multi relay wiring...only place i know to put it

[TpaS13]

alright, i know you guys have some experiance with wiring other than car audio...and this is one of the only places i know to put this crap...anyways i have 3 30 amp relays that i am wiring to 5 6" KC daylighters...i was wondering if there is anyway to use these 3 relays in a piggy back? setup or anyway i can use them to basically make 1 big one... i know its a stupid question but when i got the lights thats all it was....i only got the lights and bar no wiring or diagrams of any sort..

rob

[POST]

Using multiple relays wont give it more amperage rating, though instead it could make like a chain effect style, where one turns on, it turns on another, and it turns on the other.


But if amps dont matter, you can just wire all three to just one relay.


i just re-read it. Yeah you can just link together multiple relays. As long as you use decent wiring and DON'T max out the relay's potential, it should work fine. The 12v lead is just a signal, no real power is going through it, just enough to supply a 12v voltage to turn the relay to "pass". so that wire can be rather small in comparison, and theres no problem with linking them. Usually just get the main cable, and cap on three additional cables to distribute the connection. That would work.

[Notladstyle]

Using multiple relays wont give it more amperage rating, though instead it could make like a chain effect style, where one turns on, it turns on another, and it turns on the other.


But if amps dont matter, you can just wire all three to just one relay.


i just re-read it. Yeah you can just link together multiple relays. As long as you use decent wiring and DON'T max out the relay's potential, it should work fine. The 12v lead is just a signal, no real power is going through it, just enough to supply a 12v voltage to turn the relay to "pass". so that wire can be rather small in comparison, and theres no problem with linking them. Usually just get the main cable, and cap on three additional cables to distribute the connection. That would work.

Wiring the three relays in parallel will give you the sum of the rated amperage for the three relays. If you wire three 30amp relays in parallel, you will have a rated current flow of 90 amps. or course, getting that kind of power will be difficult with a stock setup without some serious wiring.

try to avoid putting them in the engine bay unless you put them in some sort of case, water and humidity will damage/corrode the components. especially do not wrap them in electrical tape - you will just seal the moisture inside the relay.

[POST]

Wiring the three relays in parallel will give you the sum of the rated amperage for the three relays. If you wire three 30amp relays in parallel, you will have a rated current flow of 90 amps. or course, getting that kind of power will be difficult with a stock setup without some serious wiring.

try to avoid putting them in the engine bay unless you put them in some sort of case, water and humidity will damage/corrode the components. especially do not wrap them in electrical tape - you will just seal the moisture inside the relay.

Yeah i was thinking that while i was typing that, but I remembered something you told me a long time ago and just decided it couldn't be done... oh well.


i still don't think its a good idea anyways.

[Notladstyle]

Yeah i was thinking that while i was typing that, but I remembered something you told me a long time ago and just decided it couldn't be done... oh well.


i still don't think its a good idea anyways.

could be potentially more reliable than one big relay as there would be more space to dissipate heat from the coils and smaller coils could be used.


but yeah I agree a larger relay would be betta.

[POST]

could be potentially more reliable than one big relay as there would be more space to dissipate heat from the coils and smaller coils could be used.


but yeah I agree a larger relay would be betta.

I'm not so much worried about the heat as user error and the fact that they're relatively fragile... the relay for the twin radiator fans shat on me the other day... now i REALLY have to go to radio shack! hahaha. (even though i buy relays from walmart/advance auto... i just meant i need to get out the house.)

[Notladstyle]

yeah like i was saying earlier, I made a mistake putting the relays outside in the engine compartment. I really should fix that.

[POST]

OK, check it out, here's the reasoning.

You technically CAN put all three relays in parallel on the same circuit, but its a really bad idea because if say one of those relays were just a fraction of a second faster or slower than the other relays, one or more of those relays are going to see that huge "*" amount of power at once, causing an instant melt/fire/breakdown whatever, and soon the other relays do the same for having to deal with that larger load. Putting fuses won't really help either since they'll pop right out due to the same circumstances.

Your safest, easiest, best bet is to piggyback them by having one 12v cable split into 3 (or more) cables to the relays and then feeding a separate power line/circuit to each. That way they only have to worry about their loads and will never have to risk a failure due to too high a power requirement.

I'd draw out a very simple diagram if my words are a little confusing but the company laptop kinda sucks without any mice around... i need to order some more, and i'm pretty sure you understand what i'm saying.

[Notladstyle]

Rated amperage is based on the relay's ability to dissipate the heat created by the coil and current flow across the terminal without damaging the terminal, case, or coil.

A peak surge of current for the split second it would take all the relays to engage would not create enough heat to damage the coil. It would take 3 times the rated current between 30 seconds and a minute to cause any real damage to a typical 30amp automotive relay.

[POST]

Rated amperage is based on the relay's ability to dissipate the heat created by the coil and current flow across the terminal without damaging the terminal, case, or coil.

A peak surge of current for the split second it would take all the relays to engage would not create enough heat to damage the coil. It would take 3 times the rated current for 30 seconds to a minute to cause any real damage to a typical 30amp automotive relay.

Not true, that surge would definitely blow the coil. Either seizing it shut or open or just plain pop.

Of course, thats considering only if he put in a true 90amps through it. If it were say 40amps. Probably wouldn't.



And the fact remains that no matter what, the piggyback method would be far more safe, secure and just work better.

[Notladstyle]

1. It wouldn't blow the coil. The coil would never see 90 amps. the terminals the coil pulls to contact would see 90amps.

2. Those terminals would not heat up in a split second from 90amps. Therefor there would be no damage

3. even if they did heat up over the span of several seconds, the first component to fail would be the glue on the coil, and an insulated coil can take one hell of a beating before failing.


The major downfall of using smaller relays in parallel would be the contact points between the relays which would present a higher resistance than one big relay with one big connector.

[POST]

Ok we're going to test a regular advance auto 30 amp relay against my battery plus my dual radiator fans at 100% speed... see if it blows.

I'd like to take bets on this.

Its going to cost me 5 bucks for the stupid relay.