How to wire these 10 x 48 Batteries and connect to a 4 stud busbar??

nezek88

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Hi Guys,

Edit 2: (Added Inverter model)
I'm building a 10 parallel battery bank which should be able to power 30kW max. ( x6 Growatt 5kW SPF5000ES inverters - 2 to each phase)

Question 1 - I want to use Victron Lynx power in as the busbar BUT it only has 4 input studs.
I require 10 Battery input studs and 3 inverter output studs - can that be managed by using the same stud for multiple input/outputs?

setup:

Battery:

10x Growatt Hope 4.8L-C1 Lithium Iron Phosphate Battery.
Battery Voltage: 48V

2x 5 Stack of the battery:

BUSBAR TO INVERTER

Busbar to 70mm² cable to MCCB 250a and from the breaker 35mm2 cables to each of the two inverters.


Question 2 - How would you wire those 10 batteries?
If I wanted to diagonally parallel 5 of the batteries it would require a huge cable that I don't have access to, the max cable I could use is 70mm² so i guess I could stack them 6 and 4 and parallels every two batteries before going to the inverter? I think I can do that with a 35mm².


Edit 1: Attached the battery manual.
 

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rmaddy

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You need multiple Lynx Power Ins. Buy 1 for each 4 connections.
 

nezek88

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You need multiple Lynx Power Ins. Buy 1 for each 4 connections.
OK, so if I parallel every two batteries diagonally I reduce the input requirement to 5 studs and three more for the output.
How do I connect all of these to two Lynx Power Ins?
 

nezek88

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Each battery needs a fuse at it's positive terminal.
Yes I'm being told that its recommended to fuse when its that many batteries but if parallel every two batteries and fuse their connection on the bar's positive (Lynx Power In). How should I size the fuse? it is by the max power load requirement divided by number of batteries?
30,000W MAX LOAD
30,000 / 10 Battries = 3,000W / 48v = 62.5A per battery ???
 

Zil

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Each battery in parallel must be fused to the Ampacity of the cables. The maximum amperes expected in the system. If one or more batteries fail, the load will draw from the remaining batteries. Those cables must be able to carry those amperes and be properly fused.

30,000W / 48 volts. Approximate math = 625 amperes. What happens if half the batteries fail? 5 batteries drain 125 amps each. What happens to those 70 ampere fuses? (closest to 62.5A)
 

FilterGuy

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Question 1 - I want to use Victron Lynx power in as the busbar BUT it only has 4 input studs.
I require 10 Battery input studs and 3 inverter output studs - can that be managed by using the same stud for multiple input/outputs?
I generally do not like stacking high current studs.... It is just asking for a hot connection.
Having said that, if you are going to stack them, the battery connections will be lower current and less likely to have a problem. (The batteries are only rated for 100A continuous output)

Note: The Lynx Input has a unique layout. I do not know if there is physical room for stacking large cable lugs.

As someone else mentioned. The lynx boxes are designed to easily connect together for expansion.

What size are your inverters? The first sentence in the original posts mentions 30KWh... Is this supposed to be 30KW? (5KW/inverter). This is necessary information for commenting on currents and wire sizes and fusing.
 

nezek88

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I generally do not like stacking high current studs.... It is just asking for a hot connection.
Having said that, if you are going to stack them, the battery connections will be lower current and less likely to have a problem. (The batteries are only rated for 100A continuous output)
Ok, I wont do that.
How should I wire it then?

Now I'm thinking two Lynx which gives me 8 Inputs, then I connect diagonally connect every two batteries and use 5 Input and 3 outputs on the bar? What do you think about this and how would you do it ?

For the inverter size yes its 5kW inverter , two on each phase for a total of 6 Inverters across 3 phases.
 

nezek88

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Each battery in parallel must be fused to the Ampacity of the cables. The maximum amperes expected in the system. If one or more batteries fail, the load will draw from the remaining batteries. Those cables must be able to carry those amperes and be properly fused.

30,000W / 48 volts. Approximate math = 625 amperes. What happens if half the batteries fail? 5 batteries drain 125 amps each. What happens to those 70 ampere fuses? (closest to 62.5A)

I thought that when fusing each battery the goal is actually to protect it from other batteries in the bank? assuming you have a failed battery that could potentially draw current from all the other batteries that could be dangerous but if it draws current from only 1 battery that's not too bad.

In the extreme unlikely scenario of 5 battery fail I think 70a fuses are suitable because I would want the whole bank to disconnect, each fuse one by one.???
 
Last edited:

Zil

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I wasn't thinking of a short through the bad battery. That is actually rare. Just something like some strange disconnect event the takes a battery or some out of the circuit and the device, inverter, keeps going pulling all its power from the remaining battery. Anyway, it is just speculation as the BMS will melt.
 
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