To buss bar or not to buss bar

TheHappyNomads · Jun 16, 2024

I found this image online for battery setup when i was searching around for whether or not to place a Class T fuse on each of the battery banks I'm building and it raised another question in my mind. To buss bar or not to buss bar?

I'm assuming the advantage is the ability to add additional batteries/banks and expand more easily storage capacity.

In terms of battery management is the practical reason just that you connect each battery bank to the buss bar and then just connect the buss bar to the inverters?

My build will consist of these from this thread.

MaikaiLife · Jun 16, 2024

It's not just about the ability to add additional batteries/banks, it's also about cost efficiency and wiring cleanliness. A bus bar gives a single source for either negative or positive electrons, saving cable, and allows you to tap the bar for the potential to run multiple devices such as Shunts, Charge Controllers, Inverters, Monitors, etc.

OffGridForGood · Jun 16, 2024

TheHappyNomads said:
it raised another question in my mind. To buss bar or not to buss bar?

Multiple packs = bus bars

TheHappyNomads said:
I'm assuming the advantage is the ability to add additional batteries/banks and expand more easily storage capacity.

And a bus bar can be 800A capacity more easily than a big wire can be,
A bus bar is easier to connect to at any point along it's length
A bus bar allows you to remove one pack for service easily without affecting any other battery packs while you do so.
A bus bar allows a simple way to put a fuse or breaker (or both) between each battery pack and the bus for safety and control.

TheHappyNomads said:
In terms of battery management is the practical reason just that you connect each battery bank to the buss bar and then just connect the buss bar to the inverters?

Connect each battery pack via a Class T fuse and a DC rated breaker (so you can easily isolate one pack from the ESS)
Don't directly connect the inverters to the ESS bus, instead put a 2P main shut off DC breaker/switch between the ESS output and the inverters.
I suggest a shunt after the ESS main disconnect to a smaller (4 stud or similar) neg bus after the shunt for all the neg inverter connections, and perhaps a Chargeverter connection point.
On the Pos side, after the main ESS disconnect put a main ESS Class T (mine is 400A) and then again a smaller Pos bus (4-stud or sim) after the class T for all the Pos connections for the inverters, and perhaps a pos for a chargeverter connection point.

The main reason for the class T on every battery pack is in case of an internal short in one pack, all the other packs would then be shorted to that one pack and could dump hundreds (thousands?) of amps into the shorted pack and cause a fire - the class T on each pack should be sized to not trip at the normal output of one pack, but definitely trip under the combined output of all the packs.

TheHappyNomads · Jun 18, 2024

OffGridForGood said:
Multiple packs = bus bars

And a bus bar can be 800A capacity more easily than a big wire can be,
A bus bar is easier to connect to at any point along it's length
A bus bar allows you to remove one pack for service easily without affecting any other battery packs while you do so.
A bus bar allows a simple way to put a fuse or breaker (or both) between each battery pack and the bus for safety and control.

Connect each battery pack via a Class T fuse and a DC rated breaker (so you can easily isolate one pack from the ESS)
Don't directly connect the inverters to the ESS bus, instead put a 2P main shut off DC breaker/switch between the ESS output and the inverters.
I suggest a shunt after the ESS main disconnect to a smaller (4 stud or similar) neg bus after the shunt for all the neg inverter connections, and perhaps a Chargeverter connection point.
On the Pos side, after the main ESS disconnect put a main ESS Class T (mine is 400A) and then again a smaller Pos bus (4-stud or sim) after the class T for all the Pos connections for the inverters, and perhaps a pos for a chargeverter connection point.

The main reason for the class T on every battery pack is in case of an internal short in one pack, all the other packs would then be shorted to that one pack and could dump hundreds (thousands?) of amps into the shorted pack and cause a fire - the class T on each pack should be sized to not trip at the normal output of one pack, but definitely trip under the combined output of all the packs.

Wow... that's a lot of information. Thanks! You don't happen to have any pictures of your setup as described do you? I'm much more of a visual understander

OffGridForGood · Jun 18, 2024

I have to check - or take some for ya,

To buss bar or not to buss bar

TheHappyNomads

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MaikaiLife

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OffGridForGood

Catch, make or grow everything you can.

TheHappyNomads

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OffGridForGood

Catch, make or grow everything you can.

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