3.7v 16340 Battery

[nicksydney]

Hi,

I got a 3.7v 16340 (2500mAh) battery like this one http://www.ebay.com.au/itm/New-3-7V-2500mAh-TR16340-Li-ion-Rechargeable-Battery-for-LED-Flashlight-GO-GO-/371581173088 and tested with Arduino and WS2812 LED strip (30 LED) and when the battery went below 3v the whole thing stops. The question that I have will it be possible if I use some kind of step up boost converter (not sure if it is the right name) to keep on using the battery and push 3v and above to the circuit ?. The plan is to keep on using the battery to the lowest possible way.

Thanks

[nicksydney]

Does something like this http://www.ebay.com.au/itm/DC-DC-Boost-Converter-Step-Up-Module-1-5V-to-5V-500mA-Power-Module-New-IT-/161879487895 will work ? and suitable for the circuit ?

[sleemanj]

 

LIthium Ion cells should under no circumstances be "used all the way",  it is dangerous (increasing chance of smoke and flames and running and screaming as your house burns down when you charge that deeply dischaged cell).

3v is already regarded as empty, it is not generally advisable to discharge a typical lithium ion cell below this, even 3.2v could be regarded as close enough to empty for useful purposes.

[PA0PBZ]

On top of that, it is probably the cell protection that is kicking in and shutting down at 3V, so there is nothing you can do to discharge it further.

[CraigHB]

There are many safety considerations with Li-Ion batteries.  It's really not something to mess around with due to the potential for fire or even explosion in some cases.  I'm not going to get into it too heavily since it would be a book of a post.  Here's an article to start with; link. 

There are a couple points regarding safety with flashlights you might not see right away in researching it.  Firstly you should make sure your flashlight has some kind of pressure relief or vents.  There have been instances of flashlights becoming pipe bombs due to pressure buildup when a Li-Ion battery fails.  Gasses are released from a Li-Ion battery failure at a very high rate. 

There are many unscrupulous sellers on eBay passing off poor quality batteries with greatly exaggerated capacity ratings.  These batteries are the lowest of quality and may tend to fail in a catastrophic manner.  The reason I say that is the highest capacity name brand 18650 is rated for 3600mAh and a 16340 is less than half the size of an 18650.  Anything over 1200mAh for a 16340 is BS.  Likely that battery is fake with a bogus label on it making it of untrustworthy quality and safety.  Many people are fooled by this by looking for a Li-Ion battery listed with the highest capacity.  That's what these unscrupulous sellers are banking on.  Always use a trusted brand from a trusted vendor.  There's really no exception.

[CraigHB]

The question that I have will it be possible if I use some kind of step up boost converter (not sure if it is the right name) to keep on using the battery and push 3v and above to the circuit ?.

It is possible to use a boost converter to increase voltage as required, though it calls for higher input currents which may exceed a battery's drain limit.  In most cases it's better to use a series pack and buck convert down to the required voltage.  Efficiency is better, input currents are lower, and there's a much wider selection of buck converters compared to boost converters.

As already stated you can't drive a Li-Ion cell much below 3V or it will cause damage to the cell.  The operating range for a standard Li-Ion battery is typically 4.2 to 2.7V, but limits can vary somewhat depending on the particular make and model.  For example the LiPo type cells used for powered models have a 3.0V lower limit.  High drain 18650s can have a 2.5V lower limit.  There's also high voltage Li-Ions that have a range 4.35 to 3.0V.

Li-Ion cells may or may not have protection built-in.  When they have it, a small round protection PCB is encased under the shrink wrap typically on the negative side.  The protection PCB limits voltage and current to safe levels.  A protected battery will disconnect and drop out when limits are exceeded.  When they don't have protection it's up to the circuit to ensure limits are not exceeded.  Any Li-Ion battery must have protection either built-in to the cell or externally via the circuit it powers.