High voltage LFP storage with Flying ADC BMS

[johu]

I still have around 150 LFP cells from Polo lying around and to my surprise many of them still hold some charge. I bought them 2010 and they were grossly overcharged once. So the plan is to hook them all up in series and keep swapping cells until only the good ones are left.

I will probably end up with a 128S system with 410V nominal. It is hooked up to the existing Sungrow inverter that accepts any input voltage from 150 to 650V or so. When fully built up this would be 16 kWh but I think the cells only have 50% life left in them, so more like 8 kWh.

The pack consists of 16S modules each one equipped with a Flying ADC BMS. So this also serves as a test bed for the latter.

[johu]

96 cells are now in. To my surprise still no burnt BMSes, despite even 2.1 hardware being in there.

Using a 16A breaker for cable protection and grounded the shelve to trip the GFCI when there's a problem.

Cables and bus bars are way oversized as I'm running max 15A here.

[usus]

Nice project. I wait for the third sefl 144 cells
One ideeea is to have the BMSs on the fornt and all the balancer wires beetwe therminals.
Otherwise i won't trust so much in one layer of insulation to go acros terminals (top wright module ) or crosing +/- wires (bothom left module)

BR.

[johu]

Yeah fair point. The black cables are double insulated but the red one obviously not. Will adjust that.

I had these pre-crimped wires handy but they limit me in length so BMS sits on top for now

[usus]

I know how it is to be excited of evolution of the project but sometimes need to take a step back

[usus]

I still have around 150 LFP cells from Polo lying around and to my surprise many of them still hold some charge. I bought them 2010 and they were grossly overcharged once. So the plan is to hook them all up in series and keep swapping cells until only the good ones are left.

I will probably end up with a 128S system with 410V nominal. It is hooked up to the existing Sungrow inverter that accepts any input voltage from 150 to 650V or so. When fully built up this would be 16 kWh but I think the cells only have 50% life left in them, so more like 8 kWh.

The pack consists of 16S modules each one equipped with a Flying ADC BMS. So this also serves as a test bed for the latter.

On sungrow max voltage is 600 VDC in the manual.
The caps inside are also 600VDC on Battery bus and are 5 PCs so I don't think are in in series.


Are those cells not 100Ah?
You mean 16KW for one shelf 48 pcs?
How long will take to top balance all the cells?

[johu]

Ok, that makes sense, the DC bus usually sits at 640V. So the battery voltage must leave some margin to this.

The cells were 40Ah. Now maybe 20Ah. So 6 kWh in the 96S pack

4 bricks started out perfectly balanced, I charged them to 3.6V while all 16 cells were in parallel. The other 2 packs are slowly closing in. It's maybe spent around 100 hours balancing

[usus]

Do you have good cells for one more shelf?