Wattage limit via cigarette lighter plug?

[WRDB702]

Will I be ok temporarily using a cigarette lighter as a power source if I limit the radio to 30w? 20w?

(I do plan to tie into the battery, but that hasn't happened yet and I want to get the radio into the van.)

[wayoverthere]

9 minutes ago, WRDB702 said:

Thank you for all the information (some of it way over my head).

I checked the vehicle's manual and found my cig lighters are on a 15 amp fuse.  Does that mean the radio, which also has a 15 amp fuse in the cable, should be ok at the full 50 watts if nothing else (cellphone) is plugged in to the same circuit at the time? (Amperage ratings appear to match...?)

I plan to use the radio at 20w most of the time, but may occasionally consider using the 50w setting.  

 

The circuit itself should be sufficient, but I recall someone discovering the internals of the 12v plug they used weren't quite up to the task, and we're semi melting internally. I'll try to find it later on when I can get on a computer.

[Sshannon]

Yes, you should be fine. Depending on the fuse type and tolerances, one would blow before the other. 

[WRDB702]

33 minutes ago, wayoverthere said:

The circuit itself should be sufficient, but I recall someone discovering the internals of the 12v plug they used weren't quite up to the task, and we're semi melting internally. I'll try to find it later on when I can get on a computer.

Yes. Someone did mention that.  I will need to look for a heavy duty plug & watch it closely for a while.

[WRDB702]

Update:

I purchased a heavy duty cigarette lighter plug (20amp) and have it plugged into a 15amp fused circuit in the van.  I also have 15amp inline fuses between the plug and the radio. 

I have had the radio in the van for a week now with no problems.  The radio is working well on low (5w), med (20w), and even on high (50w) without blowing any fuses.  

I will keep an eye on the connections and wiring, but I'm pretty happy with the results at the moment.

Thank you to all who provided suggestions.

WRDB702 - Jim

[Lscott]

7 hours ago, WRDB702 said:

Update:

I purchased a heavy duty cigarette lighter plug (20amp) and have it plugged into a 15amp fused circuit in the van.  I also have 15amp inline fuses between the plug and the radio. 

I have had the radio in the van for a week now with no problems.  The radio is working well on low (5w), med (20w), and even on high (50w) without blowing any fuses.  

I will keep an eye on the connections and wiring, but I'm pretty happy with the results at the moment.

Thank you to all who provided suggestions.

WRDB702 - Jim

There is likely one area you haven't checked. Your typical cigarette lighter plug has a spring loaded center contact pin on the tip. The contact area with the pad inside of the socket is really small. At moderate to high currents this area will get really hot depending on the current draw.

[WRQW589]

If you figure the conversion to RF output is only 33% efficient, then a 30w radio would consume 7A. If it's 25% efficient, it would draw 9.2A. From what I read, you should expect a lot better than 25%, probably closer to 33% efficiency. So even at 30W, your 10A plug should be adequate.

My 28 year old Bronco (1995 Bronco XLT 5.8L), which is my camping / outdoorsing vehicle has one 12v plug designed for 20A, and one 12v plug designed for 10A. The fuses are in those ranges, too. So it's not necessarily a foregone conclusion that your plug is limited to 10A. Check the fuse. And check the owner's manual. Maybe you have a lot more room than you think.

[wayoverthere]

2 hours ago, WRQW589 said:

 So it's not necessarily a foregone conclusion that your plug is limited to 10A. Check the fuse. And check the owner's manual. Maybe you have a lot more room than you think.

While the 12v socket and what it can handle is definitely important, that part of the circuit is easy to determine, either from the owners manual or the fuse rating; likewise, you can spec adequate wiring from the radio to the plug, and have reasonable assurance it can handle the load.

The hazy spot is the internal construction of the 12v plug itself, and the spring @Lscottomentions inside the plug that allows the center pin of the plug to move and maintain contact with the positive center conductor in the socket. That spring conducting between the radio side and the pin contacting the socket is the big unknown.

If I had the socket to support a big draw, and really wanted to use a 12v plug, I'd probably want to add a better connection inside the plug, between the wiring and that center pin, so it isn't dependent on the spring for current, only keeping the pin in contact inside the socket

[WRDB702]

In case someone might be interested, here is the Amazon link for the plug I used. I will be watching it closely for a while.   

14AWG 12V 24V Cigarette Lighter Power Adapter

https://a.co/d/383x5dj

[wayoverthere]

2 hours ago, WRDB702 said:

In case someone might be interested, here is the Amazon link for the plug I used. I will be watching it closely for a while.   

14AWG 12V 24V Cigarette Lighter Power Adapter

https://a.co/d/383x5dj

Well, pending hands on testing, it looks like they've made an effort to address the weak point

[WRPQ991]

If the cig  lighter plug is a problem, why not change the connection to a two wire plug, think 110V home plug with one wide one thin so you cant plug it in backwards. Or the push to connect like the front of a power supply.