Why is the output incorrect when the 24V battery powers the DC-DC?

肖柳子

Why is the output incorrect when the 24V battery powers the DC-DC? [Copy link]

 

The battery output voltage is 24V, and the voltage regulator output voltage is 24V. If a switching power supply or a voltage regulator is used to power the DC-DC, the voltage is reduced to the expected value of 12V. However, if the switching power supply or the voltage regulator is removed and the DC-DC circuit is powered by a battery, the voltage is only reduced to 9V. The battery input oscilloscope test is as follows: What is this situation? Please help

maychang

What is the output voltage of your "switching power supply or voltage regulator"? What is the output voltage of your "battery"? If these parameters are not clearly stated, what is the use of looking at the voltage waveform at both ends of the battery?

chunyang

To measure the battery voltage, the step-down DCDC must meet the minimum input voltage condition. If the voltage is lower than this, the DCDC will not work properly.

肖柳子

maychang posted on 2018-7-10 17:15 What is the output voltage of your "switching power supply or voltage regulator"? What is the output voltage of the "battery"? These parameters are not clear, look at the battery...

Thank you for reminding me, I will add: The output voltage of the battery is 24V, and the output voltage of the voltage regulator is 24V

肖柳子

chunyang posted on 2018-7-10 17:28 To measure the battery voltage, the buck DCDC must meet the minimum input voltage condition. If the voltage is lower than this, the DCDC will not work properly.

Test battery voltage 25.3V

maychang

Xiao Liuzi posted on 2018-7-10 17:35 Test battery voltage 25.3V

Is this the battery no-load measurement? Connect your DC-DC and measure the battery terminal voltage.

chunyang

Xiao Liuzi posted on 2018-7-10 17:35 Test battery voltage 25.3V

It must be tested with load, and it must be a load that cannot work normally (that is, when you said 9V). When the battery output current is insufficient, the terminal voltage will drop significantly.

肖柳子

chunyang posted on 2018-7-10 23:56 It must be tested with a load, and it must be a load that cannot work normally (that is, when you said 9V). When the battery output current is not enough, the terminal voltage will drop significantly...

The load LED light (1A current) will not work after it is connected and will keep flashing. It is no problem to use a switching power supply.

335566

Could you please tell me the DC/DC chip solution? Can it meet the requirement of 1A output?

335566

One more thing to add: if you want to output 1A, it is best to consider a certain margin. For example, 1.5A

肖柳子

335566 Published on 2018-7-12 15:41 One more thing to add, if you want to output 1A, it is best to consider a certain margin. For example, 1.5A

is enough for a 10A chip, 3A load test.

chunyang

Xiao Liuzi posted on 2018-7-12 11:22 The load LED light (1A current) keeps flashing when connected. It is fine to use a switching power supply.

It is obvious that you are not using the right battery. Replace it with a battery with a larger capacity and stronger load capacity.

335566

1. Connect the circuit and use a meter to measure the battery voltage. Is it too low? 2. Is the wire connecting the board and the battery too thin, causing the current to not flow?