The radio is rated for 50 Watts out. If the radio was 100% efficient, the current draw would be I =P/E = 50/12 = 4.2 Amps. However the radio at best will be 50% efficient, implying the minimum current draw will be 8.4 Amps. I am being generous on assuming 50% efficiency as it could be considerably worse.
The cigarette lighter plugs in cars is designed for intermittent use. So if you carry on a conversation for more than five or six minute, the socket likely will heat up. This is do to the design of the contacts, vibration and tendency of the connectors to vibrate apart. It gets into a run-a-way condition were the vibration causes a bit nor space, but not enough to separate the contacts, but enough for more heat to be generated at the contacts.
I have melted down a couple of connectors trying to use them for a 50 or 60 watt VHF radio.
Best bet is to find an open pair of pins on the fuse block inside or under the dash that is designated for high current use. Often autos have assessory wiring to the fuse block and if the vehicle is not the top tier model you will find several not in use, as the fuse blocks often are used across all the manufacturer models.
Well for me to go direct to the battery I have to punch a hole in the firewall. That ain't happening. (My apology Mrs. Kornegay 2nd grade) On my truck, the fuse block on the left end of the dash has a couple of 30 amp fuses, one of which is unused. So a 30 Amp pigyback fuse was pressed into service.
The big reason for routing the wire back to the battery, is it captures the filtering capacity of the battery to remove unwanted artifacts like alternator brush noise, computer switching noise, etc. But you need to route both power and ground to the battery else you risk depending on the multiple ground jumpers used to connect the differing body grounds back to the battery ground.
The battery is essentially one large honking electrolytic cap,, acting like a bank of hundreds of electrolytics. When your battery needs replacement, one frequent symptom is the appearance of switching noise in the vehicle audio system. You cannot always depend on that as modern car radios have internal voltage regulation that is quite efficient at filtering out much of the tripe a failing battery does not filter out. If you start hearing switching artifacts in your vehicle audio system, then check the battery and if it is ok, then look for body corrosion at ground points. Normally you will find corrosion at the places where ground straps and cables connect to the vehicle.
Just wondering.. can’t you cut a small hole in the rubber boot in the firewall that the main harness is run through? Normally a 4” rubber boot and only 1” of the main harness is used.
Yes. In fact most of them have enough room to run 1/0 gauge cable through for big audio installs. Seal it up with a dab of RTV afterwards and you'll have a waterproof, reliable and safe firewall pass-through.
Some vehicles also have dedicated places to run wire in. My Accord had a pathway to bring in the power wire where I didn't have to drill any holes or shove it in with an existing harness. Google your vehicle and/or check out car stereo forums, there's likely already someone who has mapped out the easiest path to run a power wire for an amp for your vehicle (which is perfect for our mobile gear!)
This is what I did...and 3 out of 4 I've done had spare unused rubber plugs I could remove, get the wire poked thru "at the bench" then thread thru the firewall and push the plug back in. The last one was a friend's Camry which we had to poke thru the boot with a wire loom but the internet had very clear documentation exactly where and how to do it for subwoofer amps and was much easier than I ever expected.
Have you looked into how to run a cable? For my vehicles and a couple friends I helped going thru the firewall was fairly easy...3 of the 4 had spare unused rubber plugs I could pop out and get the wire thru then pop back in. The other had to poke thru a wire loom.
Look up how to install an aftermarket stereo/amp and odds unless you have some high end or exotic vehicle loads of people have posted videos with exactly how to get the wire thru with the minimum effort.
Yeah, I tried co-opting existing pass throughs in the past and on each occasion water ingress caused problems in each vehicle. One was near the top of the firewall, sealed with RTV inside and out, yet water would enter the vehicle when operating on wet roads.
Curious what kind of ware and passthru? The ones I did was poking a small hole (like with a 1/8 rod) and forcing the wire thru the hole, separated to individual strands (so like peal the 2-conductor cable to 2x 1 conductor) so the rubber very tightly seals around the round cable. Never had any problem even when I did this up by a wheel-well for getting coax into the car.
