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Battery cables & wiring questions to Sol-Ark 15k?

In regard to the above diagram, (which is how I will be doing mine), is it still important to use the diagonal wiring of the 4/0 leads to the Inverter even though they are coming off of the bus bars and not the top/bottom battery terminals? I ask to be sure my 4/0 leads are long enough.

Is it better to do the diagonal? Yes. Without a doubt.

Is it important to do the diagonal? That is a more difficult question to answer.
  • The larger the bus bars, the less the voltage drop across them will be and the importance of the diagonal connection diminishes.
  • At some point other factors such as the internal resistance of the BMSs can be a larger factor than the advantage of diagonal wiring.
  • The objective of doing the diagonal is to ensure a more even wear on the batteries. However, if the batteries are only cycling once per day, the calendar life of the battery may get you before uneven wear does.
If you are buying all those batteries, the cost of the extra copper should not be that big of a deal. Consequently, unless there is some other physical constraint preventing the diagonal hook up.... I would recommend doing it as a 'better-safe-than-sorry' move.
 
Is it better to do the diagonal? Yes. Without a doubt.

Is it important to do the diagonal? That is a more difficult question to answer.
  • The larger the bus bars, the less the voltage drop across them will be and the importance of the diagonal connection diminishes.
  • At some point other factors such as the internal resistance of the BMSs can be a larger factor than the advantage of diagonal wiring.
  • The objective of doing the diagonal is to ensure a more even wear on the batteries. However, if the batteries are only cycling once per day, the calendar life of the battery may get you before uneven wear does.
If you are buying all those batteries, the cost of the extra copper should not be that big of a deal. Consequently, unless there is some other physical constraint preventing the diagonal hook up.... I would recommend doing it as a 'better-safe-than-sorry' move.
One more thing.

The more batteries, the more value a diagonal connection offers. If there are two batteries, hooking them diagonally fully balances the load. For each additional battery, the balance gets worse. With more than two batteries in parallel, a diagonal is still a lot better than a 'straight' connection, but not 'perfect'.

There are various wiring techniques to keep things perfectly balanced above 2 batteries, but at some point, it is just not worth it.

Also, there are two diagrams above. One with 8 batteries in parallel, the other with 2 parallel banks of 4 batteries. 2x4 arrangement is better balanced than the 1x8 arrangement.
 
Have you considered not having two separate bus bars instead one longer bus bar and landing your Sol Ark connections on each end with the batteries attached in the middle. This is how I have mine and my batteries all show fairly well balanced cells and voltages. I have had zero battery charging issues and they all stay fairly close when charging and discharging. I have 4 Trophy's as you know. 3 of the 4 came in at 230Ah and one came in as 237Ah so I see a little more variance with that one but the rest are pretty much in lock step
 
Have you considered not having two separate bus bars instead one longer bus bar and landing your Sol Ark connections on each end with the batteries attached in the middle.
I am not following. Could you do a drawing?
 
Yes when I get a min but in your drawing you show 2 positive and 2 negative bus bars with the two positives and two negatives each getting a feed out of the SolArk. I suggest you drop that down to 1 positive and 1 negative longer bus bar and bring the two positive and two negatives out of the Sol Ark and attach them to each end of your bus bar. Then attach your batteries in the middle. That way you are feeding power from each end and the batteries are drawing from the middle. In my mind the bus is energized from each end equally across the entire length. If I energize a bus from one end then the energy at the furthest point will be slightly less. If you energize both ends then potentially the middle of the bar would be the less energized but In actuality I believe you are providing the most energy possible to attached batteries by energizing both ends of the bus. I believe this is the theory behind X configuration. I am not an electrical engineer but if you think about a water pipe. The back bath at the end of the line has less pressure. If you brought another pipe from your water meter to that back bath then you would be feeding the pipe from both ends and you would have significantly better pressure on all faucets. And if you had any pressure differential it would be in the middle not at the end of the line. Just my thoughts.
 
Is it better to do the diagonal? Yes. Without a doubt.

