Do solar power banks really work, part 2: Are 4 panels really better than 1?

Portable power banks are great, they let us take extra power with us wherever we go.

Solar power banks give us the additional benefit of charging our power banks wherever we go.

But not all solar power banks are created equal.

Do extra solar panels actually give you extra charging power?

Watch and learn friends.

Link to original, “Do solar power banks really work?” video:

Link to 4 Panel Power Bank on Amazon:
Tranmix Hi-2025:

The link for the 1 panel AMZLAB ES928 power bank on Amazon no longer functions.

First movie clip was from “Bill and Ted’s Bogus Journey”
Second movie clip was from “21 Jump Street”
Background music was “Operatic 3” by Vibe Mountain

Check us out on the social media at
Twitter: @randotechinfo
Instagram: randotechinfo



  1. Excellent review ๐Ÿ‘ ๐Ÿ‘Œ . I did a testing of the both and my result found that the 4 panel took 4 days to be fully charged and the 1 panel took 7 days . This was because am in a country which is very sunny . Jamaica ๐Ÿ‡ฏ๐Ÿ‡ฒ ๐Ÿ‡ฏ๐Ÿ‡ฒ ๐Ÿ‡ฏ๐Ÿ‡ฒ โค

  2. Thank You for All that you are doing for World Peace and for our Planet…
    Peace.. Shalom.. Salam.. La Paz.. Namaste ..
    ๐Ÿ™๐Ÿป ๐Ÿ˜Š ๐ŸŒˆ โœŒ โ˜ฎ๏ธ โค๏ธ ๐Ÿ’ ๐Ÿ•Š

  3. the black image with the text… it is just THE BEST. Efficient and critic with nowadays ballooney ๐Ÿ˜€

  4. i got my wife one of these and with your video I am able to see how much roughly she charge her phone, her city got hit by a super typhoon and all the power is out so its hard to reach her, this was helpful

  5. My solution on Kilimanjaro (and what I'm recommending to those going with me in February) –> 21W foldable solar panel (clipped on backpack) + 2 10K mAh power banks (the panel charges both at the same time).

    Worked well for me early this year for my first summit. ๐Ÿ™‚

  6. Great video. If you angle the solar panels towards the sun throughout the day, laying flat only when the sun is over head you will get far greater efficiency. ; )

  7. Iโ€™m really surprised your videos donโ€™t have more views. Your content is quality and gets to the point. I wish you the best in your YouTube career!

  8. Would you realistically charge the solar Bank solely via the Sun. I think not, it's a huge gimmick. These products suck gullible people in to buying them. Realistically their solar charging power input is tiny and minimal, and not viable for power-out emergency situations. As many people are pointing out, you're much better in getting a simpler and better power bank and adding a larger separate solar panel when needed, at least >15 watts.

  9. BUT , how long does it take to charge a phone let's say the latest Android or IPhone to its complete capacity (100%)? How long will the solar panels charge for? Would I get just 1 or 2 charges per phone after I charge the panels for 6 / 12 days ?

  10. 6 days to charge the whole thing, but how long to charge a phone? The real question for me is would it be at all useful while hiking around, when there are lots of variables (tree cover, angle of sunlight, weather, etc.)

  11. As someone who didn't especially pay attention during the electricity parts of physics class (i.e. I'm sure there's someone who can explain it better, more eloquently, and/or with actual mathematical proof): here's my two cents;

    These powerbanks are pretty much always lithium-ion batteries, which are pretty finicky and thus require electronics to regulate the charging. It's safe to assume that because of this, these batteries have a limit to how fast they can charge.
    Now you tested both on sunny days only, so basically as close to 100% efficiency as one is reasonably expected to get through regular use.
    We can therefor (with a bunch of caveats) assume that you only need a 3W panel to charge a powerbank at full speed. Hence the 4 panels with 6W charged only twice as fast as the single 1.5W panel bank.

    But that does mean that if it's overcast and the panels work at only 50%, then the charging time for the 4-panel bank would've remained the same whereas the single panel bank would've doubled to 24 days.

    Now a smart person would probably be able to tell me where and how my assumptions are slightly off, but I'd like to think that the general idea itself 1) there's only so much energy per unit of time that can be jammed into the powerbank and 2) the total production of the solar panels exceed that, so that you can meet that max even at less sunny days, still holds.

  12. Great video! Thanks for putting this review together, you've helped me decide which powerbank to purchase. Can I ask where you got the tiered chess board? That is awesome!

  13. Surprisingly I implicity trust a reviewer who cant edit their own videos well. I trust their raw honesty.

    I have been trying to get inputs on this issue and yours are the clearest and most practical. Thank you๐Ÿ‘

  14. People are just confuse about solar power banks….. Don't think if you go for camping you going to charge your phone every day with this devices. The answer in no possible. The solar panels os those devices work VERY VERY VERY slow.I had one with a one solar panel on top 1 full day on the sun, never charged the battery. You better go for a good power bank, without solar.

  15. Thanks for the info, this was exactly what I was trying to figure out when I started my YouTube search today

  16. Great video. I bought the same Tranmix solar charger on Amazon for $33, and it was on limited time deal.

    I tested it out at home before our wilderness adventure and it was able to keep my heavily used iphone charged for a week without having to plug in the charger. Once on the trail, I was only able to set out the solar flaps for a couple hours, late in the day at most and it still kept both of our iphones charged.

Leave a comment

Your email address will not be published.