Fitted a Midi fuse in a Victron Lynx Distributor. Is it OK?

balachai

New Member
Joined
Mar 13, 2021
Messages
67
I've found a workaround to fit Midi fuses into a Lynx Distributor, but I haven't energised it yet. The Distributor is made to hold Mega fuses, but unfortunately they're not available in amperages below 125A, at least not rated for 48 Volt systems.

Any problems with this? Here's what I did.

1. Made a fuse extender:
- Cut a 40mm long copper bar, mine is 19mm wide & 6mm thick but 3mm should be OK.
- Drill a 6mm hole, centre is 6mm from one end.
- Drill a 9mm hole, centre 20mm from the first hole centre.
- Lightly chamfer holes, debur bar edges, sand smooth & clean with isopropyl alcohol.

2. Attached the fuse extender to the Midi fuse:
- Bolt the Midi fuse to the extender using a 12mm long stainless M5 mushroom-head bolt with washer, spring washer & nut.

3. Made a M5 post:
- Put a big washer on a stainless hex head M5 bolt, 25mm long.
- Put it through the removable Victron plastic bolt holder.
- Add a large washer and a nut and bolt it down tightly, clamping the plastic between the two washers.
- Reinstall the plastic bolt holder.
- Add 2 more nuts and a large washer.

4. Installed the fuse:
- Place the extended fuse into the Lynx Distributor.
- Secure each end with lock washer and nut. M8 at the positive busbar, M5 at the other end.
 

Fraser

New Member
Joined
Mar 25, 2021
Messages
53
I've found a workaround to fit Midi fuses into a Lynx Distributor, but I haven't energised it yet. The Distributor is made to hold Mega fuses, but unfortunately they're not available in amperages below 125A, at least not rated for 48 Volt systems.

Any problems with this? Here's what I did.

1. Made a fuse extender:
- Cut a 40mm long copper bar, mine is 19mm wide & 6mm thick but 3mm should be OK.
- Drill a 6mm hole, centre is 6mm from one end.
- Drill a 9mm hole, centre 20mm from the first hole centre.
- Lightly chamfer holes, debur bar edges, sand smooth & clean with isopropyl alcohol.

2. Attached the fuse extender to the Midi fuse:
- Bolt the Midi fuse to the extender using a 12mm long stainless M5 mushroom-head bolt with washer, spring washer & nut.

3. Made a M5 post:
- Put a big washer on a stainless hex head M5 bolt, 25mm long.
- Put it through the removable Victron plastic bolt holder.
- Add a large washer and a nut and bolt it down tightly, clamping the plastic between the two washers.
- Reinstall the plastic bolt holder.
- Add 2 more nuts and a large washer.

4. Installed the fuse:
- Place the extended fuse into the Lynx Distributor.
- Secure each end with lock washer and nut. M8 at the positive busbar, M5 at the other end.
Sounds good. I have been dealing with same issues I ended up getting slightly bigger wire to warrant the larger mega fuses higher amp ratings. Now having trouble finding a combiner box. I’m actually thinking of connecting all my strings into a lynx power in. No idea if that’s the right thing to do. Seems like it should work to get 8 wires to 2. I have string fuses and isolators before that though. Can’t find anyone who can tell me if the lynx power in can do the 200 plus volts though.
Fraser
 

balachai

New Member
Joined
Mar 13, 2021
Messages
67
I’m actually thinking of connecting all my strings into a lynx power in.

I’m actually thinking of connecting all my strings into a lynx power in. No idea if that’s the right thing to do. Seems like it should work to get 8 wires to 2.
Yeah that should work. With some creativity you can also attach a fuse holder to the positive end lug and attach another 2 wires there.
 

balachai

New Member
Joined
Mar 13, 2021
Messages
67
Can’t find anyone who can tell me if the lynx power in can do the 200 plus volts though.
Oh good question - the lynx tech specs say 60V. But it's a very robust unit with good separation between positive and negative so I don't see why 200 plus volts would be a problem, excluding the fuses of course.
 

