Fusing Victron Lynx Distributor

[D90Don]

I am building a 48v System and I have a question regarding fusing the Victron Lynx Distributor 1000. The following will be connected to the Lynx Distributor: SOK Battery Rack (5 Batteries 48v/100a connected in Parallel), Victron Multiplus II 120/35, and Victron Smart Solar MPPT 450/100. Should I fuse the Lynx Distributor with a 125a fuse for the Battery Rack, 35a fuse for the Multiplus II, and 100a fuse for the MPPT Controller with 58v rated MEGA Fuses? or go with slightly higher current rating MEGA Fuses? Also, there is a 4th opening / slot that I currently don't plan on using, but I've seen some on the forum recommend fusing so there is no red light on the Lynx Distributor. Any recommendations, most appreciated. Thanks.

 

[Brucey]

Victron Multiplus II 120/35

Typo here I think.

 

[sunshine_eggo]

Guessing the MP-II is a 48V/3kVA unit.

3000W/51.2V/.85 = 69A a 35A fuse would be inadequate.

125A fuse for the batteries should work.

Fuses are for wires, not equipment. The wires should be sized to handle the current. The fuses should be sized to protect the wire at 1.25X the wire rating.

 

[Brucey]

Without a smartshunt you’ll be reliant on the accuracy of the sok bms for state of charge.

 

[sunshine_eggo]

Without a smartshunt you’ll be reliant on the accuracy of the sok bms for state of charge.

Assuming there's a Cerbo...

 

[Brucey]

Should I fuse the Lynx Distributor with a 125a fuse for the Battery Rack, 35a fuse for the Multiplus II, and 100a fuse for the MPPT Controller with 58v rated MEGA Fuses? or go with slightly higher current rating MEGA Fuses?

For the 450/100 you want a 125A or 150A 58V mega fuse. I use 1/0 cable for mine. It can definitely approach 125A momentarily with cloud edge effect.

 

[Brucey]

Assuming there's a Cerbo...

Can only hope

 

[D90Don]

No Cerbo. Yes, Victron Smart Shunt. Property is way off-grid and no wifi, just Blue Tooth, so that was the reasoning behind, no Cerbo.
MultiPlusII is 3kva/120v/35a, it's the UL version. Thanks @Brucey and @sunshine_eggo ! I saw a video from "SotoSolar" on YouTube. He put the Smart Shunt directly on the Lynx Distributor, as well as putting the Battery Disconnect on the Positive side of the Lynx. Any opinions on that?

 

[sunshine_eggo]

Please link video at the appropriate time stamp.

 

[sunshine_eggo]

In that configuration, you would only be using two of the Lynx's shrouded connections - one for the MPPT and the other for the inverter.

All batteries would connect to the shutoff and shunt here:

 

[Brucey]

No Cerbo. Yes, Victron Smart Shunt. Property is way off-grid and no wifi, just Blue Tooth, so that was the reasoning behind, no Cerbo.
MultiPlusII is 3kva/120v/35a, it's the UL version. Thanks @Brucey and @sunshine_eggo ! I saw a video from "SotoSolar" on YouTube. He put the Smart Shunt directly on the Lynx Distributor, as well as putting the Battery Disconnect on the Positive side of the Lynx. Any opinions on that?

That should work but make sure it’s the Victron 275A switch which is rated for 60V

 

[D90Don]

So would you recommend, not connecting the Batteries to Lynx via Shutoff and Shunt? I honestly don't know enough to answer the question just came across the video and Soto came up with a different solution.. Only positive I can think of is 1 less negative and positive 1/0 or 2/0 wire in the equation.

 

[Brucey]

MultiPlusII is 3kva/120v/35a,

125A is Victrons recommendation

 

[D90Don]

@Brucey , Thanks again for the MEGA Fuse and CutOff Switch Recommendation. I've seen several diagrams with the Battery CutOut/Cutoff on the NEGATIVE side of the equation. But in this case with the Smart Shunt being on the negative side, having the cutoff switch there that could potentially mess up the calculations/readings. Seems efficient how "Soto" did it. Just have to be careful drilling out the Lynx Distributor to accept the larger size bolt.

 

[sunshine_eggo]

125A is Victrons recommendation

Always a good idea to look at what the manual recommends for wiring and fusing.

So would you recommend, not connecting the Batteries to Lynx via Shutoff and Shunt? I honestly don't know enough to answer the question just came across the video and Soto came up with a different solution.. Only positive I can think of is 1 less negative and positive 1/0 or 2/0 wire in the equation.