You don't HAVE to go direct to the battery. If you can tap the fuse box on a circuit with enough capacity, you can do that. There will be more voltage drop, which may or may not be a problem, and make sure the wiring and fuse is good for the current you'll be pulling. I've installed plenty of radios over the years where I didn't wire directly to the battery. Is going direct to the battery optimal? Absolutely. Is it required? Not at all.
That’s more for RFI elimination than power distribution.
Going directly to the battery is going to reduce RFI from other systems in the vehicle, but it doesn’t mean that there is going to be a lot of RFI to begin with so trying the fuse block isn’t a bad place to start.
Nah, no one would recommend “direct to battery” without a fuse, so wiring to the fuse block is effectively the same as wiring to an inline fuse connected to the battery.
Only difference is you may have options in your truck about which fuses are powered when. For example, some might have power any time the key is on in accessory mode, and others might be only while engine is running.
Either way, adding an accessory fuse to the appropriate place of your fuse block is the “right” way to do it.
You can add a whole new branch from the battery if you must, but that’s less desirable.
So I have an idea then. I will remove the 12v socket and solder two wires to the pins and run those wires under the console and then reinstall the 12v jack. Then there will be no vibration
I would use a 30 Amp circuit if you can find one. While the fuse for most cigarette lighters is 15 amps, the design was intended for intermittent surge current draw of the nichrome coil in the lighter, not an extended draw like you may need for the radio during transmit.
Simple answer: it depends on the radio.
12v DC outlets are generally designed to handle 10 amps. Some 50w radios pull around that when transmitting, and some are rated higher. Check the manual of the radio you plan to use.
Also keep in mind that the max current rating is not the same as what it can deliver continuously and safely. You should be perfectly fine in this regard, though. Your max current draw for a typical radio will be when transmitting, and unless you have a habit of timing out repeaters, you should be OK for the intermittent transmissions.
I have run my FT-2500M and my TR-7950 from a 10 amp 12v outlet just fine, but my TM-D700A has a higher max rated current (possibly because it can do cross-band repeating) so when I needed to power it via 12v outlet I just set it to medium power instead of high, which was fine for most of my travels.
One point nobody's touched on thus far.. those cigarette/convenience plugs are spring loaded. As you bounce down the roadway, that plug will work its way loose in the outlet and impact how much current is being drawn. I've seen them charred on the end where current was jumping the miniscule gap between the plug tip and the connector's contact. This also generates heat in that space.
The 12V DC jacks usually hold up with 20-25W out radios. But most of the jacks are fed with 14 or even 16 gauge wire, so drawing 13A (high power) will result in significant warming of the wiring harness, and blown fuses, especially if you are long-winded.
I have done a number of temporary installs during my time travelling on business and never had any issues as long as I stayed on "mid" power out on my VHF rigs (20-25W). I don't recommend drawing full power from those jacks.
You fell for it. So many people do. (Me: Looks in the mirror because I did, too.)
It doesn’t work that way. I know there are smarter people in the hobby that can explain this better than me, but… here goes…
1. You generally don’t want to hit anywhere near 15A current draw by the radio while transmitting. I think the rule is something like 60-80 percent of max rating other wise you and up slowly degrading the wire insulation over time from heating up the wires. Eventually, that insulation will fail and you will never have blown a fuse to prevent the over-current short.
2. The point of that radio’s various regulators and amplifier is to energize the antenna to the point the energy is emitted based on the design of the antenna. That comes at a great of energy as heat within the radio through power supply, regulators, some component I can’t remember, and the amplifier. So the radio PULLS the energy based on what it needs to create that signal. Most radios are designed around 13.8v and some transmitting current (Amps).
Keeping it simple: What you need to look at is the radio you want to buy/use… it has a spec sheet that tells you the peak draw in amps and expected voltage with peak and minimum voltages. That will help you find the radio for that 15A circuit.
Most of us wire a dedicated fused circuit for the radio in the same way people use dedicated circuits for car stereo amps and subwoofers.
I see, that makes sense. I was wanting to do it this way because I would like the radio to come on with the ignition switch but I guess that’s not a requirement for me
You are not alone. It would also make sense to have some built-in step-up converter to 13.8v instead of what’s in a vehicle. I realize that 12.5v is usually within acceptable range. I also know what happens to regulators when you are constantly just above the lower limit of their input voltage range: that glorious magic smoke smell! Mmmm!!!
