Battery stored at 0% -danger?

[dms25]

Hi vapers,

I just been traveling for 2 months and stored an 18650 at 50% not realizing how quick they discharge. When I put it in my Nightcore charger it read 0% and stayed that way for 5-10 minutes before charging to full.

My question is is it dangerous to still use this battery? I heard a sleeping battery can be dangerous once revived...

 

[sonicbomb]

A general rule of thumb with 18650s is if they dip below 2.5 volts then they may be damaged. My nitecore displays volts remaining not percentage, it's possible the 0% represents the minimum voltage (2.5 volts possibly). You could have changed it so it displays voltage or put the cell on a DVM to measure it before recharging so you knew what the value was. See if you can look up what 0% represents on the nitecore.
A cell shouldn't discharge itself, if it did then there may be a fault with it. I don't know, you need to do some testing and see if the cell still performs ok.

 

[dms25]

Thanks, I have a basic Nitecore UM10, I don't think it has that option. As for the battery I thought it was at 50% when I left it but I could be wrong, may have been much lower. It was stored in a Cloupor Mini+, which was off but may have somehow drained it...

 

[Baditude]

Some smart chargers have the ability to "awaken" an over-discharged battery.

Since your over-discharged battery did charge to full, it's probably ok to use. I'd keep an eye on it over the next couple of weeks to observe its health by measuring its voltage when fully discharged and after charging. If the readings are out of the ordinary, I'd consider disposing of it.

"Some Li-ion chargers include a wake-up feature, or “boost,” to allow recharging if a Li-ion battery has fallen asleep due to over-discharge. A sleep condition can occur when storing the battery in a discharged state and the self-discharge brings the voltage to the cut-off point. An over-discharge situation can also occur in a mechanical mod. A regular charger treats such a battery as unserviceable and the battery will need to be discarded. Boost applies a small charge current to raise the voltage to between 2.20 and 2.90V/cell and activate the protection circuit, at which point a normal charge commences. Caution applies if Li-ion has dwelled below 1.5V/cell for a week or longer."

Guide to Choosing a Li-ion Battery Charger