Renogy DCC50S

Harryw

Harryw

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Does anyone have any experience of the above, it’s a combined 12v 50A DCDC converter and MPPT.
I’m considering a DCDC converter but seeing as it have a MPPT too it piqued my interest. It also has a divert back to the van batteries if your leisure batteries are full diverting the solar to them, up to 25A. One thing that jumped out at of me though is that it uses a common negative, even for the PV - line, which I understood to be a no no?
 
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common negative is, well, very common.
A shared -ve is fairly normal on combo units.
It is also not uncommon to have the -ve from a solar panel connected to the battery even when the actual terminals are seperate (they are just linked internally on the controller).
 
Yes I had seen it was common to use battery negative is US/AUS systems just that Victron do not and looking at their site they go to great lengths to say why.
just waiting on Renogy to get back to me about a query I have with it, in that if there is any solar input then it limits alternator to 25A and expects up to 25A from the solar even if it a cloudy day. I wondered whether you could toggle off the solar to allow a full 50A alternator charge instead.
 
Renogy got back to me and said there was no way to inhibit solar if connected via their controls and suggested fitting an isolator to the solar in line. That I suppose could be done by a NC relay opened by the D+ signal from the alternator.
I’m now wondering whether it’s viable to just use it as a 50A B2B and keeping the existing victron Solar as this seems to be the best value 50A unit available.... I have looked at and am still considering just 30A B2B’s from Victron and Votronic or 25A from Schaudt. Once you go above 25/30A prices seem to go up exponentially, except the Renogy?

Any comments, steerage and or observations please....
 
Harryw said:
Yes I had seen it was common to use battery negative is US/AUS systems just that Victron do not and looking at their site they go to great lengths to say why.
....
Click to expand...
I'd be interested to see what part of the Victron site is saying that and in what context?

Ok - this is the reality of the situation.

The Renogy B2B/Solar uses a common ground for the Battery Connection and the Solar PV -ve. Agreed.
Breaking news ... SO DOES VICTRON.
Just because you connect the Battery -ve to one terminal on their MPPT controller and the PV -ve to another terminal on their MPPT controller, they are directly connected internally. So it makes no electrical difference if you were to connect the PV-ve to a solar controller -ve terminal or directly to the -ve terminal on the Battery. And taking this further, to the chassis on the typical van installation.

Where Victron have a certain 'type' of product which other companies do not tend to - at least in the 'direct to customer' arena - is a selection of isolated devices. An Isolated device is where BOTH the +ve AND the -ve terminals in are electrically seperated from the +ve and -ve out. I think there seems to be an assumption that the Victron Solars are Isolated like this. THEY ARE NOT.

What is the relevance of Isolation? You might want a Leisure DC installation totally separate from the Vehicle (or Boat) installation, to the extent of not sharing a common ground. That can be very hard to do if you have a split charge system as you are connecting the charging system for the Starter Battery (which has its -ve connected to the Chassis) to the Leisure battery - and for that to work you need to have the -ve as well as the positive. Usually achieved by using a chassis connection. and even if you run a -ve cable all the way to the Starter Battery, that is still connected to the chassis at the Starter Battery end.
So PV -ve on a Solar Controller is connected to -ve on the Battery which is connected to Chassis whether you like it or not.

Only way round this is to get an Isolated Charger. Victron make an Isolated version of their Smart B2B and also Isolated versions of the DC-DC Converters, so you can do that. And in THAT scenario you would not want to connect the PV to the chassis for sure but run to the Lesiure Battery - or more easily the Controller to keep the +ve and -ve aligned for tidiness.
 
Wilde thanks for the response. Re victron the manuals for the blue solar MPPT say do not ground the PV pos and Neg, there’s numerous threads on the victron community about it and most come to the same conclusion you have above, so I’m more than happy to consider PV - and battery neg are the same thing in my van..
 
I always run a pair of cables to the controller, but only because it is the tidiest way to do it. I don't think the controller would know any difference.
FWIW, before I replied I actually went out with a meter to my Victron Controller to confirm what I thought .... The -ve for the Battery, the -ve for the PV AND the -ve for the LOAD (where fitted) are common
 
xsilvergs said:
For a poor source of information you could always try watching this ....
Click to expand...
Sad to say, but it was :( too much misleading info there, but people follow that advice :(
I don't know if the stuff past the initial Victron B2B 'advice' was better as I stopped the video.

As it happens I have one of those Victron isolated B2Bs fitted currently. Joined the two negatives together so it works as a non-isolated version ;) (just saying this as if you get an isolated model and find you really shouldn't have done, or if the isolated one was all that was available at the time (like in my case), you can still install it)
 
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