Friday, July 1, 2011

Baofeng UV-3R: USB Charger

[ UPDATE and a WARNING: Luis points out that USB will only do up to 500mA. The wall charger pictured below is 1000mA. He says newer computers build in protection for this, but that he would not recommend trying this with older machines. USB power info on the Wikipedia page here. ]

Several people have said they built USB chargers for their UV-3R, so I thought I would give it a try. This worked for me, but I'm not an electronics expert, so proceed with caution - and I'm always open to suggestions/corrections.

The first thing to note is that the charger has non-standard wiring - the tip is negative and the sleeve is positive. TNJeff verified that with a meter, but it is printed on the label on my charger.

Next I cut the wire half-way between the wall wart and the plug. If you don't want to carve up your charger, you can order the 2.5 x 0.7mm plugs or even an extra charger on eBay.

After stripping the wire, I used the meter to figure out the tip was connected to the red wire and the sleeve was connected to the yellow. The opening in the tip is very small, so I had to work carefully to insert the probe and test continuity.

I took a spare USB cable and cut it in half. As you can see in the diagram below, black is ground and red is the 5V connection.

I connected USB black to plug red then USB red to plug yellow and then applied some electrical tape for my testing. (If you think the diagram below is ugly, you should see my actual cable. I'll get it dressed up and post some pictures then.) Make sure you have the USB logo on top, so that the ground is on the far left and the +5V is on the far right when you test your continuity.

You should be able to confirm continuity using your meter between the ground on the far left of the USB and the tip of the plug. Likewise, you should be able to confirm continuity between the +5V on the far right and the sleeve of the plug.

I plugged the USB connector into my laptop, inserted the plug into the UV-3R, and the radio began charging! I know this may be a super simple project for many, but I hope it is useful to someone.


  1. Hi,
    I'm little ham frenchie owning a brand new little uv-3r and I found that on the net. Hope it can help


  2. Bonjour Pierre! Merci for the link - I'll have to check that out. I took a lot of French in high school and college, but I never used it, so I lost it. My wife is fluent, but a little rusty. Thanks again for the link.

    Au revoir!

  3. I did similar charger using Nokia 2.5mm charger connector. I just had tocut of some plastic from connector to get it in the same lenght as in UV-3R. It's important to remember that polarity of the connector is different than in Nokia charger. UV-3R has positive connection in the outer case of the connector and negative connection inside the connector.

  4. This was a very useful post. Thanks very much for sharing it with us.

    As an FYI to others, the USB cable I used was a little strange to get working. I didn't bother with finding which color wire went to which pin on the USB port - I just played with the wires.

    I initially tried the red and black wires coming out of it and got 5v from my computer. When I did it with a little iPhone/iPod wall-wart I got nothing from that pair. I ended up using green and red (green -, red +) to get 5v.

    Once I'd realized it was different, I was a little saddened that it probably wouldn't work on my computer. Well it does.

    By using the green and red, it works from my little iPhone charger, computer and the Griffin USB car charger I have.

    Long story short, check other combinations with whatever devices you plan on using, while black and red are probably right for your computer to charge your radio, they may not be for other USB sources.

    Also note that one combination of wires (yellow and black maybe?) outputs ~3v....make sure you're getting ~5v.


  5. @KJ6RDR Thanks for posting the notes about your experience.

  6. Just an FYI,if you flip the Baofeng Drop in charger over it says DC 5V 500mA. Although he is right about the wall wart and 1000 mA.

  7. @clymbn Thanks for the heads up. I will have to take a look.

  8. I've been ordering Baofengs for friends a bunch lately and started to notice a few places are shipping them with UBS wall-warts and these cables.

    I started buying them instead of making them since I found them for $5 shipped. My latest purchase of two UV-3Rs and two USB cables included USB wall-warts and two USB charging cables each - I over paid this time, but got extras :)

    Anyway, no guarantees, but I've been buying from and have had nothing but good things to say.

    If you've already got the radios and want just the cable, it's the cheapest I've found.

    If you want both, I'd say just get the radio first and wait and see. The cable, when bought alone, ships via airmail in about a week so it's not a huge loss. Same price either way.

    Wheew...hope that made sense.

    1. It was a lot clearer than most of the things I write. I keep waiting (for what I don't know) before buying the second UV-3R. I think I should get a Mark II, so I can actually see all the problems/fixes/changes that everyone else is talking about.

    2. KJ6RDR, thank you for the tip. I just ordered some replacement cables from them.

  9. I'm going to have a go with a mobile USB charger 1000mA and a plug from Maplins.
    let you know if it works.

  10. If u have the cable...combine it with the yooboa 11200mah portable powerbank. U will have ten time battery capacity with mobility.

  11. Thank you for this post (from two years ago).

    It was very useful to me when I needed to make a charger for a UV-3R (original, 1 line) I got at a Ham fest (without a charger).

    I've used the cable from a mysterious vehicular accessory charger that I've fount few years ago,
    the sticker says: Adapter for C5-JT-CLA-SK.
    The oval wall- wart is a Nextel charger Model: PSM4680A / NNTN4963A by Motorola,
    rated for 5V 850mA, that I had laying around.
    Used a tiny leftover piece of a via board / development board to soldier / hookup up the different wires.

    The battery was completely depleted, charged in the radio for few hours now shows 4.1 volts when the radio turns on, so I guess either 850mA was enough, or the 850mA value is just a safety rating for it (I didn't try to measure the max current it actually produces).

    I'm happy that I've found this post (I wasn't aware of the inverted plug polarity), so thank you, Brick, for preventing me from bricking my newly purchased UV-3R.


  12. Today you can buy spare bypass USB batteries 5V very cheap, solder a plug via the standard USB coneector and it works.

  13. Depends on the battery as no good using 5V to fully charge a battery with a higher rating. 8.4V-10V should suffice