How to calculate the Max Power charge/discharge of batteries

[Bob Smith]

Hi

Everytime I think I am getting closer to get the design signed off, someone from the company I selected put new info and I feel my head is going to explode.

The initial quote was with Solax HV Batteries. The datasheet was easy to understand and there was a table showing what would be the max and nominal charge/discharge power by the number of batteries selected.



Now I am told that there is not enough technical information and (Solax have not responded after 3 weeks and chasing them) about the BMS Parallel Box which will allow to have more than 4 batteries (up to 6 on single phase) and the product is relatively knew in the UK. Therefore the designer who does not want to take any risk suggested to change the brand and consider LV from Sunsynk batteries.
One avantage of the shape of the Sunsynk is that I can install more on the wall

Nonetheless, the datasheet reads


This is for one battery. There is no indication in what I got (and could not find it on the sunsynk website) how many batteries can be put together (there is a picture with a cabinet showing 4 batteries stacked up)

I am trying to figure out what will be the charge/discharge power for 2 batteries, 3 batteries and up 8 batteries (if 8 is possible).
For one Sunsynk battery I have astandard charge/discharge of 50A*50V = 2500W. I need between 7 and 9kW (This is because of what my PV will be able to generate (not the kWp as I will have 16kWp, the 37 panels will be facing 3 orientations)


The BYD datasheet gives this



Here I can clearly see that the more batteries the more power up to 4 modules. if I were to have the LVS 8 (2 modules) this gives 130A * 50V = 6500W, the LVS 16 (4 modules) 250A * 50V = 12500W
Unfortunately the ByD cannot be installed on the wall.

Because of their shape and that I can stack them like with a rack on the wall the Sunsynk batteries would seem the prefered option if I can figure out what would be my charge/discharge power..

Sorry for the long post for a simple question really, but I thought this could give some background info to newcomers.

Thanks all


PS: I did not mention when an electrical hub (ceramic or induction) is used too

 

[bladerunnerpv]

Hi Bob,
I took a brief look at sunsynk a while ago and was left scratching my head too

I case it helps, thinking of what you were trying to do with the paralleling before, the BYD datasheet suggests the LVS system can be set up in parallel also
"Max. 64 Modules in Parallel (256 kWh)"
"Parallel tower function only available for 1 to 4 battery modules per tower"

datasheet "BATTERY-BOX PREMIUM LVS" v2.1

so you could start with 2x2 and expand to 2x4 or 4x2 ?

IIRC BYD have HVS and HVM options too which can be stacked and/or paralleled
looks like HVS are ~100V units, HVM are ~50V units.

https://www.dragonsbreathsolar.co.u...byd-battery-box-premium-hvs-hvm-datasheet.pdf
you'd have to check the compatible inverter lists...

hope this helps

 

[Bob Smith]

Hi

Hi Bob,
I took a brief look at sunsynk a while ago and was left scratching my head too

I case it helps, thinking of what you were trying to do with the paralleling before, the BYD datasheet suggests the LVS system can be set up in parallel also
"Max. 64 Modules in Parallel (256 kWh)"
"Parallel tower function only available for 1 to 4 battery modules per tower"

datasheet "BATTERY-BOX PREMIUM LVS" v2.1

so you could start with 2x2 and expand to 2x4 or 4x2 ?

IIRC BYD have HVS and HVM options too which can be stacked and/or paralleled
looks like HVS are ~100V units, HVM are ~50V units.

https://www.dragonsbreathsolar.co.u...byd-battery-box-premium-hvs-hvm-datasheet.pdf
you'd have to check the compatible inverter lists...

hope this helps

Hello @bladerunnerpv thank you for your message
I did have a look at their website bydbatterybox.com and saw they had different type of LV and HV batteries.


However, regardless of the brand I am trying to learn how to calculate the charge/discharge when I have more than 1 LV batteries.
In the above example ByD show in their data sheets how the charge/discharge is augmented the more batteries you add up to a certain level. For Sunsynk, they just give the charge/discharge for one batteries and no information if you were to have 2, 3 etc… batteries
Do you know how to calculate it?

 

[bladerunnerpv]

Hi Bob, other than post #6 following of this thread I've not seen anything

https://electricianforum.co.uk/threads/optimal-distance-between-batteries.55840/