One bussbar to rule them all... using one bar to connect multiple battery terminals.

[TWG]

Would it cause any problems to connect 4 topband 3.2v/25ah packs in parallel with one copper bus bar rather than 4 separate ones?

CORRECTION... ( I was still asleep!!!)

I did not state my question correctly... I should have said "TWO buss bars ( one for each polarity) instead of Six ( three to span 4 terminals)".

I bought copper bar and it takes less to make two long ones than six short ones. PLUS it should have less resistance in one piece than overlapping them... right?

 

[Boondock Saint]

As long as the bus bar is sufficient thickness and mass for the current, it should be a problem. There are lot's of possible bus bar configurations as interconnects. You don't have to buy something this expensive, but you see the idea behind it?

Ensure there is lots of clean surface contact area between the bus bar and posts etc or it will generate heat. (and waste your battery efficiency)


.

 

[Lt.Dan]

I dont think so... Connecting the Pos and Neg to all the batteries together doesn't jive in my mind. Maybe someone smarter than me can tell me I'm crazy though.

In parallel? Definitely.

In series? I dont think so.

 

[Boondock Saint]

I think the OP is making the difference in the little bus bars that come with batteries vs the long 4 pole ones that you make. In parallel. Of course it could just be my caffeine wearing off.

.

 

[TWG]

As long as the bus bar is sufficient thickness and mass for the current, it should be a problem. There are lot's of possible bus bar configurations as interconnects. You don't have to buy something this expensive, but you see the idea behind it?

Ensure there is lots of clean surface contact area between the bus bar and posts etc or it will generate heat. (and waste your battery efficiency)


.

I'm new at all this so I have to double check everything... but the studs on those batteries will only accommodate a 1/8inch bar thinkness and a M6 nut. I was going to use aluminum bar but at a max 5C dump on 16 of those batteries it exceeded the capacity of the aluminum at 1/8in thickness and 1/4 would not leave many threads for the nuts to hold on to. ( We all want our batteries to hold on to their nuts right??? ) - So.. I'm going with 1/8in copper bar but it is $$$ as we all know. That is why I'm being frugal and asking about using one bar to span 4 terminals.

 

[Lt.Dan]

Your picture above will work if all cells are parallel, but if you trying to achieve a series connection with 4 cells (to make a 12.8v nominal battery), then they have to be separate. If you place the cells in alternating directions (to make a series connection) and you place a bus bar across all 4 terminals on both side, then you will be shorting it out by creating parallel and series connections on the same battery!

This is the only thing I am worried about.

 

[100 Proof]

You mean like this?

 

[Lt.Dan]

You mean like this?

That is acceptable, and even what I will be doing on my batteries too. But joining them ALL together (like the picture in the first post) will short them out!

 

[TWG]

Your picture above will work if all cells are parallel, but if you trying to achieve a series connection with 4 cells (to make a 12.8v nominal battery), then they have to be separate. If you place the cells in alternating directions (to make a series connection) and you place a bus bar across all 4 terminals on both side, then you will be shorting it out by creating parallel and series connections on the same battery!

This is the only thing I am worried about.

Another question - On battery B - would it matter where on the buss bar of the end terminals - I attach to my load? My gut says to pull

I was thinking of one of these configurations...

Would it matter on battery B where I connect for the load?

Do you try to keep the farthest distance from the last connecting buss bar? If so.. the battery A would have to be connected to the inside terminal ends... Or does it matter THAT much?

 

[cass3825]

Here’s a pic of my 4p16s pack using 50Ah cells. Works great, but in hindsight I wish I would have built it as 16s4p and used 4 BMS in order to monitor each cell individually. Live and learn…

 

[TWG]

Here’s a pic of my 4p16s pack using 50Ah cells. Works great, but in hindsight I wish I would have built it as 16s4p and used 4 BMS in order to monitor each cell individually. Live and learn…

I was going to do that originally - but for a small 100ah battery - having 4 BMS seemed too complicated. I can see doing it for a large system like yours... I think LiFePo4 batteries are addicting... I want MORE POWER!!!!! Good thing I'm poor.... I really miscalculated what it would cost to build this one - not figuring in the buss bars .. a good BMS - case? External terminal ends... etc etc.