Wiring question pertaining to usb

[Skyway]

Questions for any wiring gods.
I have an idea for a mod and I would like to have a couple questions answered if anyone knows the answers.
I am going to use something like the USB breakaway board from madvapes(essentially a female mini usb plug) to add to a mod to charge a battery that would be installed inside the mod. If you are using a protected circuit battery, would the battery know when to stop charging if you hooked it up to usb power? In other words how hard would it be to wire in a usb plug in parallel to the + & - of the wiring of a mod to charge the battery whenever you wanted. Would the battery automatically start charging if power was applied to it in this fashion? Would I need to tie in a resistor/regulator to the circuit to bring down the power of the usb so it would not damage a battery.. preferably something like a 3.7v 14500 900mAh.
I would like to make a couple of these and sell to friends and whatnot and it would be cheaper, and cooler if I could just give them a cord instead of a charger.
If all of this is as simple as I am hoping, is there a way to tie an LED into the line to come on when it is done charging, something like putting an LED that only comes on when it has reached something 4.1 -4.2 volts?

 

[rannox]

The protection circuit is usually fine, but they can fail, and fail = boom if you charge it that way.

One of the simplest/safest ways to achieve what your looking for is to buy a little usb charger from madvapes or similar. Take it apart and take off the current usb connection, and connect the mini usb in its place.

 

[Skyway]

When you say usb charger, what do mean specifically? You mean something like the one that plugs into the wall but is usb on the other side or one of their passthroughs?

Edit - Is this what you are referring too?

 

[Java_Az]

You really should be using a charging IC along with the battery protection. . Charger IC chips do more then just turn on a led after the battery reaches a certain voltage. Most will do a pre condition mode where it slowly starts the charge. They regulate the amount of amps going into a battery. If someone plugged into a 3 amp USB hub (Falsely thinking it is USB it is all the same) you for sure are going to see some smoke and fire without any regulation.

With something people are sticking in there face threwout the day you dont want to mess around. Charging IC and battery protection IC Chips should be mandatory.

 

[rannox]

Java knows what hes talking about.

But yes that link you provided should work, I have the 510 version, but i think they are the same. It would be the simplest method. Your probably gonna have to do some extra wiring and regulation though anyways.

I personally put in switch to cut off voltage from the battery to the atty when you are charging, and just use it as a usb passthrough while the battery charges.

And you probably wont be able to charge anything above a 14500.

There are other better methods, but they involve ic's and other stuff.

 

[Skyway]

If they are better methods but are small in physical size I wouldnt mind hearing about them. I kind of figured it was not going to be easier than I had originally thought or more people would be doing it.

 

[ralstad]

Hello, I was looking through the forum for this very thing and found this thread.
http://www.e-cigarette-forum.com/forum/modders-forum/91081-added-usb-charger-3-7v-box-mod.html
I was also wondering if any one has looked at the USB 5V Lithium Li-ion Battery 1 Cell Charger Board on ebay
I also did a web search for micro usb break out boards and found these.
Vertical micro usb breakout board
Horizontal micro usb breakout board

 

[Skyway]

Cool, thanks for that link.