Question for those that know and have done as most pointy heads indicate that this cannot or should not be done.

Have a Deye 8KW Hybrid inverter connected to 14 X 480W panels (7S2P) on two seperate strings

Was waiting for my original battery bank (2 x 48V 150Ah Rentech) when a delay in arrival caused me to panic and buy a stop gap (2 x Dyness A48100)

Both have now arrived and are brand new about to be installed.

Question can these four bateries be installed in one bank, two banks or should I just get a second inverter and keep the packs seperate?

According to my understanding it is do-able as both are LiFePo4 (prismatic) and as long as the BMS are compatible and charge/discharge is set to lowest common denominater should be fine.

Any views or definative ideas around this would be appreciated. Use of charge controllers if needed  will be no problem.

 

Edited June 18, 20223 yr by brian1709

If you trust the batteries bms's settings are configured correctly then simply setup a decent bus bar to connect all the batteries to and let them manage themselves.

If they are all correctly top balanced then they do not need to communicate with each other or the inverter.

Hi @brian1709

"Best practice" and "will it work" usually have two different answers. 

I personally wouldn't do it for a number of reasons:

1. The inverter would not be unable to tell accurately how much power you have in your batteries as there would be no master BMS controlling the banks and no communication between the batteries and the inverter. Due to the flat voltage characteristics of Lifepo4 batteries it is impossible to accurately tell SOC from the voltages.

2. Due to the batteries BMS's not talking to each other, their BMS's will disconnect and connect to the busbar independently. The problem will be exacerbated by having different BMS's with different settings connected to the busbar and this could result in cascading disconnects due to over current draw etc as some banks of batteries disconnect due to low/high SOC's

Whilst if the chemistries of the batteries are the same and they have the same amount of cells it might "work" it is definitely not an ideal situation.

First prize in my opinion would definitely be to send one of sets of banks back. If you have just purchased them and they are unopened I would not think that would be a major issue especially if you purchased over the internet. Just check your rights on the CPA. 

Those cannot be mixed, Dyness is 15s, Rentech is 16s. (Aside from the fact that the BMSs are probably also not compatible)

Anything is possible but it's whether its done properly! I run multiple inverters / changing sources to one battery but I have a Teensy controlling the BMS communication between them all.

It could be done using something like a Teensy / Arduino / Rasp Pi and some relays but easier just to use another inverter.

10 hours ago, P1000 said:

Those cannot be mixed, Dyness is 15s, Rentech is 16s. (Aside from the fact that the BMSs are probably also not compatible)

I believe the answer to this thread is this.

If only they have the same nominal voltage, you can parallel them as dumb battery, then manually set parameters to your inverter/charger. Or you could actually make the master battery the brand you prefer, and the other is dumb.

Unfortunately, you got two different nominal voltage pack.

On 2022/06/18 at 7:03 PM, power.esrl3 said:

Unfortunately, you got two different nominal voltage pack.

You could do it with a voltage controlled relay that cuts off the battery pack with the lower nominal voltage when that packs max voltage is reached. Not ideal tough.

Ok, need to revisit this subject and again want to know if this would work. I kept the two banks, seperate and on two different inverters, so that became a non issue.

Now I received 2 X 4.8 Kw 100Ah 48V Hoselect (15Cell prismatic) from a friend that never installed it as he decided to Emmigrate.

Would these be compatible with my Dyness bank? Looking at the specs I can find on the Hoselect it seems to be the same battery, but cannot say for sure about the BMS.

Any input would be appreciated.