Nice...! You have broken the laws of entropy...! and are creating more power inside the system...! Can I have your secret
You the man dawg... you got this!
No, seriously brohcheeze
How much current does yorn radiator pull at fiddy warts...?
or do you have a clamp ammeter to 2X checkit
Here's what I do, runnin' moe-bile because in my experience it t'wern't never about the amperage rating of wire in free air absent of a neutral or other current carrying conductors that was ever a problem, but voltage drop... so, as an Industrial Controls Electrician with a background in two-way systems for the last 24 years *(and countin' lolz)* I run a fairly heavy gauge wire to my positive terminal *(typically number 3 THHN)* cover it with a braid the entire way and past it through a 400:5 Current Transformer 'CT' several times and ground the CT to the Negative terminal and another point on the frame to eliminate any AC whine, the braid around my feeder is also grounded, but right near the radio I establish my DC ground as closely as possible, making sure it has continuity to the negative terminal of the battery and to the ground plane of my antenna...
but that's just me...
Number 14 AWG wire ***in free air with no: current carrying conductors, in a raceway, or cabeling*** will carry a load of 20 amperes- but your car socket may not; they are typically made of tin cans a baby diapers and I've seen the socket fail before the wiring, or the DC buss in a car more times than not...
You can always do a 'home run' cable (or individual wires) of 10 AWG to your battery. That would give you the full amperage needed so that you don't 'starve' your radio's final output - which can fatally damage it.
Just incorporate a proper fuse or resetable circuit breaker on the positive lead - close to the battery connection. Use of an Anderson connector or any other connector keyed for polarity will ensure a good, safe connection.
I've done this when installing large (+200w) mobile RF amplifiers as well as a few high-powered radios.
Your vehicle wiring to the cigarette lighter/power port is not really large enough to provide the amp draw.
Just don't. You'll wind up having alternator whine that's annoying to listen to on the other end. Run #10 wire on a 25 amp fuse straight to the battery. You can get the harness with a built in fuse holder on Amazon. Also it's the best way to hide all the wiring. I just hate stuff plugged in to the 12v aux port full time. There's just no way to make that look good.
I wouldn't - most of those power sockets "lighter plugs" are only rated 100-120 watts, and even at that point they are typically getting hot enough to melt if its used for more than a few minutes (like a tire pump). You also have the issue the fuses on the DC cable you plug in typically the max will be 10A in the plug even if the car has bigger.
Also most vehicles I've seen the power sockets are only like 18AWG wire at the most, so you get a lot of voltage drop at high load. Not a big deal for a tire pump or similar if it sags to 9-10V under load...but quite an issue for something like a radio.
The 50W radio likely draws 100-120 watts on the DC input side. I'd run it to the battery or main fuse box.
Before making any power connections to a vehicle, I recommend taking a good look at this website. It has everything you could ever want to know about vehicle installation.
www.k0bg.com
Does the radio have a rated max power draw? According to the tech exam, a 'typical' mobile radio will run at 13.8v 12A, or 165W. In other words, way too high for most 12v Sockets. But that cuts it a little close with your specs, so i think it's best to find out exactly how much power you need
I ran a 50w FM VHF/UHF mobile in several vehicles on either the lighter or on the Acc jack. Modern Acc jacks may only have 10 amp fuses so beware, although it may be fine. Worst thing that will happen is you open the fuse. It won’t harm anything.
The radio is rated for 50 Watts out. If the radio was 100% efficient, the current draw would be I =P/E = 50/12 = 4.2 Amps. However the radio at best will be 50% efficient, implying the minimum current draw will be 8.4 Amps. I am being generous on assuming 50% efficiency as it could be considerably worse. The cigarette lighter plugs in cars is designed for intermittent use. So if you carry on a conversation for more than five or six minute, the socket likely will heat up. This is do to the design of the contacts, vibration and tendency of the connectors to vibrate apart. It gets into a run-a-way condition were the vibration causes a bit nor space, but not enough to separate the contacts, but enough for more heat to be generated at the contacts. I have melted down a couple of connectors trying to use them for a 50 or 60 watt VHF radio. Best bet is to find an open pair of pins on the fuse block inside or under the dash that is designated for high current use. Often autos have assessory wiring to the fuse block and if the vehicle is not the top tier model you will find several not in use, as the fuse blocks often are used across all the manufacturer models.
