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| How much load on ignition switch? https://slantsix.org/forum/viewtopic.php?t=19843 |
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| Author: | Sam Powell [ Sun Sep 24, 2006 6:58 am ] |
| Post subject: | How much load on ignition switch? |
I am going to bypass the old ignition switch with a toggle switch of some kind. Any idea what kind of power is required? What kind of rating would this require? It does not seem like it would be very high. Most everything under the hood is now powered by relays. The MSD is fused with a 3 AMP fuse, and the Accel uses about a 5 amp fuse on the switched lead. It is powered with a main relay. I guess I have to take into account the relays for the fans as well. I already have an unused rocker switch on the console, but I will need to go to Advance Auto and check the rating of this switch on the package of a similar new one. Any other thoughts on this arrangement would be appreciated as well. What concerns should I be aware of? I have the ignition switch outputs ganged together at a fender fuse block now. That is both the brown wire, and the blue wire. One is for crank, and the other is for run. Since the ballast resister is no loner needed, I just have them together. That would leave the key for only the accesories, and the starter solenoid. I would not mind putting the starter solenoid on a switch as well, but that would eliminate the need for a key, and would make security an issue. It might be cool to have a business like bank of toggles like they have in race cars, and airplanes. I test drove a new Mini Cooper, and they have a row of toggles just above the center console, proteced by a shield to keep people safe in an accident. By the way, tht car was really cool, but scary small, and very expensive. It I ever got one, it would be after they are old, and can be had more cheaply. Sam |
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| Author: | LUCKY13 [ Sun Sep 24, 2006 5:39 pm ] |
| Post subject: | |
What about just letting the switch activate a relay so there is no load on the switch. Then you could have as many relays as you needed to for differnt curcuits so the load would be divided up on diff curcuits. And if you needed to add something new you would only have to add another relay for the new curcuit. Also if problems accured later it would only be on one curcuit/relay and you would only loose the one involved instead of everything. It would cost alittle more this way and take more work but in the end may be a bit better. You could also us the Key Ignition still to interupt the curcuit so it still took a key to get up and running. Or just use the ignition switch still as the main switch with the relays carring all the load just like if you used a rocker switch & relays. Either way there would be no load on the Igntion switch or rocker switch. Its been awail and I cant remember if the Ammeter guage goes threw the ignition switch but it & the Heater blower & any fans would probably be the biggest possible draws that go threw the ignition switch. The starter even though it may have a big load the main load it has doesnt go threw the switch just the soliniod activationof the starter is threw the switch , the main load of it comes from the motor part of the starter and goes stright to the battery and not threw the switch. Jess |
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| Author: | Sam Powell [ Sun Sep 24, 2006 7:11 pm ] |
| Post subject: | |
The relay is a great idea Jess. I still need to know how big to make the relay now though. I wonder if ten amps would be OK? I will add averything up, and see. On my system, I have bypassed the ameter. All the heavy current runs right from the alternator to the battery, and then from the battery to the starter motor. Everything else is now pretty light duty. Even my headlights are turned on by a relay. Sam |
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| Author: | 66aCUDA [ Mon Sep 25, 2006 5:07 am ] |
| Post subject: | |
Sam A good rule of thumb to figure the amps is add the fuse ratings together of the circuits you want on your relay. Then go to the next standard size and use that one. ie heater 7.5A ww 5A cig lighter 10A=22.5A use 25A relay. Note I just picked these numbers out of my head. After you have the LOAD off I would think 5 Amps would be ok for your switch. Hope this helps. Frank |
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| Author: | lindross [ Mon Sep 25, 2006 6:58 am ] |
| Post subject: | |
I would recommend the relay on the ignition switch as well. They can handle the high current. Let the relay contacts handle the high current instead of the poor little toggle switch. |
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| Author: | KBB_of_TMC [ Mon Sep 25, 2006 11:48 am ] |
| Post subject: | |
Just FYI, the stock point ignition draws 3-4A and the electronic 6-8A. Generally, switch is less of a problem that the bulkhead connectors. Engine cooling fans take much more current; 15A is typical. The MSD 6|7|8 draws very little from the ignition switch; most of it's current is via the heavy dedicated leads. Fuses sizes are generally chosen to greatly exceed the current you expect in normal use, usually by a factor of 2 or more. Relays are a find idea; I expect to use a number of them in my next project to reduce the load on all underdash components. |
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