I recently completed my first esk8 build following this build almost exactly (Electric Skateboard : 10 Steps (with Pictures) - Instructables). I’m moving out to college in the next month and for convenience wanted to add the ability to use a wall charger rather than the battery charger/balancer. I’m a little concerned about how loud my current battery charger is (I don’t want to bother my roommate) and the inconvenience of taking out the batteries each time I need to charge them. I was wondering if there were any suggestion for a good 12s bms, and if I could have some advice on how I would wire it into my current setup? I’m a beginner when it comes to electronics so any help would be greatly appreciated!!
You can use a daly 12s bms for charge only and it’ll work. As for wiring, its a bit confusing but I figured it out.
For the first battery, your b- will go on the negative wire side of your first lipo cell. Then you should see your balancing wires and see the 1st black wire there. That will be your b1- if your bms has a b1- wire. Then you’ll mostly connect the wires as b2, b3, b4, etc. Your wiring for the first battery is completed after this
Your second balance lead is the opposite. Ignore the first black wire on the balance lead and continue with b7- b11 accordingly after the black wire. Your b12 will be the red wire on the second side of the battery. Congrats, you have made it charge only.
Now just add a charge port, fuse the positive side of the red wiring of the port and make sure the positive charge port wire is soldered on the 2nd battery’s positive terminal.
This was the reference used.
Side note: there is a red wire on the 6s lipo. In the diagram, it says to skip the red wires on the first cell with the red wire if you added the black wire for b1- but i don’t believe that needs to be skipped. This was probably a mistake on their end… Only the black wire on the second battery since you dont need to use the negative wire again.
Thank you for the help and the very fast response!! Just to double check would this be the bms that you were talking about? Daly 12s 50.4v BMS for Li-Ion Battery Packs — MBoards
Yes. It doesn’t say C-, however, you can use the P- as your C- instead. It works the same.
I have edited my original reply to make it make more sense.
Okay sorry, all the parts finally got in. So I use the negative side of the charging port and connect that to the p- on the BMS?
BMS bypassed with loopkey and discharging with lights/accessories circuit
If your BMS doesn’t have C- or CH-, then connect that wire to P-
As given by b264^
Okay, everything is wired up! Is there a way I could tell that it is charging using a multimeter or other method?
You would just plug in the charger if everything is correctly done. Did you add a fuse to make sure nothing goes wrong? Its a safe bet, but if anything, the bms would not allow charging if its not set up correctly.
Your charger should be showing charging led if its good. If not, it will stay green (or any color that shows fully charged) and you’ll need to check the balance leads. Make sure it goes from 3.7v to your series voltage. Also check if its not fully charged. That’s also a factor.
Okay, so when I plug it in the charger LED stays green and doesn’t change color (so no charging). I’m pretty confident the B-, C+, and P-/C- are wired into the correct spots, but I think my b1-b13 are incorrect.
They are wired as stated with the first black balance lead on my b- battery on the rightmost side of the connector(if looking at the image of the bms it is on the “-” side on the right end) which should be b1 correct? Then b2 is the next wire on the first battery continuing onto b6 (moving to the left along the connector with each successive one). Then I skip the first black balance lead on the second battery and continue connecting the rest of b7-b12 with b12 being the red balance lead. Finally, I tried having the red lead on the first battery not connected, but this didn’t charge and so I connected it to b13 and this still doesn’t charge. So this is where I’m a little lost. I know these are wired up incorrectly, but I don’t know what’s wrong.
If I measure the voltage across the wires (one end of the multimeter will stay on the b1 wire for now) b2 = 3.3, b3 = 6.8, b4 = 10.3, b5 = 13.8, b6 = 17.3, b13 = 20.7,
Then I switch to the multimeter to be on b7 because otherwise the rest stay as 0. b8 = 3.3, b9 = 6.8, b10 = 10.2, b11 = 13.5, b12 = 16.9.
I don’t know what’s wrong and any help would be greatly appreciated!
It’s B0 - B12.
B0 is also called B-
So you say you have
B0: 0V (B-)
B12: 0V (B+)
That means you have a broken or missing series connection in the battery, if I understood you correctly. Are these lipos?
BE CAREFUL WORKING ON BATTERIES, THEY ARE EXTREMELY DANGEROUS.
Yes, these are LiPo. And, I actually connected the red lead from the first battery into b12 according to your numbering. Would it be correct to assume this is the problem, and I need to switch the leads around so they correspond to the correct numbers as from your initial instructions?
Also just to check, is B0 the 12 AWG wire or the 20 AWG lead on my first battery?
No, never assume anything unless you want lots of fire
How would you suggest not getting lots of fire?
It looks like this large gauge series connection between the two lipos is missing.
Some BMS have a B0, some don’t. Some are B1-B12 and some are B0-B12. B0 is B-
Measuring the voltage of two wires before you connect them together. If it’s not 0.0V then don’t connect them.
Okay so if mine has 13 spots for connection then that would mean I have a B0-B12 correct? So then the new way I need to wire up is as follows:
B0 = First black lead first battery, B1 = Second Black lead second battery, … , B6 = Red lead first battery, B7 = second black lead second battery, B8 = third black lead second battery, … , B12 = Red lead second battery.
Would this be correct?
Do not connect the “little” B6 wires together, those should be connected with the “large” sized wires on the main output, the battery series connection. (This prevents you from accidentally melting something)
Okay, so I’m stupid. When I was measuring voltage across the leads I had disconnected everything in my circuit and so my batteries were no longer connected in series (by the big 12 AWG wire they were connected with before). So I plugged this in so they are now connected with the big 12 AWG wire and I’ve also redone the b0-b12 and these are now the voltages I measure. I still don’t think charging is working because the light on my charger is still green when plugged in and does not change color. These are now the measured voltages:
B12: 41.2V (B+)