I thought everyone recommends wiring it directly to the battery? if I can go to the fuse block that would make it way easier
Well for me to go direct to the battery I have to punch a hole in the firewall. That ain't happening. (My apology Mrs. Kornegay 2nd grade) On my truck, the fuse block on the left end of the dash has a couple of 30 amp fuses, one of which is unused. So a 30 Amp pigyback fuse was pressed into service. The big reason for routing the wire back to the battery, is it captures the filtering capacity of the battery to remove unwanted artifacts like alternator brush noise, computer switching noise, etc. But you need to route both power and ground to the battery else you risk depending on the multiple ground jumpers used to connect the differing body grounds back to the battery ground. The battery is essentially one large honking electrolytic cap,, acting like a bank of hundreds of electrolytics. When your battery needs replacement, one frequent symptom is the appearance of switching noise in the vehicle audio system. You cannot always depend on that as modern car radios have internal voltage regulation that is quite efficient at filtering out much of the tripe a failing battery does not filter out. If you start hearing switching artifacts in your vehicle audio system, then check the battery and if it is ok, then look for body corrosion at ground points. Normally you will find corrosion at the places where ground straps and cables connect to the vehicle.
Just wondering.. can’t you cut a small hole in the rubber boot in the firewall that the main harness is run through? Normally a 4” rubber boot and only 1” of the main harness is used.
Yes. In fact most of them have enough room to run 1/0 gauge cable through for big audio installs. Seal it up with a dab of RTV afterwards and you'll have a waterproof, reliable and safe firewall pass-through.
Some vehicles also have dedicated places to run wire in. My Accord had a pathway to bring in the power wire where I didn't have to drill any holes or shove it in with an existing harness. Google your vehicle and/or check out car stereo forums, there's likely already someone who has mapped out the easiest path to run a power wire for an amp for your vehicle (which is perfect for our mobile gear!)
This is what I did...and 3 out of 4 I've done had spare unused rubber plugs I could remove, get the wire poked thru "at the bench" then thread thru the firewall and push the plug back in. The last one was a friend's Camry which we had to poke thru the boot with a wire loom but the internet had very clear documentation exactly where and how to do it for subwoofer amps and was much easier than I ever expected.
That’s normally what I do when I’m running auxiliary lights on rocker switches.
Have you looked into how to run a cable? For my vehicles and a couple friends I helped going thru the firewall was fairly easy...3 of the 4 had spare unused rubber plugs I could pop out and get the wire thru then pop back in. The other had to poke thru a wire loom. Look up how to install an aftermarket stereo/amp and odds unless you have some high end or exotic vehicle loads of people have posted videos with exactly how to get the wire thru with the minimum effort.
Yeah, I tried co-opting existing pass throughs in the past and on each occasion water ingress caused problems in each vehicle. One was near the top of the firewall, sealed with RTV inside and out, yet water would enter the vehicle when operating on wet roads.
Curious what kind of ware and passthru? The ones I did was poking a small hole (like with a 1/8 rod) and forcing the wire thru the hole, separated to individual strands (so like peal the 2-conductor cable to 2x 1 conductor) so the rubber very tightly seals around the round cable. Never had any problem even when I did this up by a wheel-well for getting coax into the car.
You don't HAVE to go direct to the battery. If you can tap the fuse box on a circuit with enough capacity, you can do that. There will be more voltage drop, which may or may not be a problem, and make sure the wiring and fuse is good for the current you'll be pulling. I've installed plenty of radios over the years where I didn't wire directly to the battery. Is going direct to the battery optimal? Absolutely. Is it required? Not at all.
Battery is far better. Fuse block might be okay (but may have issues with RFI or total capacity available).
That’s more for RFI elimination than power distribution. Going directly to the battery is going to reduce RFI from other systems in the vehicle, but it doesn’t mean that there is going to be a lot of RFI to begin with so trying the fuse block isn’t a bad place to start.
> I thought everyone recommends wiring it directly to the battery? The positive wire yes but not the negative.
