Hello
I bought almost the same kit as the one in the photo and am now at the installation stage.
The kit contains two different fuses, each rated at 125 A.
Which one goes to the MultiPlus, and which one goes to the battery?
Regards,
NetFritz
Hello @NetFritz
if you have a Lynx Power In like the one in the picture, then you’ll have to do a bit of DIY yourself (or give your supplier a hard time).
There’s a post somewhere here explaining how to turn a Lynx Power In into a Lynx Distributor.
The Lynx Distributor has the slots for the fuses
so if both fuses are the same size, it makes absolutely no difference which one you put where
BUT using 2 fuses of the same size makes no sense
it now depends on which cables you use and how long they are; accordingly, the right fuses should be fitted
The Lynx Power In is completely unnecessary in the kit; a simple fuse holder would have done just as well. It only makes sense if, for example, you add an MPPT.
Are the fuses the 70 V version? They’re also available in 32 V, which would be unsuitable for this purpose.
The battery holder is also unnecessary, since there’s only one battery.
And instead of the odd Grid Meters with the USB adapter, I’d always recommend a Victron VM-3P75CT Energy Meter, as there’s less that can go wrong.
I hope at least that the cable is Type A 
Is the kit pre-configured, or do you still have to do that yourself?
Hello
The kit is preconfigured.
I may also carry out the commissioning with HUSATECH.
The voltage rating of the fuses is 70 V.
The Lynx Power is already fine; later, it is planned to upgrade to three phases and possibly up to four batteries.
I also have the Victron VM-3P75CT Energy Meter, which is installed behind the utility meter.
Best regards,
NetFritz
Consider using the Lynx Distributor, especially if expanding to 3-phase and adding more batteries.
The Distributors can monitor the fuses, and with a bit of tinkering you can get alerts in Venus OS and VRM.
More details in the description of my system on my profile.
Okay, then just try replacing the Power IN with a distributor. That’s the easiest way to start with.
The 125 A fuse for the battery cable is okay; it’s a little oversized for the MultiPlus. But for a system of this size, a single fuse is sufficient anyway.
But you should get the dealer to explain what exactly they were thinking and how they arrived at this solution
Not me 
If you install it correctly, i.e. with one fuse for each of the three phases, you need at least 7 modules of space in the distribution board (8 if you also protect the neutral), whereas the EM540 only needs 4 modules, including the one fuse for the neutral.
The only advantage of the VM-3P75CT is its connection via VE.Can or Ethernet, but even there it’s pretty rubbish that the RJ45 sockets face forwards, as you may need another module of space to route the cable neatly behind the cover (e.g. using a Hager TN002S).
Especially when installing it in an older existing system, you’re glad if you can still find 4 free modules.
(The meter normally isn’t allowed in the installation-side connection compartment.)
Perhaps Victron will eventually bring out a directly measuring meter (like the EM540) with RJ45 sockets behind the cover; I’d be happy to install that.
But for now, I’d rather stick with the EM540.
What more could go wrong with the EM540?
In principle, the work may only be carried out by a qualified electrician….
With the EM540, you have to route the three phases through the meter and possibly make new cables. In my opinion, there’s much more that can go wrong than with the VM-3P75CT. But I agree with you about the space requirements and the sockets on the front.
Your supplier has a suitable screw set for mounting fuses in the Lynx Power In….
The VM may also only be installed by a qualified professional.
I reckon there are considerably more botched installations with transformer metering than with permanently installed meters. When you have to bend the rigid 10 mm² cables in old installations to get the transformers over them, and then force them into the AAR, quite a lot can go wrong — not to mention the connections for the voltage measurements. I can’t think of a single advantage of transformer metering for currents of up to 63 A, apart from the marketing that suggests it’s more user-friendly for non-professionals… which it isn’t.
You’re absolutely right.
But we do want to help @NetFritz install his fuses…
The MP2 3000 has a significantly higher load capacity for 0.5 seconds.
The Mega fuse was sized accordingly, and not for the continuous load (125 A).
My 5000s have 200 A fuses specified. 9,000 W / 48 = 187.5 A. They should therefore never actually blow, except in the event of a fault.
I modified my Lynx Power In. To use the Distributor with monitoring, you still need a Lynx Shunt. In your setup, the circuit board would presumably remain without power, meaning the Distributor would be no more than a Power In with fuses, as is currently the case with mine.
The Lynx Distributor can be used with some open source software and a few cheap parts.
BOM and pictures in my build thread linked in my profile.
Software:
The 125 A is for the (single) Pylontech battery cable, not the inverter.
That’s what it says in the Pylontech manual.
The fuse(s) came that way in the kit anyway… a lower-rated one would also be sufficient for the inverter.
If you only have one 125 A battery, then the Multi is protected by the fuse for the 70 mm² cable. However, I have five batteries in parallel, so in the event of a fault the current could be as high as 575 amps.
That’s why the Multis at the distributor are fitted with fuses to protect the 70 mm² cable.
hello,
I really can’t listen to this anymore. I’m a qualified electrician and have a degree in electrical engineering, but I’m not a qualified professional because I’m neither employed by a registered electrical company nor registered with the network operator myself and running an electrical company!
Let’s just say that this sort of thing should only be done by someone who knows what they’re doing and can do it properly!
Even a first-year apprentice is a qualified professional if their employer assigns them the job!
In fact, anyone who is instructed by a registered master electrician on what they are supposed to do is a qualified professional for that work!
In my opinion, the term is also being used for a lot of nonsense, and everything I saw that had been done by a qualified professional had to be corrected by me: two wallboxes were installed, but the additional current sensors were connected not to the house connection, but to the cables leading to the respective wallboxes, where the internal ones were already connected—and they had been connected incorrectly as well!
So much for what people call a qualified professional!
bye
“The MP2 3000 does have a considerably higher overload capacity for 0.5 sec.
that’s what the mega fuse is rated for”
Erm, a serious error — I hope it’s only in the wording. The fuse rating must of course be higher than the MultiPlus’s capacity, but otherwise it’s purely there to protect the live cable against fire. In other words, the fuse must blow before the cable burns through.
And nothing else.
you’re absolutely right. The fuse must not be rated higher than the current the cable can carry (in this case, a 70 mm2 H07VK cable). The mistake here is clearly in the wording. Thanks for pointing it out.