Li-ion discharge

[dusty99]

Now that winter is here and the days are shorter I'll be doing more hiking (and maybe snowshoeing) in the dark. My new kit for this will be a Thrunite T30S w/two Eagletac 2600mAh 18650s (one in the light, one in my pocket). I'm clear on testing the batteries and recharging at 3.6v, but I won't carry my multimeter in the field and am wondering if, on a light without a low battery indicator (like this one), will I notice obvious dimming that would indicate getting near full discharge, or flashing? Assuming the light will be switched on and off it may be hard to get a good runtime estimate if I'm out several hours. What do you folks do who use your Li-ion lights through the night, or for caving or other situations that may require a battery change part way through? The last couple of years I've carried AA lights and extra batteries, and changed them when the lights dimmed or flashed, but Li-ions probably shouldn't be regularly run down to the protection cutoff, correct?

Thanks.

 

[Shadowww]

Your light has 3.3V-8.4V voltage range, which means it'll get dim before reaching lowest allowed voltage of 3.0V (that's for 2600mAh cells. 3100mAh/3400mAh cells have lowest allowed voltage of 2.5V). So you have nothing to worry about

 

[derfyled]

First off, I think you are better with a flood Zebralight headlamp to do snowshoeing in the dark and keep your TN30 in a reachable pocket. A dimmer hand-free lightning won't blind you with the reflection of the snow.

About your batteries, I'm pretty sure Eagletac cells are protected so you don't have to worry, the protection circuit will kick in when you'll reach a critical voltage. The Zebra will then be handy to change the batteries in the TN30.

 

[Justin Case]

Post deleted.

 

[m_kluch]

Discharging li-ion cells to the voltage cut-off won't hurt the cell. That's what the cut-off is there for...to stop the drain before the cell gets damaged.

 

[Justin Case]

Post deleted.

 

[m_kluch]

http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries
The shorter the discharge (low DoD), the longer the battery will last. If at all possible, avoid full discharges and charge the battery more often between uses.

That's a good read. Thanks for that.

 

[HKJ]

http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries
The shorter the discharge (low DoD), the longer the battery will last. If at all possible, avoid full discharges and charge the battery more often between uses.

An at lower voltage that discharge is done, the longer the battery will last.

I.e. fully charging the battery between discharges will shorten the batteries life compared to only half charge the battery between discharges.
It is not the low end that is hard on the battery, but the high end and the amount discharged.

 

[dusty99]

Thanks for all the great information!