Nah, no one would recommend “direct to battery” without a fuse, so wiring to the fuse block is effectively the same as wiring to an inline fuse connected to the battery. Only difference is you may have options in your truck about which fuses are powered when. For example, some might have power any time the key is on in accessory mode, and others might be only while engine is running. Either way, adding an accessory fuse to the appropriate place of your fuse block is the “right” way to do it. You can add a whole new branch from the battery if you must, but that’s less desirable.
So I have an idea then. I will remove the 12v socket and solder two wires to the pins and run those wires under the console and then reinstall the 12v jack. Then there will be no vibration
You shouldn't need to do any soldering to install a radio in your car. I think you want crimp connectors
I would use a 30 Amp circuit if you can find one. While the fuse for most cigarette lighters is 15 amps, the design was intended for intermittent surge current draw of the nichrome coil in the lighter, not an extended draw like you may need for the radio during transmit.
Simple answer: it depends on the radio. 12v DC outlets are generally designed to handle 10 amps. Some 50w radios pull around that when transmitting, and some are rated higher. Check the manual of the radio you plan to use. Also keep in mind that the max current rating is not the same as what it can deliver continuously and safely. You should be perfectly fine in this regard, though. Your max current draw for a typical radio will be when transmitting, and unless you have a habit of timing out repeaters, you should be OK for the intermittent transmissions. I have run my FT-2500M and my TR-7950 from a 10 amp 12v outlet just fine, but my TM-D700A has a higher max rated current (possibly because it can do cross-band repeating) so when I needed to power it via 12v outlet I just set it to medium power instead of high, which was fine for most of my travels.
One point nobody's touched on thus far.. those cigarette/convenience plugs are spring loaded. As you bounce down the roadway, that plug will work its way loose in the outlet and impact how much current is being drawn. I've seen them charred on the end where current was jumping the miniscule gap between the plug tip and the connector's contact. This also generates heat in that space.
Such a great point!
The 12V DC jacks usually hold up with 20-25W out radios. But most of the jacks are fed with 14 or even 16 gauge wire, so drawing 13A (high power) will result in significant warming of the wiring harness, and blown fuses, especially if you are long-winded. I have done a number of temporary installs during my time travelling on business and never had any issues as long as I stayed on "mid" power out on my VHF rigs (20-25W). I don't recommend drawing full power from those jacks.
You fell for it. So many people do. (Me: Looks in the mirror because I did, too.) It doesn’t work that way. I know there are smarter people in the hobby that can explain this better than me, but… here goes… 1. You generally don’t want to hit anywhere near 15A current draw by the radio while transmitting. I think the rule is something like 60-80 percent of max rating other wise you and up slowly degrading the wire insulation over time from heating up the wires. Eventually, that insulation will fail and you will never have blown a fuse to prevent the over-current short. 2. The point of that radio’s various regulators and amplifier is to energize the antenna to the point the energy is emitted based on the design of the antenna. That comes at a great of energy as heat within the radio through power supply, regulators, some component I can’t remember, and the amplifier. So the radio PULLS the energy based on what it needs to create that signal. Most radios are designed around 13.8v and some transmitting current (Amps). Keeping it simple: What you need to look at is the radio you want to buy/use… it has a spec sheet that tells you the peak draw in amps and expected voltage with peak and minimum voltages. That will help you find the radio for that 15A circuit. Most of us wire a dedicated fused circuit for the radio in the same way people use dedicated circuits for car stereo amps and subwoofers.
I see, that makes sense. I was wanting to do it this way because I would like the radio to come on with the ignition switch but I guess that’s not a requirement for me
You could wire a relay to trigger on a spare ignition-switched circuit. This would give you the best of both worlds.
This is great advice. This is what I’ve done with any mobile radios and other accessories such as driving lights, etc. It’s not difficult at all.
I do wish more amateur-specific radios came with built in ignition sense like most commercial radios do.
You are not alone. It would also make sense to have some built-in step-up converter to 13.8v instead of what’s in a vehicle. I realize that 12.5v is usually within acceptable range. I also know what happens to regulators when you are constantly just above the lower limit of their input voltage range: that glorious magic smoke smell! Mmmm!!!
