Power bank

Decided to get myself one, just in case... this one.

Limited use so far, just testing it out really, but it seems fine. A bit of a dilemma though- as an emergency supply it's clearly best if it's kept fully charged, but we're told that lithium batteries don't like being kept for too long in that state.

So how do people deal with that?

(I should add that at 20 quid I'll probably keep it fully charged and hang the consequences, at that price it's virtually a consumable!)

Get 2 and run each down and recharge in turn.

Charge to 50% or 75% if not planning on using for months. Don't worry if its just for a day or couple of weeks between uses.

In reply to a post by DFScale:

Get 2 and run each down and recharge in turn.

In reply to a post by jchamier:

Charge to 50% or 75% if not planning on using for months. Don't worry if its just for a day or couple of weeks between uses.

Good suggestions both... the second is the "civilised" way to treat Li batteries, but the idea of having two has some advantages... Thanks guys, need to think about it.

I have a power bank I got years ago, never use it, but it is still at 100% so you might not need to charge that often.

I have two, but they are getting on now, a trust onje at 4400mAh and a PNY at 5200, so they say. Both still okay and keeps their charge for a while, even after all these years. The problem is, my phone battery is larger than them, so they would never recharge it fully up.



Not really had any need to use them in an emergency, I use them now and again to charge the phone, just to keep then in good condition

In reply to a post by Banger:

I have a power bank I got years ago, never use it, but it is still at 100%

I'm sure it is, but 100% of what? Li batteries will lose capacity over time, and they'll lose it faster if kept fully charged. The only real way you can measure it is to discharge a fully charged battery at a known current and time how long it takes to go flat (not completely flat, ie zero volts, that would destroy it... about 2.5 - 3 volts per cell seems to be the usual figure).

When new, I could use the camera on my old iPad as a sort of wireless CCTV for quite a few hours, these days it dies after less than 20 minutes... but the charge indicator still says I can charge it to 100%

Edited by billford (Sat 18-Apr-26 10:15:45)

In reply to a post by zyborg47:

Not really had any need to use them in an emergency, I use them now and again to charge the phone, just to keep then in good condition

I don't expect to have to use it in an emergency situation, but things happen... although Sod's Law says they probably won't if you prepare for them .

I'll likely end up doing as you do- keep it at ~75% with occasional use to keep it in trim, and 100% only if I know I'm going to be away from a mains socket for an extended period.

In reply to a post by billford:

but the charge indicator still says I can charge it to 100%

It is just chemistry, batteries are consumables.

Something like an iPad running updatable software should be capable to query it. If you get iMazing (mac or PC, free version works) and plug your iPad into the computer, you can actually read out the stats the battery computer is keeping.

* Capacity when new in mAh
* Capacity now in mAh

A power bank just doesn't have this sort of computation and storage, so what is 100% capacity will degrade.

Typically 500 cycles is where degredation starts in modern quality Li-Ion; and Apple (and others) say that batteries from the iPhone 15 range (2024 ish) are capable of 1000 cycles before any really noticable degredation. Some of the Lenovo, and HP laptops have battery monitor software that can read out similar statistics.

The larger the battery (laptop, iPad) the less noticable the degredation is compared to the small (a phone) battery.

In reply to a post by jchamier:

If you get iMazing (mac or PC, free version works) and plug your iPad into the computer, you can actually read out the stats the battery computer is keeping.

Didn't know about that one, thanks, I'll have a look at it.

Whether it will work with my iPad (Mini 2) is another question- I forget when I bought it, but it won't update beyond IOS 12 (which would be IPadOS, of course).