2TY’s keep burningout

Thread Starter

BR1988

Joined Apr 14, 2021
48
Hi, It's been a while, but I'm back online. Due to some private events, I haven't gotten to my other post about the exhaust valve yet. I want to pick up this project again as soon as possible and continue to work on a solution with your support.

In the meantime I have another problem. My current solution has always worked fine, however recently I've been having problems with some built-in units. On the relay board, there are 4 2ty resistors.
These have burned through on a few units. I just can't figure out the problem. I also have units that have been working for years without burning out.
Hopefully you can help me.
Below is my flowchart and a picture of the relay board.
53C59F7F-3EEE-42F7-9134-86BA3C02BD7D.jpeg
413F4990-60C0-498F-B0FE-4ED3152FC95D.pngGreetings Bas
 

Thread Starter

BR1988

Joined Apr 14, 2021
48
The relays on that board are 5V but from your diagram you are feeding the board with 12V. If that's the case, it's not a good idea.
Hi Albert,
I understand what you're saying. The reason I use the 5v relay board has to do with the fact that the car doesn't give 12v without starting. For that reason I went lower in terms of throughput voltage. I understand that you increase the load as soon as a higher voltage is applied. But maybe stupid from me I thought that this relay board could handle that, given the values that are on the relays. This way I can control the relay board without starting the car. the voltages from the battery to the relay board vary between 11 and 14v. The valve that is controlled is open when there is no power and closes when there is power. So if you apparently drive for too long with a closed valve, the resistors get too hot and burn out? But again I thought that 5v was the minimum starting voltage, but apparently that is not the case?
 

AlbertHall

Joined Jun 4, 2014
11,529
Without a circuit of the board I can only guess, but I would be surprised if a board designed for 5V would have a long life running from 12V.
I think that transistor is what drives the relay coil so the current it has to handle would be 2.4 times greater and so would the heat generated.
 

Ian0

Joined Aug 7, 2020
3,493
Most 12V relays will pull in at 9V, so would almost always work in a 12V vehicle, whether the engine is running or not. They will still behave properly during high current cranking when the battery voltage can get as low as 9V.
Could I suggest that you use "automotive" relays, which were designed with those voltages in mind?
 

Ian0

Joined Aug 7, 2020
3,493
Without a circuit of the board I can only guess, but I would be surprised if a board designed for 5V would have a long life running from 12V.
I think that transistor is what drives the relay coil so the current it has to handle would be 2.4 times greater and so would the heat generated.
And the relay would generate 5.76 times the heat it was designed for!
 

Thread Starter

BR1988

Joined Apr 14, 2021
48
Without a circuit of the board I can only guess, but I would be surprised if a board designed for 5V would have a long life running from 12V.
I think that transistor is what drives the relay coil so the current it has to handle would be 2.4 times greater and so would the heat generated.
Here is the information file.
I did try to translate a bit because it’s in German.
Features • 4-channel relay module, 5 V • each relay requires 15 - 20 mA for switching • equipped with high-load relays (switching capacity AC: max. 250 V / 10 A ; DC: max. 30 V / 10 A DC) • relay type: two-way switch • can be switched with level High as well as level Low - can be defined for each channel via a jumper • can be controlled directly with a microcontroller (Raspberry Pi, Arduino, 8051, AVR, PIC, DSP, ARM, ARM, MSP430, TTL logic) • all contacts are accessible via screw terminals • leeds for relay status display • dimensions: 73 x 50 x 19 mm

Maar wat jij dus zegt, is dat een 5v niet meer aan kan? Maar als ik een 12v relais bord neem. Dan kan die dus ook niet meer aan dan 12v? Wat bedoel je met, als er geen cicuite van het bord? Wat kan ik doen om het duidelijk te maken?
 

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Thread Starter

BR1988

Joined Apr 14, 2021
48
Okay, so the relay board is not the right one because the input voltage is higher than the maximum accepted voltage of 5v. I get that, so the longer the 12v runs over the relays, the faster the 2ty's burn.
That's why it doesn't happen very often and there are also relay boards that just keep working because the valve stays open and then the relay board gets no power.
But if I don't want the problem at all I have to solve it, now two things are being said here.
1. Take a 12v relay board. However, if I take a 12v relay board and you start the car and start driving then you also get higher voltage sometimes 13.6v or 14v. Will that not be a problem, just like the 5v relay board?

2. We put a voltage regulator in between. So that the transmission voltage does not exceed 5V.
Isn't this the intention with the 12v relay board?

So actually both relay boards are not sufficient. Unless I put a voltage regulator in between?
 

Thread Starter

BR1988

Joined Apr 14, 2021
48
Basically.
But you don't have to buy a new relay board.
No that is right. As long as the voltage regulator does not let more than 5v through that is fine and I can continue to use the current relay board. However, those voltage regulators can still get hot, right? The higher the input voltage vs the output voltage, the hotter it gets?
 

Thread Starter

BR1988

Joined Apr 14, 2021
48
If you use the 5V relays, then add an LM7805 regulator to keep the relay voltage at 5V.
Hi,
So I bought and connected the LM7805 regulator. On the input I have connected a variable current device so that I can simulate the voltage of the car without having the relay board in the car. I have assumed that the car is moving and therefore the voltage is also over 12 volts. I have set the device to 13.4v. The output voltage of the LM7805 regulator is around 4.8/5v, so that's good. Only the LM7805 regulator gets very hot, you can smell it and you can't put your finger on it without burning it, It on for not even 1min. I don't have a ground connection so I connected the -12 (ground) of the LM7805 regulator to the negative terminal on the variable voltage (device). What can I do about it? I also bought a 12v relay board and a regulator that puts out max 12v. Would this reduce any heat, or can the LM7805 regulator lose its heat better if the -12v ground connection is connected to a ground point on the car?

hope you could tell me more.
 

bwilliams60

Joined Nov 18, 2012
1,419
Your best fix for this is to run with 12v automotive relays. They will cut in at around 6.5v, run cool from 11-15 volts without issue and regulation not necessary. If you want to keep with the 5v regulator, you will need to heat sink it and maybe install a fan to keep it cool.
 

Thread Starter

BR1988

Joined Apr 14, 2021
48
If you use the 5V relays, then add an LM7805 regulator to keep the relay voltage at 5V.
so I bought the LM7805 and attached it to a variable Voltage controller.
Your best fix for this is to run with 12v automotive relays. They will cut in at around 6.5v, run cool from 11-15 volts without issue and regulation not necessary. If you want to keep with the 5v regulator, you will need to heat sink it and maybe install a fan to keep it cool.
Hi, thanks for the reply. Could you point out some automotive relays?
I just ordered the same relayboard I have in 5v but then in 12v.

thanks in advance
 

bwilliams60

Joined Nov 18, 2012
1,419
I would just look to find an everyday SPST or SPDT 12v automotive relay for your application. If you GOOGLE standard automotive relay, you should find all kinds. They will normally be rated for about 30 Amps. They will draw roughly in the area of 100mA on the control coil. My preference is Bosch relays.
 
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