Hi!
I need some help on how to connect the two Pylontech US5000 to the T-Class power in.
Alt A or B, and do I need separate T-Class fuses for each of the cables if using Alt B?
If so, can I connect one cable lug to the same bolt as the fuse, or do I need separate bus bars? I feel hat this get expensive fast. Like $150 for that fuse from my installer…
Best, Andreas
The US5000 has an internal breaker, so fused power in’s are not really needed…
Both can go to one fuse. no link connection is needed between the US5000’s if they are both wired to the fuse / busbar. Alternatively, you can link them together, and then wire only the top battery to the fuse / busbar with no loss of performance.
Hello @zebban ,
I personally did not want to rely 100% on the US5000 BMS as “internal breaker”. Although it might be already quite safe. Just to be on the safe side, and since you anyway have two ports on the Class-T, I spent a separate fuse per US5000 in my system and did not connect the batteries among each other.
Yor are right, it gets expensive fast with the Class-T fuses. Adler EF3 in a normal Lynx distributor should be good as well and much cheaper. AIC Ratings for LiFePO4 - Class T - MRBF - #17 by B51-technician
The Class-T, for me, is only a “worst-case fatal short” fuse towards the batteries. For everything else, I rely on the PylonTech BMS and the Mega Fuses of the MPPTs/MPII.
Hello @B51-technician!
Thanks for your reply!
I’m running a three-phase system, by the way.
In the future I’ll have six (or more) US5000 units. That will require three or four T-Class power-input connections, with six to eight T-Class fuses in total. It’s going to be expensive.
The purpose of these fuses is to ensure that no battery can back-feed excess power into another battery and to limit the power in the cables as specified (120A * 1.2?). (The inverters and MPPT charge controllers already have their own fuses to protect them or to isolate the main bus in case of a fault.)
To reduce costs without compromising safety, could I connect both positive cables to a single 250 A T-Class fuse—one cable on each bolt of the fuse terminal?
If I wire multiple battery pairs this way, what happens when one fuse blows? Will the other fuse then carry more current than the remaining batteries can safely supply and blow as well? In other words, what happens if the inverters draw more current than the sum of the remaining batteries can provide?
Can we detect a blown fuse some how and reduce the inverter power?
Are those 5kVA inverters? If so, the battery pack is horribly undersized. That is not great for the batteries which have a history of not lasting in that configuration.
I would encourage you to add more.
I know I will add more soon. Running on very low settings for now.
