Idiot's guide to a self build battery

[billi]

I've been eyeing up these LF280's all morning (trying to convince myself not to buy some) and I've noticed they don't seem very heavy. The datasheet reckons they're 5.4kg each, so 15 of them to make 13kWh is only 81kg.

My 14.4kWh stack of 6 pylons is about double that.. 24kg * 6 = 144kg.

I'm wondering why the huge discrepancy, are the Pylons mostly just metal casing or what?

Good point !

[nowty]

Is your tweaked stack all good Nowty?

It was the easiest change I have ever made, didn't even need any new cables and all good.

[Joeboy]

Is your tweaked stack all good Nowty?

It was the easiest change I have ever made, didn't even need any new cables and all good.

Excellent, I am liking the idea of a remote screen showing battery voltage in the house. I'd be interested in that.

[Stinsy]

When are you expecting delivery Joe?

[Joeboy]

When are you expecting delivery Joe?

Aiming for Mid Nov (after 2nd eye surgery), the quote says 45 days from order and I'm paying the balance on the 19th Sept. I am inordinately excited about this.

Home next weekend so will be getting the groundmount string of 3 panels up top first thing and might start the wall mount for the batteries.


Is there a go to portable charger for these batteries? I ask as I'll be looking to balance them off against the Pylontechs pre final connection. I could go the other way I suppose and time the hook up for when the pylontechs are rising towards the interconnected LF280K's. Save a few quid....

[Caesium]

Well it's done - I knew this thread would turn out expensive for me

16 (I wanted a spare) LF280K at $110 each + $366 shipping (£1757 or so on a fee-free card) from Docan on alibaba. They have 30 days to ship it and then I'm guessing another 30 days on a slow boat so realistically it'll be a couple of months.

Also some long pylontech cables ordered (they seem to be on backorder most places so maybe get your order in now Joeboy), 20mm DC cable for misc interconnects (guessing I won't end up with one long chain of 15 of them), and a 15S balancer.

Considering how to bind them, I think I might just ghetto it with a few boards of ply either end of each string and cable tie it all together (metal ties maybe). Should this be sufficient? I'm not really sure how much pressure/force these things might exert outwards eventually.

You're a bad influence Joeboy

[Joeboy]

Well it's done - I knew this thread would turn out expensive for me

16 (I wanted a spare) LF280K at $110 each + $366 shipping (£1757 or so on a fee-free card) from Docan on alibaba. They have 30 days to ship it and then I'm guessing another 30 days on a slow boat so realistically it'll be a couple of months.

Also some long pylontech cables ordered (they seem to be on backorder most places so maybe get your order in now Joeboy), 20mm DC cable for misc interconnects (guessing I won't end up with one long chain of 15 of them), and a 15S balancer.

Considering how to bind them, I think I might just ghetto it with a few boards of ply either end of each string and cable tie it all together (metal ties maybe). Should this be sufficient?

You're a bad influence Joeboy

Well done, liking the poor impulse control! I am going for plywood end caps and threaded rod at 4 corners to ensure an even compression on the three banks of 5 batteries. I don't think it's worth it to shortcut it...

I am already off Pylontechs with the cables to the 2kW inverter so should just be cable and crimps now. I just chopped a spare short Pylontech interconnect cable, soldered it onto a DC cable going away towards 2kW inverter and taped it up.

I plead not guilty to 'bad influence' and would bring to the court, Exhibit A (Nowty) a serial tweaker of RE gear, I was merely a link in the chain m'lord.

I went with Senzhen Deriy new energy technology company Ltd. Some handle eh? Docan were on my shortlist too.

[Oldgreybeard]

Excellent, I am liking the idea of a remote screen showing battery voltage in the house. I'd be interested in that.

Might be worth looking at ESP Home and Home Assistant. Pretty easy to get sensors for things like voltage, current, power, temperature etc hooked up and displaying on either any device with a browser or, like I'm part way through doing at the moment, an e paper display (very low power, as used in ebook readers) as a handy reference. I'm putting together a display like this one, but with all the data from the inverter and battery system, plus the weather forecast, into a cheap Ikea photo frame (this isn't mine, just one of the projects I'm using for ideas):

[Joeboy]

Excellent, I am liking the idea of a remote screen showing battery voltage in the house. I'd be interested in that.

Might be worth looking at ESP Home and Home Assistant. Pretty easy to get sensors for things like voltage, current, power, temperature etc hooked up and displaying on either any device with a browser or, like I'm part way through doing at the moment, an e paper display (very low power, as used in ebook readers) as a handy reference. I'm putting together a display like this one, but with all the data from the inverter and battery system, plus the weather forecast, into a cheap Ikea photo frame (this isn't mine, just one of the projects I'm using for ideas):

Oh, I like that!

[Joeboy]

I read an interesting thing the other day. Apparently the aluminium cases that these Lifepo4 batteries are in are conductive and its only the paint/plastic layer that holds back communication between the packs? This means that even if only a remote possibility then the packs should be insulated from each other? I guess a thick paper sheet between cells would be enough? Anyone else heard this? Below is the text as I found it, worth knowing.

'REMINDER TO ALL! : The aluminum cases of the EVE batteries are conductive, and you should NEVER use conductive materials (like hose clamps) to strap/bind cells. If the strapping wears through the blue covering (it will) or worse through the aluminum case (it can) then short circuits can occur through the strapping resulting in cell damage, heating and some cases fire'