Analog Input

Hello everyone,
It's my first topics here. I would like to ask about problem with my arduino. I have decided to make solar tracker with voltage measurement. I make solar tracker with 4 ldr and 2 servos. Ldr are connected to analog in ( A0,A1,A2,A3).
Everything works great. When I made voltage divider and connected to analog in (A4) it doesn't work. Servos moving very slow. I have made test voltage measurment without connecting ldr and servos and it's work. I used 9v battery to power Arduino. What could be a reason ?

What could be a reason ?

I used 9v battery to power Arduino.

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9V transistor radio battery? They give limited current. Put that through a 5V regulator and only 55% of the current is left.

You could bundle 9V cells in parallel to get more current and use a buck converter to change 9V to 5V with small loss or you can bundle rechargeable AA cells that perform better and buck convert those down to 5V that you connect to board 5V, not VIN or the regulator (same trace).

Be careful to run all motor/relay/more-than-signal power through the Arduino that should only control the power through transistors or relays or other power control devices. Arduino pins total current IN and OUT should be less than the 200mA max.

What resistors did you use for voltage divider? What is the solar panel voltage? Post a schematic.

If your 9 volt battery is powering, then yes it's the problem.