I don't recommend one way or the other. I'm just saying that if you use it that way, you must connect all 5 batteries to the shut off and the shunt. You likely need an additional bus bar between the batteries and the input to the lynx.

 

[sunshine_eggo]

@Brucey , Thanks again for the MEGA Fuse and CutOff Switch Recommendation. I've seen several diagrams with the Battery CutOut/Cutoff on the NEGATIVE side of the equation. But in this case with the Smart Shunt being on the negative side, having the cutoff switch there that could potentially mess up the calculations/readings. Seems efficient how "Soto" did it. Just have to be careful drilling out the Lynx Distributor to accept the larger size bolt.

The location of the shut off has no influence on shunt calculations/readings.

Ensuring that every microamp of current moving to/from the battery passes through the shunt is everything.

 

[Brucey]

Always a good idea to look at what the manual recommends for wiring and fusing.



I don't recommend one way or the other. I'm just saying that if you use it that way, you must connect all 5 batteries to the shut off and the shunt. You likely need an additional bus bar between the batteries and the input to the lynx.

I think he’s daisy chaining the batteries with just a single pair of cables going to distributor.

 

[D90Don]

@sunshine_eggo , Thanks for confirming that info. Prior to posting this question, I did download the manuals. I found MEGA Fuse Voltage size for a 48v system in the manual, but I could not find the amperage answer after a few hours of reading. All I could find was, "Refer to the 71 page document, Wiring Unlimited, by Margret Leeftink." If there is another page that specifically states MEGA Fuse size recommendations, based on Victron Equipment and wire size being used, I missed it. Thank you again for your assistance.

 

[D90Don]

Yes, I bought the 48v SOK Rack Kit. Pre-cut same size cables to parallel the (5) Batteries. Single cable going to the Lynx Distributor. Just deciding if I want to be like "Soto" or not.

 

[Brucey]

Yes, I bought the 48v SOK Rack Kit. Pre-cut same size cables to parallel the (5) Batteries. Single cable going to the Lynx Distributor. Just deciding if I want to be like "Soto" or not.

The other option is something like this (but shorter jumper cables).

 

[Brucey]

Personally I'd go with the direct attach to the exposed bus connections like the video given you only have the one set of battery terminals to attach.

 

[D90Don]

Thank you for the picks @Brucey ! That is a pretty slick set up. Nice and Neat. So this installation used DC Breaker as the Shut off? This set up uses a Copper Bar between the Cable and Distributor. Any advantage to this, versus just connecting the Breaker and or cable directly from the Smart Shunt directly to the Distributor? It is good to see other options.

So the verdict is in, 125 amp MEGA Fuses on MPII Inverter and 125 - 150 Amp MEGA Fuse on the Batteries If I wire it to the Lynx directly. And 125 Amp on the Controller. Thanks Again to the both of you.

 

[D90Don]

Just following up with some additional info I came across from another blogger on YouTube, EXPLORISTLife, "The sizing of the MEGA fuse protecting the wire form the Lynx Distributor to the charge controller is based on Victron's recommendation, which is stamped on the side of the charge controller (and if there is no stamp, is sized based on the charge controller size). While looking in the Smart Solar MPPT Manual, I could only find reference to the Voltage Size of the MEGA Fuse, Not the Amperage.

 

[740GLE]

Even if you use a copper bus bar from Lynx to the shunt as in that video, the shunt needs shims 1/4” or so to what ever your mounting it to, they aren’t on the same plane as if you were connecting Lynx to Lynx.

I did this exact same set up (with the blue seas switch) and the down side I ran into was that blue seas switch mounting (4 bolts) and then final cable connection. I had to unbolt the entire Lynx bolt the switch to the Lynx and make my cable connection that I can’t undo unless I fully unmount everything again.

It looks nice and meet, but maintenance to retighten down that blue seas bolts is going to be a bear.

 

[Brucey]

Thank you for the picks @Brucey ! That is a pretty slick set up. Nice and Neat. So this installation used DC Breaker as the Shut off? This set up uses a Copper Bar between the Cable and Distributor. Any advantage to this, versus just connecting the Breaker and or cable directly from the Smart Shunt directly to the Distributor? It is good to see other options.

So the verdict is in, 125 amp MEGA Fuses on MPII Inverter and 125 - 150 Amp MEGA Fuse on the Batteries If I wire it to the Lynx directly. And 125 Amp on the Controller. Thanks Again to the both of you.

The bus bars are simply to go from 5/16ths to 3/8ths hole sizing for another project I was working on, if you drill your holes out you won't need them. They were from explorist.

Yes the mnedc250 is the main battery shutoff and over current protection.