besugosolar
New Member
- Joined
- Oct 24, 2022
- Messages
- 14
Hello! Long post, please read and try to clarify my doubts, will be much appreciated!!!
So a few weeks ago I asked here if B-Cells would be ok, and some of you told me what to expect, the store manager, by e-mail told me they would be fine, and gave a 1 month return window, etc etc... So I went for it, these were sold by European Store NKON which has a STELLAR reputation and cost me 590 Euros for 8X130Ah Cells, which is a great price... They arrived well packaged, no signs of anything wrong, and all read the exact same with my 2 digit only cheap multimeter 3,26V, for a total of 26,2V
Bad news - weather went horrible for 2 straight weeks, no sun... To make matters worse I only have 2 panels installed right now, working on putting the rest on the roof, so only roughly 500W of solar power - that most of the time was generating 20-30W from 9am to 5pm... So I set my BMS (Jiabaida\JBD) to trigger cut-off at 2,6V and it did one night - I know I was almost zero, but I am living totally off-grid, my lead acid batteries died, and I had to go to almost 0% SOC... Anyway soon after weather started changing and some sun started to show up and this is where it all starts
My system right now (only 2 panels installed as I said)
8S 130Ah Cells
MPPT charge controller
500W solar panel power +-
4000W peak inverter\2000W continuous
JBD 100A BMS
Xiaoxiang App on Android and iOS
So...
I wanna know how to set this up correctly for the best useability\longevity ratio
Want the cells to last for a long time, but I don't really discharge more than 20% overnight... More like 10 to 15% since I only run the inverter, lights, fridge, a efficient laptop and maybe 3 mins microwave at night... And in fact the BMS confirms - 10% drain overnight...
Thing is... Since I never got to 100% yet I don't know my SOC right now, and how close I am to 100%! And if the cells delta etc is ok
So this is what I'm getting and what I configured, you tell me what's wrong and what you would do
Weather here: Never below 0ºC, no worries, never above 30º inside no worries either
BMS settings
High cut-off: 3.65V
Low cut-off: 3,0V
BMS cell voltages set from 0 to 100% using iOS app using a chart, or several, I found online, and I do know they are resting voltages - that i know, not a total noob
So, now what I wanna ask is... Today my BMS read 100% for the first time, and honestly with 4 consecutive sunny days I thought they could really be there, in fact they should be close, but they kept receving the same 12A charge, around that, as they were receiving before getting to 100% in the BMS, and the voltage never above 27.2V, around 3,4V per cell... The highest cell read around 3,41V, the lowest around 3,39 - 20mV delta... Is this acceptable?
I know JBD BMS has a low balance current, and these are B-Grade probably not matched cells, but they seem close... Now that I'm almost reaching 100% do you think the BMS will be able to bring them to balance?
Also about the settings in the MPPT...
Charge Voltage (Absorption): 28,8V (3,6V per cell)
Float Voltage: 27,2V (3,4V) per cell... Probably will lower these after the first cycles to try to mantain 90% max charge or something
When the MPPT senses they are full the current will drop, right? Since the voltage never really got to 28,8V I can assume despite the BMS claiming SOC was 100% they weren't? (Sun is setting now, no production anymore, and the voltage has dropped to 3,36V per cell, more or less, so I think they definitely are not 100%, but close right?)
What would you change? What can you advise me? Thanks!!!
So a few weeks ago I asked here if B-Cells would be ok, and some of you told me what to expect, the store manager, by e-mail told me they would be fine, and gave a 1 month return window, etc etc... So I went for it, these were sold by European Store NKON which has a STELLAR reputation and cost me 590 Euros for 8X130Ah Cells, which is a great price... They arrived well packaged, no signs of anything wrong, and all read the exact same with my 2 digit only cheap multimeter 3,26V, for a total of 26,2V
Bad news - weather went horrible for 2 straight weeks, no sun... To make matters worse I only have 2 panels installed right now, working on putting the rest on the roof, so only roughly 500W of solar power - that most of the time was generating 20-30W from 9am to 5pm... So I set my BMS (Jiabaida\JBD) to trigger cut-off at 2,6V and it did one night - I know I was almost zero, but I am living totally off-grid, my lead acid batteries died, and I had to go to almost 0% SOC... Anyway soon after weather started changing and some sun started to show up and this is where it all starts
My system right now (only 2 panels installed as I said)
8S 130Ah Cells
MPPT charge controller
500W solar panel power +-
4000W peak inverter\2000W continuous
JBD 100A BMS
Xiaoxiang App on Android and iOS
So...
I wanna know how to set this up correctly for the best useability\longevity ratio
Want the cells to last for a long time, but I don't really discharge more than 20% overnight... More like 10 to 15% since I only run the inverter, lights, fridge, a efficient laptop and maybe 3 mins microwave at night... And in fact the BMS confirms - 10% drain overnight...
Thing is... Since I never got to 100% yet I don't know my SOC right now, and how close I am to 100%! And if the cells delta etc is ok
So this is what I'm getting and what I configured, you tell me what's wrong and what you would do
Weather here: Never below 0ºC, no worries, never above 30º inside no worries either
BMS settings
High cut-off: 3.65V
Low cut-off: 3,0V
BMS cell voltages set from 0 to 100% using iOS app using a chart, or several, I found online, and I do know they are resting voltages - that i know, not a total noob
So, now what I wanna ask is... Today my BMS read 100% for the first time, and honestly with 4 consecutive sunny days I thought they could really be there, in fact they should be close, but they kept receving the same 12A charge, around that, as they were receiving before getting to 100% in the BMS, and the voltage never above 27.2V, around 3,4V per cell... The highest cell read around 3,41V, the lowest around 3,39 - 20mV delta... Is this acceptable?
I know JBD BMS has a low balance current, and these are B-Grade probably not matched cells, but they seem close... Now that I'm almost reaching 100% do you think the BMS will be able to bring them to balance?
Also about the settings in the MPPT...
Charge Voltage (Absorption): 28,8V (3,6V per cell)
Float Voltage: 27,2V (3,4V) per cell... Probably will lower these after the first cycles to try to mantain 90% max charge or something
When the MPPT senses they are full the current will drop, right? Since the voltage never really got to 28,8V I can assume despite the BMS claiming SOC was 100% they weren't? (Sun is setting now, no production anymore, and the voltage has dropped to 3,36V per cell, more or less, so I think they definitely are not 100%, but close right?)
What would you change? What can you advise me? Thanks!!!
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