rechargeable battery

Forum 2005-2010 (read only) Hardware Troubleshooting
1

Hi,

im working on a project with arduino, led matrix and accelerometer, it should be autonomous , so the use of a battery is mandatory. Also it should be rechargeable so i ask you guys wich is the best solution.

I suppose Li-ion batteries is a correct choice
How is it to recharge the batteries through the usb interface? Do we need a recharging circuit ? how much voltage should it give to feed arduino +the matrix+the accelerometer?

So, i thanK you if you guide me with brief infos

2

Lithium batteries are particularly intolerant of incorrect charging; simply connecting the battery to USB would be a good way to generate a fire or explosion (no, I am not kidding).

Since Li technology batteries are ~3.6V, you need either a 3.3V arduino variant with an LDO regulator, 2 cells, or a boost regulator.

There are ICs available specifically designed to charge Li cells from USB voltages (MAX1555, etc).

-j

3

In addition Li batteries have to be protected from over discharge to prevent permanent damage, so some kind of low voltage cutoff/turn off is required.

Unless you really require the higher power density ( you also pay for this increased density) you are probably better off with other less fussy types of rechargeable batteries.

Lefty

4

Hey, thanks both of you for the answers.

Soo, which solution would you choose to power an arduino + a led matrix + an accelerometer and provide it with rechargeable feature?

5

I think a nice solution would be this:

with this

am i right?

6

Yes you will need those parts from sparkfun, a lithium backpack from liquidware or NiMH batteries

http://www.liquidware.com/shop/show/BP/Lithium+Backpack+Stealth

9V battery clip with 5.5mm/2.1mm plug : ID 80 : $2.95 : Adafruit Industries, Unique & fun DIY electronics and kits and Tenergy 9V 250mAh NiMH Rechargeable Battery - Tenergy and Tenergy Power

Or you can use a 6 AA battery holder with a 9V battery connector and AA NiMH batteries Philmore BH363 - 6 AA Battery Holder and Tenergy Power and 9V battery clip with 5.5mm/2.1mm plug : ID 80 : $2.95 : Adafruit Industries, Unique & fun DIY electronics and kits

AA and AAA NiMH batteries are particularly useful since you can use them for your *duino as well as other devices :slight_smile: