The new battery showed full charge on LCD display but would not run motor. Connecting voltmeter across positive and negative of controller input,(battery output) meter could not settle on a voltage OL...... ) before BMS read 54.1 volts. . Decided to change it but the new one had no switch connection. 1st question: Is it possible to install a switch by breaking the B+ line to the 13s header? Back to story: I plugged in the header (because it was easiest) and proceeded to solder other connections. The P- connection had a small spark when I connected it. Now with new BMS I have 41 volts @ output of battery, 54.1 between B+ and B-. Did I blow up the new BMS by connecting 13s header first? I started checking install instructions on the internet and it seemed they wanted connections made in a certain order.
Installing a BMS
- Thread starter OMcComis
- Start date
Wire the bms leads to the battery , checking voltsages as you go then check voltages after you have the leads wired up before plugging the connector in. yes You wire in a certain order. What BMS? Might be time to buy a new Bms and read the instructions before installing BMS.
Later floyd
Later floyd
docw009
1 MW
The old metal case silverfish battery still used on low end ebikes does switch the B+ leads, but that switch is a big one, There is a surge current into the controller capacitors when you attach a battery to a controller that has been powered down. The switch has to handle that arcing on its contacts, but yes, sparking is normal when you connect a live battery to the controller.
I always connect the header last. Make the P-, B-, and C- (if used) connections first. There are transistor switches between B- and P-, B- and C', and they are off until the header is connected.
Have you checked the cell voltages on the balance connector? Have you started at B0 and walked a meter from B1 to the last lead, making sure the voltages increase in order, and that each cell voltage is between 3 and 4.2V? This should have been done initially to verify that the battery was working right, and that the BMS was at fault,
I always connect the header last. Make the P-, B-, and C- (if used) connections first. There are transistor switches between B- and P-, B- and C', and they are off until the header is connected.
Have you checked the cell voltages on the balance connector? Have you started at B0 and walked a meter from B1 to the last lead, making sure the voltages increase in order, and that each cell voltage is between 3 and 4.2V? This should have been done initially to verify that the battery was working right, and that the BMS was at fault,
Thanks for the info. Yes, section of battery was checked for proper voltage, I've learned much since original post, like don't solder with 13s header plugged in, one of the replacement BMS had a place to install a switch that was bridged to a O ohm resistor, I desoldered this resistor with 13s header connected and BMS never worked again. I think the soldering tip being grounded shorted the B+ line of battery.
Unless the B- end of the battery was connected to the ground the soldering iron was plugged into (assuming the soldering tip is grounded, which isn't always the case), that couldnt' happen.
Since batteries are not normally plugged into the wall directly like this,
it's not very likely. (even if you have a non-isolated charger, and it was connected to the battery and the wall while you were soldering, so that the ground from that was connecting the battery negative to the wall ground, and the wall ground was connecting the grounded-tip soldering iron to the battery negative).However, ESD (static electricity) from an ungrounded iron tip (or ungrounded fingers touching the BMS) can cause all sorts of damage, immediate or latent, and this is a pretty common thing with all sorts of electronics. (less today then a couple decades or more ago, as ESD protection is more common and better in all sorts of components, but still unfortunately not enough to stop it all).
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Sometimes they just go poof. (a lot of this stuff is not very well made)
For explanations...I tend to grope for those, too, for everything I see around me--I've just accumulated a lot of little bits of information about many things that lets me explain some things better, and eliminate some possibilities. (not that my explanations or eliminations are always correct ).
(a lot of this stuff is not very well made)For explanations...I tend to grope for those, too, for everything I see around me--I've just accumulated a lot of little bits of information about many things that lets me explain some things better, and eliminate some possibilities. (not that my explanations or eliminations are always correct
).New BMS solved the problem what happened with others is still speculative I have video of most of it because I was making a video on how to fix your battery (what a joke, if I ever get to editing it, pretty sure it'll turn into a video of how not to change your BMS.
docw009
1 MW
BMS sure are a crap shoot. I bought one from Annpower, an aliexpress seller that worked. So I bought two more for future use. They sat around for half a year, and I go to use one. It's dead. So is the other, Bummer, Probably static.
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