Help me confirm my setup (3x 16s1p 280Ah)

[MaximusAnonus]

Hi,
for my sanity sake please do help me confirm the correct order of actions for my packs.

It's 3 packs of 16 cells each, on custom made stainless steel rack, shelves made of Cetris (essentially sawdust and concrete), end plates made from 15mm (1/2 inch-ish) Pertinax (FR-2? in the US?) with 1mm Pertinax plates (1/32 inch-ish) plates in between the cells. All held together with six M6 threaded rods per pack.

So right now it's all roughly assembled, NO compression is applied.
The cells in each pack are connected in parallel. Packs aren't connected together.
I will discharge the packs to 3.00V.
Then I will make final touches to makes sure the whole contraption is square and without any twist etc. And GENTLY "compress" the cells. "Compress" as in there will be no slack in the threaded rods and the cells won't move when pushed from the side etc.
After that's done I will charge the cells together to 3.65V.
Then I will disconnect the busbars, connect my new custom made busbars, balancing leads, connect the BMS, fuses etc. and it's all done.

Correct?

 

[#40Fan]

Looks good to me.

Even though you might not be looking for a specifc torque to tighten the nuts on the all-thread, I would still use a torque wrench to ensure they are all uniformly tightened.

 

[MaximusAnonus]

Good idea. I reckon it will be just a few N⋅m (single digit ft⋅lb) fortunately I've bought a very small torque wrench for stuff like battery terminals and fuse terminals so I can dial that down pretty accurately.
It'll take some time tho. Should've bought more powerful battery tester. That anemic 40A version will take forever. ?

 

[Bleedingblue]

Looks good to me. I hand tightened mine with a ratchet and just used God given common sense on how much torque to apply to the nuts to not break them off like so many else have done

 

[MaximusAnonus]

Hi,
I'm charging the 1st pack and I do wonder does this still look ok to you?

I aligned the cells as best as I can do. The difference between the sides is 0.5mm max.
But the cells aren't perfectly aligned (about 50% charge).

Is this something I should be concerned with? Looks like a very slight swelling.

 

[MisterSandals]

I'm charging the 1st pack and I do wonder does this still look ok to you?

Charging from the middle will result in unbalanced current to the cells. The current will flow along the path of least resistance, across the middle cells and charge them disproportionately.

Put the negative and positive on opposite ends for better results.

 

[MaximusAnonus]

It's 40A on 16 cells. Surely this wouldn't cause the light swelling?

 

[LydMekk]

Charging without a BMS is a risky sport and may create swelling if cells overvoltage.

 

[MaximusAnonus]

Talk about not having a clue lmao.

 

[TomC4306]

Charging without a BMS is a risky sport and may create swelling if cells overvoltage.

They're in parallel.

 

[Steve_S]

Top Balancing your cells to 3.600-3.650 until the amps taken hits 14A to 10A and your done. Allow the cells to settle for at least 2 hours and check your voltages etc. NOTE that Voltage WILL drop as that is perfectly normal & acceptable, they will likely settle to around 3.500 within 2 hours.

When you are happy with the results (as long as they do NOT settle below 3.400 (sitting static) you're good to go.
When "compressing" the cells, do it only "hand Tight" and at 3.200 Volts per cell which is 50% SOC. (Dead Horse topic I won't argue, I use Factory Info not public raucous debate)
Remember the working voltage range for LFP is from 3.000 to 3.400 with Nominal Voltage being 3.2 volts per cell. TIP ! It is best to do this when everything is at an Ambient Temp of 25C/77F and YES it does make a difference.

Once you've assembled your packs with BMS and have all your settings done, charge your battery packs to 3.500 until Amps Taken drop to 14A.
BTW, The EndAmps/TailCurrent for 280AH Battery packs is 14A. Without load once full that should settle close to 3.425 V per cell +/- a bit (normal).

 

[MaximusAnonus]

When "compressing" the cells, do it only "hand Tight" and at 3.200 Volts per cell which is 50% SOC.

I did hand tightened these at 3.000V. Do you think I've damaged the cells by that?

 

[Steve_S]

I did hand tightened these at 3.000V. Do you think I've damaged the cells by that?

No that should not be a problem as long as pressure is even across the cells.