Need Some Advice on Using Relays (Preventing Counter-EMFs)

[hayze]

The fogs won't run as DRL. They will work only with the parklights (and the fog light switch).

Anyway, what do you guys think of the Cole Hersee relay I linked to and ctrl-V'd the specs for? It will switch two 55W incand bulbs in series. Would you use this relay for this job?

 

[-Virgil-]

The fogs won't run as DRL. They will work only with the parklights (and the fog light switch).

I still haven't seen you put forth a sound reason to do this.

 

[hayze]

The reason is because I never use my fog lights at night (with the low beams). They do not do anything but cause contrast and constrict my pupils by illuminating the foreground. So I would like to get some use out of them in the day. Aesthetics is another reason: I think it looks good on my car to have only parklights and fogs (in the day only). As long as its legal and safe, then I don't see a problem with it.

Also, as of new years 10, the new wiper/headlight law in Ohio requires lighting in the day during rain, and I do not burn my HID bulbs in the day because I see no reason to.

Anyway, what do you guys think of Cole Hersee relays? Is this a good name?

 

[Alaric Darconville]

The reason is because I never use my fog lights at night (with the low beams). They do not do anything but cause contrast and constrict my pupils by illuminating the foreground.

Another reason why fog lights should only be used at low speeds (although a proper set of foglights shouldn't be doing that to you so badly).

So I would like to get some use out of them in the day.

Then use them in the daytime, but only when it's foggy and at low speeds.

Aesthetics is another reason: I think it looks good on my car to have only parklights and fogs (in the day only). As long as its legal and safe, then I don't see a problem with it.

It looks stupid on your car, on my car, on anyone's car, to have only parklights and fog lights on in the day. Mostly because it's illegal and it's not safe.

Also, as of new years 10, the new wiper/headlight law in Ohio requires lighting in the day during rain, and I do not burn my HID bulbs in the day because I see no reason to.

The law requires your headlights to be on. Not your fog lights, not your dome light, not your "Heartlight", not your check engine light. Headlights.

 

[Alaric Darconville]

This Married to the Sea comic pretty much sums up my opinion on people modding their cars to do ridiculous things: http://www.marriedtothesea.com/051510/my-earlobes.gif

I think running fog lights with just the parking lights in the daylight in the absence of fog is just dumb, but I don't think it's wrong to install (properly designed) fog lights.

 

[Alaric Darconville]

Then use them in the daytime, but only when it's foggy and at low speeds.

Actually, don't even use them then. If it's in the daytime, surely there's sufficient ambient light to see the road markings. I suppose if you REALLY feel the need to use them, then use them. You should still slow down, though-- fog will decrease visibility even in the daytime. As I've said before, they don't magically allow you to drive the speed limit as if they were some sort of Bat-device on the Batmobile.

I'd probably enjoy driving in rain, fog, and snow much more were it not for all the other jerks that think their all-wheel drive and ABS and fog lights exempted their vehicles from the laws of physics.

 

[hayze]

Darkonville, regarding the fog light mod, you did say it was unsafe in addition to how you don't like it by opinion. Is it really unsafe for day driving without fog at a time when I would otherwise have no other lights (besides parklights)? If so, why? If I'm considering the mod, then I'm all ears on opinions and reasons I shouldn't for safety.

Scheinwerfermann, I'm ordering the turn DRL module soon here, but they are slow at emailing me back with questions I asked. So let me ask, if you happen to know, about how much current the unit will draw from the ignition circuit I splice into. I have two other relays spliced into that circuit, so I'm watching out with drawing more. Will it draw as much as the bulbs use, or does the bulb power still come from the OEM turn signal/hazard relay? In other words, does it just draw tiny amounts for control/switching, or does it actually draw for the bulbs?

As for the relays, I grabbed a few other kinds off that page with internal suppression diodes and sockets with 16AWG terminals. The original topic of back-EMFs is now handled. Thanks much for the advice on EMFs.

Lastly, a quick question on fuse types... I've been using mini-blade fuses for inlines, but I grabbed some AGC ones (the glass tube ones) this time because they seem to come in smaller values and increments. I've always used blade fuses before meaning this is the first time I'm trying a new type. Is there any reason I should stick with blade fuses and not use the glass tube ones? I read that sometimes the contact tips get hot because of poor manufacturing. Does anyone have any advice on this?

Thanks for all replies.

 

[Alaric Darconville]

Darkonville, regarding the fog light mod, you did say it was unsafe in addition to how you don't like it by opinion. Is it really unsafe for day driving without fog at a time when I would otherwise have no other lights (besides parklights)? If so, why? If I'm considering the mod, then I'm all ears on opinions and reasons I shouldn't for safety.

As happens to me in email at work, and on facebook, people misspell my name when it's spelled for them right there on the got-dang page...

Any time you're running lights unnecessarily, you're generating glare. Fog lights are notorious for producing glare for oncoming drivers. For one, many of them are mounted on articulating joints and so can go out of proper aim very easily.

