Thursday, May 1, 2008

Lithium Backpack: Charging it

The Lithium backpack not only is a heap of coulombs powering your Arduino based [____ ] but according to the orange status LED, it can also be charged too!

This is how you charge it from 5v...

Plug the Lithium Backpack into the Arduino through the red and black wires (shown above) while the Arduino is powered by USB. The Lithium Backpack automatically senses a power source and charges the battery. Optionally, you can charge through it's USB mini plug.

1000mAH provides a nice helping of juice for a mobile project.

Charging is completed when the orange LED shuts off, making a completely dead battery ready to go in just a couple of hours, which is perfect during your afternoon nap.


Cai said...

What kind of signal is on the "Status" pin? I didn't see it on the schematic on Is it the same as the status LED; is it high when charging and low when full or does it provide a voltage level to determine charge state (like tied to battery +). Also, I don't see the 3.3V on the schematic.

Chris said...


The status pin is actually just tied directly to the lithium battery's positive terminal. Measuring the voltage here you can estimate the life of the battery.

Those schematics need to be updated to include the 3.3v and status. I will try and post more updated ones.

The 3.3v is rated for 100mA and the 5v is rated for 500mA continuous.


Developer said...

Hi, I have a question. I have mounted the backpack with arduino and it charges over arduino's usb. I need to change the switch when I disconnect the usb in order to switch on arduino and i need to change the switch in order to charge de backpack. Are there any method to detect the plug of the arduino's usb (5v) and change the "switch" to charge position and viceversa?

If this is possible we have a automatic charge method for backpack using the arduino's usb and avoiding to change the switch every time.

Thanks a lot and sorry for my englishman.

Aaron, Vicki Tunell said...

what does it mean when the orange LED flashes.
My backpacks have a hard time charging. most of the time when i try to charge them, the orange LED flashes only once and then goes off, even when the battery is dead.

Severino said...

Hi Aaron,

Sometimes the wire connector on the lithium ion battery becomes loose. Try repositioning the wire so it can hold its connection.

If you are still having problems shoot me a message

I hope this helps.


Unknown said...


With a 2200mah pack, how long will it take to re-charge and what current does it draw whilst charging?



Unknown said...

Hi Jon, this circuit takes ~5hrs to recharge the battery. While it's charging, the system draws ~400mA

Unknown said...

Hi I've got the 2200maH board for the mega and would like to use the status as a battery level indicator on one of the analogue input.

Can you advise me on the expected full voltage value for a 100% charged battery and also the minimum battery voltage before a recharge is necessary to avoid overdraining to the cell.

Kev Lewis

Melwin said...

During the Battery recharging over the OnBoard Mini-USB is the arduino get energy from the backpack?