(Hopefully) Simple question - powering a circuit/recharging a Lithium battery

Thread Starter


Joined Feb 12, 2013
Long story short: The micro-usb charging port on my bluetooth keyboard broke. It's powered by an internal lithium battery. Here's a picture:


Here`s a picture of the plug and socket it uses:


I'm wondering if there is a way I can charge the battery directly. I believe those types of batteries have onboard overcharging chips, so I figure it wouldn't be too dangerous.

Alternately, I was wondering if I could wire up an AA battery to the same connector as the lithium ion one. If so, what is that connector called, and are there any concerns about voltage etc?

Just a note - I'm a full time graduate student in a stream entirely unrelated to engineering. I'm trying to save myself $50 to keep myself going with this keyboard. So if this project would require hours upon hours of research and lots of money in parts, its not worth undertaking.

Thank you! I just want my keyboard working again and to learn a bit in the process :)

Thread Starter


Joined Feb 12, 2013
PS. I should note I have access to a soldering iron.
I did see this thread: http://forum.allaboutcircuits.com/showthread.php?t=80906
And one of the options is doing something along those lines. However, I don't know the voltage output of the built in battery, and I wouldn't know how to wire it up - I don't know which of the red/yellow/black cables is +,-,GRD (guessing red is + and yellow is -).

I would love some baby-steps information.

Edit: I found a sticker that says "Power Rating: 3.6v = 30mA" . I've got three AA NI-MH batteries here, each with a voltage of 1.2v. I figure I could wire them up together... Though I would prefer to find a way to charge the internal battery (much neater than making a dongle and wiring them up).
Last edited:


Joined Jul 9, 2011
(guessing red is + and yellow is -).
I guess red is + and black is -.

I had the same problem on a Sony X10a, I replaced the original connector with some other two-pin connector and connected it directly to the battery.

On my battery was marked 4.2V charging voltage, 3.6V rated voltage. So I'm charging it with a current limiting power supply at 4.2V @0.5C. It works.

They can have different charging voltages and is not a good idea to overcharge them, they can get damaged, overheat etc.