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Off-the-Grid Blog Solar Powered Tropical Beverage Cooling Mug -Blog #3 - the solar charging system
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  • Author Author: robogary
  • Date Created: 16 Jun 2023 7:28 PM Date Created
  • Views 1674 views
  • Likes 8 likes
  • Comments 6 comments
  • Wrongco
  • robogary
  • offthegridch
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Solar Powered Tropical Beverage Cooling Mug -Blog #3 - the solar charging system

robogary
robogary
16 Jun 2023

Welcome to the fabulous Solar Powered Tropical Beverage Cooling Mug blog

The 2 previous blog episodes:

Solar Powered Tropical Beverage Cooling Mug - blog #2 - the solar panel characterization

Solar Powered Tropical Beverage Cooling Mug -Blog #1 - the concept

 image

Blog 3 ties the solar panel to the battery pack, where the measurements taken are to validate the design.

  • The batteries are THUNDERBOLT MAGNUM, AA NimH rechargables, Battery capacity 2200 mAh
  • Qty 5 Fully charged changed NimH  batteries in series, at about 1.3v a piece =6.5V, tho I measured just a bit higher 6.8V.
  • I was sure the buck power supply was set for 12V = 6.2V out.  
  • Note the buck PS and battery pack are separated by an RGP30J 0614 600V 3A (125A surge) diode.

image

The solar panel was first covered with paper for shade. Solar Panel volts = .7 , the milli ammeter in series with the output measured 0.

Removing the cover on the solar cell in full sun at noon, the solar panel read 8.6V , 58 mA , battery volts 7.2, buck power supply 7.8V.

The buck PS was adjusted for 6.8V , the mA = 0 , and solar panel output volts = 13.3 .

The buck P.S. was tweaked for 4mA current , barely trickle charging, the solar panel out = 13.1V , Buck P.S. out = 7.2V batteries 6.74.

The buck P.S. was readjusted for max charging mA in full sun with fully charged batteries. The absolute peak mA in those conditions = 56mA. The batteries had 7.1V , the converter out was 7.74V, the panel output volts were 8.5V  

 After these readings were taken, the buck P.S. was adjusted down again for 6.7V out showing 2 mA charging current.  

Conclusion:

The solar charger will work, but the Volts-load curve didnt match up with the previous table measured with a resistive load.

Maybe it needs viewed with a scope, and more experiments done with battery charge levels varied.  

solar panel covered

image

solar panel full sun

  image

trying to read the converter circuit series mA in the bright full sun, without blocking the solar panel

image

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Top Comments

  • robogary
    robogary over 2 years ago +1
    Duuude - you probably needed a sip of the tropical beverage in that mug to record better readings
  • DAB
    DAB over 2 years ago +1
    Interesting project, but I hope you realize that with the poor efficiency of solar cells, you could get a much better mug heater if you just used a lens to concentrate the sunlight directly.
  • robogary
    robogary over 2 years ago in reply to DAB +1
    The mug is a refrigerator :-) Your point is well taken and just hold your breath for blog #5 (or maybe #6) where I reveal all the engineering calculations. They are hilarious.
  • robogary
    robogary over 2 years ago in reply to anniel747

    They are all NimH batteries. One was a different supplier , ok for a short test. 

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  • anniel747
    anniel747 over 2 years ago

    Mix N' Match batteries?

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  • sandeepdwivedi17
    sandeepdwivedi17 over 2 years ago

    Cool Project

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  • robogary
    robogary over 2 years ago in reply to DAB

    The mug is a refrigerator :-)  Your point is well taken and just hold your breath for blog #5 (or maybe #6) where I reveal all the engineering calculations. They are hilarious. 

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  • DAB
    DAB over 2 years ago

    Interesting project, but I hope you realize that with the poor efficiency of solar cells, you could get a much better mug heater if you just used a lens to concentrate the sunlight directly.

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