Bus connections for my new pack build

willo

Solar Addict
Joined
Apr 8, 2020
Messages
412
I've been futzing around with how to build the pack in my sailboat.
I had the idea to use copper 101 bus bars last time, but trying to drill them in a decent manner without my drill press (Boat is 2600miles from my house)
was painful. I didn't like the results.

So, I'm doing round 2 and I am changing it up - and I've ended up returning to the design of my previous build.
Interestingly, I completely ignored this work when trying to design the new pack. It turns out that my brain still thinks the same way.
On my RV build, I made up 2awg jumpers. I've decided to do this again. The twist is that in my RV, I used pairs of 280Ah cells. In my Boat, it's triplets.
img_20210424_181614-jpg.46557


I looked at making up braided copper bars at home, using my 12ton press and some pipe to make up custom ends.
However, the gauge available for that is somewhat poor. Of the few sellers documenting, 1" braid was 8awg effectively.
I may come back to the idea and consider making some up to replace the parallel bars.

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Messing about on my whiteboard I ended up with this last night.
It uses three 2awg flexible bus jumpers at each interconnect.
2awg is good for 120A at length and even more at short distances like this.
Still, that puts me at 360A throughput. Not bad.
Each jumper is the same length.
Note the staggered bus bars used to parallel the cells. I drew up the minimum needed - this is fully dependent on how many bars I have.
The stagger is to keep them parallel to the packs. (yeah, I can washer it as needed.)
I have 1 bus bar per cell (with shipping delays I didn't ask the vendor to send me the doubles they promised)

On the ends, I'm making up bus bars with the 101 I previously bought.
I'll drill them, test fit, and then nickel plate them.
By using flexible jumpers to the bars, I'm allowing for flex and I don't have to be super precise with my drilling.
. Those will be used to terminate 1/0 gauge wire to my inverter/fuse.

I'm reasonably happy with this design.
Each set of interconnects requires 6x ring terminals. For the 8s pack, I need 7 sets, so 42 terminals total.
I ordered 50 along with some 2awg tinned marine wire and even splurged on a hydraulic crimper (instead of my hammer crimper)
 

S Davis

Solar Enthusiast
Joined
Sep 25, 2021
Messages
165
I thought about using wire and lugs but was worried about all the crimps and movement/vibration in a mobile application. I have an extra 30 3/0 lugs now.
 
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