Picked up a 26800 mAh powerbank pointed out in the Amazon Deals thread. At something like $14 it was a no brainer. Of course, now with COVID etc I just don’t go anywhere so really have no need for such a thing. Its cheap enough that I am probably just going to keep it fully charged so that if I need it I will have as much as possible available. OTOH, for my needs, 1/2 to 2/3 would be very likely to cover whatever I need so therefore I should probably store it that way and then if I do decide to travel I can just fully charge it before I go.
How much difference would either approach amount to? I know that the batteries last longer if stored at a lower state of charge. If I really wanted to max the life and performance I would just use it 20 - 80%. However, my needs aren’t that great and I can’t imagine it not lasting at least 5 years no matter how much I abused it. (I do not expect to expose it to extreme temps.)
If you want to maximize storage life of a lithium ion battery, the difference between full and half charged should be double or more the calendar shelf life.
However, as you said, 5 years is a reasonable life expectancy for a lithium ion battery stored at full charge, at room temperature.
I kind of suspect when all these discounted products with Lithium cells inside are not current items —- I have several PB that I’ve left fully charged — they’ve held up pretty good , about 80-90% capacity still —I’ll cycle them a couple times a year just for the hell of it — The 26800 you speak of for $13, if you get a couple of years out of it — Good — I’ve bought some Efest cells that I barely got that out of — They’re garbage
If you are gonna store the unit with semi charged batteries with the hope of getting a bit more life out of it, you run the risk that you won’t have the a working tool when you need it.
After fooling around with PB for several years —- I’m just figuring out some of them have low power modes that let you charge devices to zero amp draw —until now I would use a single cell PB to charge my Fitbit —- It was the only one that would charge it to 100%
I’ve made a few of my own DC only UPS systems. All you really need is a small 12 volt battery, a 12 volt DC regulator, and a battery charger. Plug the battery into the charger, attach the 12 volt regulator to the battery, and attach your loads to the regulator. Depending on the charger and regulator, you may need to add a diode or two as well. My modem, router, and security cameras all run on 12v DC. You can buy all the parts you need for under $20 + whatever battery you need.
That’s correct, except for the fact that 12v on a lead acid battery is about 50% soc (although that is the bottom of the “useable” range of most lead cells). That’s why you use a battery charger. The regulator stabilizes it to 12 volts out of the system, the charger runs 13.75v in for a float voltage, no need to sit a SLA battery at 14.4v.