Bus bar for paralleling multiple batteries

SD_DRACULA

Apparently paralleling 2-3 packs is best done via busbar to keep the temps low and the load constant instead of connecting them to each other and having a main + and - cables.

Looking two busbars that can take 300a and I want something that looks nice in an enclosure not just a naked copper bar.

Only thing I seem to find is something like this

https://www.amazon.co.uk/Distribution-4-Posts-Terminals-Automotive-Battery/dp/B0CPBC3NC2/ref%3Dpd_ci_mcx_mh_mcx_views_0?pd_rd_w=kLvxm&content-id=amzn1.sym.6aea875e-359f-49f3-864f-cff62d586b6a%3Aamzn1.symc.ca948091-a64d-450e-86d7-c161ca33337b&pf_rd_p=6aea875e-359f-49f3-864f-cff62d586b6a&pf_rd_r=MMJ0TD93BARYRFD9VFFP&pd_rd_wg=UzGTm&pd_rd_r=874c6f8f-041b-4546-b99d-34d8cfea501d&pd_rd_i=B0CPBC3NC2&th=1

Any other suggestions?

10-10-20

I though I'd find bus bar at some of the electrical wholesalers' sites, but none to be seen really. I did find some here though:

https://mpe-online.ie/?post_type=product&taxonomy=product_cat&product_cat=0&s=bus+bar

It's a company in Mayo, FYI.

Have a read of this document also:

https://www.victronenergy.com/live/_media/ve.bus%3Arva_-_theory_on_wiring_large_systems.pdf

Pages 9 to 13 especially.

SD_DRACULA

This is how I'm thinking:

10-10-20

https://www.boards.ie/discussion/comment/121946380#Comment_121946380

Looks ok, just keep the conductors the same length and the diameter of the cables sized appropriately.

darraghsherwin

I am using these busbars https://www.amazon.co.uk/HOIIME-12-Distribution-Terminal-Performance/dp/B0B941ZWPS/

I am only pushing 100amps as that is the limit of the inverter

SD_DRACULA

https://www.boards.ie/discussion/comment/121946391#Comment_121946391

I am thinking 35mm2 from battery packs to the bus bar and then 70mm2 from bus bar to breaker and breaker to inverter.

Each pack will be limited to 100a so I think the numbers are ok

jasgrif11

@SD_DRACULA I have the ones you are looking at from Amazon. I would definitely recommend them. Very robust and easy to have 4 x 50mmsq cables in them. I’m pushing 180A no issue.

oaklands

In your image, I would put the cable to the isolator & Inverter into one of the 2 middle positions of the busbars on both + & -

In reality those Jean Muller isolators (I have same) have really beefy terminals. It may be possible to connect all 3 wires to the each of the terminal avoiding the need for bus bar.

The fuse in the isolator should be for 100A + some margin & designed to protect the weakest of all the cables shown above. ALL cables should be rated for at least 100A+.

SD_DRACULA

https://www.boards.ie/discussion/comment/121946551#Comment_121946551

I have 200a fuses in it and yeah currently I can fit 2x35mm2 cables just fine on the terminals of the JM, lugs back to back, but I doubt can fit three (going to try)

I'd prefer less cable breaks if I can avoid them.

Also if I push more than 200a over the JM, will my fuses blow and I need 300a ones?

oaklands

You could try mounting the metal part of the bus bar directly to the JM teminals..... then connecting the battery wired to the other positions on the bus bar.

Although insulating the bus bar & allowing it to open might be a challenge.😁

A fuse will be useless if the cable melts (or worse) before the fuse blows!!!!

So if you got 190A sustained for some reason...fuse may not blow......but cable/bms/cells???????????

SD_DRACULA

https://www.boards.ie/discussion/comment/121946868#Comment_121946868

I know what you mean I could insert one (or two) of the battery bus bars in the terminal of the JM and then have 3 holes for the battery lugs but yeah enclose it in a box or something.

Don't see why my cables should melt at 190a, divided by 3 packs, is nothing for 35mm2 cables? Each bms of each pack is 200a as well so no issue there, am I missing something? Other than blowing the JM fuses if I go over 200a at 15kw o'clock?

Then again every battery pack has a 200a dc breaker in it so I'm not sure I even need the JM other than disconnecting everything at once.

oaklands

@SD_DRACULA I started writing a response that opened up a lot more Qs than answers. So instead, just treat my comment above as a general point that fuses are there to protect the cables & the cables are essentially everything from the Inverter to the B+/B- terminals of the cells inside each battery.