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18650 battery charged with solar panel
#21
(08-25-2020, 08:37 AM)Hrvatin Wrote: Could i connect all that using lets say 30 of these mini panels?

https://www.seeedstudio.com/2W-Solar-Pan...edium=blog

You could, yeah. But the efficiency will be low, you'll need more square inches/mm to get the same output, and you'll spend more in the end. Also you'd probably need a blocking diode for each panel, which lowers it's output and increases costs/complexity

(08-25-2020, 08:37 AM)Hrvatin Wrote: Ok, managed to find some more ifno regarding hot spot. It says next
Power consumption : <3.5w
Charger : AC 100-240V, DC 5V 1A
And it comes with 1500mah battery, claiming it lasts up to 6 hours

Sorry for so many questions that make you no sense, my knowledge about electricity is close to none. If yoi have some internet service questions i will gladly help ?

Ok, so the based on the calculations that were mentioned earlier, you'd only need "half" of what we estimated as I was going off 2A.

Ask questions, that's how we learn Wink
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#22
Not sure why you would put a hotspot + USB charger outlet in/on a chair, but up to you....
The 3.5W power draw is assumed to be 24hours/day = 84whrs
It would be better if it was switched off when not being used, eg over night/when you are sleeping, etc.
You have to be able to get the 84Whrs (+ some losses) into the batteries from direct sunlight during sun-up hours.
If the panels are on the chair & you sit on the solar panels, obviously that would block sunlight... & reduce the collection hours.
Say you have 6 good hours of sun & don't cover/shade/sit-on the panels, you would need to get 84whrs in 6 hours.
So that's 84Whr/6hr = 14W of solar panels at their NOCT output (approx 80% of the advertised W).
So to get the 84Whr/day you would likely need about 20W of solar panels allowing for some losses.

If you used the USB charger outlet that would be extra w's to consider like above.
Say 2 hours of 5V @2A = 2x 5V x 2A = 20Whrs.
Now you need 84 + 20 = 104Whrs/day.....

The Solar panel output would need to be efficiently matched to the cells via an MPPT charger (or have more solar panels & accept more losses).
Note the solar panels would need full direct sunlight, not indoor lights or behind curtains, etc.

You would need to use a proper charge controller for the batteries so you don't fry the batteries &/or cause a fire.
Running off solar, DIY & electronics fan :-)
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#23
If you look at reviews of hotspots, e.g. this recent Wirecutter review, you'll see that they get between 13-20 hours with 4000-5000 mAh batteries. That scales to between 4 - 7.5 hours at 1500 mAh (and the quoted 6h is in the middle, so consistent). So that seems to be a good estimate to use. Keep in mind that it may vary greatly depending on how active the radio(s) are.
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#24
To be honest i was a bit surprised when i read it can hold on for 6 hiurs with 1500mah.it is after all 4G router that is online constantly + wifi on

If i understood corectly, i could pull this all out with 50wat panel? Or with those mini panels i posted earlier
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#25
The linked Wirecutter reviews tests via "a laptop tethered to it and playing NASA TV’s YouTube stream continuously". Without knowing your actual usage conditions we can't do much better than such ballpark estimates. If you already have the hotspot then you can simply measure how much power it uses during your typical usage scenarios, which can then be used for much more precise runtime estimates.
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#26
https://m.alibaba.com/amp/product/62315199085.html

This is the only narrow enough thing i found online instead bunch of smaller pannels that woukd perhaps work for me. Of course im heavily sceptical since its from alibaba. Figured since its almist 30 centineters long i would reduce the loss of power with lets say 15 these instead 30 small ones from earlier reply
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#27
(08-25-2020, 02:36 PM)Redpacket Wrote: The 3.5W power draw is assumed to be 24hours/day = 84whrs
It would be better if it was switched off when not being used, eg over night/when you are sleeping, etc.

Could make it so that when you sit down on the chair, the hotspot is powered on, then a timer of like an hour before it shuts off if not in the seat.

But agreed, definitely need to have some kind of toggle switch to power down while not in use. No sense in wasting power. After all, if it's going to be charged by solar, you want to keep those cells as full as possible as long as possible in case of days of overcast.



Curious, and I'm sure others are too, just why are you trying to put this in a chair??? Why not just have it on the house or such? Is this out in some kind of field far away from a house or something??
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#28
Yes, this is far from house in open field. That is my problem,good idea with this turn of/on sensor! I found some company called MrWatt that builds custom soze panels so i am waiting for their response for now

Can i buy solar cells and put them together?
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#29
You can build solar panels from solar cells. but in the end, they aren't worth it and there's a learning curve to construction. They are very brittle and easily broken. I would recommend buy premade panels
Proceed with caution. Knowledge is Power! Literally! Cool 
Knowledge is Power; Absolute Knowledge is Absolutely Shocking!
Certified 18650 Cell Reclamation Technician

Please come join in general chit-chat and randomness at Discord Chat (channels: general, 3d-printing, linux&coding, 18650, humor, ...)
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#30
Your whole build incl solar panels, electronics + batteries would have to be waterproof if outdoors....
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Running off solar, DIY & electronics fan :-)
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