Electrical gurus: am I planning this correctly?

[John Hopkins]

Why use two relays if both are going to be switched off with the ignition? you could simply buy one relay with two contacts..Also be aware that as the bike changes revs the battery voltage changes this results in ripples..for instance I get a surge effect on my bike camera as I ride around the tight twisties and drop the speed for speed limits due to innefficient regulation on my 5v transformer.

I guess you are aware that USB works on 5 volts not 12 volts.

John.

[John Hopkins]

I bet you wished you had never asked now..we all say different things..

Try the one you think best and save the thread, then if you have promlems try the one you think next best..

John.

[meeve]

Thanks for the links on the pre-made wiring harnesses and to scrapdog2grand for the free freight offer. I have to be honest that part of this is for me to learn to do something that I've never done before so at this point I'm going to try the homegrown method first and see what happens.

John Hopkins - I planned it with two relays because I don't know how a relay with two outputs works..or that they even existed . The Usb port I am installing has a 12v input and a 5v output.

Nope not sorry I asked the question at all...I assumed I would get a bunch of different ways to do what I was thinking...that's the cool part, just like life, most questions have more that one right answer.

[John Hopkins]

Originally Posted by meeve

Thanks for the links on the pre-made wiring harnesses and to scrapdog2grand for the free freight offer. I have to be honest that part of this is for me to learn to do something that I've never done before so at this point I'm going to try the homegrown method first and see what happens.

John Hopkins - I planned it with two relays because I don't know how a relay with two outputs works..or that they even existed . The Usb port I am installing has a 12v input and a 5v output.

Nope not sorry I asked the question at all...I assumed I would get a bunch of different ways to do what I was thinking...that's the cool part, just like life, most questions have more that one right answer.

You could google 12vdc double pole changeover relay..but all you need to know is that a relay works by putting 12v across a coil which creates a magnetic field around a bar and pulls a plate against it which stays there as long as the voltage is applied, this plane is attached to contacts which then open or close, you connect your circuit to each side of these contacts which act as a switch..so turn on your ignition switch this powers the coil, the contacts close and whatever you have connected starts to work..when you buy the relay make sure that you have enough currant rating (amps) on the contacts..

The USB port will still need something to give you 5v from 12v, but it may be part of the kit..You should ask your supplier..

John.

[jpr1968]

Originally Posted by meeve

That's exactly the plan. Both 12V feeds from the battery will be fused and will be on two separate 30A auto relay's.

Re the load on the existing headlight or tail light circuit...perhaps I understand relays incorrectly, but aren't the switched power sources only providing power to the relay coil whereas the accessories themselves are drawing power from the battery with how I plan to wire it?

You didn't misunderstand. You will only be adding the coil of the relays tp the other circuits. You can purchase a relay with 2 sets of normally open contacts and save on the amount of wiring you'll be doing.

[Scrapdog2grand]

Originally Posted by meeve

Thanks for the links on the pre-made wiring harnesses and to scrapdog2grand for the free freight offer. I have to be honest that part of this is for me to learn to do something that I've never done before so at this point I'm going to try the homegrown method first and see what happens.

No problem, I understand, and its a great way to learn.
I wish could offer you the relays at a better price than what I have listed on my site, but cost is still high for me as I try to source stuff from suppliers. The Micro matsushita are perfect for lighting, and the Mini Matsushita is great for everything else. the 87A terminal is also great to wire the positive battery tender lead to. they are very good quality and reliable. so if there is something you need even if its not listed just hit me up with an email, Posi-locks, Molex perma-seal, connectors, adhesive lined shrink tube. can probably take 5% off, and the free shipping offer still stands.

[meeve]

You can purchase a relay with 2 sets of normally open contacts

Been trying to find one...are we talking a DPDT relay?

Very interesting topic and I've learned a lot about relays today! (Sorry if I'm boring all those that know this stuff inside and out)

So from what I read today and from your suggestions:

- I could do it as originally planned using 2-SPST relays

- or I could power both accessories using 1-SPST relay connecting the + of both to pin 87.

- or I probably could install a DPDT relay, bring one power source to it, connect my accessories to the NO terminals and leave the NC empty.

Cool stuff! Thanks for the help folks!
Terry

[Scrapdog2grand]

Originally Posted by meeve

Been trying to find one...are we talking a DPDT relay?

Very interesting topic and I've learned a lot about relays today! (Sorry if I'm boring all those that know this stuff inside and out)

So from what I read today and from your suggestions:

- I could do it as originally planned using 2-SPST relays

- or I could power both accessories using 1-SPST relay connecting the + of both to pin 87.

- or I probably could install a DPDT relay, bring one power source to it, connect my accessories to the NO terminals and leave the NC empty.

Cool stuff! Thanks for the help folks!
Terry

The way you intend to do it is fine If you plan on having the relay for the aux lights go off with the high beam on. And you will still need 2 relays like you planed, cause I doubt you want your USB ports to turn off with the Hi Beam.
If you want the aux lights on with High and Lo, then use one relay tied into the tail light as you planned, for the USB ports and the Aux lights.
Fuse both circuits individually, one main fuse before the relay, and smaller fuses for each circuit comming out of it. But I do know you know this already.