BMS now installed and the old one out. Process took about 30mins from start to end. The longest part being moving the Pylontechs on the top off and back on.

Simple 1 for 1 swap out. Lets see if we get any more errors, but I cant see anything... yet. If I get errors then it is probably my Inverter, which is a much bigger issue!

@batalto

I hope that you have resolved your problem, the grid needs all the help that it can get at the moment.

@derek-m no issues since I swapped it. So looks like it was a bad board. I'll see if I can fix it and I've got another BMS then!!

Small update. I ordered another Seplos box over Christmas and it should be winging its way to me by the end of the month (hopefully). It's the new version with the Bluetooth connection. I also asked for another Bluetooth connection for my existing battery, which was supplied for $10. Seplos also gave me a nice discount for being a returning customer - so props to them.

@chickenbig has also kindly sold me some of his surplus 280ah Lifepo4 cells - 16 in fact. They'll be collected tomorrow and hopefully with me for Friday. Then I'll need to top balance. This time I'm going with a suggested practice of combining them into 14v groups (4x3.5v) as I'll be able to get more power into them with my power supply, so it'll be quicker. Then do a final top balance with all the cells at 3.6v once they've all been brought up.

As ever I'll try to document my experience. To pay for all this I've sold some of my Pylontech batteries and I'll be selling the rest once this battery is up and running. Then my last step will be to swap out my chargers for ones with more grunt. My current ones will only charge at 3.2kW. I want at least 4kW (80A) so I can ensure my 30+kWh of batteries can be charged in 4hrs. 2 x 4kw x 4hrs = 32kwh of charge capacity... Perfect

Nice!

Out of interest, what kind of price are you managing to get for your Pylontechs?

My Seplos kit arrived a couple of weeks ago with all the loose bits in a cardboard box as per the company's previous communication regarding their improved packaging procedure.

@korwraith I sold 2 of my US2000 batteries for £750 each (£0.31/wh), including cables. I still have 2x US3000 and 1x US2000 batteries left. But not selling those until the new Seplos battery is in and the Pylontechs will be surplus - Literally wont be able to use them. I'll be selling the US3000s at the same price per wh (so about £1100)

Cells have arrived - So props to @chickenbig he's been a great seller!

I am top balancing in blocks of 4 x 280ah cells. I'll do the cells at 3.5v each, so 14v total. Then when all 4 packs are done, I'll put them in series and do 3.6v across all the cells.

If I do the whole 16 at 3.2v I can only put in 32W: 3.2v x 10A     If I do 14V I can get 4x the power into 1/4 of the cells. Hopefully it'll be much quicker than the 2 weeks it took last time. Then again the box isn't here, so not like I am in any rush!

First set of 4 is up to 3.56V so I've moved to the second set. This is way quicker than 3.6V as a first step

Second set also charged, so now the third and I imagine the 4th will be on tomorrow. Then I think I'll connect them all up to make the battery and leave them to equalise before I do the final top balance when the box arrives at the end of the month (hopefully).

I've had to bring cells into the house due to the low temperatures outside (where my workshop/shed is). So they are charging in a spare room - 16 in parallel at 3.6V and 10A. In for the long haul....

Cells are basically top balanced now - 3.63V. I've turned off the charging as I don't want to over charge and I will now wait until the Seplos kit arrives to balance up to the 3.65V. Should be a very quick install from this point onwards! Just got to play the waiting for a box to arrive game

I don't think you need wait until you get the Mason box from Seplos before 'finishing off' the top-balancing @batalto

In any case you've been doing it with four cells at a time and in series... which defeats the object of the exercise.

Now you've got them all at a high level of charge, simply place all 16 in parallel and drive in the last bit of the charge with the power supply set at 3.64 volts (if that's the top voltage you've chosen).
They absolutely must all reach this same voltage before you try hooking them up to the BMS in the Mason box.
The ones you did first will not have retained the voltage you took them to.

For others who come across this discussion in months to come, the above pedantic explanation of top-balancing is due to the Mason box have a BMS which has passive balancing.
Ie it can slowly drain a small over-charge from a cell, but it cannot add any charge to a cell with a lower voltage than the others.

I'm about to deploy a BMS which has integral active balancing.
In theory that should be capable of completing a balancing operation which 'hasn't quite been completed'.

But in reality, it could take many days to do so because the maximum active balancing current is 1A.

A bench-top power supply, such as @batalto and I have, can deliver 10A+ and is therefore preferable.