Hello!
Finalizing my repair story.
My previous posts:
GXMnow: I had thought about pulling one cell out of each of these, and going with 7s, even if the intent is to end up in series at 14s. It is a better voltage range for the majority of inverters out there. These are bolted together Samsungs, so a cell will just pop out.
diysolarforum.com
GXMnow: I had thought about pulling one cell out of each of these, and going with 7s, even if the intent is to end up in series at 14s. It is a better voltage range for the majority of inverters out there. These are bolted together Samsungs, so a cell will just pop out.
diysolarforum.com
GXMnow: I had thought about pulling one cell out of each of these, and going with 7s, even if the intent is to end up in series at 14s. It is a better voltage range for the majority of inverters out there. These are bolted together Samsungs, so a cell will just pop out.
diysolarforum.com
Summary:
1) My BMS and inverter had survived all the tortures and now work fine
2) Precharching resistor is the only way to go by now
1) Repair.
Luckily there was only one burnt transistor: D-S, G-S - everything was 0 Ohm in it. Gate 100 Ohm resistor saved the driver I guess.
After soldering it out now "Discharge" and "Charge" switches work as designed: cut off current to zero amps.
View attachment 79602
2) Experiment
I agree that next experiment is quite stupid and unnecessary.
But!
Imagine the following situations:
a) You turned off a BMS with "Discharge" switch and now want to turn it back on again using "Discharge" switch in app
b) There was some fault situation in a battery, BMS turned it off, now it waits for some timeout or fault has gone for some reason, and then BMS turns the battery back on again.
The result:
- current is extreme (500-1000 A or even higher)
- BMS goes into "Short circuit" error mode and waits for timeout (60s)
- after timeout everything repeats.
View attachment 79604
Case 2:
- you switched off battery with "Discharge" option
- if you switch it on again with "Discharge" option you'll get "Short circuit" and... see above.
Case 3:
- problem in balancing wire
- BMS doesn't see that cell and goes into fault mode (battery off)
- for some reason balancing wire begins work fine again -> BMS turns on battery -> "Short circuit" and see above.
Case 4:
- cell undervoltage protection occured
-
....sorry I don't remember and didn't try it now. Can anyone remind please will BMS wait (in off state) until charging starts? Or it will turn on after the cell voltage rose over Cell-Undervoltage-Release value?
Here's current measurement. I didn't set correct range but judging from skyrocketing curve slope I assume it was ... maybe around 1000A.
View attachment 79603