Will leaving an almost dead li ion battery overnight reduce its capacity?

Batteries and Chargers Rechargeable Batteries
1

I used two lights for over an hour on high, a sanyo 18650 (2600mAh) and king kong 26650 (4000mAh), reducing their voltages to 3.06V and 3.18V (i forget which was which), but both were pretty much dead even though i was not quite at the the low voltage warnings, i came home and went to sleep, and the next day i proceeded to charge them, i only have one charger, i charged the sanyo which took the expected time (based on another thread of mine where it takes 6 hours at 650mA to charge when its empty), and charged the 26650 for about 3 hrs, then took it off and slept the next night (not wanting to charge it unattended). The next day i put it back on the charger and it was done in an hour.
I don’t have any way to test its capacity, but going by its charge time it could not have got 4000mAh of juice it should take.

Both batteries have about a dozen discharge cycles on them

Thoughts?

2

In the long run, yes, but leaving it uncharged overnight won’t affect its performance or capacity.

3.70-3.75 volts is the optimum storage voltage, but most of my cells are at 4.00V so that I still have some capacity to use them.

3

I’d like a charger where i can select the charge to voltage for storage, but i might burn many hours of light this weekend so i need fully juiced up, and i only have a cheap single battery one led indicator charger
The usage that led to this thread was unplanned, i had 15 mins to prepare for 2 people using 2.8A of XM-L goodness, i found out the strobe is useful for something, racoons don’t like it

4

Then you really won’t like 2600 lumens of random strobe…

5
6

this is your answer to everything, one day someone will ask for the meaning of life and you will reflexively post this charger

7

Been there, done that. It is.

Oh, and it’s actually two chargers in one spiffy little box. If you need to charge at like 70 amps, you can slave the two sides together.

8

must be a dull life then :stuck_out_tongue:

for those who can afford to charge at 70 amps…

9

Buy this without selling your kidney :

10

i’ve been told you can only do 3.8V for storage on this charger, is that still true?

11

At 3 volt, there is no harm. It starts when you leave it like that and voltage further drops and even than its negligible-at least with quality cells. Serious damage only results from reverse charging.
Storing at 4V is bad, especially at summer temps.
The only reason for recommended storage 3,7-3,8 is having some capacity for self discharge.
With higher capacity cells and Panasonics you can store at 3,6 or even lower. It is actually beneficial for the cell.

After all there has been reports of laptop pack several years old with cells at 1,5V still having 100% of their capacity.

12

Yes, it can either charge or discharge so that the cell’s voltage becomes optimal for storage.

13

He’s got two… and no charger… sounds like a good solution to the problem…

14

The Accucell-6 Lion STORAGE function is to 3.8v/cell. It will either charge or discharge to this level depending on the state of the battery. You can DISCHARGE at a max of 1A with that charger.

If you want to fine tune it you can use the NiMh discharge function and specify the TOTAL finishing voltage (for a pack if that’s what you have) exactly.

One of their biggest advantages is being able to determine capacity of the cells as it measures both input and output. Once you have that ability you never want to go back to blinking LED.