3.6V is considered the nominal voltage, certainly not the low end cut off.

3.0V is considered basically the highest voltage. Most chemistries suggest even lower, 2.8, or even 2.5 in some situations assuming you can control the cutoff carefully. Perfectly safe to do so. You only start to have issues when you’re south of 2.5 without a load.

Most advanced battery usages let the cells drop even below that during heavy load.

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shadowpho 20 hours ago | parent [-]

>3.6V is considered the nominal voltage, certainly not the low end cut off.

This is not right (3.6v certainly is and can be cut off depending on device and battery).

One thing you are not considering is discharge after the cut off. Fuel gauge, protection circuitry, the cut off circuitry and battery itself has some discharge.

So you don’t want to have the cut off being too low because then the battery is permanently dead after not using it for X period of time.

You want to leave some margin there.

Depending on product, battery chemistry and design I have seen cut-off at 3.0-3.6v.

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Kirby64 19 hours ago | parent [-]

Anyone setting cut-off at 3.6V either is using it in some insanely industrial, ludicrous application where you need to handle cases like multiple years in storage... or doesn't know how to properly design their protection circuitry.

The margin is already there at 3.0V. You can still recharge batteries discharged below 3.0V. It just becomes dicey below ~2.5V.

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shadowpho 17 hours ago | parent [-]

>Anyone setting cut-off at 3.6V either is using it in some insanely industrial, ludicrous application where you need to handle cases like multiple years in storage... or doesn't know how to properly design their protection circuitry.

It really depends on application, battery size and leakage. In consumer world of electronics for example there’s an often requirement to make sure device turns on after being on a shelf for 1/2 - 2 years.

Then when you do the math it ends up needing to set the limit to 3-3.6v.

>The margin is already there at 3.0V. You can still recharge batteries discharged below 3.0V. It just becomes dicey below ~2.5V.

The margin isn’t big enough for some products. Furthermore some of the more leading edge batteries (in terms of energy density) have higher leakage which requires having more margin.

	▲	dmitrygr 17 hours ago \| parent [-]
		^^ this