Idiot's guide to a self build battery

[Joeboy]

Finally got around to running a 12V striplight in and tagging it back to a 12V 80Ah LB which is charged by our roof mounted WT.

A long route to light yet it works. 12.24V on the LB.

[Swwils]

What's the price difference between the CATL cells and a pylon stack?

How do you integrate the two?

[nowty]

Just make sure of your max voltage for the Pylontech. (Over 55v and they will require a new BMS).

So as well as the new "C" versions being 0.5V lower max charging spec when compared with older versions, they want another 0.3V below their own lower spec when using manual control.

Mine are still ok as I charge to 56.4V but need to subtract my extra cell, so its 56.4V - 3.5V = 52.9V.

But its something for others with parallel packs to watch out for, the max charge voltage should be 53.2V and not 53.5V as it says in the general spec. I certainly was not aware of that.

[Tinbum]

So as well as the new "C" versions being 0.5V lower max charging spec when compared with older versions, they want another 0.3V below their own lower spec when using manual control.

Mine are still ok as I charge to 56.4V but need to subtract my extra cell, so its 56.4V - 3.5V = 52.9V.

But its something for others with parallel packs to watch out for, the max charge voltage should be 53.2V and not 53.5V as it says in the general spec. I certainly was not aware of that.

Under BMS control the max the battery will ever ask for is 53.2v for the C types inc the new US5000.

[Joeboy]

What's the price difference between the CATL cells and a pylon stack?

How do you integrate the two?

Hey pal, it's all in the thread.

[Caesium]

What's the price difference between the CATL cells and a pylon stack?

How do you integrate the two?

Prices are around $110 per cell, then add on $400 or so for shipping and stuff. I'd say a rule of thumb seems to be its currently working out around £2000 for 15 of these cells, shipped to the UK. The 280Ah cells are 0.9kWh (3.2v * 280Ah) each, so thats about 13.5kWh. Compare that to Pylontech prices from a supplier of your choice But don't forget you need to add in quite a lot of extras really (balancer and/or BMS, cabling, fuses, breakers).

Integration is really as simple as paralleling them up. Most of us doing the build so far are, I believe, currently relying on the Pylontech brains to keep talking to the inverter, treating this as a dumb DIY extension to that. But I'm going to take it a step further soon and remove my Pylontechs completely once I get my second battery delivery. Updates to come on that in due course

Do recommend reading through the entire thread if you're considering this though, its long but full of good info.

[Joeboy]

Last piece arrived this afternoon, I now have at a glance cell voltage display above Nowty's sheet of excellence.

[Swwils]

Ahh ok makes sense.

Surprised that the inverter doesn't notice this and complain!

Aren't pylon a werid 15S pack instead of 16S?

[Caesium]

Surprised that the inverter doesn't notice this and complain!

There's not much for it to notice really. The battery still looks like a Pylontech battery, its just bigger capacity. I think the Pylontechs do report their capacity back to the inverter so it theoretically could notice that the battery is taking a lot more charge than it should. But do any in practise? I seriously doubt it.

Aren't pylon a werid 15S pack instead of 16S?

Yes exactly, we have 15 in series if you want to parallel them up with Pylons

I will be uprating mine to 16S once I remove the Pylontechs but that's a story for another post

[Joeboy]

Ahh ok makes sense.

Surprised that the inverter doesn't notice this and complain!

Aren't pylon a werid 15S pack instead of 16S?

As Caesium says, it is quite simple and worth doing. I ask anyone thinking of doing it to read the whole thread so we know they are reasonably aware of what they are getting into.

In saying that, I completely blew the charge window last night and started this morning with only 45% soc!

The upside of that failure on my behalf is an inadvertant real world use test of the new battery storage capacity. We've had a kWh or so coming into the stack from PV at best yet we are sitting at 31% soc. To ensure we get to the 21.30 charge window without touching the grid I'm hoping to use the Hyundai Ioniq 5 to cook homemade chips later.