How would I use IMRs so they don't over-discharge?

[OrlandoLights]

I want to get a Malkoff LED drop-in, and use 2 IMR cells with it. The cells and drop-in don't have protection circuits. The cells are safe chemistry, but shouldn't be discharged below 2.5v I believe. Is there a practical way to use these cells with the Malkoff without over-discharging?

 

[StarHalo]

Try to keep them over 3.6v, and use a digital multimeter to check them.

 

[mdocod]

There isn't really a practical way, sorry. IMR cells are better suited to direct drive applications where the user will see dimming before severe over-discharge has occurred.

 

[Yoda4561]

Do a runtime test when you get them, check the batteries with a multimeter every 15 minutes to see what voltage they are. When they hit 3.5 to 3.6 volts that's your realistic safe runtime. Roughly 40 minutes on an M60 I think. If you charge at 30 there will be no problem.

I personally don't have an issue with mentally keeping track of how much runtime I have on the light, if there's any doubt I check with a multimeter real quick and if they need a charge I'll swap in the spare cells and recharge the used ones.

 

[OrlandoLights]

Thanks for the answers. I think I can mentally keep track of the time the battery is used, the way you suggested, Yoda, so I will get a multimeter. Do you actually pull the battery out of the light to test it, or do you just take the head off and test the battery in the light?

 

[mdocod]

I would suggest removing the battery for the voltage test, sticking test leads into the head of a flashlight will increase the risk of a mistake that could lead to a dead short. It would also require that the tailcap be activated to do this, and if it were a clicky style such a dead-short would probably destroy the switch; While the maximum recommended discharge rate is pretty high, I have no doubt that into a dead short these cells could probably punch out 20-40+ amps.