Instead of a normal switch I’m using a relay and a momentary push button, but that’s besides the point. (I’ve tested this with just a normal switch as well)
Problem: Under load, the BMS will turn off. This happens only when there is a ticking noise beforehand.
Sometimes, when I turn the board on / move the BMS or the wires around / drive the board forward a bit, I start hearing this quite rapid ticking noise. It is periodic. Usually it’s 3 times per second, sometimes it gets into this rhythm of 2 ticks, then one skipped. I’ve checked that the BMS or ESC housing isn’t touching any exposed wiring or the battery. I even tried another ESC, completely out of the enclosure. Another important thing to mention is that sometimes moving the BMS around shuts it off.
This has me thinking that there’s a near short somewhere, and it’s sparking, or sometimes completely shorting and turning off. I’ve tried lifting the BMS up and looking at it from all sides, but I don’t see any sparking. I’ve also noticed that the ticking doesn’t happen if there’s no load for the BMS (i.e., an ESC attached).
Final nugget of info is that out of the 11 balance wires, I only have 10. I assume that the pack negative / 0th wire is wired together with the main negative terminal on the BMS anyway. So in this wiring picture, I’m missing the bottom B-
So, has anyone experienced something like this before? Could it be a loose balance wire connection? Is the BMS faulty? Have I wrongly assumed that the top / bottom copper bus bars of the BMS are all connected to the B- and Load- terminals, and that my solder job is to blame? Should I source another balance wire to add the missing B-? Help me, I need to finish this board for my friend in 4h before I leave the country
To clarify what “the BMS turns off” means: it means that the ESC loses power until I again separate, and bring back together the e-switch wires. (Or, in my case, toggle the relay off and on again)
Well, it charged the battery fine, and it has 11 balance wires so it’s definitely a 10s BMS. When it’s not ticking it works perfectly, I just can’t give my friend a board that “sometimes likes to tick and turn off”
Hmm…that’s hella strange. I’d imagine the gates are shutting which is causing the sounds, so probably you’re getting a low voltage on a cell…I.e. a loose lead somewhere
I tried your theory by unplugging one of the balance leads, but no ticking. It just worked, matter of fact, lol.
However, I’ve discovered that even in its new position, my relay is still too sensitive to the current in the adjacent wires, and is switching on its own So board won’t be ready by tomorrow anyhow because of that fact.
I hooked up an 18W 5V converter to the BMS (to have a more predictable load), which is successfully making it cut out every 2 out of 3 times instantly on startup. Something is definitely not right
Aaaahh. Want me to see what I’ve got that you could replace it or at least I can send you the money back? When did you get this? My mind is a little hazy…?
So board won’t be ready by tomorrow anyhow because of that fact.
