programming cc and connecting powerwalls?

[Ampster]

i dont understand why the company advertises that they can be put in parallel then? is there a reason they cant be put in parallel? sorry just trying to make sense of all this.

The reason the company advertises that way is to sell batteries. I think we earlier had a converstion about my feelings about the owner of the company. There are a lot of issues that need to be addressed to successfully put them in parallel. I take a risk management approach to understand the risks, evaluated whether they can be mitigated, apply those mitigations if cost effective or don't connect them. If you want several opinions so you can make up your mind go to diysolarforum.com and search for other users of those batteries.
You are also free to take the advice of the many sages here, including @Sunking, and forget about the batteries you bought. I am clearly in the minority and have been called a member of the Green Mafia and an Environmental Jihadist. I am just a DIY hobbyist who built his first Heathkit over 60 years ago but I am not a professional.

[Mcmullen7242]

i dont understand why the company advertises that they can be put in parallel then? is there a reason they cant be put in parallel? sorry just trying to make sense of all this.

[Ampster]

I do it professionally. I am not DIY.

Yes, and people should listen to your advice. There is a whole segment of the population out there that have critical thinking skills and like to hear several opinions and make their own decisions. Some will make bad decisions and the gene pool will become better.

[Sunking]

Are you sure about that? When I bought them I specifically told them I will be paralleling them and they said that’s not a problem, also they advertise that they can be put in parallel on the website

I do it professionally. I am not DIY.

[Ampster]

You can connect Lithium batteries in parellel if you understand the issues. I prefer to do it at the cell level, but with low cost BMSs many DIY users are getting low cost storage with used batteries like the above.
For another opinion go to diysolarforum.com

[Mcmullen7242]

You cannot connect lithium battery packs in parallel.

Are you sure about that? When I bought them I specifically told them I will be paralleling them and they said that’s not a problem, also they advertise that they can be put in parallel on the website

[Mcmullen7242]

57.4 volts is 4.75 volts per cell. Either that is way over charged, cell count in series is incorrect or that is some Lithium chemistry I am unaware of. It is consistent with the numbers they published. Perhaps it is 14S, in which case those cell voltages are consistent with NMC and the set points I gave you earlier are all wrong. How many BMS wires are there? I will answer the questions in your other post in a subsequent post.

I am not sure because everything is enclosed in the case and I’ll have to take it all apart to check. The only things showing outside the case is the port for the Anderson sb50 connector, the voltage meter, and breaker.

[Sunking]

You cannot connect lithium battery packs in parallel.

[Ampster]

..... Also I don’t need to buy a new bms correct?
Can I program the one that the batteries came with?

I don't know anything about that BMS. You will have to see what luck others have had. I lot of people have purchased those batteries and have experience with them that I don't have.

I thought to put them in parallel I would just need to make two Anderson y connectors putting two positives together and two negatives to one Anderson sb50

Yes that works or Andersons to a common buss bar where your fuses or breakers are to protect the wire. A lot of people like breakers to disconnect for diagnosis. Blue Sea makes a good AB switch also.

[Ampster]

Just checked the batteries, one is at 57.4 and the other is at 58.3

57.4 volts is 4.75 volts per cell. Either that is way over charged, cell count in series is incorrect or that is some Lithium chemistry I am unaware of. It is consistent with the numbers they published. Perhaps it is 14S, in which case those cell voltages are consistent with NMC and the set points I gave you earlier are all wrong. How many BMS wires are there? I will answer the questions in your other post in a subsequent post.

[Mcmullen7242]

Just checked the batteries, one is at 57.4 and the other is at 58.3

[Mcmullen7242]

Thank you very much, I’ll check the voltage on the batteries shortly and let you know. Also I don’t need to buy a new bms correct? Can I program the one that the batteries came with? I thought to put them in parallel I would just need to make two Anderson y connectors putting two positives together and two negatives to one Anderson sb50

[Ampster]

.......
Nominal Voltage: 52.5V

This number seems too high. Do you have a voltage for what your pack measures at its current state of charge>

Configuration: 12S

This is a critical number to remember in order to translate pack voltage, charging and other settings into per cell numbers.

Chemistry: Li-ion

That is a generic term that includes LFP NMC and others. Most likely this is NMC which has per cell ranges that I will discuss later.

Maximum Charge Current: 65A
Maximum Discharge Current: 130A

Good to know for determining wiring size and breaker sizes. Since you will be putting these in parallel those numbers could double but you probably won't be able to charge at that rate and probably don't need to discharge at that rate.

Cell Over Charge: 4.20V

This is the biggest clue that the chemistry is probably NMC which is the same as my Nissan Leaf modules and similar to my Teslas. I set the Absorb voltage on my Leaf pack to 4.05 per cell which translates to 48.6 volts on your charge controller for Absorb.
Temporarily I would set the high voltage disconnect at 4.1 per cell or 49.2 for HVD as it is sometimes abbreviated. Later these voltages need to be coordinated with your BMS so you have a backstop in case one system or the other fails. More on that when you program your BMS.

Cell Over Discharge: 2.75V

I usually set this conservatively at 3.5 volts per cell or 42 volts.
Let us know when you hook up your BMS and we can walk through those settings. With a used pack I am always careful as I cycle the battery to make sure any of the 12 cell groups in series are close to the same voltages. If not you will have to try some methods to top balance that can be discussed later.

[Ampster]

have you heard of anyone hooking bigbattery's powerwalls in parallel?

Yes, they are doing it with $120 BMSs. Daly, Ant and Chargery are some of those BMSs that I believe come in 12S varieations. There are some YT videos out there. I am only a casual observer of those and do not have much in the way of helpful knowledge. I will take a stab at your battery settings above.

https://www.youtube.com/watch?v=R_fuEP_LDkc

[Mcmullen7242]

have you heard of anyone hooking bigbattery's powerwalls in parallel?