How many amps does a kg-UV9GX use?

[CMG1012]

I purchased the battery eliminator (dummy battery with cigarette lighter plug) for the UV9GX. It is rated for 12v input and outputs 7.9v. I am looking to purchase a usb to female cigarette port adapter, however they all appear to be rated at no more than 8-10w use. Would that be enough to power the radio? I’m unsure of how many watts or amps it will pull from the adapter. 

[BoxCar]

1 hour ago, CMG1012 said:

I purchased the battery eliminator (dummy battery with cigarette lighter plug) for the UV9GX. It is rated for 12v input and outputs 7.9v. I am looking to purchase a usb to female cigarette port adapter, however they all appear to be rated at no more than 8-10w use. Would that be enough to power the radio? I’m unsure of how many watts or amps it will pull from the adapter. 

That's probably a Chinglish problem. Those plugs are usually rated for 8 to 10 amps not watts.

[CMG1012]

3 minutes ago, BoxCar said:

That's probably a Chinglish problem. Those plugs are usually rated for 8 to 10 amps not watts.

USB A Male to 12V Car Cigarette Lighter Socket Female Converter Cable (8W Max) https://a.co/d/ghPnHLR

[SteveShannon]

The USB 2.0 spec limits current draw to 500mA (100mA per port and up to 5 ports).

However, USB chargers can supply up to 1.8 amp. At 5 volts that’s about 9 watts. 
 

Cigarette lighters on the other hand can attempt to draw much more than that, depending on the wiring and fuse. 
Using a USB to cigarette lighter female port should only be used for very low current items. I wouldn’t try to power a five watt transceiver that way. 

[CMG1012]

 

21 minutes ago, Sshannon said:

The USB 2.0 spec limits current draw to 500mA (100mA per port and up to 5 ports).

However, USB chargers can supply up to 1.8 amp. At 5 volts that’s about 9 watts. 
 

Cigarette lighters on the other hand can attempt to draw much more than that, depending on the wiring and fuse. 
Using a USB to cigarette lighter female port should only be used for very low current items. I wouldn’t try to power a five watt transceiver that way. 

That makes sense, thank you. 

[axorlov]

2 hours ago, CMG1012 said:

I am looking to purchase a usb to female cigarette port adapter

Not sure I understand the use case. You've got battery eliminator already, so you can use it in car. Do you want to use this battery eliminator at home? And power it from USB power adapter? This will not work for two reasons: USB provides 5V, while you'd need 12V (maybe 9V, depending on a construction of battery eliminator); and small USB power bricks for phones provide "dirty" power, i.e. the voltage is not filtered from ripple noise.

You would need something that puts out at least 12V (again, maybe 9V will be enough) and something that provides "clean" power, like MFJ-4103, for example. But that's going to be expensive.

[CMG1012]

10 minutes ago, axorlov said:

Not sure I understand the use case. You've got battery eliminator already, so you can use it in car. Do you want to use this battery eliminator at home? And power it from USB power adapter? This will not work for two reasons: USB provides 5V, while you'd need 12V (maybe 9V, depending on a construction of battery eliminator); and small USB power bricks for phones provide "dirty" power, i.e. the voltage is not filtered from ripple noise.

You would need something that puts out at least 12V (again, maybe 9V will be enough) and something that provides "clean" power, like MFJ-4103, for example. But that's going to be expensive.

No. I’m going to use it in the car. My cigarette lighter port is being used by something else, but my car has a lot of usb ports available. So I was going to buy a “usb to cigarette converter”. The input of the converter is 5v 2A and the output is 12v 0.8A. The max stated watts is 8 watts. I wasn’t sure if that was enough to run the radio. Here is the link to the product:

USB A Male to 12V Car Cigarette Lighter Socket Female Converter Cable (8W Max) https://a.co/d/dJI8JUt

[KAF6045]

2 hours ago, CMG1012 said:

I purchased the battery eliminator (dummy battery with cigarette lighter plug) for the UV9GX. It is rated for 12v input and outputs 7.9v. I am looking to purchase a usb to female cigarette port adapter, however they all appear to be rated at no more than 8-10w use. Would that be enough to power the radio? I’m unsure of how many watts or amps it will pull from the adapter. 

