So many numbers!

And they all look the same after a while. Such is my predicament when working with multiple battery chemistries, be it the LiPos for my RC flying things, the LiIon I salvage from old laptops, or even the LiFePO4 I'm getting for my home energy backup projects. At any rate, be it a manual charge cycle using a bench power supply or just checking state of charge with a voltmeter, I find myself recurrently searching the interwebs for the voltage limits or the approximate charging profile of a particular battery all the time.

Let us build a place I can collect that information for later reference... I'm sure no one has thought of this before!

Base voltages for multiple chemistry

chemistry	V nominal	V min	V max	Wh/kg	Wh/L	W/kg	comments
Lead Acid	2.0	1.8	2.1	30-40	80-90	180
NiCd	1.2	1.0	1.45	40-60	50-150	150
NiMH	1.2	1.0	1.25	60-120	140-300	250-1000
LiIon	3.7	2.8	4.2	100-265	250-693	250-340	typical min is 3.0v
LiPo	3.7	2.7	4.2	100-265	250-730
LiHV	3.7	2.7	4.35				LiPo High Voltage
LiFePO4	3.2	2.5	3.65	90-110	220	200
LTO	2.4	1.8	2.85	60-110	177		Lithium Titanate Li4Ti5O12

The minimum voltages are, as far as I can understand it, really the minimum the cells might be able to reach without suffering catastrophic degradation, and for that reason are obviously not the working minimum voltage to target.

Then there's under load voltage vs resting voltage. The voltage sag under heavy loads is very significant and at no point should a battery be allowed to sag below the minimum voltage, or better yet, a safe margin thereof. For LiPo batteries and high power consumption drones, for example, the full throttle voltage measured at the cell might be 3.0v whereas the resting voltage will be at 3.7v or 3.8v. At this point the battery is at risk of sustaining damage if it continues to be used.

Thus, at least for LiPo and for high discharge rates, the minimum voltage under load might be set at 3.3v or 3.5v to play safe. On landing a check of the voltage might show 3.8v per cell and still we would have used some 80% or more of the available charge. It's really not all that straightforward.

A lot of the information collected comes from Wikipedia, of course, and is to be taken with the usual disclaimers along the lines of "do your own research". I take no responsibility for exploding batteries, near impossible to put out lithium fueled fires or any other damage that may derive from you operating on the information set forth here. The only reason I'm compiling this information is because I forget....