DIY Li-Ion rechargeable battery pack

[Novastar]

Great explanations, Eastern. And lol @ the Nova-quote, hahahh. It seems we're running into this a lot lately--the whole "debacle" of mA vs. mAh. Oh well. In perspective, I certainly did not understand this for a LONG time until Corbin explained it to me back in 2005. You can hardly expect people with ZERO electronics experience to understand quickly though... so... if anyone understands... I do.

One other note...

I have been told by someone who is pretty darn "expert" in the Li-Ion industry that using individually protected cells (keyword: individually...) to make 7.4v packs or 11.1v or whatever... can lead to long-term problems.

Now... I have NEVER seen an issue with this as of yet--even though I don't make 7.4v packs with individually (keyword: individually...) protected cells. But I see them being used ALL the time (Yoda does so with his Graflex Chassis setups, and many many folks use the 2 x 14500 "AA"-style cells in little AA spring packs, which are wired up for the voltage).

I'm not sure what that means, since... it's obviously conflicting with the guy I know (who works for a very well-known high tech company which I cannot say).

Additionally, it's also fairly common thought that cells that go into packs are supposed to be metered/tested in ways that show they should go together. What do I mean? Well, I mean to say--like LEDs and "binning"... no two are created totally identical. Some are closer together as "matches" than others. In this case--the cell chemistry, inherent resistance, discharge rates, TRUE capacity (down to the last little bit)... is supposed to match darn well.

Unfortunately, you can't really determine this on your own when you have two cells in front of you. Hopefully those cells are from the same company, bought at the same time... and GOD FORBID you buy 2 cells from differing companies at differing times with differing mAh capacities... and then throw a 7.4v PCB on them and call it good!! O.O This could be dangerous... or simply just cause problems later on.

Again, I don't know what the long-term effects of putting together "pre-protected 3.7v" cells... but I figured I should just say... mise en garde.

BOTTOM LINE = It's a good standard practice for building Li-Ion packs to use (initially) unprotected cells... and then throw on the correct PCB for 7.4v, 11.1, 14.4, blah blah blah... and don't mix brand types, nor "mAh" types... and don't use one cell you got in 2006 and one from 2009. I know, it's pretty obvious. heheh

LINK TO VIDEO TUTORIAL (7:24):
Although it's near the end of the video (7:24)... .... --> http://www.youtube.com/watch?v=DNcc2oZWmO8