Relay of choice

[Luv2fly]

I was planning on using a relay to control a few add on circuits(seat heaters, power outlet, backup lights etc.). What aftermarket simple relay seems to be most popular? I know amperage requirements are a factor.

Thanks

[chopthebass]

Mmmm heated seats!

Do you have heat mats that install in FFR seats? If so, where did you get them? Can you publish an idiots wiring diagram showing how to incorporate a relay?

[edwardb]

Relays are a commodity item and I'd challenge you go find any that aren't from China any more. Many are really cheap. At least cheap feeling including loose cover, etc. I was buying the best ones I could find, including pretty expensive ones at NAPA, which often has better quality. After I lost the cooling relay in my Mk3, really started to look harder. The best I've found so far are from McMaster. They don't list the brand, but they're Hella (China of course) and seem to be decent quality. The cooling relay in my Mk3 has been OK since I switched to that one. I used several of them for my Mk4 build. They're not particularly expensive, and they have several configurations including higher amperage.

For the heated seats, have installed them in both of my builds. Love 'em. I used these: http://www.cobraheat.com/Automotive-Seat-Heaters_c_18.html. The name is just a coincidence. Some guys use the waterproof ones. I just used the regular ones. Nice and toasty. They have all the wiring, switches and relays. Nothing to add but 12V. I think Mike Forte carries these, although I just ordered them direct. You have to take the seats apart to put the pads in, but it's not too hard.

[chopthebass]

Nice one Ed. Thanks

[chopthebass]

Hey Ed, where is a good place for the seat heater switch? Did you put yours on the dash?

[Luv2fly]

Thanks for the great info. I'll check McMaster.

[VdubJoe]

I use ones from Del-City. Of course China too but ive been using them for a while. I use the ones with skirts and resisters already installed.

Joe

[edwardb]

Hey Ed, where is a good place for the seat heater switch? Did you put yours on the dash?

For my Mk4, I put them in the dash. Right near the center along the bottom.

http://i867.photobucket.com/albums/ab234/edwardb123/Factory%20Five%20Mark%204%20Roadster%20Build/Dash/th_IMG_2290_cropped_zps1da9ed1a.jpg (http://s867.photobucket.com/user/edwardb123/media/Factory%20Five%20Mark%204%20Roadster%20Build/Dash/IMG_2290_cropped_zps1da9ed1a.jpg.html)

http://i867.photobucket.com/albums/ab234/edwardb123/Factory%20Five%20Mark%204%20Roadster%20Build/Dash/th_IMG_2290_zps06eab60f.jpg (http://s867.photobucket.com/user/edwardb123/media/Factory%20Five%20Mark%204%20Roadster%20Build/Dash/IMG_2290_zps06eab60f.jpg.html)

For my Mk3, I put them in a small box under the dash.

http://i867.photobucket.com/albums/ab234/edwardb123/Factory%20Five%20Mark%203%20Roadster%20Build/Dash%20and%20Wiring/th_IMG_1238.jpg (http://s867.photobucket.com/user/edwardb123/media/Factory%20Five%20Mark%203%20Roadster%20Build/Dash%20and%20Wiring/IMG_1238.jpg.html)

Some guys put them in the tunnel. There was another thread where a guy installed them under the seat. Good is whatever works best for you.

[rich grsc]

There is no need for a relay on backup lights or power outlets.

[Luv2fly]

I know you can wire most accessory circuits without a relay. But the lack of switched power(feed through a fuse box circuit) leaves few options. You can either power everything through one terminal from the ignition switch, or have every accessory constantly powered from the battery feed. I feel better running heated seats, accessory power outlet....etc from a circuit that is switched. I also wish to avoid a high amperage draw through the ignition switch. One low amperage feed can power many higher amperage circuits.

[edwardb]

I know you can wire most accessory circuits without a relay. But the lack of switched power(feed through a fuse box circuit) leaves few options. You can either power everything through one terminal from the ignition switch, or have every accessory constantly powered from the battery feed. I feel better running heated seats, accessory power outlet....etc from a circuit that is switched. I also wish to avoid a high amperage draw through the ignition switch. One low amperage feed can power many higher amperage circuits.

If I'm understanding your point, you want to add additional circuits but don't have any circuits left in the fuse box? Probably the cleanest is to add an auxiliary fuse box. Painless has them in 3 or 7 circuit versions. I used a Painless 70203 in my Mk3 build. Ron Francis probably makes something similar. It properly fuses the circuits and doesn't add any load to your ignition switch. You could use a relay for each circuit as you described, but you still need to have a fuse or circuit breaker.

[VdubJoe]

Here's the assembly I'm adding got it from Del-City. Added 6 fuses .
http://www.delcity.net/store/search/p_10960.h_26034.t_1.n_y.jsp?item=73897

29001

Joe

[Avalanche325]

One low amperage feed can power many higher amperage circuits.

What you are saying is backwards. The feed has to have the capacity off all of the other circuits combined. One HIGH amperage feed can power many LOW amperage circuits.

I agree that seat heaters need relays. They usually come with them in the kit.

Aux power circuits should be fused, but there is no need for a switch. They won't draw any current unless something is plugged in.

You do not need to use a relay for backup lights. They simply are not a large load.

Don't try to use relays like fuses. They are not a protection device. They are for controlling a large load with a small control circuit. One thing they do is add MANY possible points of failure into your circuit. You are now running two circuits (control, and load), and every connection, switch, and length of wire is a potential failure point. Just one relay itself is 6 possible failure points (4 connections, coil, and switch). If you need more fuses, add more fuses.

[Luv2fly]

You got it. Maybe my explanation wasn't worded correctly. Low amperage control circuit controls high amperage feed circuit. Thanks for all the input. That fuse block from Dell City looks like a winner!