A big enough powerbank

[papaof2]

Yes, this powerbank is big enough to charge ALL of your USB chargeable devices ;-)

From the specs: "almost charges the iPhone 12 Pro Max 4 times, the Galaxy S10 for 5.3 times or the Note 10 for 4.5 times or a tablet 2+ times"

So it can handle your GPS for several hundred miles or your USB fan overnight.

www.newegg.com/ace-cards-poker-rubberized-red-black-ravpower-rp-pb41-26800-mah-26800mah/p/39G-001N-000G1?Item=9SIAP08EWW1855

26800maH powerbank, 3 USB outputs (5.5 amps combined output)

$22.99 and free shipping until 13 June 22.

I have one on the way so I'll know more next week.

[papaof2]

The powerbank has 3 outputs: 5 volts at 2.4 amps, 5 volts at 2.1 amps, 5 volts at 1 amp.
The RavPower RP-PB41 is older technology as it charges via a micro-USB connector at a maximum rate of 2.1 amps. Since this is for when-needed backup, the long charging time (12+ hours from fully discharged) isn't a concern.

I think I mentioned the battery-powered fan/light I got from Amazon to have a convenient source of light and limited cooling for short summer power outages. That unit will run on the lowest settings with a charger connected - including the 26.8AH RavPower powerbank. That ups the time for the fan and light to both be on from 14 hours to about 48 hours. I can charge both from the backup power system or I can use the solar panel with a 5 volt, 2 amp USB output. I think that combination was a good investment - even more so with all the "weather related" outages the past few days ;-)

[papaof2]

I started some capacity tests on the powerbank (using a one amp load) and found that the USB power meters I have only go to 9999mAh :-(

I tried doing it in segments, checking ever few hours, noting the power at that point and resetting the power meters. The idea is fine but the execution is difficult - I'm not likely to stay awake enough continuous hours to reset the power meters before they overflow. I had notes up to 19,500mAh but then I dozed off on the sofa and when I woke the powerbank had shut off. As the power meters lose their minds when power is removed, I had no long term data. I can say that the powerbank will provide at least 19,500mAh at 1 amp. I need to find my USB patch cords so I can connect the powerbank to one of the battery discharge meters (line-powered meter) and have the actual mAh when the powerbank shuts down. Maybe next week...

[papaof2]

Some time ago, I posted a link to the RavPower RP-PB41 26800 maH powerbank that was on clearance in June of 2022. That post is here: pawfiction.proboards.com/thread/1828/big-powerbank

The powerbank has outputs rated at 1 amp, 2.1 amps and 2.4 amps. Those have been tested with an adjustable USB load and they all deliver the rated current.

I've recently done some more testing to see how much of the advertised capacity can be extracted from the powerbank. Remember that the powerbank uses lithium-ion cells (3.7 volts nominal) to store the power and a boost converter to produce 5 volts output (actually 5.06 volts) from that 3.7 volt battery so the 26800 maH battery will NOT deliver 26800 maH at 5 volts. The expected maH would be ( 3.7 / 5 ) * 26800 or 19832 maH at 5 volts. There is also some loss in the DC-DC up-conversion process so the actual delivered maH will be something less than 19832 maH.

The 1 amp output was tested at 0.5 amp, the 2.1 amp output at 1 amp and the 2.4 amp output at 2 amps. The power measuring device was set to discharge the RavPower until the USB output dropped below 4.7 volts (the typical USB lower limit is 4.75 volts, so this is a reasonable test voltage).

The 0.5 amp test delivered 17870 maH or 17870 / 19832 = 0.901 or 90.1% efficient. (17.87 AH)
The 1 amp test delivered 17510 maH or 17510 / 19832 = 0.882 or 88.2% efficient. (17.51 AH)
The 2 amp test delivered 16500 maH or 16500 / 19832 = 0.831 or 83.1% efficient. (16.50 AH)

Those are good total power figures for a $22.99 delivered powerbank. My needs are for high total capacity, not higher charging currents so the RavPower RP-PB41 works fine for me. If you want higher USB currents, USB-C connectors or faster charging of the powerbank, you'll have to buy something newer and more expensive ;-)

Charging is slow. With a 2 amp wallwart, the powerbank loafs along at 1.1 amps input, needing 20 hours to recharge the 22237maH used from the battery bank. 17510 / 22237 = 0.787 or 78.7% efficient for the charge process.

Remember that the powerbank probably has an overdischarge protection device which will prevent using the last bits of power from the battery bank. The amount of recharge (22237 maH) divided by the battery bank's capacity (26800 maH) = 0.829 so only 82.9% of the battery bank's power is available. That ensures that the powerbank can be charged and discharged several hundred times. Trying to squeeze every electron out of a lithium-ion battery will cause a rapid decrease in its capacity and its ability to hold a charge.

The powerbank lives in the "In the dark" box that's behind a chair in the family room. That box contains multiple powerbanks of various sizes (most with some level of built-in lighting) plus USB plug-in lights of several sizes so most of the portable lighting is in that box, along with charger/testers for NiCad/NiMH and 18650 lithium-ion batteries. The chargers run on an AC wall wart or 12 volts DC so we always have a way to charge and test those batteries. If we're watching TV when the power goes out, the TV is on a pure sine wave UPS that's good for 45 minutes or so and the TV has a USB-powered LED strip taped to its back so the wall behind the TV isn't dark and the room isn't totally dark when power goes out.