I have latching LED switch which I would like to disconnect it from Vedder anti spark and connect it to built in Bestech BMS switch to save on space in my enclosure. Here are the schematics of this model.
Based on above is my below connection diagram correct? Switch is rated for 6/12/24 V and max of 3A so might be slightly dimmer than at 6V ( I will bench test it later). I want it to light up when pressed.
I think it looks fine @SilentException⌠what do you think?
Yes but you donât want that. Why? Well letâs say one parallel group or cell in the series pack is âbadâ and it is out of balance. Example of 3S pack: 4.0V 3.8V 4.0V Charger will charge until pack gets at 12.6V and at this point the pack will be something like: 4.3V 4.0V 4.3V = 12.6V Some of the cells will be overcharged, not a good idea.
Momentary switchâŚnot going to work 
You need latching one.
Iâm sorry, it is latching switch. Not sure why I wrote momentary. It must have been 12hrs shift I have just finished at work Would wiring be correct?
I know. I would never do that. It was just to help me understand how the Charger Works, and how it âseesâ the battery. I got it nowâŚ
God, no. I think you might burn something using those connections. Just use a switch part as a switch and LED part as a LED. Simple
@SilentException Ohh silly me. So + and - on the latching switch are for LED voltage and NO ( normally open) and C ( common) are for the switch! Makes sense
I guess resistor wonât be needed - LED can take 3A max and 5V on Vesc is I think 1A max. Thanks!
This sounds very implausible to me. You might be looking at switch rating and not the LED.
Sorry for the late reply. It would be best to balance the packs before assembling them but if you donât have a hobby charger, then you can get around that as long as all packs are close to the same charge. I once experienced a problem when I had to replace a pack whoâs main power cable came loose inside the case. the new battery was at storage charge and the rest of the pack was somewhere over 4.0v per cell. In that case the charger stopped before the total pack voltage could reach 42v so the bms balancing was not triggered. I had to go in and charge the new pack separately to equalize it with the rest of the battery. After that everything was fine. Frankly, I donât know of any BMS that can balance cells as well as a good hobby charger can.
Thanks for your response! What margin would be acceptable for the cells? What voltage is common for âstorage chargeâ?
according to my hobby charger, 3.8v per cell is storage charge. as far as the maximum acceptable margin for the bms, I really donât have any hard numbers for sure but my best guess is no more than 0.1v per cell.
Ok Iâll have a look at my batteries when I get them in. If any doubt Iâll contact you here in this topic with my measurements, maybe then we can see what is ok as a margin! Thanks! This is a really nice topic full of very useful information
why this switch is useless? the BMS has the E-switch built-in⌠i dont understand that 
The electronics for the E-switch are built into the bms. There are 2 wires coming from the bms that have to be connected to a physical on/off switch.
The switch that comes with the charge port is useless because it is a momentary switch, not an on/off switch.
@Namasaki you helped me out allot so I have another question for you (other may also help, no problem haha).
Is this gonna work or am I going to destroy everything 
I connected the BMS to the charger, this way I didnât need to fit it into my board. Connected the C- to the charger -. And the B- is going out the the charger port, so to the - of the lipo. Got the eswitch connected to a simple on/off switch, the one with just two poles, to be able to switch it on and off. I just need to connect the balance wires, but that something thatâs always necessary. There is an anti-spark and switch between the VESC and the lipoâs so in theory with the board off there will be no power from the charger that goes to the VESC. Which should make it extra save for the VESC.
This should work, but I havenât seen this before so I just wanted to check. I might have missed something important that ill blow everything up 
I canât tell much by the picture. Make a diagram and post it and Iâll take a look
In short itâs like the image. Only thing missing from the image to keep it simple is the charger port and socket. And the part where the wire from the lipo goes to the anti-spark. (which are coming from the same connector as the wires the charge port uses)
When looking at the diagram I noticed there is nothing different from wiring it directly to the lipo except for the P- not being used. Which in this case is not needed.
I need to see everything in the diagram or else I canât say itâs good or not. And are you bypassing discharge? And if yes, why bypass with an 80a bms ?