Accounting for internal circuit losses -- a 5W output could result in 10-15W input. At 13.8V (nominal running voltage of a vehicle) that would be about 1A of current. USB provides 5V, so you are already looking at some voltage converter circuit. 15W at 5V means a 3A current draw (which would be transformed to just over 1A at 13.8/12V). As mentioned, a dedicated USB (fast) charger provides less than 2A at full draw.

Quote

No. I’m going to use it in the car. My cigarette lighter port is being used by something else, but my car has a lot of usb ports available. So I was going to but a “usb to cigarette converter”. The input of the converter is 5v 2A and the output is 12v 0.8A. Essentially max is stated to be 8 watts. Wasn’t sure if that was enough to run the radio. Here is the link to the product:

Unless that "something else" is drawing near the standard 10A lighter socket capability (my prior vehicle had a 10A lighter socket, AND a 20A "power" socket), your best route would be to purchase a socket expander -- available in two or three (maybe 4) port forms.

https://www.amazon.com/Splitter-Te-Rich-Cigarette-Lighter-Extender/dp/B07919SSGH/ref=sr_1_7?keywords=12v+extender&qid=1664328184&qu=eyJxc2MiOiI0LjY1IiwicXNhIjoiNC4zMSIsInFzcCI6IjQuMjEifQ%3D%3D&sr=8-7

(Hmmm, actually has a 3A charging port!)

https://www.amazon.com/Splitter-Te-Rich-Cigarette-Lighter-Extender/dp/B07919SSGH/ref=sr_1_7?keywords=12v+extender&qid=1664328184&qu=eyJxc2MiOiI0LjY1IiwicXNhIjoiNC4zMSIsInFzcCI6IjQuMjEifQ%3D%3D&sr=8-7

Edited September 28, 2022 by KAF6045
Second quoted section added

[CMG1012]

3 minutes ago, KAF6045 said:

Accounting for internal circuit losses -- a 5W output could result in 10-15W input. At 13.8V (nominal running voltage of a vehicle) that would be about 1A of current. USB provides 5V, so you are already looking at some voltage converter circuit. 15W at 5V means a 3A current draw (which would be transformed to just over 1A at 13.8/12V). As mentioned, a dedicated USB (fast) charger provides less than 2A at full draw.

Shoot. Looks like the converter I was thinking of purchasing wouldn’t cover it. Input rated at 5v 2A and output at 12v .8A. Thanks. 

[KAF6045]

2 minutes ago, CMG1012 said:

Shoot. Looks like the converter I was thinking of purchasing wouldn’t cover it. Input rated at 5v 2A and output at 12v .8A. Thanks. 

Refer to my edited post...

There is a reason 100W Amateur stations use 22-30A power supplies (the 22A linear [transformer] supply my first rig had was only rated for intermittent transmit, I currently use 30A switching supplies). 22A @ 13.8V -> 303.6W, the 30A -> 414W.

[axorlov]

43 minutes ago, CMG1012 said:

My cigarette lighter port is being used by something else

Ok, got it. As pointed by others, USB port is not going to provide enough power. I would use something like this: https://www.amazon.com/Yantu-Cigarette-Lighter-Adapter-Splitter/dp/B07CM7PJQB/ref=sr_1_4?crid=1PG8W3KZE8W61&keywords=lighter+splitter&qid=1664330596&qu=eyJxc2MiOiI0Ljg2IiwicXNhIjoiNC4zNyIsInFzcCI6IjMuODkifQ%3D%3D&sprefix=lighter+splitter%2Caps%2C700&sr=8-4

Or better, solder/splice short wires with Anderson Power Poles or T-connector to existing cigarette lighter socket and use the same Power Poles or T-connector on your battery eliminator.

[CMG1012]

Thanks all!