FAQ: RELAYS; how they work and how to wire it up...

[koolaid_kid]

I use a socket for all of my relays (my bikes and my TransAm). Once everything is wired up, I put silicone in the end of the socket where the wires enter. Then I put dielectric grease in the socket end where the relay plugs in. This makes it relatively waterproof.
IMHO sockets are much easier to use than individual wires, plus I don't have to worry about which wire goes where.

One thing I would like to point out that many seem to miss: Relays are rated at 40 Amps Off (87a) and 30 Amps On (87). Many seem to believe that they have a 40 Amp relay when really they have a 30 Amp relay because they use terminal 87.

 

[posplayr]

One thing I would like to point out that many seem to miss: Relays are rated at 40 Amps Off (87a) and 30 Amps On (87). Many seem to believe that they have a 40 Amp relay when really they have a 30 Amp relay because they use terminal 87.

Interesting;

 

[koolaid_kid]

Interesting;

Yup. For example, my current batch are Yong Lin YL-314-C-12VDC. The printing on it says:
NO: 40A/14VDC
NC: 30A/14VDC
Normally Open (87a) 40A, Normally Closed (87) 30A.
I never dug into it so I am not sure why, but every one I have ever seen has been the same. CYOA, perhaps?
This observation only applies to 40A 5-terminal Bosch-style relays, others may differ.

 

[posplayr]

Yup. For example, my current batch are Yong Lin YL-314-C-12VDC. The printing on it says:
NO: 40A/14VDC
NC: 30A/14VDC
Normally Open (87a) 40A, Normally Closed (87) 30A.
I never dug into it so I am not sure why, but every one I have ever seen has been the same. CYOA, perhaps?
This observation only applies to 40A 5-terminal Bosch-style relays, others may differ.

here is a detailed spec on the Tyco formerly Bosch relays

http://www.weltronics.com.cn/pdf/pline/TycoElectronics/12434032588960.pdf

 

[koolaid_kid]

here is a detailed spec on the Tyco formerly Bosch relays

http://www.weltronics.com.cn/pdf/pline/TycoElectronics/12434032588960.pdf

On page 73, 1 Form C is the 5 terminal relay. It is listed as 25/35A continuous. This allows a bit of surge when things start up and they can market it as a 40A relay. But the 35A continuous is for terminal 87a, which I normally do not use. The 25A is for terminal 87, which is the one I normally use. At a nominal 12V, this is 300 watts, which is a significant amount of power for anything bolted to a motorcycle.

 

[posplayr]

On page 73, 1 Form C is the 5 terminal relay. It is listed as 25/35A continuous. This allows a bit of surge when things start up and they can market it as a 40A relay. But the 35A continuous is for terminal 87a, which I normally do not use. The 25A is for terminal 87, which is the one I normally use. At a nominal 12V, this is 300 watts, which is a significant amount of power for anything bolted to a motorcycle.

You will note that the "Max Limiting Continuous Current" is a function of temp and the 25/35A is at +85 degC. The turn-on currents are much higher (45/120A) and turn-off slightly lower (20/30A)

 

[koolaid_kid]

85C ~= 185F, which is probably the closest for our uses.
125C ~= 257F, which may be closer for under the hood of my TransAm, which means their current capacity drops off to 15A. I have several under the hood, but none have ever failed. I wonder...

 

[rizan.diana]

Hi. I have 3 inquiries.

what happen if join using wire relay pin no. 87 with another relay pin no. 87?
Is the power still produce 12v or more than 12v or the relay might get malfunction?
And is the relay A pin no. 86 will feed current from another relay if relay B is switching on?

 

[Steve]

1. If you join two pins #87, you have the same thing that you would if just one of them turned on.
Might need a diagram to see what you are trying to control and why you have two relays that might be connected to each other.

2. The power will never go above 12 volts. Well, OK, it will go to about 14 volts as the charging stuff happens, but you will NOT get 24 volts. Malfunction? Likely not, but will still need to see a diagram or have a very good verbal description of what you are trying to do.

3. Will definitely need a diagram or description of this one. NOTE: pin 86 never "feeds" anything. It is part of the switching coil. You either feed it to trigger the relay or you connect it to ground. Again, a diagram to see what you are trying to do or a GOOD verbal description.

.