![]() ![]() I must say, lipo's are hard to work with because for there variable voltage. I will test some after I get my imax b6 charger. With the voltagedivider calculator I can clearly see wich E resistors get what voltage, so it will still be accurate. The the other three, I want to make a building kit of my project, it would be nice to use resistors instead of pots. Thanks for allot of helpfull information.įor 1 cell, I don't need a single resistor? Do I not need to limit the current on the analog in? You will have quite the time getting all the calibration set-up correct for each of the three multi-cell taps to scale correctly and then the subraction factor to obtain individual cell values, but you seem to have a good understanding of what is required. 20 turn trimmer pots (10k ohms or higher) can make decent voltage dividers that can be adjusted to give the ratio you wish. So make sure you 'calibrate' you program using the power source you will normally be using.įor measureing the other three cells you will need three voltage dividers. This +5vdc voltage will be slightly different when changing from external voltage to USB voltage. The standard Arduino A/D setup is using the board's +5vdc Vcc as the measurement reference. Keep in mind that you will have other 'calibration' issues to deal with. ![]() Yes, cell one's terminal will only go as high as 4.2vdc (at max charged cell voltage) so it can wire directly to a analog input pin as it will 'fit' in the standard 0-5vdc range of the processor chip, no voltage divider required. But can I just plugin the "+" of that cell right into the analog-in? Did not dare to try it without resistor. My previous circuit did work, but not correctly?įor cell 1, I don't need a voltage divider, it's never going over 5v. Is my circuit correct, but do I need different resistors to not divide it? I just tested it, I get a reading of 1.88v on cell1, thats not correct, why? It seems I divided the voltage by a factor of two. If I understand correctly, it should look like this. So the Gnd are always attached, but the test I did was with a 12v battery, so I needed to connect "-" somehow, without it the reading was all over the place. The lipo also powers the arduino from Vin and Gnd. But that way, cell 4 will be less accurate than cell 1 reading because of it's higher voltage. It's good enough to make 4 different voltage dividers. Thats the most accurate, but I have no idea to do that. It's more complicated.Īnd even more complicated to make ranges like, cell 1 2.5-4.5v, cell 2 6-13v. So if I want more accuracy I need 4 different voltage dividers that need different code. So it can handle the reading of cell 4.īut that cost me accuracy because cell 1 only read 3-4v. I need to use one type of voltage divider that can detect up to 17v. And cell 4 may read 14.8v, subtract all other cells to get cell 4 voltage.īut to make ik easy. So the scripting must subtract cell1 from the reading of cell2 to show cell 2 voltage.Ĭell 3 may read 11.1v, and need to subtract cell 1 and 2 to get cell 3 voltage. So to see each cell voltage I need to calculate it.įor example, cell 1= 3.7v, it reads 3.7v, easy.Ĭell 2 may read 7.4v. Remember, I'am a noob, so every advise must be in noob language.īecause at first I tought I could read 4x 0-5v. But this plan isn't going to work I gues.Ĭan someone help me with monitoring all 4 cells? And help me with a circuit drawing? I don't know how exactly use a voltage divider, and what code I need for that. And calculate the total voltage by counting all cells together. My plan was to display all cells on a lcd display. I read about voltage dividers, but I gues I need a different divider for every cell :o This makes it verry hard for me to simply monitor all cells. So it's was in serie, and the next cell and the next were also in serie. I tested it with my multimeter, and it was 7.54v. And I gues I need a 4pin on/off switch to turn on and off both the - of the dean plug power cable of the lipo, but also the - on the recharge plug to prevent power loss on storage.īut I want to monitor all 4 cells at the same time, so I first tried to read the second cell, and arduino displayed 4.94v! I first tried to use only one 10K resistor, it worked, but the power led on the arduino started to burn, even when it wasn't connected to USB, so I gues the arduino is using it as a power supply somehow.īut even with the resistor it is using power. This way I could read 3.71v on the serial. I used 2x 10K resistors, didn't know how it supose to work, so I just tried. I'am a Arduino noob, but I managed to monitor one cell. ![]() I have a 4 cell lipo that I want to monitor with the Arduino Duemilanove.
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