignored my suspicion about it being related to cooling, and instead he felt that it was more likely to be an issue related to the input and output voltages (if I remember correctly), and I just gave up the discussion in the end, because they were working well on the half power setting, and doing the job I needed. 

Or at least they were working until yesterday. The behaviour I'm seeing in the dodgy one now is a different thing again, but anyway, worth asking for their thoughts about it, as you say.

To be fair the BB1230 has performed faultlessly so I'm not rubbishing all their products, or their service. They will try to help and diagnose stuff, and these days that's not a common thing. I've heard bad things about Renogy's customer service for example, whereas with Sterling you can always talk to someone who knows their stuff. 

 

That said, even if it gets repaired, I'm fed up with the BB1260s, and I would prefer to just get all the Sterling products off my boat tbh, and get some victron units instead. 

 

 

Edited by Tony1
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As I said before, I'm not sure you'll have a better experience with the Victron units. My 30A tends to overheat and throttle to 50% output after a fairly short time. It's in the engine bay, but there are complaints on Victron's forum of that happening even in outside conditions.

 

Adding a little cooling fan to blow air over it is reported to help, unsurprisingly. I keep meaning to do that.

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12 minutes ago, Francis Herne said:

As I said before, I'm not sure you'll have a better experience with the Victron units. My 30A tends to overheat and throttle to 50% output after a fairly short time. It's in the engine bay, but there are complaints on Victron's forum of that happening even in outside conditions.

 

Adding a little cooling fan to blow air over it is reported to help, unsurprisingly. I keep meaning to do that.

 

Thanks for the reminder Francis, and I admit I am a bit concerned that the victron units will be no better, and might even be worse, in terms of heating issues.

That's why I don't just want to rubbish the BB1260s as such. As I said, the BB1230 (30amp) unit has run faultlessly whenever needed, it is a truly excellent and highly versatile unit that I would recommend to anyone. 

But I guess B2Bs with larger current outputs like the BB1260 are a bit prone to heating issues?

My cunning plan is to try out one of the victron 30 amp units for a week or so, and see if there are any heating issues.

I was optimistic because the 18 amp victron unit seems to run really well with no overheating issues, but we'll see. Maybe 30 amps is a different matter to manage with just cooling fins and no actual fan.... 

 

 

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10 minutes ago, redwing said:

Have you considered a Mastervolt alpha pro instead ?

 

Yes, an upgraded alternator plus a controller like the alpha pro was definitely  the route I should have gone down, and its what I would always recommend for people looking to get more charging current from their engine.

 

BUT my canaline 38 doesnt have a poly V  belt, and it would have needed a crank upgrade before I could fit a more powerful alternator. And I had already started spending money on the  B2Bs. 

Given that I only need engine charging anyway on about 90-100 days per year (because of all the solar panels), I couldn't justify the very significant expense of the crank upgrade, the controller, plus a new alternator. 

 

If I ever buy another boat, one of the things that will always be on my must have list is a decent alternator with a poly V belt, so that I only need the alpha pro fitting in order to be ready for a lithium battery install. 

 

 

Edited by Tony1
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8 hours ago, Francis Herne said:

As I said before, I'm not sure you'll have a better experience with the Victron units. My 30A tends to overheat and throttle to 50% output after a fairly short time. It's in the engine bay, but there are complaints on Victron's forum of that happening even in outside conditions.

 

Adding a little cooling fan to blow air over it is reported to help, unsurprisingly. I keep meaning to do that.

 

I thought you might be interested as you've got one of these things- I've just installed the victron 30 amp B2B unit and run it for 50 mins, and you are absolutely right- it does get very hot. The fins at the back are too hot to touch for more than a second or two, and even the main case of the unit gets uncomfortably hot to the touch.

I can see why people recommend pointing a fan at it. You have to wonder how hot the internals are getting for the case to be so hot- but they sell shedloads of them, and the campervan/motorhome folks love them.  If there was a real risk, we'd be seeing campervans in flames by the score up and down the country. 

The victron unit gets as hot as the BB1260, but the BB1260 has a fan, so in theory it dissipates its heat quicker and better. 

