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I want to install the Orion TR Smart 12 | 12-18 isolated not because it is isolated but because an 18A non isolated version is not available. I am planning to use it to charge my start FLA battery from a LiFePO4 house bank when needed. My question is can the two negatives be combined as shown in the attached drawing.
Thanks
Tim
Just to let you all know, I have same setup and have spoken to Victron technical. It will all work ok with a common ground on the isolation B2B, it will just loose the isolation protection
The difference between isolated and non isolated when it comes to grounding is that isolated have separate grounds for each bank, and non isolated have one common ground. I’d say you don’t want to combine grounds on an isolated unit.
Hi @randy-putnam
Are you saying that combining the two grounds will not work, or just that the batteries will no longer be isolated.
Thanks
Tim
Check out this video from Battle Born. Hope that helps.
https://youtu.be/GpNDeQN4O-o
Hi @randy-putnam
I looked at the video but it doesn’t really answer the question. As per my original post, I would be quite happy with a non isolated charger but unfortunately there is no 18A non isolated charger available. Hence the question as to whether combining the grounds on the isolated charger would work, albeit in a non isolated mode.
Thanks
Tim
Got it. Per your drawing I’d say this set up would not work, because you basically have 2 separate fields. One is input and one is output. My understanding is that the Orion TR Smart needs a complete + - circuit for each or it will not convert the input voltage and amps to the output voltage and amps. Combining the negatives in this case may not activate the conversion, and I’m not sure if it would do any harm to the charger. My setup uses the 12/12-30 TR Smart with input on the start (FLA) battery and output on the 2 100AH Battle Borns in parallel (house bank). It’s set up to limit the alternator current to a max of 30 amps into the LFP house bank when the engine (boat) is running.
I guess you could give it a go. But you can try emailing victron at salesUSAcanada@victron.com. I did this and got an answer back the next day.. Good luck.
I have the same question to make, as the smartshunt requires the negative of the starter battery connected to the loads negative (to the shunt) I have connected the negative of the starter battery to the negative busbar, i was thinking that I can wire the orion imput negative from the busbar to the orion-tr, and the orion negative output to the busbar.
Thanks for all
I don't think it is a problem to use the same negative. In the boats the negatives of the different banks are connected.
simultaneous charging isolator works with positives. The negative is common.
I am going to mount 2 Orion TR Smart 18 + 30A in parallel to go from 250 AGM battery to the lithium bank from the alternator charge.
I understand that the 2 banks are isolated?
Hi guys, I have same issue, I have isolating DC-DC converter but now I would like to keep both negatives together. I have lead acid starter battery and Lithium leisure battery so not sure if this will make any problems.
The van is wired with negative together from dealer and has a shared fridge negative. I could try isolate everything but it would be easier to keep them together.
I have emailed Victron support to see what they say. I was wondering with common negative does the controller still switch on automatically and still charge correctly
¡Hola!
En un Booster Orión tr smart 12/12-18a.
de cuantos seran los fusibles de proteccion?
miEn el de 30a se instalan de 60a,interpretó que en uno de 18a debería de ser de 30a o de 40?
Reviving the subject..! :D
Could I do that then, to save some wire and still kind of keep the ''isolation protection ''part of the unit ? 
Ah, ok. What I understood was that the ''isolation'' in question was in fact a way to regulate current from both input and output while keeping those circuits isolated from each other in case there was dirty current from the vehicle battery that could affect the output to the leisure batt/batt bank. Doing it this way to be sure that both currents were clean. Thanks for your comment, greatly appreciated.
