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48 v 40 amp mega fuse?

Fraser

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Joined
Mar 25, 2021
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hi everyone. I’m stuck. I can’t find any fuses with small enough amperage to work with my victron 150/35 mppt and the lynx distributor. The wire size I’m using was 10mm going out. I thought a 40 or 45 mega fuse would do. Can’t get one for 48v system.......So I’m looking to use the max wire that mppt will take which is 16mm I think. Would that on a 2 ft run be ok with a 100 amp fuse?
please help!
Many thanks in advance.
 
The Blue Sea Systems wire/fuse chart shows that a single, unbundled, 105ºC 6AWG wire (a bit smaller than 16mm²) can handle up to 125A. Therefore a high quality 16mm² wire can handle more than 125A. So as long as your 100A fuse is rated for 48V then you should be good.
 
For systems starting to reach this size, it is typically considered more appropriate to make your connections through a "load center" rather than simple fuses. Utilizing breakers that are mounted inside the load center you have choices between 30 and 250A. Here's a load center that's designed for my Conext 4024. They are brand specific, but you can select one that can be used with your Victron. They are typically designed to hold all the breaker associated with the whole system, for the solar arrays, the controller, and the main DC leading from the batteries to the inverter.

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The Blue Sea Systems wire/fuse chart shows that a single, unbundled, 105ºC 6AWG wire (a bit smaller than 16mm²) can handle up to 125A. Therefore a high quality 16mm² wire can handle more than 125A. So as long as your 100A fuse is rated for 48V then you should be good.
Many thanks! That has helped.
 
For systems starting to reach this size, it is typically considered more appropriate to make your connections through a "load center" rather than simple fuses. Utilizing breakers that are mounted inside the load center you have choices between 30 and 250A. Here's a load center that's designed for my Conext 4024. They are brand specific, but you can select one that can be used with your Victron. They are typically designed to hold all the breaker associated with the whole system, for the solar arrays, the controller, and the main DC leading from the batteries to the inverter.

View attachment 47842
That sounds interesting. I honestly haven’t been able to find things like this. I first bought a combiner box for the solar strings but found it couldn’t take the amount of watts I had in my array. I wouldn’t know what I was looking at in that box. My electrician would but I would have to watch some YouTube to have any idea. ?
 
Many of us are using the Bussman/Blue Sea Series 187 circuit breaker downstream of the solar charge controller. However, in my case I have a 12 volt system, not 48 volt. There was a thread a couple months back that pointed out that a 48 volt system is often operating above 48 volts and a 48 volt rated over current protection device may not be appropriate. I don't recall if it was Blue Sea Systems or someone else that was going to derate their OCP from 48 volt to a lower value so it was clear that they would not work on a "48 volt" system.
 
That sounds interesting. I honestly haven’t been able to find things like this. I first bought a combiner box for the solar strings but found it couldn’t take the amount of watts I had in my array. I wouldn’t know what I was looking at in that box. My electrician would but I would have to watch some YouTube to have any idea. ?

It sounds like you might have 1500W to 2000W of PV panels and a 48V system. Not particularly big.
A combiner box doesn't know much about watts. Its components have a maximum voltage spec, each fuse/breaker has a current rating, and the wires/busbars have a maximum current.
Hard to believe the combiner box wouldn't work for your system. What are the quantity/specs/links to your PV panels and the combiner?
 
Many of us are using the Bussman/Blue Sea Series 187 circuit breaker downstream of the solar charge controller. However, in my case I have a 12 volt system, not 48 volt. There was a thread a couple months back that pointed out that a 48 volt system is often operating above 48 volts and a 48 volt rated over current protection device may not be appropriate. I don't recall if it was Blue Sea Systems or someone else that was going to derate their OCP from 48 volt to a lower value so it was clear that they would not work on a "48 volt" system.
Yes must be sized for the equalizing (highest) voltage of your batteries. Mega fuses are rated 32V which works with all 12V and most 24V systems.
 
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