Relay Coil Question

[vinter93]

Hello.
I'm doing a project in my car with the help of a relay.
It is working fine but I need some advice on something.
The circuit that serves as a switch to the relay provides 12v with the car off but with the engine running it provides around 14v.
My question is, is this too much for the relay Coil?
It is a 12v 40amp relay.
Model Nagares RLP/4-12.
I tried to find a technical sheet but couldn't find the answer to my question.
Thanks in advance.

 

[telectrix]

should not cause a problem. with other loads in use, that 14V will drop slightly. it's the charging voltage from the alternator.

 

[vinter93]

should not cause a problem. with other loads in use, that 14V will drop slightly. it's the charging voltage from the alternator.

The switch comes from the roof lights, with the car off it outputs 12v, with the car on it outputs 14v, doesn't seem to lower the voltage, at least for the time I was measuring.
If it doesn't drop the voltage and it feeds the coil for a long time, will the 2v difference be dangerous?
I'm afraid it could melt or something

 

[telectrix]

can't see it being a concern. a relay should handle a couple of volts above 12V. don't forget, your vehicle has several 12V relays for various purposes, and they all get the same.

 

[vinter93]

can't see it being a concern. a relay should handle a couple of volts above 12V. don't forget, your vehicle has several 12V relays for various purposes, and they all get the same.

I thought about that as well but I also thought that the relays could be powered by the battery output instead of the alternator out, thus feeding them with 12v instead of 14v.
But I'm no expert on the matter, I suppose it is a possibility so I wasn't sure if that was a viable comparison method.
I'll leave it as is with the 14v, what is the worst that can happen?

 

[freddo]

The battery voltage will be over 12V when the engine is running otherwise it wouldn't charge. I assume the roof lights in the vehicle just switch on and off? Modern cars with lights that dim up and down are unlikely to be happy with a relay coil connected to them. EMF suppression should also be considered, info here.

 

[vinter93]

The battery voltage will be over 12V when the engine is running otherwise it wouldn't charge. I assume the roof lights in the vehicle just switch on and off? Modern cars with lights that dim up and down are unlikely to be happy with a relay coil connected to them. EMF suppression should also be considered, info here.

Yeah, unfortunately they dimm a bit from off to on, it was causing some buzzing noise on the relay but I looked around and was able to fix it with a 16v 1000uF across the relays switch and a diode on the negative switch terminal.
It is on the negative side because that terminal has constant 12v and when the light is on it drops to 0, thus completing the circuit.
The negative side actually serves as the switch, the positive side of the bulb has constant 12v (14 when the car is running, I only noticed that today, that's why I was worried about the relays tolerance to 14v).
Anyway, I'll keep it as is, I was just worried since I didn't know the cars wiring would go to 14v when the engine is running.
I learned something new today

 

[telectrix]

the reason that the voltage increases to 14V when engine is running is that the battery needs a charging voltage 10-15% higher than it's output voltage to charge it. that's what the alternator does. similar with alarm systems.... the charge voltage is generally 13.6V.
if this wer not the case, the battery would discharge and go flat.