Used my new P7 torch for the first time last night (basically it was brilliant for the money) and am now wondering whether I should fully discharge the 18650 cell(s) before charging them back up to help with capacity.
Any thoughts?

Don’t think it matters with LiIon. You shouldn’t store them fully charged AFAIK, keeping them in the fridge will also help.

Fully discharging Lion batteries is a *BAD* idea. Assuming you have ‘protected’ cell’s it’ll never actually occur, but if you brought unprotected cells, it’ll break them (possibly flip the polority).

The fridge thing applied to NiCads. Li-Ions don’t have any memory. In fact, it’s better to charge them from half full.

Just had a better look and Woody you’re right……. full discharges are actually not good and frequent partial discharges/charges are better. The bit about the fridge is also right 🙂

Cheers.

Lumicycle recommentd NOT discharging Li-Ions completely, storing them in the fridge, but not the freezer and storing them at 40% charge. Apart from timing this, I am not sure how you can tell that a battery is at 40% though.

Courtesy of batteryuniversity.com

Stumpy:
As the 18650 is a 3.7v cell I would have thought it would be 3.7/10×4 = 1.48v
BUT on my protected Trustfires is says that the cutoff discharge level is 2.75v….. so it would never get to 1.48v.
So I dunno 😕

As the 18650 is a 3.7v cell I would have thought it would be 3.7/10×4 = 1.48v

sorry, the voltage does not linearly reflect the capacity, the discharge curve has a distinct knee. I don’t think it’s possible to estimate intermediate capacity levels, but chargers are able to determine full capacity when reached from the voltage/current profile

“Fully Discharged” isnt 0v. Well, it is, but it’s more complex than that. They mean at 40% capacity, not 40% output voltage (i.e. 3.7*10/4 isnt correct). The voltage/stored capacity curve is not linear…