Hardwire BCD996XT and remote RH-96 question

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KF7ZXT

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After weeks of turmoil, I've finally been successfully programming (with great ease) my 996XT, using FreeScan for those of you who got involved in my "software wars".

I'm now planning installation of the 996XT and the RH-96 remote head. I'd like to hardwire them both to switched power in the fuse panel, though I plan on installing a an in-line switch in the concealed base unit so it's not running whenever my vehicle is - only when I want to use it (I presume this will add some life to it).

I have a late model Volkswagon. My really dumb electronics question is this: which fuse slots should I hardwire it into? I have many open slots of 5, 10, 15, 20, and 30 amps that are open. I have a map of amps and which ones are switched and which ones aren't, but don't want to blow out my units connecting to the wrong slot.

So, which slot for:

- the 996XT
- the RH-96 remote head

I'll confess I didn't spend hours pouring over power supply tech specs before asking this question, but my knowledge is limited anyway so I figured I'd just ask.

Many thanks in advance.
 
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VE3CRO

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If you are using the 12V cable that came with the scanner it doesn't matter which one you use. Whichever vehicle fuse block connection you use the 2Amp in line fuses are the ones that count.
 

KF7ZXT

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VE3CRO,

Thanks. I will be using the power cable (not the AC adapter or the cigarette lighter cables) that came with the scanner.

Forgive my ignorance, but does plugging it into a 5 amp slot vs. a 30 amp slot increase the likelihood that I'll blow the 2 amp inline fuses. Based on what your saying, it sounds like I should use the minimal amp slot necessary, as in a 5 amp slot.

Thanks!
 

VE3CRO

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Any amperage over 2 will blow the in line fuses.
Using the 5 amp slot would protect the scanner from anything over 5 amps if in the very very unlikely event the 2 amp fuses are defective.

The maximum amperage that can appear in the line is dependent upon what the scanner draws, not what is being fed into the line from the other end.

The only dumb questions are the ones that aren't asked. No forgiveness required.
 

redbeard

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Everything VE3CRO said is true, but a few clarifications may help your understanding more.

How do you know the spots you are going to connect to are 5, 10, 30amp, etc? Most fuse sockets are marked with a number to reference the location of the fuse, not it's amperage. The fuse itself of course will give you the amperage it's rated at, or at least be of a certain color that would indicate it's size.

Do you have a multimeter, or at least a cheap test light? Also how do you plan to connect the wire to the fuse/socket?

I have used jumpers that you attach to the fuse then insert it back into the socket but they tend to be either too big or bend the socket making it loose. My favorite is the fuse with an integrated wire and butt connector already attached. That is unless there is an empty socket I can utilize, then that is always first choice. A crimp-on male spade connector usually works fine then. You can find all the above at Auto Zone.

Use a ring terminal on the ground and go to a nearby dash support screw that you checked with a meter/test light to be sure it is a good ground.

Lastly, it does make a difference which side of the fuse you tap, because an empty socket has one terminal going to the 12V source and the other that goes to the device(s) being powered by the fuse. If you put a 10A (for example) load on the device side of a 5A fuse it will blow. Always put you tap on the source side, so the fuse you tap doesn't have to carry the load. Your power cord's fuse will be your protection.

Use a meter or light to test which terminal in the empty fuse socket is hot. You can try with the ignition on or off too, maybe you will prefer one that is only hot with the ignition on so your scanner comes on when you start the car. Maybe you want one that is always hot so you can leave the scanner on by accident and kill your battery in the winter...I mean listen with the car off.
 

KF7ZXT

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Thanks for all the great info. I did hardwire a Valentine One detector years ago, so fortunately I'm generally familiar with process.

My vehicle actually comes with a nice map of all the fuse slots, their specs and so on - but testing with a meter sounds like a great idea. As non-electronic as I am, I do have a meter.

But one more question about the remote head. It does not have an inline fuse, unless it's in the cigarette lighter attachment. My plan would be to just cut off the cigarette lighter connector and attached a spade connector that then goes in a fuse slot, but then their is no fuse. Is that a problem? It hasn't been for my Valentine One for over 10 years in two different vehicles...but, I don't want to do something stupid and fry it right out of the box.

Many thanks
 
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davidmc36

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I don't have a remote head but......most cig lighter plug-ins have a fuse behind the spring loaded positive "button". Maybe you could screw the end off and see what size it is. That's usually how they are made so you can replace them.
 

redbeard

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If you didn't use a fused cord, your scanner would be wired directly to a high current source with no fusing. That's a no-no.

For your situation I still suggest a fused cord, as the wire routing from the fuse panel to the scanner leaves the possibility of wire abrasion which would need fuse protection in case it were to short against a dash panel or bracket. If you blow a fuse in your car's fuse panel because of this, you could be left without headlights at night while on a back country road at 3AM going 50MPH. Better to blow the fuse on the cord wired to the fuse source instead of the fuse in the panel.
 

pb_lonny

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Some really good advice in this thread.
Can you post a photo of your fuse block so we can see how you are trying to do this.
 

ofd8001

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Fuses are over-current protection intended to preclude more current going through a wire than it can safely handle. Otherwise you are running the risk of a fire. Me being a conscientious fire chief discourage running a risk of fire.

Factory supplied fusing is intended to protect factory supplied wiring. If you add additional wiring that is smaller in size, which means it has less current carrying capacity, you need to add a fuse appropriate to the size of wire used. This fuse should go as close as possible to the point where you make the connection. Any wire between the connection point and the fuse is essentially unprotected.
 
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