Battery questions

Battery questions: 3,7V Li-ion Battery - it means that i need to charge it at 3,7v not more not less? When do i know when a battery is fully charged?

3.7V will be low voltage. Fully charged will be ~4.2V.

Chips like MAX1811 are used to control charging - limiting the charge current to 100mA or 500mA and turning off the current when charged. http://datasheets.maximintegrated.com/en/ds/MAX1811.pdf

You can get more charge/discharge cycles by only charging to 4.1 or 4.0V, and definitely try not to fully discharge them.

There is no such thing as a memory effect with lithium ion.

Thank you guys :)

CrossRoads: 3.7V will be low voltage. Fully charged will be ~4.2V.

Chips like MAX1811 are used to control charging - limiting the charge current to 100mA or 500mA and turning off the current when charged. http://datasheets.maximintegrated.com/en/ds/MAX1811.pdf

Hum can i do the same with an arduino? If so, how?

Hum can i do the same with an arduino?

Yes, but it is a very bad idea. What other posters failed to mention is that lithium-type cells can be destroyed by either overcharging or by over-discharging. Special ICs have been created to control the charge process and cost only $1, so use them.

jremington:

Hum can i do the same with an arduino?

Yes, but it is a very bad idea. What other posters failed to mention is that lithium-type cells can be destroyed by either overcharging or by over-discharging. Special ICs have been created to control the charge process and cost only $1, so use them.

Oh it makes sense : ) I found out this one (which is less costly than the "MAX1811"), do you think I'll be able to charge 3.7v lipo batteries? http://www.ebay.com/itm/200957296476?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

The TP4056 is one such IC. Consult the data sheet for the details.

jremington: The TP4056 is one such IC. Consult the data sheet for the details.

I would but i don't understand it, would you please take a look on it =(

Wow, less than a dollar US for the IC, about $3 USD for the chip on a board with a USB plug. Constant current charge to full charge voltage, then the charge cuts off completely when 1/10th current is reached so it doesn't ruin the cell by overcharging.

http://www.tpmicro.com/goods.php?id=47

http://www.newegg.com/Product/Product.aspx?Item=9SIA2C516B4618

tsunamy_boy: I found out this one (which is less costly than the "MAX1811"), do you think I'll be able to charge 3.7v lipo batteries?

Just an idea, a lazy approach, you can consider look for a Lipo balanced battery charger as it allows you to charge different types of batteries and set different charging parameters i.e. max charge voltage and discharge Lipo batteries for storage, to maintain its life span.

It is pretty hard to beat that Newegg deal! On the other hand that board will only work for 5V input power and some other chargers are quite a bit more flexible.

I really like the USB/solar lithium battery charger from Adafruit. While quite a bit more expensive, it also works remarkably well with the wild voltage swings of a typical 6V solar cell module. Under low light conditions the charger uses a large capacitor to store up enough energy to give a "burst" of charge. Great for remote weather stations, small mobile robots, etc. https://www.adafruit.com/products/390

For the very best deal on 6 V solar modules, check out the offerings at Seeedstudio.com.

Thank you gentlemen, i think i get it now i just need to test it out

jremington: It is pretty hard to beat that Newegg deal! On the other hand that board will only work for 5V input power and some other chargers are quite a bit more flexible.

The datasheet says it'll take up to 8V (absolute maximum).

And yeah, Seeedstudio does have nice solar panels. I have a few myself.