Help me size bus bars

DIY
, ,
1

I have a secondhand self build campervan. The current wiring is a bit of a mess, and I want to fit two busbars to tidy it and to allow for multiple cables to go to a (new) single li-ion battery.

The inverter is 3000W (250A)
The 12v load fuses total 70A
The mppt is 30A, going to a ctek
Theres a victron smart charger for shore power hookup, that’s 30A
And we want to add a cable from the starter battery to the other ctek, which would require a 300A breaker.

Added together that’s 680A x 1.25 = 850.

Do I really need busbars rated over 850?

Or is my logic wrong?

Thanks!

2

No, you do not bus bars rated for over 850A, but you do need beefy bus bars. The Victron Lynx products would be a good choice. See video here for a broader discussion of sizing bus bars: https://youtu.be/xCZEvgtnihk?si=-qrNEZk7W3E-S1AJ

1 Like
3

This book contains lots of info: https://www.victronenergy.com/upload/documents/The_Wiring_Unlimited_book/43562-Wiring_Unlimited-pdf-en.pdf

Why not use a Lynx distributor? That’s rated to 1000A.

Also I would look into a LiFePo4 battery, Lithium-ion is a lot more expensive and only used in specific use cases.

4

Published ratings and actual capability aren’t the same thing in the case of the Lynx products. But don’t take my word for it. Many threads have been posted on the community if you want to explore it. Including some by me. The Lynx products are great, even in very large systems, if you spread the batteries, sources, and loads evenly across the DC bus. See the video I posted above. Cheers!

5

Remember some of the items listed are taking current from the lithium battery and some putting it into the battery so they are not additive. Work on your max continuous loads and max continuous charging and take the larger of the two.

1 Like
6

That’s a great video, thanks for sharing!