Where to place the Blockmons?

I have CALB 180AH cells arranged in 3p4s arrangement for 540AH @ 12v. These are used in my self built campervan. I just received my Watchmon4 and am wondering where the ideal placement for the Blackmons would be? Right down the middle?

Thanks in advance!!

Here is my setup





If you have a shunt, don't connect it directly to the cells like the picture on their website shows to do...unless they changed it

Wattsup said:

Here is my setup





If you have a shunt, don't connect it directly to the cells like the picture on their website shows to do...unless they changed it

Click to expand...

Nice setup. I only have 4 Blockmons total for my setup. So 1 for each group of 3 cells. I was more curious if there is a recommended placement when attaching the Blockmons to a parallel group.

Thanks!!

In the centre will be fine.
Just make sure the bolts still have enough reach with a blockmon & links, etc stacking up.

Note that at the left side of your pack, the cable/fuse, etc should connect to the top side ie the cell marked #10.
You have kept the nice parallel current flow design until the left side 3 cells!

Redpacket said:

In the centre will be fine.
Just make sure the bolts still have enough reach with a blockmon & links, etc stacking up.

Note that at the left side of your pack, the cable/fuse, etc should connect to the top side ie the cell marked #10.
You have kept the nice parallel current flow design until the left side 3 cells!

Click to expand...

Thanks for the tip! Ill make up a new cable and make the adjustment.

The parallel bus bars carry a lot less load than the series bus bars;
The series bus bars carry the full current draw.
The current the parallel bus bars carry reduces by 1/nth for each parallel link with n being the number of cells from the series link to the end parallel cell.
In your setup n=3 so the 1st parallel link carries 2/3 of the current draw and the 2nd 1/3.
If you put all the series links and end terminals in the centre it would give you n=2 in both directions so the parallel bus bars would carry 1/2 the current draw.
Same formula works for your Blockmons on the parallel bus bars, as they draw such a small current wherever is convenient is fine.

PJon said:

The parallel bus bars carry a lot less load than the series bus bars;
The series bus bars carry the full current draw.
The current the parallel bus bars carry reduces by 1/nth for each parallel link with n being the number of cells from the series link to the end parallel cell.
In your setup n=3 so the 1st parallel link carries 2/3 of the current draw and the 2nd 1/3.
If you put all the series links and end terminals in the centre it would give you n=2 in both directions so the parallel bus bars would carry 1/2 the current draw.
Same formula works for your Blockmons on the parallel bus bars, as they draw such a small current wherever is convenient is fine.

Click to expand...

So if Im understanding you correctly. The mostideal setup would be to run the series straps right down the center? If I were to do that. Would the positive and negative cables stay where they are currently positioned? Or should those be moved to the center as well?

Thanks!

Ideally the cables would move to the centre as well so the end bus bars are centre tapped as well.
Unless you have a fairly high current draw its pretty accademic, especially as your series and parallel bus bars look to be the same.
Your series bus bars are under much more load in any situation.

Jon said:

Ideally the cables would move to the centre as well so the end bus bars are centre tapped as well.
Unless you have a fairly high current draw its pretty accademic, especially as your series and parallel bus bars look to be the same.
Your series bus bars are under much more load in any situation.

Click to expand...

When the rooftop A/C is running. I can see + or - 120amps at 12volts. The alternator can supply 130amps chargingas well. I dont know if that qualifies as a high load or not. So far, the bank has performed well. When I check the links under load. They never feel warm.

GeauxWandering said:

PJon said:

The parallel bus bars carry a lot less load than the series bus bars;
The series bus bars carry the full current draw.
The current the parallel bus bars carry reduces by 1/nth for each parallel link with n being the number of cells from the series link to the end parallel cell.
In your setup n=3 so the 1st parallel link carries 2/3 of the current draw and the 2nd 1/3.
If you put all the series links and end terminals in the centre it would give you n=2 in both directions so the parallel bus bars would carry 1/2 the current draw.
Same formula works for your Blockmons on the parallel bus bars, as they draw such a small current wherever is convenient is fine.

Click to expand...

So if Im understanding you correctly. The mostideal setup would be to run the series straps right down the center? If I were to do that. Would the positive and negative cables stay where they are currently positioned? Or should those be moved to the center as well?

Thanks!

Click to expand...

Yes. You may as well move them all to the center. It doesn't look difficult to do. It may not make a huge difference. However after 100s of cycles it might.

Either method has it's good & bad.
I would not change the links other than left side ones per my earlier post, this seems to be the accepted best practice.
There's a few different factors here:
a) balancing device position (low current device, doesn't really matter which cell these are on)
b) main load/charging current path (much higher currents, important to understand)
c) higher or lower currents in the parallel links with different link designs
d) cell current flow/life imbalance from parallel link voltage drop
With a nominally 12V pack & relatively high currents like this pack, the cell load imbalance will be higher if you change to series links down the middle as suggested.
The centre cells would see a little more use with the "outside" cells (ie top & bottom ones) seeing a bit less.
The parallel method you have now keeps the current & cell usage per cell a bit more equal.
That said, the short, solid copper links will have very low resistance & so it's not as important as if you had longer cables joining cells etc. ie the cell current imbalance effect would not be much.
Bolt length is going to get more interesting....