Need some help with building my first 16S LiFePO4 battery packs.

Hello from Europe!

I have Deye SUN-12K-SG04LP3-EU three phase 12kW hybrid inverter and want to build couple of battery packs for it. I've spent many nights on reading, have formed some opinions, but there are still some unknowns. Would be great to get some help from more experienced guys.

TL;DR version:
* which fuses should I buy in Europe for 60A 250A?
* which connectors should I use for connecting/disconnecting the battery packs?
* where can I buy genuine JK BMS?

Long version:

Inverter supports 40~60 V batteries and has charging/discharging current of 240A. I'd like to be able to fully utilize it. The current seems to be a bit large, so I've decided to build two 16S battery packs and use them in parallel. I'm going to use 50mm² wires for connecting everything, their specification state that they can be used for up to 274A continuously, should be enough.

Unless something goes wrong, I'm going to use LF280K cells. I've already ordered them, they should be delivered in a month or so.

For the protection, I'm going to use some kind of fuse. Haven't decided which fuse to use. It might be either Class T from amazon.com ($45 for holder, $40 for the fuse, + shipping, + taxes?), or something cheaper that would be available in Europe. I'm bad at finding the right fuses, there seem to be too many types of them (I do know that ANL fuses from aliexpress is going to be a bad choice), so might as well just go with Class T from Blue Sea Systems and/or Littelfuse from amazon.com, I hope they will never trip and I won't need to buy them again

I don't trust DC breakers from aliexpress, but the ones from well known brands that I was able to find were rather expensive. My current plan is to skip using DC breaker and leave handling accidental slight overloads to the fuse…

For connecting/disconnecting the battery packs, I might be using Anderson SB175 connectors. That way, I would be able to quickly disconnect them (no need for a switch). Or, perhaps, there are better connectors? I've never used any connectors with such large currents, Anderson was chosen only because I saw it being mentioned in this forum.

Now for the BMS… From what I understood, there are three main brands - Daly, JK and JBD. While I have seen some comments about failing JK, they seem to be repairable, whereas Daly seems to have much more issues (or is it just much more popular?) and seems to be harder to repair. I don't really remember why I chose not to use JBD.
My initial plan was to get 250A Daly BMS - they have 125A charging current, 250A discharging, perfect for my needs. Though, after seeing all those comments about issues with Daly, I think it would make more sense to get the JK BMS. Probably something with 2A balancing current and 200A charging/discharging current (unless there's something from JK with 250A or 300A charging/discharging current).
Where can I buy JK BMS that would not be fake/scam? Is https://vi.aliexpress.com/item/1005006014535487.html the right store on aliexpress? It says "Pre-order", "Releases on Oct 20", can we trust it? Or has it been already postponed several times?

I use Blue Sea ANL fuses with Midnite Solar DC breakers. I just installed BMS from lithiumbatterypcb.com looks that company that makes JBD.

As you are building 48V/16S packs with EVE 280AH cells, they can handle an output of 280A for 1 hour and take 140A for 2 hours to charge. That is pushing them to the spec limit. With battery packs in parallel, you are actually dividing both the load & charge between the battery packs. Two of these batteries could deliver 560A.

JKBMS are fine, they sell a LOT and of course there will always be a dud but then there is the "user" factor too... People forget that Static can kill fine electronics... The new version is JUST coming out and still limited as they are still debugging them... There is nothing MAJOR, just a fair number of tweaks, mostly software (PC) and the firmware. They will support many inverter types and they are slowly implementing the support for the many brands. JK is also the ONLY SMartBMS with proper Active Balancing built in and that does make a positive difference.

The link to HankZor is correct, their prices - ugh...

In Latvia, you should have fairly easy access to Victron components and they sell busbars, fuses etc... In fact their Lynx Power bars use Mega Fuses.

On DC Breakers & Fuses, you are quite correct, stick to name brand known good... Bottom line, you're protecting your ass & investment at the same time, NOT the thing to compromise on. Blue Sea products are readily available on Amazon (even in EU) and Midnite Solar uses Carling Technologies breakers which you can order as well via amazon. DO NOTE that DC Breakers have shifted to using Polarized Breakers in North America finally (which fools went nuts over) but they are common in Europe and most nations require Polarized Breaker to pass for safety.

Hope it helps, Good Luck.

Damn... Missed your answers :D

"Leaked specifications" of LF280K state that both charge and discharge rates of those cells are 1C (continuous), pulse charge/discharge - 2C for up to 30 seconds, so two battery packs could safely deliver over 1000A for 30 seconds without harming the cells. The limiting factor in my case would be the inverter - its specification states that the max charge/discharge current is 240A. This limit can be lowered in inverter's configuration.

I ordered those BMS, but the buying process is kind of weird - not like anything else I have ever ordered from aliexpress. At some point, the order was closed (canceled?) and the payment was refuned. At that point I thought that I'll never receive those BMS, but they were actually delivered yesterday. Not sure what I have to do now to actually pay for those BMS.

After I ordered them, Andy from OffGridGarageAustralia posted a new video on youtube where he described a lot of issues with those new BMS, but it seemed like the basic functionality (setting limits, charging, discharging, balancing) was working fine.

As for the fuses, I'm now leaning towards using two fuses in each battery pack - cheaper ANL for dealing with slight unexpected overcurrents (might be 250A or 300A) and more expensive Class-T for dealing with major issues (400A?). That would be cheaper than using proper DC breakers, but should give enough safety. Would that make any sense?

Steve_S said:

The link to HankZor is correct, their prices - ugh...

Click to expand...

As I wrote, the buying process turned out to be "kind of weird" in my case, but it now seems to be finalized. The final price is actually not too high, it's much lower than I expected. It could be that a set of Daly components (BMS, display, balancer, interface card, "parallel current limiting module"?) would have been more expensive.

Here below is one of my simplified diagrams for paralleling AIO type systems with paralleled batteries showing 12V as the example, but applied up to 48V systems.

The most basic form uses, 1 Fuse or Breaker per battery pack, the fuses can be Class-T or Megafuses. 12V->24V can also use MRBF fuses.
A "Main Breaker/Fuse" can also be installed between the Switch & AIO (or in this example the AIO Busbar. That has to be rated accordingly.

There is a catch though.
You have a Deye SUN-12K-SG04LP3-EU three phase 12kW hybrid inverter. That translates into 48V @ 250A draw and as this AIO is High Frequency it is capable of pulling 500A from 48V Battery Bank for surge handling. (this is rough math, no corrections for losses or inefficiencies).
The surge handling is only a short period event so that is not a major concern.
If you are going to have a "Master" Fuse/Breaker between the Battery Bank & AIO, this should be rated to 250A.
The EVE 280K Batteries can discharge up to 1C (280A for 1 hour) and take 0.5C (140A Charge for 2 hours).
Fuse each battery pack to match the BMS, if you got 200A BMS', then use 200A Breakers...
With Batteries in Parallel, both the Charge & Discharge energy is shared (divided) between the individual battery packs, proportionately.