Help me understand the Surefire M6 electrically..

[The Toecutter]

Please shed some light on the battery set up on the M6.

I understand that its only running at 9 volts, but really it's 18 volts of batteries running parallel down to 9 volts. So essentially, it's a big 9 volt battery at this point?

You can get 500 lumens out of 9 volts? The M6 setup just gives it more power reserve?

Why won't the 500L bulb run bright on a M3T? I've tried it and it's underpowered. It's still 9 volts? Shouldn't it just have less runtime?

Why not run the M6 at a full 18volt series and push out 1000L or more with shorter run times? It would be a nice option to have...

 

[jason9987]

I dont think the 123s can handle the current draw needed in just series there voltage probably drops significantly, now you could probably run the LOLA from 3 cells but you'd get less than half the runtime probably 15-20 minutes

and about your question about getting 500L out of 9 volts, the amount of lumens depends on the wattage you could proably ge 1000L out of 3volts but you'd need a source that could handle a very large current draw much more than a single 123 could provide, now it might be possible with a li-poly that handles huge amounts of current draw. But I think it is generally more efficient to use a higher voltage lower current for the same wattage.

 

[Gunner12]

The CR123 batteries are running both parallel and series. The series gives it 9V and the parallel gives it the amperage needed to light the MN21 brightly. The three CR123 batteries of a M3 does not have enough amperage to light the MN21 at full brightness.
Running the MN21 at 18V will blow the bulb. The filament can not take 18V, it might be able to take more amps though.

Electricity is like a pipe. The voltage represents how wide the pipe is and amperage represents how much water is flowing through the pipe.

 

[defusion]

The CR123 batteries are running both parallel and series. The series gives it 9V and the parallel gives it the amperage needed to light the MN21 brightly. The three CR123 batteries of a M3 does not have enough amperage to light the MN21 at full brightness.
Running the MN21 at 18V will blow the bulb. The filament can not take 18V, it might be able to take more amps though.

Electricity is like a pipe. The voltage represents how wide the pipe is and amperage represents how much water is flowing through the pipe.

That analogy isn't really accurate. It would be better to say, amperage is how fast it's moving, and speed*wideness = total amount of water, or with electricity the power (wattage).

But i agree with everything else, about the batteries and bulb and such.

 

[CM]

Voltage is meaningless without associating it with current when talking about the M6. CR123 cells can sustain about 1A or so, and about twice that in short bursts. The MN21 draws about 4A if I recall correctly That's too much for a single series string of 123's so Surefire used a series parallel arrangement so that the voltage is about 6V (normally 3x123's in series is 9V) under the immense load of the MN21. However, the parallel arrangement allows the CR123's supply the necessary current to run the HOLA. A single string of 3x123's in series (like in the M3T) will NOT supply the necessary current.

Li-Ion cells work extremely well with 2x18650 in the M6. The lamp voltage and current seems to be a perfect match for this configuration. Two decent 18650 cells in series will power an MN21 probably for longer bursts than you can get with 123's. Li-Ions will also power the MN15 (for the M3T) for over two hours in the M6! This is what I call the "LOLA" for the M6 and it gives an incredibly nice beam with great throw and really great runtime.

 

[FILIPPO]

Why not run the M6 at a full 18volt series and push out 1000L or more with shorter run times? It would be a nice option to have...

less than 20 minutes of runtime? I don't see what you can use it for....:thinking:

probably only a "wow" light.:naughty:

 

[jason9987]

18 volts through the MN21 would almost definitely instaflash the bulb

 

[mdocod]

The analogy I like is as follows: (water)


Voltage = water pressure available at faucet
Battery resistance = size of faucet (lower resistance = bigger faucet, more cells in parallel or larger cells)
Circuit Resistance to Bulb = Hose Diameter
Bulb Resistance = nozzle at the end of hose

a CR123 is like a faucet with a 1 inch opening with 50PSI behind it.
Putting 3 CR123s in series is like upping the pressure to 150PSI with the same faucet size.
Putting 2 CR123s in parallel is like increasing the faucet size to 1.414 inches (double the area). but PSI stays 50.
Putting 2 sets of 3 series CR123s in parallel is like having a 1.414 inch diameter faucet with 150PSI

A M6 driving a MN21 is like having a 1/2 inch nozzle at the end of a large hose supplied by a 1.414 inch diameter faucet. the result is plenty of pressure at the nozzle, huge flow, huge throw. The 150PSI at the faucet is reduced to about 115PSI at the nozzle from resistance in the faucet and hose. (9V becomes ~6.75V at the bulb)

A MN21 in a M3T is like having the same 1/2 nozzle at the end of a large hose, that's hooked up to a 1 inch faucet, half the cross-section area as the M6 setup, so the nozzle doesn't flow anywhere near as much water, and doesn't shoot it nearly as far. The 150PSI at the faucet is all "used up" so to speak, there isn't enough flow available to hold pressure through the line with such a large opening at the end. The result is about 50PSI at the nozzle instead of the 115PSI necessary to shoot the water worth a darn.

 

[LED61]

Well put Mdocod!!