# Should new 18650 be charged before first usage?



## ionorbit (Jun 26, 2010)

I have two brand new Panasonic 2400mAh 18650's that measure 4.16 and 4.17 volts. Should they initially be used as-is untill they need recharging, or should I top them off with a charge before their first use? I am trying to maximize battery charge cycle life. Thank you for any recommendations.


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## TooManyGizmos (Jun 27, 2010)

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I'd top them off - but not exceed 4.20v .

~


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## 45/70 (Jun 27, 2010)

As TMG said, you could top them off if you wanted. At 4.16 and 4.17 Volts though, you're Panasonic cells are pretty much at full charge, as is.

Maximizing Li-Ion cell life is more about controlling the depth of discharge and avoiding deep discharge, than anything else. For example, a cell that is charged to 4.20 Volts and discharged to only 3.80 Volts will likely last 3-4 times longer than a cell that is charged to 4.20 Volts and discharged to 3.50 Volts before recharging. Also, charging cells to only 4.10 Volts rather than 4.20 Volts, can extend the number of cycles considerably. 

Topping off Li-Ion cells doesn't really hurt them, provided you use them before too long, and don't store them fully charged. It is best to store cells at around 40% SOC (state of charge) when not in use. Also, keeping unused cells in your fridge at 35-40 F can increase lifespan by a factor of two, or more. Using these practices, I have RCR123 LiCo cells that are 5+ years old and still retain >80% capacity 24 hrs after charging.

Dave


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## TooManyGizmos (Jun 27, 2010)

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All new cells I have received were at about 3.80v

I've never gotten a new cell that read 4.15 to 4.20 right out of the mail-box.

Sellers store them @ shelf voltage of 3.80 to prolong their shelf life . As 45/70 says - it's not good to store them at full charge.

So if they are NEW ..... I'm wondering why they are charged so high already ?

I said top em off cause NEW cells should arrive to you almost depleted and in need of full charge before use.

~


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## ionorbit (Jun 28, 2010)

Thank you TooManyGizmos and 45/70 for the great and thorough info about the new 18650's. I was also suspicious about the almost fully charged batts. I'll need to contact the seller to see if he did a courtesy charge before mailing to me. I got them from LarryDFW on an LED forum site.


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