Fraser

New Member
Joined
Mar 25, 2021
Messages
53
Oh good question - the lynx tech specs say 60V. But it's a very robust unit with good separation between positive and negative so I don't see why 200 plus volts would be a problem, excluding the fuses of course.
Thanks for your reply. Yeah it works a treat. I’m using it. All my solar positive and negatives go to it and right on the ends of the lynx I run my cables off into the mppt.
 

Jet

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Joined
Jun 22, 2021
Messages
38
While typing a post to find a similar solution I came across your thread. I really want to connect my Orion Tr 12/24 string to the Lynx Distributor. The problem is I need a 30amp fuse which Mega fuses don't come in of course. Is there any way you could make another one if I paid you? Please :)
 

jameshowison

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Joined
Jul 30, 2021
Messages
98
Working on a similar issue. I have a 48v battery system and the mega fuses are not sized for reasonable wire sizes for 48v. I asked about this here, but no replies: https://diysolarforum.com/threads/fuse-and-distribution-for-48v-loads-inc-48-12-converter.31390/

There is also a similar discussion on the victron boards: https://community.victronenergy.com/questions/87051/mrbf-fuse-in-lynx-distributor-at-48v.html although I'm not entirely sure what they mean by "longer stud"

Does anyone know if it would be possible to fit the Blue Sea MBRF stud offset (aka Terminal Fuse block) into a Lynx system (the Power In version without the board and second positive studs). Here's the Blue Sea MBRF stud offset:



Drawings suggest maybe? Depends on how much vertical space from the positive bus bar to the top of the Lynx enclosure.

This would at least enable going down to 30amp fuses rated for 48v systems, which would get the wires down into the 16 and 14 gauge range.

 

jameshowison

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Jul 30, 2021
Messages
98
There is also a similar discussion on the victron boards: https://community.victronenergy.com/questions/87051/mrbf-fuse-in-lynx-distributor-at-48v.html although I'm not entirely sure what they mean by "longer stud"

Does anyone know if it would be possible to fit the Blue Sea MBRF stud offset (aka Terminal Fuse block) into a Lynx system (the Power In version without the board and second positive studs). Here's the Blue Sea MBRF stud offset:



Drawings suggest maybe? Depends on how much vertical space from the positive bus bar to the top of the Lynx enclosure.
So that's a definite no. Not really surprising, given the long stud for the MBRF fuses. So if those are added to the positive bus bar in the Lynx (which is the "upper deck") there's no way the lid closes. This is the "Power In" version of the Lynx FWIW (so no second +ve stud).

MBRFandLynx.png

OTOH you could attach the BlueSea MBRF battery terminal stud mount on the ends of the bus bar. See pic. That's not really useful for my 48v application but perhaps for others. The whole mount would not be covered, though with parts of the MBRF mount exposed.

MBRFandLynx2.png

So my plan is to return the Lynx (which the bluetooth victron shunt doesn't connect usefully with anyway) and work with the BlueSea MBRF Common Source Fuse block (and some matching sized bar for -ve bus.).

5196.png
 

HighTechLab

Small Business Owner
Joined
Sep 23, 2019
Messages
706
Why buy a 1000a busbar, and fuse down to a meager 30 amps? Wouldn't it be better to a, for example, use 100a fuse and sub-fuse panel with the smaller 15/20/30/40a fuses coming out of this subpanel instead of going straight onto a extremely high current bus?

Also, there is the Lynx shunt that works much better with this system than the smartshunt.
 

jameshowison

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Jul 30, 2021
Messages
98
Thanks. Reason might well be that I don’t know what I doing :)

So you are suggesting a small high amp bus bar pair for the high amp stuff (battery, inverter, link to smaller bus bar). And a lower amp bus bar/distribution center for smaller stuff. Basically add a 48v distribution similar to the 12 amp distribution.

Thing is that I can’t find 48v nominal rated (ie up to 58v) bus bars or distribution centers. I linked 58v mini fuses above but I can’t find any centers rated to accept those, just ones for 12 and 24. I know Amps are primarily but busbars and distribution centers also have voltage ratings, it seems.

I don’t see people attaching MPPT (mine are 35 amps) or Orion (mine is 30 amp) to things other than the busbars.
 
