Can a new battery go bad if unused
My old 2008 macbook's power adapter died recently and since I was not sure if the problem was it or the battery, I ordered a new generic battery as well just to speed things up.
After I received my new adapter, I discovered that it was the problem so I continued to use the old original aging but working battery.
My question is, can I leave the new Lithium-Ion generic battery I bought in its sealed packaging until I need it? Will it degrade if left unused or should I swap them once a week to keep the new one alive...?
56 Answers
Li-ions self-discharge, although very slowly. If you leave it for a very long time (probably many months) it could discharge so far that its "electronic fuse" will open. Once that happens, it's a paperweight.
It probably came to you with a charge in the 40 to 60% range, as that is supposedly the most stable for storage.
If you're not going to use it, I would check it every month or so. If it's dropped below about 20%, then charge it to bring it back up to 60% or so before storing it again.
If it were me, I'd switch to the new one and keep the old as a "just in case" spare. The new one should give you better runtime.
6In my opinion - you should swap these batteries once in a month and discharge battery to 40-60% before storage.
Lithium Ion batteries "go bad" when they are stored in discharged state.
It is all about battery voltage. If voltage is too low - undesireable chemical reactions will happen and battery will degrade.
If battery is not empty and not used for long time - it will be fine. However batteries are not perfect and they slowly discharge without load. If you leave full battery for few months - it may self-discharge and when voltage drop to "almost empty voltage" - it will start degrading and loosing capacity.
If it is stored near empty state - it will degrade and loose capacity.
More about battery storage (including Li-Ion):
BU-702: How to Store Batteries (at batteryuniversity.com)
(added later: batteryuniversity.com is a website created by some company, do not consider this as 100% reliable source of scientific informations)
There are many opinions about "ideal" charge for battery storage. Some people say 40% is the best, some people say 60%. In article linked above:
3Lithium-ion must be stored in a charged state, ideally 40 percent. This assures that the battery will not drop below 2.50V/cell with self-discharge and fall asleep.
I would cycle them. Li-Ion batteries have a shelf-life, which can be extended by keeping them at 40% charge, but they will decay no matter what. Using the batteries gets the most work out of them before they finally die.
I don't know the answer to this in general; however, here’s a relevant incident:
Last year (2016) I found myself using a very old Tablet PC (circa 2004) and decided to buy a secondary battery for it to maybe nudge its cord-free time up past the 2 hour mark. The secondary battery was one of those which slots into a modular CD/DVD bay, (remember those?).
I found it on eBay for $20 and while unboxing the obviously time-neglected unit, I thought, "Well, here goes nothin!"
I was happily surprised to discover that it was in fine working order and could hold a solid charge!
That thing had been on a shelf somewhere, untouched for around 12 years, and it effectively doubled the battery life of my old machine.
I don't know what that means for your question, but it's another data point to pin to the board, anyway.
1I think you're probably better off using both. But most importantly don't leave a battery without use for more than a week on either a full charge or an empty charge. 70% is best.
Also best way to keep a battery long is to rarely do a full cycle (down to 0%) but use the battery on a daily basis.
I use LIFE batteries in my RC aircraft. Most of these aircraft have been in storage for up to 2 years with a "Storage Charge" showing 6.4 volts (2S). When I check them now they are still at 6.4 volts showing no degradation. All twelve of my models use these batteries and they are all holding perfectly without any degradation. After using NiCd and NiMh for 40 years and becoming used to their constant maint needs, these batteries are quite amazing IMHO.
