Non isolated or isolated b2b?

[Dee101]

I am quite electric blind, and I’m just about to purchase a Victron 30ah dc to dc charger.
My motorhome is a 1995/6 Hymer B654.
Would I be right in saying that the non-insulated version would be fine for this vehicle?

 

[Hoovie]

I am quite electric blind, and I’m just about to purchase a Victron 30ah dc to dc charger.
My motorhome is a 1995/6 Hymer B654.
Would I be right in saying that the non-insulated version would be fine for this vehicle?

that would be isolated rather that insulated and yes

 

[Dee101]

that would be isolated rather that insulated and yes

Thank you, again. Just so I’m sure, you are saying the non-isolated version will be ok?

 

[Rogerwyn]

Just fitted a none-isolated to my van with no problems, did check continuity to earth from the negative on the leisure battery to make sure I didn’t require the isolated typ.

 

[St3v3]

Either will work.

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[bigtwin]

Either will work.

And, for educational purposes, what are the differences and when would you choose one over the other?

Ian

 

[St3v3]

And, for educational purposes, what are the differences and when would you choose one over the other?

Ian

Isolated means the negative of the input and output isn't internally connected in the charger.

In a MH both engine and hab batteries will be connected to the chassis. Either can be used as an isolated charger won't be bothered by both of it's negatives being at the same potential (I.e. joined)

AFAIK, the isolated thing is for boats.

 

[Rogerwyn]

And, for educational purposes, what are the differences and when would you choose one over the other?

Ian

Some vans have a separate 12v leisure system which is not earthed through the vehicle chassis for various reasons, in this case you need the isolated version, if your leisure battery is earthed through your chassis then the none-isolated will work ok.

 

[Al n Val]

I’m selling one in the classifieds if anyone is interested, that and a vanbitz battery master

Al

 

[St3v3]

Some vans have a separate 12v leisure system which is not earthed through the vehicle chassis for various reasons,

Do you have any examples of what vans, and what reasons?

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[nabsim]

Do you have any examples of what vans, and what reasons?

Would using 12v on a 24v truck conversion mean you would need isolated Steve? Not that I am likely to do it, just out of interest really. I though isolated was where there is no common ground or where a common ground in not wanted such as boats as you said

 

[St3v3]

Would using 12v on a 24v truck conversion mean you would need isolated Steve?

No, both negatives can - and will be for simplicity - be connected to the chassis. Not doing so could potentially get you into trouble. A 12V item in the hab area that joins the ground of it's feed to the body could cause all sorts if problems.

Exactly as mine is, and funnily enough, using an Orion, non isolated lol.

 

[Rogerwyn]

Do you have any examples of what vans, and what reasons?

There was a post last year regards this and op had an isolated system I’ve never come across this myself and have tried to find the post without success, I think it was an A class.

 

[bigtwin]

There was a post last year regards this and op had an isolated system I’ve never come across this myself and have tried to find the post without success, I think it was an A class.

And probably a truck based MH? jongood ?

Ian

 

[Hoovie]

If there is any doubt which is needed, you could always get an isolated one anyway. It will work in an installation where there is an isolated ground OR a common ground. A couple of years ago, for some reason Victron were only supplying the isolated units in volume and I ended up doing a lot of those type due to the supply issues. Joining the two -ves on the Charger terminals is a simple way to essentially convert isolated to non-isolated. (not something you would aim to do usually mind as the Isolated is noticably more expensive).
In fact, unless there have been some changes pretty recently, in the 12V-12V range, if you don't want the 30A model, but the 18A one, you HAVE to get an Isolated one as they don't even make a non-isolated 18A Orion-Tr

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[jongood]

And probably a truck based MH? jongood ?

Ian

sorry Ian, I'm not really understanding the question but my 24v and 12v systems are both earthed to the chassis.

 

[St3v3]

And probably a truck based MH? jongood ?

Ian

I have 24V engine batteries and 12V hab. Both negatives are joined to the chassis.

 

[autorouter]

In nearly all motorhomes the vehicle electrics and the habitation electrics have a common negative, usually connected to the chassis. In most vehicles the alternator negative is connected directly to the chassis, If you want to charge the leisure battery with a split charge relay, its negative has to be connected to the chassis too. I would say all motorhomes have this, but I recall that one motorhome discussed on here had an isolated habitation system. I think it was built by an ex-boater. I think it was done like that to utilise one of those dual-battery solar controllers that has a common positive rather than a common negative.

Victron make stuff for all kinds of systems, domestic, industrial, mobile, marine etc. There is a need for isolated DC-DC chargers and converters in some situations. A motorhome doesn't require it. However if you have an isolated device, bought by mistake or donated by someone, it can be used just the same, by joining the two negatives together.

 

[BOOMEL]

Just fitted a none-isolated to my van with no problems, did check continuity to earth from the negative on the leisure battery to make sure I didn’t require the isolated typ.

Can I ask how you did that?

 

[Rogerwyn]

Can I ask how you did that?

