Random Renewables Thread

Pylontechs are all 15S. Wouldn't recommend them though 😂

BTW you can't have comms between your existing pack and your Solis inverter AND between any other pack and your Solis inverter at the same time

Nah not prone to overvoltage, the BMS will protect the cells. 3.55V is pretty much fully charged but not all that high. LiFePO4 can be charged to 4.2V without damage

Not sure if your plan is going to work, far easier to just do what @graememk and I suggested yesterday: just have your old Dyness do the comms with your Solis. Then hook up another 15S pack and it will just toggle along doing the same as the Dyness. The individual BMS on Dyness and on your other 15S pack will each protect their own batteries

If you want to test, you could just hook up 15 of any LiFePO4 cells in series - not even use a BMS if you are only going to test for a few seconds - and see if the plan works. I have some cheap 32700 cells you could use for your experiment if you like 😂

Since we're on the topic of batteries, how's about a video about flow batteries?

Unfortunately they're not for residential applications, but they seem to be getting more and more large scale

To me this is one of the more exciting battery technologies coming out because it only uses commonly available materials and is very easy to maintain and recycle

And to be fair to Redflow, they have batteries in the field for almost 8 years now so this is well beyond some lab concept

So the other way round is exactly what I wanted to know/test/validate. Basically if I had like 800AH of lifepo4 cells and a jk bms commuinicating with solis inverter I can have the dyness set as slaves. The solis + dyness only allow 50A charge discharge, I think it's the dyness bms but would like to be sure before committing to anything.

JK BMS doesn't talk natively to inverters though!

Personally I don't like all that talk anyway and machines that make their own minds up and tell each other what to do. I prefer them to just stick to their own thing and do as I tell them 😀

Right well that rules that out, I wont be using a JK bms in that instance. I'm not going soldering wires together to make a comms box. Even the chinese server rack batteries you buy can talk natively to solis. That's annoying. Daly BMS (while getting mixed reviews) seem able to communicate with solis.

Back to the drawing board.

Because without comms, the SOC on the inverter displays in voltage instead of percentage, and theres a warning light about can fail. Both of those annoy me no end

Yes, that throws the can fail error. To be honest, pack voltage is a better indicator of SOC anyway than the BMS predicted SOC, but I like seeing percentages and no warnings!

I think I'll just have to familiarise myself with the voltage range of 15S packs and go from there. I'm sick of the 50A limit.

Yeah I'm doing the same, but you only really have to do it once (set max and min pack voltages) in your inverter. The BMS will protect the cells. You could do your own table by multiplying the first column here by 15, but you are well versed in working with data 😁

What dyness battery you have? Mine sit at around at 56.5v when at 100% so your voltage seems low for 96%, mine is 53v at 96%

I did have to update them recently as I noticed the SOC was drifting and it turns out they got shipped from the factory with some sort of stupid 55.5v limit and they were never reaching 100%, rock solid since.

I assume you only have one of them 5.12kwh? And also the solis can only sustain 63a anyway so why bother for another 13a?

That's why I said multiply first column by 15 😂

Worth getting onto dyness and asking them to check the serial numbers and what FW version/parameters are on the batteries.

Maybe you need an update as well.

And you're at 17kwh usable unless you want to drain them to 0% and damage the cells eventually.

Yes its still on the default settings, 100 to 10 discharge. I dont have anything connected online anywhere, given how bad updates have been.

To be honest I think I need to either get something 15S with a bms that can speak to Solis and paralel it with the dyness, or just sell the dyness and go for the usual 16S setup

If I werent intending on expanding significantly anyway, yes I'd agree.