Fusing for victron busbar w 12000xp, 3 power pros and 3 chargeverters?

[staylucky]

Setting up a new off-grid system with an EG4 12000xp inverter, 3 indoor power pro batteries and 3 chargeverters. There's no solar yet. The chargeverters are powered by a 14kw Kohler generator.

For better balance among the batteries and future expansion, and for the chargeverters, I'm looking to go with an external busbar rather than the parallel kit. I've read a lot of different opinions about how much fusing is necessary/smart. My takeaway is that for interrupting current with the paralleled batteries, it would be smart to have a class T fuse for each battery. I'm not sure if I need any other fuses, since the inverter & chargeverters have breakers.

Here's a rough drawing of what I am considering using 2 interconnected Victron Lynx class T busbars connected to 1 Lynx Power in unfused busbar.



Please let me know what you think! Thanks, Chris

 

[ScrodusGargleRotten]

You need to think about an inverter or chargeverter internal short.

Yes the batteries are all fused, what happens when 400 amps goes to the chargeverters 4 awg wires?

 

[staylucky]

Thanks for the response.

So class T fuses on the batteries (250A) and MEGA fuses on the chargeverter (125A) and inverter (2 x 200A)?

How important is placement of each connection? Assume higher amps toward the center of the busbar?

Thanks, Chris

 

[Bridgetown]

Just a thought, since I have an interest in the 12000XP:

If you use 150A T-Class fuses at each of the three batteries. You can use the 2/0 cables supplied with each battery to connect to the Lynx. As well as meet the surge demands of the 12000xp. Surge spec of 18000W at 5 sec. requires 416A to meet the 5sec surge of the 12000XP.

Surge current math (@5sec): 18,000W/.902eff/48V = 415.7A

So...each battery must be able to supply 416A/3 = 138A to meet the surge current of the 12000XP

As reference:
NEC Table 310.16: AWG 2/O can handle 175A at 70 degrees C
Battery current of 12000XP running at rated 12,000W requires 12,000W/.902eff/48V = 277A or 92.3A/battery

 

[Wattson25]

Your setup with the EG4 12000XP inverter, 3 Power Pro batteries, and 3 chargeverters powered by a 14kW Kohler generator sounds solid for an off-grid system. Switching to an external busbar like the Victron Lynx setup is a smart move for balancing and future expansion—great thinking!

Your plan with two interconnected Lynx Class T busbars and a Lynx Power In unfused busbar looks promising. Adding a Class T fuse for each battery is a wise choice for interrupting current and protecting against faults, especially with paralleled batteries. Since your inverter and chargeverters already have breakers, you might not need additional fuses unless you're concerned about specific high-current paths or redundancy.

Without solar yet, your focus on battery management is spot-on. I’d say your design is a strong start, but if you want extra peace of mind, you could consider a main fuse between the busbar and inverter for overall system protection.