The leisure battery is under the drivers seat in our van, fitted the Victron to the rear frame of the passenger seat, victron earth to van earth, positive in to vehicle battery and positive out to leisure battery, i used 16mm cable with 2 inline resettable 60amp fuses.
I did check continuity by removing the cover off the vehicle battery, next to the battery was the main chassis earth, checked continuity from the leisure battery negative to chassis earth.

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[BOOMEL]

Ok so I think the attached wiring diagram is correct, however there are some questions:

• Does anyone know whether the NE325 has a profile charge e.g. Bulk etc
• Does the management cable come with it
• What size cables, I am assuming 16mm with M10
• Where does the cabling go re the shunt
• What wire is used for the jumper switch
• Can I replace the NE325 with Victron non isolated DC to DC instead in the attached diagram? I have Victron MPPT and shunt and it would be good to keep it all the same

Many thanks Mike

 

[autorouter]

The SmartShunt is a method of measuring the amps going into and out of a battery. Normally the B terminal connects to the negative terminal of the chosen battery. In your case, you have a pair of leisure batteries that you want to monitor. You can connect one negative to the B terminal, and have a link between the two leisure battery negatives, as in your diagram. Or you can connect two equal links from the B terminal to each of the two leisure batteries. Either way is fine.

However, everything else to the leisure battery negative must go to the SmartShunt A terminal. That includes any B2B connection, and any chassis/earth connection. If anything goes direct to the battery, it bypasses the shunt and cannot be accounted for. So the wire from the DC/DC charger needs to be moved.

The starter battery voltage can be measured using a separate wire from a special terminal. It doesn't go to either A or B. Note that it only measures voltage, not amps and State Of Charge like the main terminals.

 

[BOOMEL]

The SmartShunt is a method of measuring the amps going into and out of a battery. Normally the B terminal connects to the negative terminal of the chosen battery. In your case, you have a pair of leisure batteries that you want to monitor. You can connect one negative to the B terminal, and have a link between the two leisure battery negatives, as in your diagram. Or you can connect two equal links from the B terminal to each of the two leisure batteries. Either way is fine.

However, everything else to the leisure battery negative must go to the SmartShunt A terminal. That includes any B2B connection, and any chassis/earth connection. If anything goes direct to the battery, it bypasses the shunt and cannot be accounted for. So the wire from the DC/DC charger needs to be moved.

The starter battery voltage can be measured using a separate wire from a special terminal. It doesn't go to either A or B. Note that it only measures voltage, not amps and State Of Charge like the main terminals.

I have the shunt in and working already. I think this is the wiring that you are suggesting?

Regards and thanks

Mike

 

[GrahamPye]

In nearly all motorhomes the vehicle electrics and the habitation electrics have a common negative, usually connected to the chassis. In most vehicles the alternator negative is connected directly to the chassis, If you want to charge the leisure battery with a split charge relay, its negative has to be connected to the chassis too. I would say all motorhomes have this, but I recall that one motorhome discussed on here had an isolated habitation system. I think it was built by an ex-boater.

I'm replying to this (oldish) thread as it has the same title as the question I was about to ask...

I'd thought that a non-isolated B2B was what I wanted for My Pilote, until I came across this remark by Lenny HB in reply #8 to this thread: 2 x victron 12-12 -30 non isolated chargers from engine battery what size positive cable is needed where he said

Doesn't solve the problem that the non isolated one is not suitable for Motorhomes unless you really know what you are doing.

Obviously I don't really know what I'm doing!!!

Thanks, Graham

 

[autorouter]

I'm replying to this (oldish) thread as it has the same title as the question I was about to ask...

I'd thought that a non-isolated B2B was what I wanted for My Pilote, until I came across this remark by Lenny HB in reply #8 to this thread: 2 x victron 12-12 -30 non isolated chargers from engine battery what size positive cable is needed where he said
Obviously I don't really know what I'm doing!!!

In theory, the non-isolated version is better than the isolated version for use in a vehicle because usually the two battery negatives are connected to the chassis, which is a requirement for example for charging both batteries via the split charge relay. However in practice there are problems, but they are similar to the problems an isolated version would also have.

If you look at post#6 of that thread, Lenny HB explains why there can be problems. Basically in a coachbuilt, as opposed to a panel van, there is often no convenient metal chassis nearby to connect a solid negative return. The existing wiring might be minimal size, and also quite long runs, so considerable voltage drop. If good thick wiring is used from the leisure battery negative all the way to the chassis or the starter battery negative, then that problem can be overcome.

There's another small problem that probably the new thick wire won't fit in the terminals of the B2B. That's why it was suggested that the thick wire is terminated just short of the B2B, on a big terminal post or busbar. Then a very short wire of maximum thickness to fit in the B2B terminal then links the B2B to the busbar.

If properly installed, the isolated or non-isolated version is fine, and the non-isolated version is less expensive

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[GrahamPye]

If properly installed, the isolated or non-isolated version is fine, and the non-isolated version is less expensive

Thanks - I'd understood the distinction between MHs and PVCs as far as the chassis was concerned but I thought I must be missing something else!

Nigel (Ivy) told me last night that non-isolated was right for me too, so I'm just about to order it from him (along with the Fogstar and Inverter

Graham