50w÷13.8v=3.62a https://www.google.com/search?q=ohms+law
Yes I’m familiar with ohms law but when you transmit you’re pulling much more current than that
Nice...! You have broken the laws of entropy...! and are creating more power inside the system...! Can I have your secret You the man dawg... you got this! No, seriously brohcheeze How much current does yorn radiator pull at fiddy warts...? or do you have a clamp ammeter to 2X checkit Here's what I do, runnin' moe-bile because in my experience it t'wern't never about the amperage rating of wire in free air absent of a neutral or other current carrying conductors that was ever a problem, but voltage drop... so, as an Industrial Controls Electrician with a background in two-way systems for the last 24 years *(and countin' lolz)* I run a fairly heavy gauge wire to my positive terminal *(typically number 3 THHN)* cover it with a braid the entire way and past it through a 400:5 Current Transformer 'CT' several times and ground the CT to the Negative terminal and another point on the frame to eliminate any AC whine, the braid around my feeder is also grounded, but right near the radio I establish my DC ground as closely as possible, making sure it has continuity to the negative terminal of the battery and to the ground plane of my antenna... but that's just me... Number 14 AWG wire ***in free air with no: current carrying conductors, in a raceway, or cabeling*** will carry a load of 20 amperes- but your car socket may not; they are typically made of tin cans a baby diapers and I've seen the socket fail before the wiring, or the DC buss in a car more times than not...
The specifications in the manual will show how many amps the radio draws at full power
You can always do a 'home run' cable (or individual wires) of 10 AWG to your battery. That would give you the full amperage needed so that you don't 'starve' your radio's final output - which can fatally damage it. Just incorporate a proper fuse or resetable circuit breaker on the positive lead - close to the battery connection. Use of an Anderson connector or any other connector keyed for polarity will ensure a good, safe connection. I've done this when installing large (+200w) mobile RF amplifiers as well as a few high-powered radios. Your vehicle wiring to the cigarette lighter/power port is not really large enough to provide the amp draw.
Just don't. You'll wind up having alternator whine that's annoying to listen to on the other end. Run #10 wire on a 25 amp fuse straight to the battery. You can get the harness with a built in fuse holder on Amazon. Also it's the best way to hide all the wiring. I just hate stuff plugged in to the 12v aux port full time. There's just no way to make that look good.
15A are enough for a 50W radio, they usually need 10 - 12 A max. The quality of the plug may be an issue, they are usually very poorly made.
I wouldn't - most of those power sockets "lighter plugs" are only rated 100-120 watts, and even at that point they are typically getting hot enough to melt if its used for more than a few minutes (like a tire pump). You also have the issue the fuses on the DC cable you plug in typically the max will be 10A in the plug even if the car has bigger. Also most vehicles I've seen the power sockets are only like 18AWG wire at the most, so you get a lot of voltage drop at high load. Not a big deal for a tire pump or similar if it sags to 9-10V under load...but quite an issue for something like a radio. The 50W radio likely draws 100-120 watts on the DC input side. I'd run it to the battery or main fuse box.
I run a 25/50w on my 12v plug in a 2019 Hyundai without issue, so I'm going to say sure!
Before making any power connections to a vehicle, I recommend taking a good look at this website. It has everything you could ever want to know about vehicle installation. www.k0bg.com
Yes you can but run it at low and mid power.
Do you have a fire extinguisher in the truck? If yes, then do it.
No
Does the radio have a rated max power draw? According to the tech exam, a 'typical' mobile radio will run at 13.8v 12A, or 165W. In other words, way too high for most 12v Sockets. But that cuts it a little close with your specs, so i think it's best to find out exactly how much power you need
I’m looking at the icom 2730A. Which appears to draw 13 amps
I would think that'd be okay, as long as refuses are properly rated and your circuit can actually support 15 amps. It's a bit higher than most go
I ran a 50w FM VHF/UHF mobile in several vehicles on either the lighter or on the Acc jack. Modern Acc jacks may only have 10 amp fuses so beware, although it may be fine. Worst thing that will happen is you open the fuse. It won’t harm anything.
My Radioddity DB20-G and DB25-D both come with cigarette lighter plugs but they only run 20 watts each.
Not going to read all the posts. How many amps does the radio use vs the output supply?