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2004 chevy trailblazer_lt
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Discussion Starter · #1 ·
So for those who have some kind of mobile communication radio installed in their TV, what's the easiest way of getting power for the radio? Since we have the fuse box under the rear seat, I assume it's easy to get power off that box.
 

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So for those who have some kind of mobile communication radio installed in their TV, what's the easiest way of getting power for the radio? Since we have the fuse box under the rear seat, I assume it's easy to get power off that box.
I personally ran a secondary power wire under the front dash with a 6 awg from the battery, and then it is fed into a junction box which has a 3rd fuse box, which feeds the strobe power supply, the siren, the scanner, the GPS, the headlight flasher, the CB (which I havent installed yet), the rear led's.

And yes Roadie, I know that was a very long run-on sentence.:raspberry
 

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if you want something quick and easy just tap into the radio power wire or the cig lighter.
:nono:I would not go near the radio. Its amperage all ready falls just under its rated fuse. If you cause a short to the radio and fry it, I have a feeling your going to be a little pissed.:hissy:
 

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Discussion Starter · #5 ·
I have one of those adaptors from Radio Shack to connect my CB to the lighter, however, it gets disconnected quite often, and it takes up one of the cig plugs, which means I can't have my satellite radio and my GPS on at the same time (normally used for travelling)
 

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i would be pissed if i fried my radio. if you put a fuse with the cb and radio wire would you still need to worry. also would it be safe to hard wire to the cig lighter wires.
 

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Discussion Starter · #7 ·
Well, at this point I'm seriously considering an Anderson Powerpole. Since I'm going to the Hamfest next weekend I'm surely getting ideas there, but if someone with a TV has already done something, I know it's possible.
 

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I see no problem with re-routing the power feed from the cig lighter. I would not tap into it though so that you arent using both at the same time. It is fuse 13 in the under hood fuse box. Theoretically you could replace the fuse with whatever size you need, but keep in mind that the wire from the fuse to the cig lighter will probably only handle the amount of amps as the fuse that is all ready in there. Another thing to keep in mind is that, that fuse is a constant power off the battery and is not on the ignition relay. My personal recomendation would be to run the constant off the battery through the fire wall, there is a gromet in the firewall that you can push through, into a relay and then run a small wire from a existing fuse with a jumper, to to the switch input on the relay. That way you have your power source and it will only work when the key is either on or the vehicle is running. You can find a fuse that runs off the ignition with a volt meter and a friend (or wife/girlfriend) that can turn the vehicle on and off till you find one.

How many watts is your radio running? If you are running a rig that is putting out like 1000 watts, I would definitely run a capacitor!!! Otherwise you will probably fry your alternator.
 

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2004 gmc
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1) Using the main cig lighter wiring is a bad idea for one very subtle reason. Blowing that fuse also disables the OBDII power feed, so that if you need your Service Engine Soon codes read, the plug in scanners will barf and not light up. Using an aux cig lighter is advisable for small radios.

2) The main radio power feed is permanent 12V, not switched by the accessory position of the ignition switch. There are actually few circuits fed directly by the ignition switch, which is a high failure rate item anyway.

3) I would recommend a relay fed by the battery (or the megafuse terminal up front) and controlled by accessory or run signals. I've posted these before, but I can trace a few if you want to use an add-a-fuse to snag a control signal. Unless you always remember to turn off the radios and don't need a relay.
 

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You are the one who says you should never pull anything off the mega fuse? :confused:
Don't remember that. I remember posting that you CAN steal 50-60 amps off the rear fuse block without worrying because the megafuse DOESN'T feed every fuse in there. I wired my rear seat deep discharge battery this way, and it draws 40-45 Amps when discharged.

But in this case I should have been more precise - "a relay fed by the battery (or the megafuse terminal up front that's fed by the battery)..."
 

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Don't remember that. I remember posting that you CAN steal 50-60 amps off the rear fuse block without worrying because the megafuse DOESN'T feed every fuse in there. I wired my rear seat deep discharge battery this way, and it draws 40-45 Amps when discharged.

But in this case I should have been more precise - "a relay fed by the battery (or the megafuse terminal up front that's fed by the battery)..."
Yeah, I was wrong. I was thinling of your post about where not to hook jumper cables. Sorry
 

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yeah Coyote.. watts and amps are totally different things.. :yes:
I understand this, but apparently I was taught wrong, and I am trying to find the correct info. I know amps X volts = watts. IE a 1000 watt rig pulls 83.3r amps when transmitting.

This is the way it was explained to me and apparently it is wrong so feel free to correct it.... (but please don't insult, I am just trying to find the correct info)

When using a high wattage mobile radio, it is a good idea to run a inline power capacitor to try to alleviate some of the amp drag from high wattage conversations. I was told the reason for this is that when a high wattage rig keys up it in turn pulls more amps to power the amplifier.

NOW, once again, I am apparently wrong in this, so don't beat me up for wanting to find the correct info.
 

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Ohms Law

Watts - Power (P)
Volts - EMF (E)
Amperes - Current (I)
Resistance - Ohms (R)

ExI=P
E/I=R
E/R=I
P/I=E
IxR=E
P/E=I

E (squared)/R = P
I (squared) x R = P
P/ I (squared) = R
E (squared) / P = R
Square of P X R = E
Square of P / R = I
 
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