How to connect 10x 48V/15kWh Batteries with 3x Inverters/Chargers?

[finalius]

I plan to build a 3 phase (230V) grid-couples ESS with rouhly 150kWh storage. I don't want/need any emergency power or off grid support. I've searched the forums and internet in general and came up with the following components:

• 10x Gobel Power GP-SR1-PC200 (EV280 or EV314 Cells, depending on availability, for a total of 144 or 160kWh)
• 3x Victron MultiPlus-II 48/15000/200
• 4x Victron Lynx as Busbar
• Victron Erkano GX

I want to connect every battery with their own fuse straight to the bus bar and space the inverters evenly in order to distribute currents as good as possible and hence have as little voltage drop as possible.

I've attached the schematic I came up with. With this setup, the busbar should not see more than 250A of current at any given location. The idea is that all battery cables have the same length (they come with the battery, so that should be easy) and all inverter cables would also have the exact same length.

The inverters would always run coupled, i.e. they should always create the same load (inverting or charging) on the DC busbar.

My question is that I see two seemingly contradicting statements: Victron says in their 3 phase presentation that you should connect all the inverters to one bus bar and hence don't split the batteries. But I also read frequently (on here and from Victron) that you shouldn't connect more than 4 batteries in parallel, because balancing the batteries gets tricky.

Do you think my schematic is a good design or how can it be improved?

Also, I don't need to go with the exact components I've chosen, so if you have different recommendations, I'm all ears!

 

[MisterSandals]

But I also read frequently (on here and from Victron) that you shouldn't connect more than 4 batteries in parallel, because balancing the batteries gets tricky.

Can you show where this was stated on this forum? I think the sentiment is that no matter how many you connect in parallel, they need to be wired in a balanced manner. You description of wiring with equal wires to a bus bar satisfies that.

S

Thread 'Calculation of parallel string battery currents'

Apr 5, 2022

Hi, everybody! I'm a retired EE. I didn't want my EE skills to fade away after retirment, so I exercise them when I can. Whenever I see a non-trivial circuit analysis problem on one of various forums I frequent, I challenge myself to solve it. Recently I watched Will's video about current sharing in a parallel battery string, and it occurred to me that the string is just a circuit. It could be solved using standard circuit analysis techniques giving theoretical values for the battery currents. I wondered if this has been done before and posted on the web. I found a link on this forum...

• Solarod
• Replies: 153
• Forum: General Battery Discussion

• 

I didn't read all of this but seems relevant:

O

Thread 'Too Parallel - when is it too much - Max Parallel connections?'

Nov 12, 2024

Hello all,

I am still running a legacy 12v setup and I need/want to know what are the factors that govern parallel banks. I currently have a string of 6 but have availability to add another 4 batts. The manufacturer says the max I can run 8 but they don't say why. I have seen other manufacturers say that they only support 4 but they don't say why. I am still new to this whole space and want to stay away from AI to get something like this answered and I simply don't have enough time to read 10000 posts to boil down an answer.
For me and my ignorance level I would have thought it would...

• OfflineAlberta
• Replies: 43
• Forum: General Battery Discussion

• 

 

[finalius]

Can you show where this was stated on this forum? I think the sentiment is that no matter how many you connect in parallel, they need to be wired in a balanced manner. You description of wiring with equal wires to a bus bar satisfies that.

I just find some sentiment that more than 4 requires "special attention", like fusing every battery, but I was not sure if that's all that's needed fore more parallel, hence this thread These posts were very infulencial on my schematic - that's why I went for lynx distributors all the way, so I can fuse every battery individually.

 

[740GLE]

Are you planning to use 70v mega fuses of the victron Lynx?

Many here will say with each fuse protecting 16s 280ah battery, you should have class t per battery.

 

[finalius]

Are you planning to use 70v mega fuses of the victron Lynx?

Many here will say with each fuse protecting 16s 280ah battery, you should have class t per battery.

Thanks! I was originally not putting much thought into the kind of fuses, but stumbled into that rabbit hole now thanks to your comment.

Given that such a 16s Battery Module can have many kiloAmps of short circuit current, not using the mega fuses seems like a good idea (although a Elektronik "EXTREM" on youtube tried to get different mega fuses to arc with 5.5kA and didn't manage).

Thanks to youtube, I stumbeld across the Alder EF3 Fuses. They have a breaking capacity of up to 50kA and are significantly taller than the megafuses, but apparently fit nicely in the Victron Lynx Distribution according to MeineEnergiewende on youtube. BUT they do have over double the cold resistance (about 1mOhm for the 150A fuse, compared to 0.38mOhm for the MEGA 150A fuse). Also, I found an online shop that sells them to Switzerland (won't post the link)

Can you give me a concrete type of Class T fuses so I can compare them to the EF3?

edit: also, given that all the Gobel Powers come with a 250A magnetic breaker, do I even need the fuses in the Victron Lynx Distributor?

 

[740GLE]

Not sure how many people trust the cheap breakers on these batteries more than is disconnect switch.

Seems like belt and suspenders is the preferred method with fuse.

I run a 24v system and have mega fuse on one battery and a MRBF on the other plus disconnects.