Joined
Nov 30, 2019
Messages
12,696
I've found a workaround to fit Midi fuses into a Lynx Distributor, but I haven't energised it yet. The Distributor is made to hold Mega fuses, but unfortunately they're not available in amperages below 125A, at least not rated for 48 Volt systems.

Any problems with this? Here's what I did.

1. Made a fuse extender:
- Cut a 40mm long copper bar, mine is 19mm wide & 6mm thick but 3mm should be OK.
- Drill a 6mm hole, centre is 6mm from one end.
- Drill a 9mm hole, centre 20mm from the first hole centre.
- Lightly chamfer holes, debur bar edges, sand smooth & clean with isopropyl alcohol.

2. Attached the fuse extender to the Midi fuse:
- Bolt the Midi fuse to the extender using a 12mm long stainless M5 mushroom-head bolt with washer, spring washer & nut.

3. Made a M5 post:
- Put a big washer on a stainless hex head M5 bolt, 25mm long.
- Put it through the removable Victron plastic bolt holder.
- Add a large washer and a nut and bolt it down tightly, clamping the plastic between the two washers.
- Reinstall the plastic bolt holder.
- Add 2 more nuts and a large washer.

4. Installed the fuse:
- Place the extended fuse into the Lynx Distributor.
- Secure each end with lock washer and nut. M8 at the positive busbar, M5 at the other end.
A picture is worth 1000 words.
 

jameshowison

Solar Enthusiast
Joined
Jul 30, 2021
Messages
98
Is it ok to have multiple wires coming to the same stud in a Victron Lynx? Think multiple 12 AWG wires, fused with a holder or in-line fuse outside the Lynx? Is it ok to have those going to the same stud? They would definitely fit in the outside holes! I think that's pretty common for smaller busbars, but I can't see anything showing that arrangement with the Lynx.
 

Sprks

Solar Enthusiast
Joined
Apr 1, 2021
Messages
58
I've found a workaround to fit Midi fuses into a Lynx Distributor, but I haven't energised it yet. The Distributor is made to hold Mega fuses, but unfortunately they're not available in amperages below 125A, at least not rated for 48 Volt systems.

Any problems with this? Here's what I did.

1. Made a fuse extender:
- Cut a 40mm long copper bar, mine is 19mm wide & 6mm thick but 3mm should be OK.
- Drill a 6mm hole, centre is 6mm from one end.
- Drill a 9mm hole, centre 20mm from the first hole centre.
- Lightly chamfer holes, debur bar edges, sand smooth & clean with isopropyl alcohol.

2. Attached the fuse extender to the Midi fuse:
- Bolt the Midi fuse to the extender using a 12mm long stainless M5 mushroom-head bolt with washer, spring washer & nut.

3. Made a M5 post:
- Put a big washer on a stainless hex head M5 bolt, 25mm long.
- Put it through the removable Victron plastic bolt holder.
- Add a large washer and a nut and bolt it down tightly, clamping the plastic between the two washers.
- Reinstall the plastic bolt holder.
- Add 2 more nuts and a large washer.

4. Installed the fuse:
- Place the extended fuse into the Lynx Distributor.
- Secure each end with lock washer and nut. M8 at the positive busbar, M5 at the other end.
Any chance you might have a photo of this workaround? Thanks!
 

Sprks

Solar Enthusiast
Joined
Apr 1, 2021
Messages
58
A MIDI fuse is 30mm on center.
An AMG fuse is 50.8mm on center.

I am also curious to see a photo of said workaround.
smooth Joey, currently designing 24V system and like the OP i initialy like the clean in/out of the Lynx D box but up against same fuse size issues. Pic is from Electrodacus Beginners Guide as im hopefully using that BMS. I will be adding 2 additional circuits (second DC-DC charger in parallel and second MPPT) to whats in the pic. Second (upper) 200 amp fuse goes to inverter. Might i need to make my own BB instead? Im trying to wrap my head around best way to do this.. any advice/input appreciated.... thanks
 

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smooth Joey, currently designing 24V system and like the OP i initialy like the clean in/out of the Lynx D box but up against same fuse size issues. Pic is from Electrodacus Beginners Guide as im hopefully using that BMS. I will be adding 2 additional circuits (second DC-DC charger in parallel and second MPPT) to whats in the pic. Second (upper) 200 amp fuse goes to inverter. Might i need to make my own BB instead? Im trying to wrap my head around best way to do this.. any advice/input appreciated.... thanks
I suggest you size the fuse for the wire.
8 awg pure copper wire with insulation rated for 105C can take up to an 80 amp fuse.

