Electric Gurus! Two way switch questions!

[midnitewarya]

I do appreciate your input. You actually did sway me on a couple of the accessories, the rock lights for sure don't need a relay.

Watching that Jeep burn, and knowing that I'm not the greatest with my hands all led me to want to build the safest thing possible. To protect me from myself, lol.

The only reasons it would have heated up is if:
A: there was a short and no fuse
B: the wires were too thin to handle the load
C: the wires were not properly connected.
Aka: human error

They probably used little bitty wires connected with electrical tape on some devise that draws a lot of current. For example putting power to 4-KC lights with 20g speaker wire will result in melted wires and fire.

I've wired everything from competition grade stereo systems, to remote control airplanes, and never once have I had to add relays.

IMO
The reason auto manufactures use them is to allow them to save weight and money by using smaller wires, thus smaller looms of wires running throughout the vehicle.

I think you are being a bit paranoid, but hey, it's your rig, not mine, do what ever you want. I was just giving my 2¢ Trying to help, but it sounds like you've got it under control. Good luck.

 

[AR_K5]

It's good knowing you are at least open to suggestion.
I guess my main point is, why have a switch (toggle) to control another switch (relay) to turn something on when the right fuse (not too big) will work? And how safe can it be when it becomes so complicated you don't fully understand exactly how or why it works, and you are the designer.

 

[AR_K5]

I also wonder if perhaps you might be confusing relays with circuit breakers, which they are not. Should a short circuit occur the relay will continue to feed power until the circuit is broken or the relay is shut off.

 

[Blue85]

This should help you understand
Volts = pressure
Amp = volume
Watts = units
Amps x Volts = Watts
Watts/amps=volts
Watts/volts=amps
1 amp @ 1 volt = 1 watt

If voltage is pressure, then by the same analogy, Amps is flow. Volume implies stored energy - i.e. a capacitor or battery. Watts is still power, everything in your list is "units".

And the added resistance from multiple connections does not increase amp draw, it reduces it (that's sort of the definition of resistance), so there is less power in the lights and more heat in the connections. Total power consumption is reduced because your supply voltage is fixed. If we could increase the supply voltage to compensate for the added resistance (original light output), then current would be equal and power increased.

 

[Blue85]

How many accessories will you power this way? They do make 4-pole switches (anything bigger is fairly specialized and expensive) and with a 4PDT switch + 4 regular switches you could do this "master on" scheme with no relays and no diodes. This one would also give you a "master off".

http://www.delcity.net/store/search/p_789861.h_789892.t_1.n_y.jsp?item=7920008

If 4 isn't enough, you could split into 2 banks of 4, each bank having a master on.

 

[AR_K5]

If voltage is pressure, then by the same analogy, Amps is flow. Volume implies stored energy - i.e. a capacitor or battery. Watts is still power, everything in your list is "units".

The added resistance from multiple connections does not increase amp draw, it reduces it (that's sort of the definition of resistance), so there is less power in the lights and more heat in the connections. Total power consumption is reduced because your supply voltage is fixed. If we could increase the supply voltage to compensate for the added resistance (original light output), then current would be equal and power increased.

I was trying my best to put into terms that were somewhat easier to understand without writing a book, because it's not so easy to understand. Now that I have read it again, I can see that I did a very poor job. So bear with me because here I go with another attempt.

Think of it as if a battery were air or water tank.

The 'Reserve Capacity' rating of the battery would be the kind of like the maximum volume of air or water the tank will hold.

'Cranking Amps' are how many amps can be delivered into a short for 30 seconds at 80°, another way of saying it would be cranking amps are it's maximum discharge rate, cold cranking amps are it's discharge rate at 32°F or 0°C.

Volts would be the pressure that pushes air or water out of the tank if you open a valve on the tank (I look at it like it's top speed), to get more out you have to increase the amps, in a circuit that would be like increasing the diameter of the valve and hose.

Watts is a measure of the amount work that can be done, or "energy" in joules/second. (1 watt = 1 joule/sec) it tells you how fast the powered device will use the energy that is stored in the battery.

Ohms are a measure of resistance (like friction), each conductor will slow down or restrict the flow of energy. So if you connect a long air hose with multiple fittings to the the air tank it will be moving slower at the (business) end of the hose than it would be if the hose had no fittings, but even a hose with no fittings will have some resistance. This resistance causes a loss of voltage that must be compensated by an increase in amperage in order to maintain the wattage needed to power the device/circuit.

Using conductors (wires) that are too small creates a situation where energy has to flow so fast keep up with the demand that the friction of the electrons passing through the conductor creates heat thus melting wires.

It's all very confusing and hard to explain but this was the best example and I could come up with. I hope it helps.

 

[AR_K5]

If you previously read the above post you should read it again. I had to go back and edit it.

The wife was nagging me while I was trying to think and punch all of that out on my phone, after reading it again I noticed it still wasn't very clear.

Sorry about that.

If you are smarter than I (that's not saying much) and see where I still have it wrong please feel free to correct me, as it will even help me to further understand.

The long and short of it is, I don't see how it's possible to decrease the load on a circuit by adding more switches (relays), wires, and connectors.

You may be successful in reducing the amperage inside the cab but in the end the overall work load is increased due to adding a second circuit just to control a relay (switch) that turns on the first circuit. To me its just that much more that can go wrong, making it that much more difficult to diagnose when it does. All you need is the right inline fuse that way if a short ever occurs and the amp load exceeds it's capacity it will pop. Relays are not breakers and will not shut off unless their power supply is shut off.

 

[dyeager535]

One idea to consider is to get an electrical center from some car in a junkyard - one with relays and fuses already in it. Then you just rewire it all from the bottom to suit your needs. It's likely that many of the relays will already be tied into a buss bar. I got one from a Ranger or something - it had like 6 relays in it, slots for mini fuses and maxi fuses and already had a couple of those diodes.

From what is being said, I think this is probably the best bet.

If you like adding electrical stuff (who doesn't?? lol) then you will probably want the added capacity that the underhood relay/fuse centers provide anyway, right?

Inline fuses are a PITA. Having all of that stuff in one location makes sense. It's also a lot cleaner. You can get real creative with these things. I use one terminal off the stock fuse block to power certain circuits on the underhood relay/fuse setup in my truck with 12V key on. With the fuse/relay panel setups, you only need one "hot" to the panel from the battery, and use relays as/if necessary to turn things on with the ignition. If you want switches, then you can decide to either use relays to power the accessory, or get some properly rated switches to run wiring directly.

Running relays will save you money if you can reduce the amount of thicker wiring you would have to run otherwise, and I would assume save on the switch cost itself.