Rechargeble flashlight with battery pick up

ive tried and tried to do this but i am not a programmer im trying to get a battery pickup to recharge my flashlight but nothing is working this is the flashlight script

using UnityEngine;
using System.Collections;

[RequireComponent(typeof(Light), typeof(AudioSource))]
public class Flashlight : MonoBehaviour {
public AudioClip clickSound;
public float batteryLifeInSec = 300f;
public float batteryPercentage = 100;

private bool on;
private float timer;

void Update() {
	Light lite = GetComponent<Light>();
	timer += Time.deltaTime;

	if(Input.GetKeyDown(KeyCode.F) && timer >= 0.3f && batteryPercentage > 0) {
		on = !on;
                    audio.PlayOneShot(clickSound);
		timer = 0;
	}

	if(on) {
		lite.enabled = true;
		batteryPercentage -= Time.deltaTime * (100 / batteryLifeInSec);
	}
	else {
		lite.enabled = false;
	}

	batteryPercentage = Mathf.Clamp(batteryPercentage, 0, 100);

	if(batteryPercentage == 0) {
		lite.intensity = Mathf.Lerp(lite.intensity, 0, Time.deltaTime * 2);
	}
	
	if(batteryPercentage > 0 && batteryPercentage < 25) {
		lite.intensity = Mathf.Lerp(lite.intensity, 0.5f, Time.deltaTime);
	}
	
	if(batteryPercentage > 25 && batteryPercentage < 75) {
		lite.intensity = Mathf.Lerp(lite.intensity, 0.8f, Time.deltaTime);
	}
	
	if(batteryPercentage > 75 && batteryPercentage <= 100) {
		lite.intensity = Mathf.Lerp(lite.intensity, 1, Time.deltaTime);
	}
}

}

I have this on s spotlight under the main camera i cant get a separate script to read form this one so when i pick up the battery it adds batteryPercentage i realy appreciate your help

Update 1 :

Would this work? cant test not at my pc

        using UnityEngine;
        using System.Collections;
        
        public class Battery : MonoBehaviour { 
        
        public Battery_pickup Battery_pickup;
    
    void OnTriggerEnter(Collider other){
     
        void Update () {
             //pick up
              void OnTriggerEnter(Collider other){ 
                  if(other.gameObject.tag == "Pickup") { 
                  //add Charge 
                  Destroy(other.gameObject);
                  Flashlight.batteryPercentage += 10; 
                  }
        }

        using UnityEngine;
        using System.Collections;

Update 2 :

   public class Battery : MonoBehaviour { 
    
    public Battery_pickup Battery_pickup;

void OnTriggerEnter(Collider other){
 
    void Update () {
         //pick up
          
              if(other.gameObject.tag == "Flashlight") { 
              //add Charge 
              Destroy(other.gameObject);
              Flashlight.batteryPercentage += 10; 
              }
    }

This should be in a file named Flashlight.cs, see my comments for corrections I’ve made.

using UnityEngine;
using System.Collections;
 

[RequireComponent(typeof(Light), typeof(AudioSource))]
public class Flashlight : MonoBehaviour {

	public AudioClip clickSound;
	public float batteryLifeInSec = 300f;
	public float batteryPercentage = 100;
	
	//Declare lite outside of a function so all functions within the class have acess to it.
	public Light lite;
	 
	private bool on;
	private float timer;
	
	void Start(){
		//moved this to Start function.  Start is called only one time, on start up during run time.  thats all you need	
	    lite = GetComponent<Light>();
	}
	 
	void Update() {
	
	    timer += Time.deltaTime;
	     
	    if(Input.GetKeyDown(KeyCode.F) && timer >= 0.3f && batteryPercentage > 0) {
	   	 	on = !on;
			audio.PlayOneShot(clickSound);
	    	timer = 0;
		}
	 
	    if(on) {
	    	lite.enabled = true;
	    	batteryPercentage -= Time.deltaTime * (100 / batteryLifeInSec);
	    }
	    else {
	    	lite.enabled = false;
	    }
	     
	    batteryPercentage = Mathf.Clamp(batteryPercentage, 0, 100);
	     
	    if(batteryPercentage == 0) {
	    	lite.intensity = Mathf.Lerp(lite.intensity, 0, Time.deltaTime * 2);
	    }
	     
	    if(batteryPercentage > 0 && batteryPercentage < 25) {
	    	lite.intensity = Mathf.Lerp(lite.intensity, 0.5f, Time.deltaTime);
	    }
	     
	    if(batteryPercentage > 25 && batteryPercentage < 75) {
	    	lite.intensity = Mathf.Lerp(lite.intensity, 0.8f, Time.deltaTime);
	    }
	     
	    if(batteryPercentage > 75 && batteryPercentage <= 100) {
	    	lite.intensity = Mathf.Lerp(lite.intensity, 1, Time.deltaTime);
	    }
	}
}

Now I will do the Battery Class…