Is this circuit design correct?

we秦羽

Is this circuit design correct? [Copy link]

 

 

I want to connect multiple batteries to the circuit board, and then control them through a single-chip microcomputer to charge them in turn, charging only one battery at a time. The picture below is a wiring diagram of a 4S battery consisting of 4 cells connected to a charger, with the on-off switch controlled by a MOS tube. Is this feasible?

maychang

[……Is this feasible? ]

Most likely it won't work because I can't understand the circuit.

we秦羽

maychang posted on 2023-12-22 18:42 […Is this feasible? ] Most likely it is not feasible, because I don’t understand this circuit.

The 4s battery is 4 cells of about 4V connected in series. The line on the right is the total voltage of the negative and positive poles 16V, and the left is the balance head of the battery. Each line is the wire between each cell in series, so the voltage is different, which is used for balanced charging.

None of this is important, I just want to ask if it is possible to use MOS tubes in this way to control the on and off of these lines.

maychang

we Qin Yu published on 2023-12-22 19:04 4s battery is 4 4v battery cells connected in series. The line on the right is the total voltage negative and positive 16v, the left is the battery balance head, each line is...

[These are not important, I just want to ask if it is possible to use MOS tubes to control the on and off of these lines. ]

Since these are not important, I will only discuss whether MOS tubes can be used in this way to control these lines.

In the first circuit, each MOS tube gate is marked with "signal". According to the rules of drawing electrical schematics, these five MOS tube gates are connected together. These five connected gates are connected to the "MCU 5V control signal" through a resistor.

However, the source potentials of these five MOS tubes are different, so the five tubes may not all be turned on when the "microcontroller 5V control signal" is a high level of the microcontroller.

Conclusion: Not feasible.

we秦羽

maychang posted on 2023-12-22 19:28 [None of these are important. I just want to ask if it is possible to use MOS tubes to control the on and off of these lines. ] Since none of these are important, then I...

I changed it a bit, is this ok?

Or can I ask how to design this circuit? My requirement is very simple, that is, the microcontroller controls whether this battery is connected to the charger through the MOS tube, thank you!

maychang

we Qin Yu published on 2023-12-22 19:38 I changed it a bit, is it okay? Or can I ask how to design this circuit? My requirement is very simple, that is, the microcontroller communicates...

[I changed it a bit, is this okay? ]

Can't.

Your "MCU 5V control signal" is generated by the MCU, and the power supply for the MCU is 5V. The MOS tube you added is a source output, and its output amplitude cannot be greater than 5V, but only smaller than 5V.

If the newly added MOS tube is not used, and the MOS tubes are directly driven by the single-chip microcomputer, and the negative output terminal of the power supply for the single-chip microcomputer is GND, then the MOS tube in the lower right corner can be turned off and on by the single-chip microcomputer because the source of the tube is connected to GND. However, the sources of other MOS tubes are not at ground potential, so they cannot be controlled by the single-chip microcomputer.

we秦羽

maychang posted on 2023-12-22 19:45 [I changed it a bit, is it okay? ] No. Your "MCU 5V control signal" is generated by the MCU, which is...

Then I would like to ask if it would work if I use a triode instead?

maychang

we Qin Yu published on 2023-12-22 20:08 Then I would like to ask if it will work if we change to using a triode?

[Then I would like to ask if it would work if I use a triode instead? ]

Compared with the 5th floor, this picture not only changes to using triodes, but more importantly, changes from source output to collector output.

The collector output has voltage gain, the source output has no voltage gain (less than 1).

After changing to collector output, the microcontroller control logic is opposite to before: when the microcontroller outputs a low level, each MOS tube is turned on.

Because your charger output is up to 16V, and the maximum voltage allowed between the gate and source of the MOS tube is usually 20V, so the gate of each tube can withstand it.

This circuit can be controlled by a single chip microcomputer to turn on and off each MOS tube. But I did not say that those "unimportant" functions of this circuit can be realized.

maychang

we Qin Yu published on 2023-12-22 20:08 Then I would like to ask if it will work if we change to using a triode?

I don’t think those “unimportant” functions can be realized.

we秦羽

maychang posted on 2023-12-22 20:38 [Then I would like to ask if it would work if we use triodes instead? ] Compared with the fifth post, this picture is not only about using triodes, but more importantly, the source output...

Thank you! Your answer is very professional. As long as it can control the shutdown and conduction, it will be fine. There are no other functions.

mazhenhang

How can I get points quickly? Does anyone know how to get points as a newbie? Sorry for bothering me!

maychang

we Qinyu published on 2023-12-22 20:44 Thank you! Your answer is too professional. As long as it can control the shutdown and conduction, there is no other function.

However, this circuit has great limitations. The current charger is 16V, and if it is 24V, this circuit cannot be used.

The correct design should be that each MOS tube has an independent and isolated driving circuit.

富贵闲人

It is not feasible. At least the battery has no overcharge safety protection. If you connect it to charge directly, the battery may be in danger easily. Could you please take a look at this?

tagetage

The overall design of the plan is wrong. No matter how you change it, it will be wrong.

se7ens

The idea is good, but it is very difficult to implement, and the driver is a big problem

秦天qintian0303

It looks like your batteries are connected in series, so it is impossible to charge a single battery, and your charger cannot output so many voltages.