Lithium Battery Monitor

[metRo_]

Hi all
As we know if a Lithium battery runs low it will be damaged so I'm looking for somekind of monitor that I can use that break the power from the circuit if the Lipo run low voltage. I looked on ebay but everything I found are chargers :s

Do you know anything that can I use on my circuit? It consist on a Lipo battery and some leds, I just don't want the battery to go  below 3.6V.

[VK5RC]

I can't find the exact circuit easily but silicon chip magazine in the last 12 months had a low voltage cut off circuit,  it had very low drain current,  regards Rob

[TriodeTiger]

Isn't this the prime use for a voltage reference? i.e. the TL431:
http://www.digikey.ca/product-detail/en/TL431CZ/1026-TL431CZ-CHP/2521470

You can set it to anything you want between a bit above 2V and up to around 30V.

[goingjag]

I thought Lithium's kept their voltage high right up until they are almost dead, with their amperage dropping off? 

It may be a function of electronics in my Ryobi Lion battery packs, but they work great until they have no juice left, then nothing, unlike my ni-cads which start loosing their punch as the get used up. 

The Lion's always recharge fine, and there is no warning with them to not drain all the way down, but then maybe they already incorporate the electronics you are looking to create for your project.

[VK5RC]

Here is the article http://www.siliconchip.com.au/Issue/2013/September/LifeSaver+For+Lithium+%2526+SLA+Batteries
It uses a zener diode reference,  the tl431 only uses down to a few mA so it may be better.
I think good LiPo tools cut off battery before they discharge too much.
I recall also seeing an ad for a LiPo controlling chip,  which I recall also controlled charging as well as cut off voltage.

[metRo_]

thank you all Reading this https://www.eevblog.com/forum/projects/lipo-protection-charging-module/ I found that there is lipo batteries with built in protection. How do I know if per example it http://www.clickplus.pt/p2346 has builtin protection or not?

BTW I found on ebay the protection circuit: http://www.ebay.com/sch/i.html?_from=R40&_sacat=0&_nkw=Protection+Circuit+Module&_sop=15