placing diodes

Thread Starter

JOEFORNS

Joined Mar 30, 2020
4
I'm wiring up two more headlights on my motor cycle . do I need to put a diode on the relay switch to protect my battery from reverse flow of electricity ? If I do where do I place it (five pin diode)
 

fmrPIC

Joined Nov 11, 2016
22
I think you are referring to a bridge rectifier. Usually they match the capacity of the alternator. There is some back EMF from the relay coil but it should not be an issue. If your relay was designed for a car or motorcycle, it will likely have protection. I think power load may be more of a concern. Check your manual and add up the watts.
 

dl324

Joined Mar 30, 2015
16,839
Welcome to AAC!
do I need to put a diode on the relay switch to protect my battery from reverse flow of electricity ?
Some automotive relay sockets come with an integral snubber diode. If it doesn't, you need to tell us how the coil is being switched. The diode is more to protect a transistor or switch contacts from back EMF generated when the coil field collapses.
If I do where do I place it (five pin diode)
Never heard of a 5 pin diode; 2 and 4, but not 5. Post a part number and/or picture.
 

MisterBill2

Joined Jan 23, 2018
18,167
You do not need a diode to protect the battery from the transient spike that is generated when the relay power is switched off. That is because the switching device is a mechanical switch and it will not be affected at all by the very short and quite small inductive spike. A transistor controlling the relay might need protection, or possibly not.
So you will not have any problems if you do not add a diode.
 

danadak

Joined Mar 10, 2018
4,057

MisterBill2

Joined Jan 23, 2018
18,167
In general inductive clamps / snubbers are good. If L load being switched by a mechanical
switch it aids in reducing contact burn and oxidation of the contacts. If sensors
are attached to the L load, helps to minimize injection current into their pins.

https://www.hw-group.com/cs/podpora/how-not-to-destroy-a-relay

https://www.ia.omron.com/support/faq/answer/36/faq02804/

https://www3.panasonic.biz/ac/e/control/relay/cautions_use/index.jsp



Regards, Dana.
Omron brand cube relays with a well hidden internal diode once caused a HUGE headache on one service call that I did. It was after the second shift at a blow molding plant and we installed a control upgrade, and I got a cube relay and socket from their stock room, and did not see that the relay had a built in diode. So of courseit got installed backward, and the controller did not operate it and the machine would not work for the morning shift. It took quite a few hours to find that the flaw was that the diode was connected in reverse. Exchanged the two relay coil connections and the machine ran fine. I NEVER use Omron relays or other parts since that time.
 

shortbus

Joined Sep 30, 2009
10,045
I would never prohibit the use of a particular manufacturer due to what would essentially be inattentivity and a mistake on my part!o_O
Max.
But then again you understand things. Omron is not the only company making relays like that, they all do. He just happened to get one the went from Omron to Omoron.
 

MisterBill2

Joined Jan 23, 2018
18,167
L learn to avoid some products because they are inadequately labeled, and that can lead to errors in assembly. Perhaps you have never had less experienced panel builders working for you.
 

MaxHeadRoom

Joined Jul 18, 2013
28,617
That is one of the best relay manuf. out there, they provide AC relay with R/C snubber, DC plain or with reverse diode, LED indicator, or both.
There is generally a diagram on the cover that shows the configuration and pin #'s. So very seldom there should be confusion.
I still see no reason to blame the manufacturer? :confused:
Max.
 

Thread Starter

JOEFORNS

Joined Mar 30, 2020
4
I think you are referring to a bridge rectifier. Usually they match the capacity of the alternator. There is some back EMF from the relay coil but it should not be an issue. If your relay was designed for a car or motorcycle, it will likely have protection. I think power load may be more of a concern. Check your manual and add up the watts.
I've got another question . I added two more headlights to my bike so I got two relays and hooked the original high low switch to them and jumped the power from low to high then ran low wire and high wire to original headlight then from high wire to both extra head lights . on low only middle one works (like its wired) but when I put it on high beam the outside bulbs work an the middle one cuts off . what am I doing wrong , are my relays not strong enough or should the be wired to the low beam side ? thanks for your tme
 

Reloadron

Joined Jan 15, 2015
7,501
Much of this depends on the bike and how it was designed to work. I see no mention of make and model of the bike? I ride a 92 Harley Electroglide. Replaced my headlight and side spots with Daymaker LED lights. The spots only are on when low beam is in use. Switching to Hi Beam disables the spots. This is done through the switching matrix and is intentional.
I added two more headlights to my bike so I got two relays and hooked the original high low switch to them and jumped the power from low to high then ran low wire and high wire to original headlight then from high wire to both extra head lights .
You added two additional headlights or you added spots? Never saw a bike with three headlights, two yes but three nope. Have you got the manual for your bike including the wiring diagram? You make no mention of the current capability of these relays? A typical 12 VDC coil automotive relay is normally a 30 amp contact relay and I doubt any lamps you could add would need 15 amps each.

I can't tell you why your bike is doing what it is doing since I know nothing about whatever you have? Really need a schematic to even guess why you are seeing what you are seeing.

Ron
 

MisterBill2

Joined Jan 23, 2018
18,167
Much of this depends on the bike and how it was designed to work. I see no mention of make and model of the bike? I ride a 92 Harley Electroglide. Replaced my headlight and side spots with Daymaker LED lights. The spots only are on when low beam is in use. Switching to Hi Beam disables the spots. This is done through the switching matrix and is intentional.

You added two additional headlights or you added spots? Never saw a bike with three headlights, two yes but three nope. Have you got the manual for your bike including the wiring diagram? You make no mention of the current capability of these relays? A typical 12 VDC coil automotive relay is normally a 30 amp contact relay and I doubt any lamps you could add would need 15 amps each.

I can't tell you why your bike is doing what it is doing since I know nothing about whatever you have? Really need a schematic to even guess why you are seeing what you are seeing.

Ron
I see motorcycles with three headlights quite often. They do it so that they can be seen better.
For the problem of the one light going out when the others switch on, the first step is to check the voltage at that light's terminals. My guess is that the voltage drops but does not go to zero. Check that and let us know.
 

Reloadron

Joined Jan 15, 2015
7,501
I see motorcycles with three headlights quite often. They do it so that they can be seen better.
For the problem of the one light going out when the others switch on, the first step is to check the voltage at that light's terminals. My guess is that the voltage drops but does not go to zero. Check that and let us know.
Does this motorcycle have three headlights?
MC Headlight Spots.png

How about this one?
Motorcycle headlight spots.png

How many headlights on this one?
MC Dual Headlight.png

The last image is a dual headlight configuration, the first two images are single headlight with side spots. My bike is like the first two images. The lights are always on when riding. When low beam is selected the headlight and side spots are active. When selecting Hi Beam the Higher aimed and brighter high beam comes on and the side spots extinguish. That is by design and less knowing make and model of a bike and having a wiring drawing we have nothing. I can't see how anything can be troubleshot or even a good guess made?

Anyway while I have seen singles with side spots and seen dual headlights and seen headlights configured to behave in assorted switching sequences I a have never seen a bike with three headlights.

Ron
 
Top