Does BB stand for Busbar?
If yes, then no.
Just use a lynx distributor with 8 awg and 60 or 80 amp mega fuses.
What exactly do the circuits connect to?
I need to know to give you a definitive answer.
 

Sprks

Solar Enthusiast
Joined
Apr 1, 2021
Messages
58
I suggest you size the fuse for the wire.
8 awg pure copper wire with insulation rated for 105C can take up to an 80 amp fuse.

Does BB stand for Busbar?
If yes, then no.
Just use a lynx distributor with 8 awg and 60 or 80 amp mega fuses.
What exactly do the circuits connect to?
I need to know to give you a definitive answer.
Im being educated here.... new to DIY. Designing/building my system as 230ah/24V. (I have 8 230ah EVE cells yet to be assembled into a battery) I Like smaller wires and intrigued with Electrodacus BMS. I now see that MEGA fuses go down to 40amps so i can use 10awg cable (for smaller loads) and utilize the Lynx Power In. This question is what lead me to this particular thread....
To answer your question for loads:

2 ea DC-DC 12/24 15 chargers
2 ea MPPT chargers for separate solar arrays
1 ea 24/12 converter
1 ea 3000/24 inverter

= 6 total. Lynx has room for 4. I either double up the Lynx, or parallel connect the DC-DC's and MPPT's before Lynx....?

I gather from this forum its best to post a complete diagram (which im working on now) and let the collective experience/wisdom do what it does so well.

Thanks again!
 

jameshowison

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Joined
Jul 30, 2021
Messages
98
Im being educated here.... new to DIY. Designing/building my system as 230ah/24V. (I have 8 230ah EVE cells yet to be assembled into a battery) I Like smaller wires and intrigued with Electrodacus BMS. I now see that MEGA fuses go down to 40amps so i can use 10awg cable (for smaller loads) and utilize the Lynx Power In. This question is what lead me to this particular thread....
To answer your question for loads:

2 ea DC-DC 12/24 15 chargers
2 ea MPPT chargers for separate solar arrays
1 ea 24/12 converter
1 ea 3000/24 inverter

= 6 total. Lynx has room for 4. I either double up the Lynx, or parallel connect the DC-DC's and MPPT's before Lynx....?

I gather from this forum its best to post a complete diagram (which im working on now) and let the collective experience/wisdom do what it does so well.

Thanks again!
Take a look at the Bussman LMI midi fuse holder. They have a 6 way. These seem to be hard to come by at the moment.

But at 24 volts can’t you just use the blue seas fuse holders? Check out their 150 Safety Hub. That has midi fuses for high amps and blade fuses for low amps.
 

tonyg

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Apr 5, 2022
Messages
93
Fellow DIY-ers, I couldn't believe my eyes, but it seems that LittleFuse does Mega fuses for lower amps (60A to 500A) and 70V rated. :D
Here it is an url from the UK:

I'm sure you'll find something in the US as well; anyways, it was worth searching - spent ages on this topic.
Hope it helps.
 

jameshowison

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Messages
98
Fellow DIY-ers, I couldn't believe my eyes, but it seems that LittleFuse does Mega fuses for lower amps (60A to 500A) and 70V rated. :D
Here it is an url from the UK:

I'm sure you'll find something in the US as well; anyways, it was worth searching - spent ages on this topic.
Hope it helps.
Nice, that seems like a great option, looks to be available in US as well, says "new product".

FWIW I ended up using Midnite MNEPV DIN rail mounted breakers (after the Power-In busbar, with a single Mega Fuse @125amp for the inverter).
 
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