I’m planning on using an unprotected Tenergy 14500 cell with the Fio v3. I’m unsure if the Fio v3 has a built in low voltage dropout so it doesn’t damage the battery or if even the Fio v3 can charge li-ion cells safely. I may go with this board https://www.sparkfun.com/products/11231, but I also am unsure if it can work with an unprotected cell as well.
Any input is appreciated. Thanks!
What makes you think the Fio v3 has a low voltage dropout built into it?
Do the schematics and relevant datasheets for the parts noted on the schematics not make sense?
I’ve looked a bit closer at the schematic and I found that the 3.3V regulator is the MIC 5219. http://www.micrel.com/_PDF/mic5219.pdf
It looks like the MIC chips has a 500mV low voltage dropout which is much lower than the 2.6V desired for Li-on batteries. My next question would be what would be the recommended way of protecting and charging the cells.
That 500mV means that the linear voltage regulator input must be that much higher than the output to provide a proper regulated 3.3 volt. It has nothing to do with an under voltage cut-off to protect a lipo chemistry battery.
I must say there are some odd net-label on the Fio-3 schematic containing 1.?? and 2.?? that make no sense in their meaning. It prevents me from tying up the sections togehter in my mind and see how they relate. Is that an indication of expected voltage level, or some weird version number reference?
In that case, to make my questions short and sweet. What would be the best way to protect a li-ion with a Fio and also be able to charge it easily.
Well, it does have a charger chip on it, so it should do something like that. I just can’t figure out how it operates myself. Maybe you should ask Sparkfun Tech support for the product details and functionality by email. Support through the forum is more of a community driven thing. Though on some occasions a Sparkfun employee responds here and there.