Infinisolar V4 5.6KVA/5600W Hybrid Grid Tied Inverter & DIY Powerwall (Safe BMS?)

Announcement - Help us fight the BOTS! Please report all spam including stuff in your inbox!

DiabloSV

New member
Joined
Nov 23, 2021
Messages
3
Hi Everyone,

I am new here and sorry if I am asking silly questions, I am currently starting my own DIY Powerwall project recycling used laptop batteries and started testing, I am planning on building a power wall and I want to make use of the following inverter.

Details of Inverter:
RCT Infinisolar V4 5.6KVA/5600W Hybrid Grid Tied Inverter, PF 1.0,48V DC, Build-in 6000W MPPT Solar Charger with 450V DC Max Open PV voltage, BMS & Wifi, Battery free Operation, Include Parallel Kit for parallel Operations up to 9 Units

The best information I could get from this product was from this site.

I want to know if the BMS in this inverter will be safe for a DIY 18650 Powerwall project. The first phase of my project will be using the grid to charge up the batteries and I won't use panels, for now, I need a massive UPS as our power in our area is very unreliable with multiple power outages. I was thinking of doing a 14s40p or 14s60p setup to start with, depending on the quality of the batteries, going to take forever to test with just one charger.
 

Korishan

Moderator
Joined
Jan 7, 2017
Messages
6,572
I want to know if the BMS in this inverter
Well, first off, it doesn't have a BMS in the sense of "balancing" or monitoring the batteries cells. So doesn't matter if it's Lead Acid, Li-Ion, Li-Fe, or some other chemistry. You would still need a separate BMS that does individual cell monitoring (this is any single or parallel group of cells connected together).
So aside from that, looks decent. The only issue I see right off is that the output power is pretty low, only 3.5kW. It can charge at 5kW, though, which is nice.
Charge current of 100A will be the limiting factor on battery size, though. You probably wouldn't want to go any larger than 400p. (note: this can be in any configuration, so 4x 14s100p, 2x 14s200p, 1x 14s400p, 8x 14s50p, etc as long as the overall is 400p). This would equate to about 0.25A/cell. Any larger and it would take too long to recharge the battery bank(s) connected to it.
Also, you wouldn't want to go any smaller than 100p, as this would be putting 1A/cell, which unless you are using high drain cells, would shorten their life cycles (ie, if using reclaimed long term storage cells like bell, sensor, laptop, mobile device, etc cells).
 

DiabloSV

New member
Joined
Nov 23, 2021
Messages
3
Thank you for the valued answer Korishan, there are two versions, the 3,6KW & the 5,6KW version, I want to get the 5,6KW system(5600Output / 6000W Input)

This means I will need more batteries, luckily I have another 200 laptop batteries coming my way next year. :)

I was planning on building the system on (14 x 1s60p) now I am looking at changing it to (14 x 1s100p) configuration to start, this means I need to monitor 14 banks with a separate BMS if I understand it correctly. Are there any budget recommendations for a separate BMS unit? Preferably something on the budget side for now as the budget is a little tight to start off with.
 

Oberfail

Member
Joined
Jun 22, 2021
Messages
99
The Inverter only checks the voltage of the whole battery package, your BMS takes care of checking each series string voltage & balances them if needed. My favourite cheap BMS's, are the "Smart" Bms's from there: https://www.lithiumbatterypcb.com/p...battery-pcb-board/smart-bms-of-power-battery/
The official bluetooth app has all the settings i wanted, but comes with some limitations.

Also, laptop batteries are not meant for high current charge & discharge applications. Try to stick to a max discharge & charge current of half its left capacity. If a cell has 2000mAh left, it would be 1000mA discharge & charge max. Applying that to your inverter would be a 14s200p pack.
To keep your cells alive as long as possible, limit the charge voltage to 3.95v per pack and discharge voltage above 3.0v. There is a big chemical entropy change right after 3.95v till 4.1v in those cells. You can read more about it here: https://secondlifestorage.com/index...ge-at-full-voltage-4-2-4-0v.11385/#post-79859

Try to get some people that help you to gather all the needed materials, you can probably get some more batteries from trash collections places or repair shops.
 

Korishan

Moderator
Joined
Jan 7, 2017
Messages
6,572
I was planning on building the system on (14 x 1s60p) now I am looking at changing it to (14 x 1s100p) configuration to start, this means I need to monitor 14 banks with a separate BMS if I understand it correctly.
well, technically, that's is a 14s60p or 14s100p. You build large packs of cells that are connected in parallel, then you connect each one in series to get the voltage. So if you have 14 packs of cells with 100 cells connected in parallel, that's 14s100p. This would require 1 BMS for that string
 
Top