Xuba 12v 100ah from alibaba

[Philo DuFresne]

I purchased two of these batteries, thinking i can order two more fairly soon(2 months or so). Brian said they will have matched BMS, and low temp cutoff. Am i missing anything obvious about these batteries? The price just seems so great, and the company gets high marks so far here and in online reviews. Thanks for any help or advice. Just fyi, I'll be running a 24v system and a 2000w 24v inverter.

This product is no longer available.

This product is no longer available.

m.alibaba.com

 

[Steve_S]

TBH, you should have bought ONE 24V/100AH prebuild and then the next would go in Parallel giving you 24V/200AH.

By setting batteries in Series to make up 24V, if one cuts off for any reason you will have issues. If charging at 24V and the 2nd batt cuts off then 24V will hit that one 12V battery. NOT GOOD. Hopefully, the 2nd BMS will cut off fast, else POOFDA the magic smoke appears.

If set in Parallel, each battery can operate as an independent entity if need be.
They will share load & charge between the pair.
They would balance each other voltage wise through their use cycle.
None of the above applies to Series Connected Batteries.

 

[Philo DuFresne]

TBH, you should have bought ONE 24V/100AH prebuild and then the next would go in Parallel giving you 24V/200AH.

By setting batteries in Series to make up 24V, if one cuts off for any reason you will have issues. If charging at 24V and the 2nd batt cuts off then 24V will hit that one 12V battery. NOT GOOD. Hopefully, the 2nd BMS will cut off fast, else POOFDA the magic smoke appears.

If set in Parallel, each battery can operate as an independent entity if need be.
They will share load & charge between the pair.
They would balance each other voltage wise through their use cycle.
None of the above applies to Series Connected Batteries.

There is no way to protect against that issue? It seems like a lot of folks use 12v in series to make 24v, or the 3.2v to make the 12v is huge. All these people are running this risk? What's the best plan, because the batteries most likely aren't going back to Shenzhen, return the 24v inverter and get a 12v?

 

[Steve_S]

IF the BMS is capable of coping with series connections (great many are not) you'd be ok.
It takes 4 cells to make 12V or 8 cells for 24V, when using LFP. They could use 50AH cells and parallel them internally too by using 8 cells to combine them up for 100AH total.

12V systems are usually fine up to 2000W Max from an Inverter because the amps drawn for 1000W = 83A, 2000W=166A (not derated) and that would allow for momentary surge capacity.
24V is good up to 5000W (generally kept below 4000). 1000W÷24=41.6A / 4000W=166A draw. (Not derated).
Multiple Amps by 1.25 for deration & margin.

 

[Philo DuFresne]

Can i purchase something like a secondary BMS, or something completely different, i am new, and add it to buffer against that effect? I'd like to keep the 24v inverter, if possible, for the smaller wires and added efficiency.

 

[Steve_S]

Design & plan usually comes before any purchasing. You did not mention what you are doing, what equipment etc.
Sorry but I cannot read minds, do nor do forensic reconstruction, nor can I guess.

1 Battery Pack = X# of cells, 1 BMS (4S for 12V / 8S for 24V) and a fuse per pack.

See links in my signature for more info as well.

 

[Philo DuFresne]

Oh, i have 4 100w panels, a 40amp mppt, both renogy, the premium kit, a 2000w 24v psw inverter, the 2 batteries i mentioned, and the fuses, wires, fuse blocks, etc, that Will recommend in his book/on his site. I did think i was done with design, you are the first person i have seen mention this potential issue.

 

[Philo DuFresne]

Can i ask what the general perception of Renogy is? It seems like it's a running gag for the more experienced crew, but is there anything actually wrong with it, or is the quality good?