I’m a new victron user about to embark on my first ess build.
I’ve (pre)ordered 3x Multiplus II 6k5 and am designing the rest of the system now, current topic fusing.
I see the regular multiplus ii have a chapter called “4.3 connection of battery cables” which includes some cable/fuse guidance.
Opening the same chapter in the Multiplus II 6k5 manual shows an empty table, probably because it’s still in the making.
Can anyone recommended the power-in and distributor fuse size for my system?
I have 3x Multi II 6k5 with 3x 16kWh/48v battery bank in parallel.
Which victron power in do you have? With the T Fuses? also which battery bank?
If max discharge rate of the BMS is 200a per battery i would recommend Littelfuse class-T 225A 125V
For the distributor side to the 6k5 i would go with mega fuse 225a
The power-in is the t-class and the cable length is 1m per cable (A total of 2x 2 meter positive and negative run between inverter and battery (times 3))
The batterybanks are 3x a Gobel Power GP-SR1-JK314 with 16x314Ah per battery. JK-BMS with a 200Amp breaker.
Max discharge is 200a. So tfuse 225a is okay for the Battery’s.
On the distributor side. You can properly go a little bit higher on the fuse side of the mega fuses to 250a. For the 6k5 it is 11kw max output. 11kw / 48v = aprox 230amp
If you take a look at the victron docs for the old multiplus 48/8000. they advice a 300amp fuse.
Megafuse is marginal for 48V lfp, AIC of a potato, perhaps some NH type fuses for each inverter that can actually handle the available fault current from the lfp batteries?
6x 200A Adler EF3 fuses which fit into the MegaFuse holders
Adler EF3 can clear 50.000A instead of 2,000A of a MegaFuse.
For the Distributor, you can add a small I2C-USB adapter from AliExpress and flash an open-source software to get fuse monitoring including alerting in VRM and Venus OS.
If you aim for a main breaker between battery Lynx and MP2 Lynx, go for specialized Jean Mueller NH00 DC breaker which can handle 80V DC up to 800A.