Manual voltage control of single cells - Part 1: Soldering the knob / switch Hello,
to eLogger project: Unfortunately, so far I could not install the eLogger V3, because I still miss some connections, which will order or get a friend of mine. Technically, it would be possible to incorporate eLogger any time. However, I would be able to unplug it when needed without any tools from the circuit if you experience any problems.
voltage monitoring of individual cells: Intermediate however, I have already implemented a new project almost. I want to use the service door of the scooter to provide an interface through which one can measure all the voltages of all 20 individual cells easily, also, for example while driving.
this it is necessary that at each of the 20 cells of both the negative and the positive pole is tapped for voltage measurement. Since I use the BMS20-550pro Ide ²-e, can be easily tapped the voltages on the sense lines of the BMS. Has the advantage that the leads are then protected even by the fuses of the sense lines to 500mA.
Furthermore, a possibility to switch between the cells is necessary, since the voltage of each cell, not all cells in series to be measured. Therefore have to be put to the "switch" theoretically a total of 40 lines. Practically there are only 21 lines because of the positive terminal of nearly all cells in series, too automatically to the negative terminal of the next cell in series is equal to: + [=] - + [=] - + [=] - + [=] -
Since only tension to be measured, the cross-section is not so important, and therefore offers itself as an old cable parallel printer cable. This includes 25 separate small strands.
to be sure to switch the order right, theoretically you would need a 2-pole 20 times the switch / knob. That's unfortunately not, at least not at affordable prices. That leaves the possibility of an electronic circuit. This would certainly be the most elegant. Since I am not a specialist in this area, however, and thus no electronic circuit would hammer out, I've changed my mind and simply resorted to four 2-pole 6-way rotary switch used. Makes a total of 24 positions. In each case, a switch position of rotary switch I have not been established. In this rest position, they are normal, there is only one shot on a predetermined, desired position about the voltage of a single cell to be passed through.
The switches I installed in a small plastic housing. Here you have to look how to do it best. Unfortunately, behind the flap on the scooter is not unlimited space and you have to try just wants to host the switching unit and how to get into it well. The solution in my case did not succeed 100% ideal may be served by the door and through work.
The soldering of the switch is basically logical and theoretically easy, but in practice quite tricky. Above all, you have to write 100% sure which wire was soldered where or to which battery cable which ran (in my case, BMS interface) is. I have to take a picture of the BMS interface and pasted directly from a piece of cable next to it. Also a sketch of how the rotary switch is helpful. Here you have to win any beauty contests so. The main thing you look through yourself.
The last step should necessarily use all cable wires are measured with a multimeter by the cable and the rotary switch with every possible single-switch position!
