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50amp PWM - would like it (12V) Switched - Connect Where??
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tat3r Offline
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50amp PWM - would like it (12V) Switched - Connect Where??


I have a 50amp PWM that I would like it connected to a 12V switched source so that it cannot be turned on unless, say the fuel pump is operating. Basically, I don't want it to "accidentally" be running if only the auxillary power from the car battery is switched on.

This would additionally be a safety feature should the car be in an accident - it won't continue to produce HHO in the event of a collision and the engine is rendered inoperable.

SO, where can I connect this that can handle the 50 amp load the PWM will draw?
I should mention that the input wire is connected to a 60amp relay insided the PWM box, that then has wires going throughout the PWM circuit board, etc.

So, since the Switched Input wire is being routed to the 60 amp relay, which then goes to the 50amp PWM, with that configuration in mind, does anyone know of a switched source that can handle that? Or would it still try and draw upto 50amps from that switched line?

It's on a 95 Jaguar XJ6

Thanks
(This post was last modified: 06-15-2009 09:18 PM by tat3r.)
06-15-2009 06:49 PM
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Pinhead Offline
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Post: #2
RE: 50amp PWM - would like it (12V) Switched - Connect Where??
You won't find a switched source that can supply 50 amps. Your only option is to use a couple of 40 amp relays wired parallel to each other and have their coils wired to your fuel pump power wire.
06-15-2009 07:39 PM
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tat3r Offline
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RE: 50amp PWM - would like it (12V) Switched - Connect Where??
(06-15-2009 07:39 PM)Pinhead Wrote:  You won't find a switched source that can supply 50 amps. Your only option is to use a couple of 40 amp relays wired parallel to each other and have their coils wired to your fuel pump power wire.

I should have mentioned that the input wire is connected to a 60amp relay insided the PWM box, that then has wires going throughout the PWM circuit board, etc.

So, since the Switched Input wire is being routed to the 60 amp relay, which then goes to the 50amp PWM, with that configuration in mind, does anyone know of a switched source that can handle that? Or would it still try and draw upto 50amps from that switched line?
06-15-2009 09:19 PM
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Gary Offline
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RE: 50amp PWM - would like it (12V) Switched - Connect Where??
You're worried about the wrong thing anyway. Cars have batteries that should explode in a crash: you dont' see that. Your generator can only pop the bubbler in this event anyway, and that has little chance of hurting anyone under the hood. You could add a flash exhaust valve if you like.
Your input wire could work as mentioned prior to the relay. It can work off the fuel pump or the oil pressure switch.
06-16-2009 03:34 AM
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mike Offline
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RE: 50amp PWM - would like it (12V) Switched - Connect Where??
The whole point of the relay is that a very small amount of current is required to switch the relay on, and then the 50 Amps is handled by the relay itself. It's basically a switch that you can control by giving it 12 volts, and it only draws milliamps from the controlling circuit.

Therefore you can connect to the fuel pump relay, oil pressure switch etc, like Gary said. Often there is an auxillary circuit that will only be hot when the engine is running, provided.

If you use the fuel pump relay, check it's voltage over time. Make sure that it stays on for several minutes while the engine is idling. Sometimes the fuel pump is controlled by this relay meaning that it will turn the pump on and off using that relay when the pressure is high enough in the injector header. Most of the time the fuel pump is separately controlled and the fuel pump relay is on all the time the engine runs. But check it to be sure this is the behavior of yours.

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06-16-2009 10:38 AM
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tat3r Offline
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Post: #6
RE: 50amp PWM - would like it (12V) Switched - Connect Where??
Thanks guys! I was wondering if the purpose of the relay was to draw off of minimal power and handle the increase of amperage in the PWM. So it sounds like I can essentially tap into a normal (normal being, not 50amp wire) wire.

Is there a switched wire in the steering column that you guys know of that I could connect to that operates similarly to the fuel pump or oil pressure switch (only on when the engine is on)?

One of the wires says "12V power" and the other "12V switched" - could both of these connect to the same switched wire a talked about in first paragraph OR does one always have to be connected to a 12V hot wire?

Thanks
06-16-2009 04:42 PM
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mike Offline
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RE: 50amp PWM - would like it (12V) Switched - Connect Where??
You'll have to check your wiring diagram, or your Haynes manual or other source of data about your vehicle to find out where to get that voltage source. I use my fuel pump relay on my car. It works for this and is always on when the engine runs, and shuts itself off if the engine stops running.

The switched circuit you mentioned, probably comes on when the ACC key position is set, and this will not be suitable. You could be sitting in your car listening to the radio, fall asleep, making HHO all the while, and have a bad experience when you start up your car.

You need to find a circuit that is only on when the engine is running. The fule pump relay and oil pressure switch are just examples of possible places where this can be found.

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06-17-2009 08:55 AM
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tat3r Offline
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RE: 50amp PWM - would like it (12V) Switched - Connect Where??
Thanks Mike,

So I could connect the 12V power AND the 12V+ switched wire to the same connection? They don't have to be different?

Also, you said you connected to the fuel pump relay - do you mean to the wire coming out of the relay or to the actual relay?
06-17-2009 10:33 AM
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colchiro Offline
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RE: 50amp PWM - would like it (12V) Switched - Connect Where??
You want the high current wire to connect to the battery and switched via the relay similar to this:

+12v car battery ----- fuse ----- relay ----- cell ----- ground


The relay will get turned on similar to this:

+12v when ignition on* ----- fuse ----- relay coil ----- on/off switch with LED* ----- gnd.

*The source can be from the fuse block with a special clip on holder or from your fuel pump relay, depending on how lucky you feel. The wiring may need to be modified to get your led on your switch to work. I haven't wired one for over a year so am not 100% positive, but I think the led wire in the switch goes to ground.

Rick

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06-17-2009 12:51 PM
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mike Offline
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Post: #10
RE: 50amp PWM - would like it (12V) Switched - Connect Where??
tat3r,

You need to look at a schematic diagram of a relay. See below.

[Image: attachment.php?aid=1229]

This shows circuits of 2 different voltages, but in this case the voltages are the same. 12 volts will activate the relay, and 12 volts will flow into the electrolyzer. But the big difference in the circuits is the amount of current being carried. Only a tiny current is needed to activate the relay. So that current will come from your fuel pump relay. But the HHO generator will be on a separate circuit. It will have much larger wire to carry the current needed to drive an electrolyzer. Its this high current circuit that the relay will control.

As to where you connect to the fuel pump relay, you will probably tap the wire to make your connection.


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06-17-2009 02:35 PM
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