 

On the plus side, the victron unit didnt throttle back its current output once during the 50 min run, so I think as long as my nerves can stand it running so hot, it should be fine. 

I'm not going to get another one of them yet, though, I think I'll give it another week or two before deciding whether to sell the good BB1260 and replace it with another victron unit.

 

One point I will make in favour of the BB1260- it kept up its half-power 29.6 amp charge rock steady throughout (as it always does to be fair), whereas the victron units seem to slightly reduce their output as the battery voltage starts to creep up during the charge. The output only reduces by a couple of amps, but you would rather it stay constant. 

 

So I think there is a decent chance your unit is getting a bit overheated in the engine bay, and you might see less frequent throttling down if you could install it somewhere cooler? 

Perhaps you could take the cables and the B2B through to the cabin somewhere? 

 

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52 minutes ago, Tony1 said:

So I think there is a decent chance your unit is getting a bit overheated in the engine bay, and you might see less frequent throttling down if you could install it somewhere cooler? 

Perhaps you could take the cables and the B2B through to the cabin somewhere?

It's on the to-do list - both for that temperature extreme, and the opposite where my lithium batteries don't love hovering around 0°C in recent weather. Not trivial on a 30ft boat though, it's waiting on the interior refit I've been planning for a while so there's somewhere to put the stuff.

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18 minutes ago, Francis Herne said:

It's on the to-do list - both for that temperature extreme, and the opposite where my lithium batteries don't love hovering around 0°C in recent weather. Not trivial on a 30ft boat though, it's waiting on the interior refit I've been planning for a while so there's somewhere to put the stuff.

 

That's interesting, that you are thinking of bringing your lithiums indoors. 

Opinion seems very divided. Lots of people whose opinion I respect think its fine if you keep them in the engine bay, especially if you have warming mats underneath them (which are powered by the batteries themselves.

But I still have sneaking doubts about it. If for example I get up at 7.30 on a winter morning and the engine bay is at minus 5 degrees, and if I switch on my 1000 watt 240v mini kettle, that will draw at least 80 amps from the batteries, which is the largest load they ever get in normal use- is that definitely, definitely ok?

If the mats keep the whole battery above zero (or whatever the current official policy is - someone will be along to clarify the most recent advice), then you would imagine even an 80 amp load wont damage the batteries.

Certainly we're not hearing stories on here about lithiums being damaged by putting loads on them at very low temperatures, so it must be ok. right? 

But personally- and admittedly more from superstition than facts- I'm keeping mine in the cabin for the time being. 

 

 

Edited by Tony1
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Sitting on the uxter plate, they were at 2° when the canal was frozen a couple of inches thick. I'm not especially concerned about discharging, but charging below 5° is discouraged and below 0° prevented by the BMS as that can cause significant damage. I don't have heater pads, and without shore power it's not something I'm keen to burn power on.

Edited by Francis Herne
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2 hours ago, Tony1 said:

 

That's interesting, that you are thinking of bringing your lithiums indoors. 

Opinion seems very divided. Lots of people whose opinion I respect think its fine if you keep them in the engine bay, especially if you have warming mats underneath them (which are powered by the batteries themselves.

But I still have sneaking doubts about it. If for example I get up at 7.30 on a winter morning and the engine bay is at minus 5 degrees, and if I switch on my 1000 watt 240v mini kettle, that will draw at least 80 amps from the batteries, which is the largest load they ever get in normal use- is that definitely, definitely ok?

If the mats keep the whole battery above zero (or whatever the current official policy is - someone will be along to clarify the most recent advice), then you would imagine even an 80 amp load wont damage the batteries.

Certainly we're not hearing stories on here about lithiums being damaged by putting loads on them at very low temperatures, so it must be ok. right? 

But personally- and admittedly more from superstition than facts- I'm keeping mine in the cabin for the time being. 

 


There is no issue with discharging Li below zero. Down to about -20 anyway, and you are never going to get below that. The internal resistance will be a bit higher at low temperatures and this will cause a bit of heat to be produced which will raise the battery temperature a few degrees under fairly heavy load.

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