My code doesn't open all four channels in relay module - arduino

Question

I am making a Home automation. I have used arduino-uno, HC-05 bluetooth module and four channel relay module. I am currently stuck when I enter 'z' from my mobile my all channels of relay won't act as open switch.
I don't know why all the switches can't be opened simultaneously. Is it a problem of arduino or relay or the code ?
String inputs;
#define relay1 2 //Connect relay1 to pin 2
#define relay2 3 //Connect relay2 to pin 3
#define relay3 4 //Connect relay3 to pin 4
#define relay4 5 //Connect relay4 to pin 5
int val1=0;
int val2=0;
int val3=0;
int val4=0;
int val5=0;
void setup()
{
Serial.begin(9600); //Set rate for communicating with phone
pinMode(relay1, OUTPUT); //Set relay1 as an output
pinMode(relay2, OUTPUT); //Set relay2 as an output
pinMode(relay3, OUTPUT); //Set relay1 as an output
pinMode(relay4, OUTPUT); //Set relay2 as an output
digitalWrite(relay1, HIGH); //Switch relay1 off
digitalWrite(relay2, HIGH); //Swtich relay2 off
digitalWrite(relay3, HIGH); //Switch relay3 off
digitalWrite(relay4, HIGH); //Swtich relay4 off
}
void loop()
{
while(Serial.available()) //Check if there are available bytes to read
{
delay(10); //Delay to make it stable
char c = Serial.read(); //Conduct a serial read
if (c == '#'){
break; //Stop the loop once # is detected after a word
}
inputs += c; //Means inputs = inputs + c
}
if (inputs.length() >0)
{
Serial.println(inputs);
if(inputs == "a")
{
if(val1==0)
{
digitalWrite(relay1,LOW);
val1=1;
}
else
{
digitalWrite(relay1,HIGH);
val1=0;
}
delay(100);
}
else if(inputs == "b")
{
if(val2==0)
{
digitalWrite(relay2,LOW);
val2=1;
}
else
{
digitalWrite(relay2,HIGH);
val2=0;
}
delay(100);
}
else if(inputs == "c")
{
if(val3==0)
{
digitalWrite(relay3,LOW);
val3=1;
}
else
{
digitalWrite(relay3,HIGH);
val3=0;
}
delay(100);
}
else if(inputs == "d")
{
if(val4==0)
{
digitalWrite(relay4,LOW);
val4=1;
}
else
{
digitalWrite(relay4,HIGH);
val4=0;
}
delay(100);
}
else if(inputs == "z")
{
if(val5==0)
{
digitalWrite(relay1,LOW);
digitalWrite(relay2,LOW);
digitalWrite(relay3,LOW);
digitalWrite(relay4,LOW);
val5=1;
}
else
{
digitalWrite(relay1,HIGH);
digitalWrite(relay2,HIGH);
digitalWrite(relay3,HIGH);
digitalWrite(relay4,HIGH);
val5=0;
}
delay(100);
}
inputs="";
}
}

Answer 1

Many times relays use much current. And arduino has limited current capacity maybe these is the reason why they can't be opened simultaneously.