Is it important to do the diagonal? That is a more difficult question to answer.
  • The larger the bus bars, the less the voltage drop across them will be and the importance of the diagonal connection diminishes.
  • At some point other factors such as the internal resistance of the BMSs can be a larger factor than the advantage of diagonal wiring.
  • The objective of doing the diagonal is to ensure a more even wear on the batteries. However, if the batteries are only cycling once per day, the calendar life of the battery may get you before uneven wear does.
If you are buying all those batteries, the cost of the extra copper should not be that big of a deal. Consequently, unless there is some other physical constraint preventing the diagonal hook up.... I would recommend doing it as a 'better-safe-than-sorry' move.

Have you considered not having two separate bus bars instead one longer bus bar and landing your Sol Ark connections on each end with the batteries attached in the middle. This is how I have mine and my batteries all show fairly well balanced cells and voltages. I have had zero battery charging issues and they all stay fairly close when charging and discharging. I have 4 Trophy's as you know. 3 of the 4 came in at 230Ah and one came in as 237Ah so I see a little more variance with that one but the rest are pretty much in lock step
Yes. That is what I will be doing. I forgot to add the picture.
 

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One more thing.

The more batteries, the more value a diagonal connection offers. If there are two batteries, hooking them diagonally fully balances the load. For each additional battery, the balance gets worse. With more than two batteries in parallel, a diagonal is still a lot better than a 'straight' connection, but not 'perfect'.

There are various wiring techniques to keep things perfectly balanced above 2 batteries, but at some point, it is just not worth it.

Also, there are two diagrams above. One with 8 batteries in parallel, the other with 2 parallel banks of 4 batteries. 2x4 arrangement is better balanced than the 1x8 arrangement.

OK - thank you again. I am adding a link to the bus bars I am considering. I have already ordered and received the tinning solution to do myself.
Using your 2 banks of 4 batteries idea (with your drawing attached), would these bus bars be adequate. The site is in Spanish, but the bus bars are 19"L x 1"W x .25"D. They say the rating is 550A. Would these provide what I need?

https://novusred.mx/energia/tierra-...4My4UA92d71XZCeBf6-u1ENaJ1hqJo8vyUV4W1mT69dQ4

15342-barra-de-union-de-tierra-fisica-para-montaje-en-rack-19-75932.jpg

1671002322768.png
 
OK - thank you again. I am adding a link to the bus bars I am considering. I have already ordered and received the tinning solution to do myself.
Using your 2 banks of 4 batteries idea (with your drawing attached), would these bus bars be adequate. The site is in Spanish, but the bus bars are 19"L x 1"W x .25"D. They say the rating is 550A. Would these provide what I need?

https://novusred.mx/energia/tierra-...4My4UA92d71XZCeBf6-u1ENaJ1hqJo8vyUV4W1mT69dQ4

View attachment 125775

View attachment 125774
From the size of the copper, those would work well. However:

1) The bolt pattern will encourage you to make each wire from the battery to the bus bar a different length. Don't do it!. Make all the wires from the battery to the bus bar the same length. The objective is to keep the resistance to each battery identical.

2) The bolts look pretty close together. Make sure the big lugs from the wires will fit next to each other without interfering with each other.
 
From the size of the copper, those would work well. However:

1) The bolt pattern will encourage you to make each wire from the battery to the bus bar a different length. Don't do it!. Make all the wires from the battery to the bus bar the same length. The objective is to keep the resistance to each battery identical.

2) The bolts look pretty close together. Make sure the big lugs from the wires will fit next to each other without interfering with each other.
Ok. Yeah, I thought that was odd. I will definitely use equal length wires to and from the bus bar. I will also space out the lugs as much as possible.

I am able to get these for roughly $50 USD including the hardware and insulators, so I was willing to make do with the bolt patterns.

Thanks again for your help.
 
Have you considered not having two separate bus bars instead one longer bus bar and landing your Sol Ark connections on each end with the batteries attached in the middle. This is how I have mine and my batteries all show fairly well balanced cells and voltages. I have had zero battery charging issues and they all stay fairly close when charging and discharging. I have 4 Trophy's as you know. 3 of the 4 came in at 230Ah and one came in as 237Ah so I see a little more variance with that one but the rest are pretty much in lock step
Curious how this is working. I am planning two positive 4/0 cables and two negative 4/0 cables from solark 15k to the battery bus bars also.
 
Curious how this is working. I am planning two positive 4/0 cables and two negative 4/0 cables from solark 15k to the battery bus bars also.
Two 4/0 lugs wouldn't fit in the terminals in my 15k. 2/0 definitely fits and 3/0 probably fits.
 
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