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Planing to use Victron lynx 1000A Shunt but can only find fuses up to 800A

BillCaswell

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Jan 10, 2020
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I would think that the lynx 1000 system would require/support a 1000 Amp fuse? I can't find any 1,000 Amp CNN fuses. What am I missing from this?CNN fuse.pnglynx system.pngScreenshot 2023-01-20 at 13.19.13.pnglynx shunt.pnglynx wo cover.png
 

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In my sailboat, the 20hp electric bow thruster motor is driven by the house bank. It runs at 700 amp for a few seconds at a time. There is also a start up inrush current that I need to factor into my design. There may also be the 90A windlass running and other loads.

But my point is that the Victron lynx system is marketed as a 1,000 amp system. How can this be if the biggest fuse that I can find is only rated at 800 amps?
 
It is common for a busbar to have a total rating that is different than the per-connection rating.

With a 4-lug 1000A busbar, you can not have 1000A going in on two of the lugs and 1000A going out of two of the lugs, but you could have 500A going into two lugs and 500A coming out of two lugs.
 
Charitable interpretation is they misunderstood the question.
Less charitable interpretation is they pretended to misunderstand the question.

The way to make this work is put a nickel plated copper stunt double in place of the shunt fuse.
The stunt double should be the same dimensions as the busbar.

Each battery should be fused as close as possible to the positive terminal.
Each branch circuit should also be fused at the distributor.
The fuse in the shunt is kinda pointless in a properly fused system anyway.
Especially in a 24 volt or higher system with LFP batteries.
 
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It is common for a busbar to have a total rating that is different than the per-connection rating.

With a 4-lug 1000A busbar, you can not have 1000A going in on two of the lugs and 1000A going out of two of the lugs, but you could have 500A going into two lugs and 500A coming out of two lugs.
I get that the total throughput can not exceed 1,000 amps, which may be a combination of, for example two 500 amp connections going into the lynx power in. Both sources = 500 amp each x 2 to give 1,000amps. But if the max fuse that one can find is 800 amp, per advice from Victron, then how is this a 1,000 amp system?

Screenshot 2023-01-24 at 11.11.56.pngScreenshot 2023-01-24 at 11.15.55.png
 
how is this a 1,000 amp system?
Simple.... You can have as much as 1000amp going in and out. However, all 1000A will not be through one lug, it will be split between lugs.

As I said above, I have seen other busbars where the total current capacity is greater than the current rating for any one connection.
 
I get that the total throughput can not exceed 1,000 amps, which may be a combination of, for example two 500 amp connections going into the lynx power in. Both sources = 500 amp each x 2 to give 1,000amps. But if the max fuse that one can find is 800 amp, per advice from Victron, then how is this a 1,000 amp system?

View attachment 131317View attachment 131316
That is 1000 amps from 4 connections per the photo above. 250 amps per connection so buy 250 amp fuses to make your connections. I personally used 300 amp Mega fuses.
 

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Simple.... You can have as much as 1000amp going in and out. However, all 1000A will not be through one lug, it will be split between lugs.

As I said above, I have seen other busbars where the total current capacity is greater than the current rating for any one connection.
I get this. I am focused on the lynx shunt not supporting more than an 800amp fuse. That to me is the bottleneck. Won't the fuse blow when you exceed the current rating of the fuse, in this case using the Victron fuse of 325 amps, or a Littelfuse @800amp.
That is 1000 amps from 4 connections per the photo above. 250 amps per connection so buy 250 amp fuses to make your connections. I personally used 300 amp Mega fuses.
Yes, I understand. I am referring to the lynx shunt. See the middle unit in my pictures.
 
I get this. I am focused on the lynx shunt not supporting more than an 800amp fuse. That to me is the bottleneck. Won't the fuse blow when you exceed the current rating of the fuse, in this case using the Victron fuse of 325 amps, or a Littelfuse @800amp.

Yes, I understand. I am referring to the lynx shunt. See the middle unit in my pictures.
You do not have to worry about that fuse because it’s just fusing the small amount of power required by the shunt itself. If you look closely I chose to use the Victron smart shunt and mine is attached. If you’re using this for a battery bank to an inverter you are paying a lot for stuff you do not need. You actually only need a Victron Power in ( maybe 2 of them depending on how many batteries) and a smart shunt. You do not need a power in, Lynx shunt and a Lynx distributor.

Also the shunt whichever way you go is only attached to the negative buss. The positive buss is passed straight through to the power in and distributor so no fusing needed. Same with the negative except the shunt sits in the middle still no fusing needed. The only fused thing is the power needed to operate the shunt and it’s software.
 
I get this. I am focused on the lynx shunt not supporting more than an 800amp fuse. That to me is the bottleneck. Won't the fuse blow when you exceed the current rating of the fuse, in this case using the Victron fuse of 325 amps, or a Littelfuse @800amp.
Got it. I was not following before sorry. Yes. When the shunt is there the system's continuous current is limited to the fuse size.
 
The positive buss is passed straight through to the power in and distributor so no fusing needed. Same with the negative except the shunt sits in the middle still no fusing needed. The only fused thing is the power needed to operate the shunt and it’s software.
That fuse in the lynx shunt is going to see 100% of the system current.
 
Got it. I was not following before sorry. Yes. When the shunt is there the system's continuous current is limited to the fuse size.
That is totally incorrect see my explanation above. I have one and so do hundreds of others. No, absolutely no shunt is fused for the loads or rated current flow. The only fused connection for ANY shunt is for the power lead to power the shunt itself.
 
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