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Jbd bms limiting charge to 3.341 per cell after pack over voltage.

Yurtdweller

Solar Enthusiast
Joined
Nov 23, 2020
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273
Location
USA
Newly built 280ah pack. Due to bad solar weather, this is only the second time I've hit full capacity. Yesterday, I had a 'pack over voltage' cutoff. This was expected, due to difficulty programming the Ampinvt charge controller, since corrected(I think). The cc is reporting 100-ish watts off an 800 watt array, but the BMS is only allowing around 45 watts, and seems to be turning charging on and off rapidly (5x per minute) even though this is not indicated on the dashboard, only on 'reports' (see screen cap). Voltage test of full pack indicates 13.35. Voltage test at cc indicates 13.73. BMS seems to be limiting each cell to 3.41. Cells are well-balanced. BMS is jbd SP04S020A4S. My other pack(bought built) with Daly bms and running with a cc that could not be programmed properly regularly hit high voltage cutoff without issues. Should I try resetting the BMS?
 

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Reset BMS. No apparent change. Reset cc Ampinvt, which I intend to return, as soon as I decide on a new 80 amp cc. Now cc shows 180watts, and BMS reports 118 watts?, But at least it's steady and charging. BMS now reports 270ah capacity, (it indicated 241ah capacity previously) but I suppose that I'll have to wait until it tops off to know if that is accurate. I guess the cc may have been limiting for some unknown reason:/ This cc manual does not indicate parameters for lithium setting. Perhaps the fact that the cc is reading higher voltage than the battery is the problem. Apparently the BMS reports 'charging stopped' as the cc stopped charging rather than the BMS stopped charging. Both devices have poor documentation:( I failed to check battery voltage during yesterday's hvd, as I was ill. Will update thread as I learn more. Going to be trial-and-error, I guess.
 
Update: turns out I am loosing over half a volt in my wiring between the cc and the battery. I didn't notice before, because I was letting my bms handle charge cutoff because my old cc couldn't be properly adjusted. I will be looking at what I can do to reduce voltage loss. Meanwhile, I'll adjust my current cc to compensate.
 
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