Regulated/unregulated...what does it all mean?!!?

Forgive me for asking a question that has probably been asked a 1000 times - but I can't find any info on it.

With reference to P7 flashlights, can some clarify the whole regulated/unregulated issue? If it's unregulated, does it not have a driver, and is therefore connected direct to the battery?

I have a 5 mode MTE SSC P7 - by virtue of it being 5 mode, does this mean its NOT directly driven? ie. does it need a driver to acheive the 5 modes? If this is the case does this mean it also regulated.... or can it have a driver and still be unregulated?

AND if it is regulated does this mean the brightness would be constant for a certain time and then just shut off? As opposed to dim slowly as with a non regulated flashlight?

I'm thinking of getting an add on battery pack and its been said that some MTE SSC P7s have delicate drivers - how can I tell if my P7 has one these drivers?

Sorry lots of complicatedly asked questions - hopefully you'll get the gst of what I'm on about!!

Thanks

J

While I think I understood what regulated and unregulated means, I would be interested in the technical aspects, why light an Olight M20 runs regulated on CR123A, but not on 18650, while an M30 is the opposite?

Regulated, as I understood : Your flashlight maintains its initial level while the voltage of the batterie drops to a certain point, where it either shuts off or switches to a level below.

Unregulated, as I understood : Your flashlight starts at 100% but gets dimmer and dimmer while the voltage of the cell drops to just glow in the end.

LED's need about 3.3 volts. Some a little more, some a little less. Few battery configurations deliver this voltage under load, so most lights have some sort of circuitry to change what the battery delivers into what the LED needs.

Here are a couple possible configurations:

Direct drive: LED is connected to the cells without any circuitry in between. If the LED is big enough (heathsinked P7 on 3 D cells) or the batteries are weak enough (3AAA cells with five 5mm LED's) the LED wont cook itself from too much current. Sometimes a resistor is added between the LED's and the cells to drop the current a bit to prevent the LED's from cooking themselves.

Buck circuit: The voltage of the cells is higher than what the LED needs, so the circuit steps the voltage down.

Boost circuit: The voltage of the cells is lower than what the LED needs, so the circuit steps the voltage up.

Some circuits have flat regulation, that means the light output stays the same for the whole runtime. Some don't, that's when you get a sloping down discharge curve.

The Olight M20 has a flat curve on 2 primaries (6volts) because the circuit is a buck circuit. It doesn't have flat regulation on 1 18650 cell because once the voltage of the cell is lower than the Vf of the LED the buck circuit doesn't buck anymore, the LED runs in direct drive from a partially discharged cell and the lower the voltage of the cell gets, the lower the output of the light is.

There's no clear definition on what regulated and unregulated exactly means, some people only call a flat discharge curve regulated, a sloping discharge curve is then called semi-regulated.

I'd say that "regulated" means that the circuit in the light regulates how power current goes to the emitter(trying to keep the output steady). If the circuit only boosts(or limits) the voltage so that led lights up(or doesn't fry) and does not adjust the boost(or "resistance value") value according to the situation, then it is not regulated.

https://www.candlepowerforums.com/threads/173963
More reading for you.
Norm