Hello
Can someone share a simple circuit design where more than 10 cells (18650 lithium for eg) can be shown , to perform a volt monitoring arduino of this series stacked cells, using flying capacitor approach?? i have seen very simple ones not clear how or what the components are, and where are the 10 o 20 cells connected and how...thanks in advance!!
Maybe a diagram will help.
yes that is what im asking for
Ask "Search Forum", the tab up to the right in this window. Plenty ot tobics to find about this topic.
yes i did and i did not find what im asking for, in case you have seen a complete more than 10s cells stack using this approach please post , it does not exist unless you can think this is enough for such a requirement (not clear for me , where the bats are located, how to place 20 if this is suitable for 20s, what capacity is required for the cap, etc
Still no idea what you are trying to accomplish. Can you point to an article or circuit?
You should look for the principle and understand how it works. If You look for a complete example to copy You'll be stuck there.
What is the capacity needed?
Switching GND is nearly always dangerous.
Can you explain this circuit? I can't make sense of it.
So you can monitor each individual cell in a battery.
This is my diagram and I will not re-post it here.
If you want more capacitors just duplicate what you have here. That is simply more capacitors and more relay drivers.
Do you understand the function of the dotted line? It is to show that the relay is a double throw relay.
The sample capacitor need to be only about 1nF.
This is as good as it gets try expanding it to two capacitors and post your interpretation of the expanded circuit for us to check here.
Is there a reason why you want to build this from scratch using relays rather than using a battery monitor IC?
Mike, I know what is trying to be achieved and I know how to do it with relays and one capacitor, but I don't have a clue how that circuit is supposed to do anything, let alone monitor battery voltages. I'm hoping it's genius and I'll learn something, but right now I can't see it.
Me neither.
This might help:
These links will explain it better then I can.
The 2 Web pages you linked to in post #14 are interesting and have taught me some things I didn't know about using flying capacitors in inverters, they offer nothing about what the OP is asking about, which I quote below as a reminder:
If the circuit in post #8 can be used for the OP's purposes I, and I suspect the OP, am still puzzled about how that would work.
I suggest this circuit:
The voltage to be measured from each relay goes through the relay above, with the top relay, K1, being the only one that passes the voltage on to the flying capacitor. Because of this arrangement it doesn't matter if 2 or more relays are operated at the same time, there is no possibility of shorting the batteries together, the highest relay in the chain will be the one connected to the flying capacitor, the lower ones are disconnected.
Relay K4 passes the voltage on the capacitor on to the Arduino to be measured. K4 also controls the negative connection to all the other relays ensuring they cannot be operated at the same time as K4, so maintaining isolation between the batteries and the Arduino.
Missing from the schematic are:
Not the flying cap principle.
A flying cap presents only one cell at the time to the A/D, thus utilising the full resolution of the A/D fot each individual cell.
Post#45 here shows my DIY flying cap setup for 24 cells, with small-signal relays anf TPIC drivers.
Leo..
Capacitor voltages essentially mirror the battery cell they are connected across. Normally, we use ground as a reference, but when dealing with cells in series, this becomes more complex.
If we connect a series of capacitors across a series-connected battery pack (e.g., 10 cells), the bottom of the pack is grounded, and the top floats at 10 times the individual cell voltage. In this configuration, the negative side of each capacitor ends up sitting at the voltage level of the previous cell, not at ground.
Each capacitor still only sees the voltage difference across the cell it’s connected to. However, since each point in the series is at a different potential, you can't simply connect your measurement equipment with one side grounded, or you'll short parts of the battery.
To measure the voltage across a specific capacitor (and thus the corresponding cell), you must temporarily isolate the capacitor from the battery and connect both of its leads to your measuring device, typically grounding the negative and measuring the positive side. For a short period, this allows the capacitor to hold and present the true cell voltage, which can then be safely measured.
If you attempt to measure without switching the capacitor out of the live circuit, you risk creating a short circuit path. This is why switches or relays are typically used to isolate the capacitor from the battery circuit during measurement.
The principle is the same the voltages just increase as the number of cells increase.
Maybe this explains it better!
No, that is a multi level inverter which uses flying capacitors for an entirely different purpose.
