M4 Devastator Runtime on AW rechargeables

Hey guys,
I just did a runtime test on my M4 using an MN16 lamp and 2 of AW's 1600MAH protected 17670 cells.

With a current draw of 2.54 Amps, the MN16 should have a runtime of approximately 37 minutes on the 1600mah cells.

On freshly charged cells, I got a runtime of 35minutes, all with essentially the same brightness.

However, when the timer hit about 35minutes, the flashlight just completely switched off, just like what my A2 does.... Is this normal for an incandescent on rechargeables? One minute it was at full brightness, next, it was completely off...

The temperature of the torch was 44 degrees celcius, but the batteries were only slightly warm.

Im pretty happy with that - a little concerned about the sudden turning off, but happy

Also, I was wondering with the new unprotected LG 18650 cells Ive ordered, when would be a good time to charge them?

With the MN16 LA, the 2400mah LGs should run for 57 minutes - should I charge them well before that?

I dont normally use the m4 for long periods of time, maybe 10 minutes at the most - so should I charge them after every use?

Thanks guys, Ive finally moved over to rechargeables after seeing the rate the M4 swallows batteries , and Im slowly getting the hang of it

Protaeus said:

...protected 17670 cells....completely switched off...Is this normal for an incandescent on rechargeables? One minute it was at full brightness, next, it was completely off...

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Yes, it's normal. As you know, lithium ion cells come in two varietites; protected and unprotected. The protection circuitry does a couple things. First, it prevents shorts and reverse-polarity damage. Instead of sparking or exploding, it just shuts down. The other thing it does is shut down the battery to prevent over-discharge. Discharging a li-ion too low will damage the battery. The protection prevents this. Thus, when it reaches that point in usage, the light will just shut off, without the dimming tail you're used to with primaries. Unprotected cells won't shut off, but should be turned off when you see that they're dumping to prevent damaging them.

With unprotected cells, charge them as soon as you see a rapid dimming of the light. If you keep using the light after it has dimmed, it will strain the batteries and may cause them to vent (creating a torch bomb), vent with flame, or worse...explode. Also it's good to actually not completely run down LIon cells and then recharge them, as this shortens their life iirc. I recharge mine when they are at 20% or so...or when i get bored. Using a DMM, open circuit of 3.5V is pretty much 0% capacity.

Protaeus,

You were pretty close in your statement of 57 min on the 2400s and MN16. I tested mine the other day and it ran 62 min before I shut it down due to the yellowish tint growin ever so more.

But for the first 45 min, she held bright as the first 2 min! I love that.

The MN15 or the N2 should run for at least 90 min or so!! Great to know we have that kind of runtime in our M4 setups if needed. I keep an MN16 in one of mine and an MN21 in the other just about all the time.

By the way have you got the MN20 yet? hburner.

Not yet Hburner, but it should be here any day now. Good to know how flexible the M4 really is!

hburner said:

Protaeus,
You were pretty close in your statement of 57 min on the 2400s and MN16. I tested mine the other day and it ran 62 min before I shut it down due to the yellowish tint growin ever so more.

Click to expand...

Seems we are all doing the same. I've been using the 2400s with the MN16 too!