How to measure acceptable battery drain?

Archive SparkFun Site Questions/Comments
1

I’ve been trying to get into a few DIY projects and I figured I’d start light, but I’m still hitting snags. I understand that Lithium Ion batteries are not ideal for high drain situations, but I’m not sure how to measure what is acceptable.

I’m looking to make a portable LED light that would have a long battery life, and with each LED running at 20mA the 2000mAh polymer lithium ion batteries would be pretty sweet. The 6Ah would just be icing on the cake given the size. Can anyone shed some insight as to how I read the max drain from the tech sheet? Its not in a format friendly to people lacking the proper background.

That being said, I’ve read lithium ion batteries have the nasty tendency of exploding when not used properly. Should I be at all concerned with the oodles of harsh warnings I read on other battery sites? (which ironically have prices worse than here even though all they sell is batteries!)

Thanks for any help in advance! I look forward to becoming a part of this community.

2

The manufacturer’s website will probably have multiple curves showing the battery lifetime at various discharge rates. I’m guessing that the datasheet you have only shows battery life at a single rate, is that the problem?

And YES. You should treat lithium ion cells with caution. Read the datasheets carefully and adhere to the specs.

3

Not quite what I meant. The sheet shows 0.2C5A discharge where the 5 is subscript in the document. I’m not sure what that means though. Basically I want to know the max amperage I can safely draw from the battery. (ie. at 20mA each, how many LED’s would be safe to have connected at once)