As dusk approaches, the wash of light in front of the car, combined with the dashboard being lit due to the use of the parking lights, may mean that you may forget that the headlights are not actually on, therefore possibly resulting in night driving on only parking and fog lights. Not too safe.

Lastly, a quick question on fuse types... I've been using mini-blade fuses for inlines, but I grabbed some AGC ones (the glass tube ones) this time because they seem to come in smaller values and increments. I've always used blade fuses before meaning this is the first time I'm trying a new type. Is there any reason I should stick with blade fuses and not use the glass tube ones? I read that sometimes the contact tips get hot because of poor manufacturing. Does anyone have any advice on this?

Blade fuses seem to offer easier removal and replacement (if you have that plastic hoozit to pull them out, easier detection of a blown fuse, and, most importantly, much lower chance of breakage that potentially could cause injury. I've had one glass fuse break on me while I was removing it from my Dart's fuse panel. Not fun! (Also, I probably was doing it wrong.) Also, many of the the in-line fuse holders for glass fuses are needlessly 'complex' (with a spring in them and an odd opening/closing mechanism) and seem to not offer as good an electrical connection as the snap-in connector (but there's the risk of fuse breakage with the snap-in kind).

The glass fuses made to SAE standard J554 make it harder to substitute amperage fuse without creative solutions, but that makes them ostensibly safer than the blade type which allow switching of amperages among their form factor. Suppose your horn/stop/tail fuse goes out for some reason-- you can take the fuse out of the lighter plug or A/C position (so long as it's the rating of the subbed in fuse is equal to or lower than the blown fuse) after correcting the fault, and get home safely.

 

[Kuryakin]

There's another advantage of blade type fuses. The fuse and a good fuse bock for them have considerably lower resistance than glass fuses, and the fuse contacts are far more reliable. Look at a glass fuse, in its holder, and look at the size of the fuse element, the number of connections from wire to wire, etc., and just by looking at it, you can see why blade type fuses are simply a far better idea.

 

[uffstuffson]

Sorry if someone already mentioned this , I don't have time tonight to read all posts but have you thought about using an MOV (metal oxide varistor) to dissapate any extra cemf from the coil discharge?

edit:
Here is a great resource for different ways to supress the transient voltages caused by the stored electrical charge in the coil of the relay. Also talks about why you need to worry about it.
http://relays.tycoelectronics.com/appnotes/app_pdfs/13c3311.pdf

 

[Kuryakin]

Basically, diodes or resistors are cheap and work very well. The amount of energy to be dissipated is relatively small. The speed at which the contacts open isn't an issue for a resistive load on a 12VDC circuit. MOVs are great, but are overkill by a huge margin here.

Sorry if someone already mentioned this , I don't have time tonight to read all posts but have you thought about using an MOV (metal oxide varistor) to dissapate any extra cemf from the coil discharge?

edit:
Here is a great resource for different ways to supress the transient voltages caused by the stored electrical charge in the coil of the relay. Also talks about why you need to worry about it.
http://relays.tycoelectronics.com/appnotes/app_pdfs/13c3311.pdf

 

[uffstuffson]

Basically, diodes or resistors are cheap and work very well. The amount of energy to be dissipated is relatively small. The speed at which the contacts open isn't an issue for a resistive load on a 12VDC circuit. MOVs are great, but are overkill by a huge margin here.

Yes you're right about the overkill. I am an industrial service electrician so I use them everywhere there are sensative electronic components (plc's, dc drives, ac freq drives, etc.) connected to any sort of coil controlled contacts or where there is chance for large induced spikes. They are extremely accessible to me (I have an unknown/ungodly amount of them out in the service van right now heh heh) so I tend to forget other don't have that access. Plus that is their intended design, but you are right there is no problem with using a diode.

 

[Kuryakin]

The other issue is the MOVs you have are designed to snub at line voltage levels, they aren't likely to do much at 12VDC. True, there are MOVs that do work at low voltages, but they are fairly uncommon.

Yes you're right about the overkill. I am an industrial service electrician so I use them everywhere there are sensative electronic components (plc's, dc drives, ac freq drives, etc.) connected to any sort of coil controlled contacts or where there is chance for large induced spikes. They are extremely accessible to me (I have an unknown/ungodly amount of them out in the service van right now heh heh) so I tend to forget other don't have that access. Plus that is their intended design, but you are right there is no problem with using a diode.

 

[hayze]

The other night, I got the Stern-signal DRL module wired up. I like this mod a lot. The only difference is that I used a relay to power the yellow wire. Two 7440 bulbs are too much current for the IGN-ON wire I dug up. Anyway, thanks for the help on this thread. Note that the low beams are not on in these pics... that's just the camera flash. Only the front turn signals are on.

My mechanic friend helped me mount it under the fusebox with a c-shaped mounting bracket thing

Just showing everyone real quick... it works great by the way.

 

[Alaric Darconville]

Nice-- now you have DRL function without excessive glare-- and at reduced vehicle emissions over the headlight DRLs (and turn signal bulbs are cheaper to replace than quality headlight bulbs-- another win).

Nice photoessay, too!