Re: Note 5 battery was at 5% or less upon first start up
According to an article I read (it was from techrepublic and about battery myths can't post links yet) it says that optimal battery performance is between 40-80%
Close - you shouldn't let it drop to below 40%, but 40%-100% is optimal.
so upon first start up after purchasing my Note 5, battery level should be in that range.
No, that depends on how long the battery cells were stored before you got the phone. Which is why all lithium batteries should be conditioned when you first get them (including the one in the phone). Fully charge (that means the phone says 100%, then you charge for an additional 30 minutes), then use the phone normally until it shuts off (which should be around 10%-20%). Do that 3 times - 3 charges, 3 shutoffs. Then fully charge the battery and don't let it drop below 40% again. (See
The Care and Feeding of Lithium Polymer Batteries.) People will tell you that modern lithium batteries don't needs conditioning - your battery is the reason they do.
If not, my battery is apparently old
No, under ideal conditions (around 76°F and an initial charge of 50%) lithium batteries normally lose about 5% per month. If the temperature is elevated or very cold, that could go up to as much as 25% per month. And 4 months in a warehouse isn't unusual.
My Note 5 was at 5% or under when it was first handed to me at Best Buy Saturday. Should I be concerned?
My only concern is how it acts during its 4th cycle. If you don't get normal life by that time (and I'd leave it on 24/7 until the end of the 4th cycle), have the Samsung rep at Best Buy have the battery replaced. (Or, if you're concerned, bring it in tomorrow.)
It's not a calamity, though. I seem to recall that - due to the fact that lack of a user-replaceable battery is one of the things killing sales on the N5 and S6, Samsung will replace the battery for $40 even after warranty (and yours is within the normal straight swap period - give them the phone and they give you a new one).
I wouldn't even accept a battery they'd set the phone up with when I bought my phones at Best Buy. I told them to give it to me without setting it up, use the charger or use their own battery - mine wasn't going to be used until it was fully charged. The used the charger. (The battery is still okay after 2-1/2 years.)
The factory would not have shipped that phone with 5% charge
Not normally, but mistakes happen (like hitting the power button as you're sealing the case, so the phone is on for a few days, then shuts off at 5%. One deep discharge isn't going to shorten the life of the battery more than the normal difference from one battery to another.) Or it could be a battery with a high-resistance dendrite (which is a defect). There's no way to be sure until it's been through a couple of charge cycles.