How to continuously charge 18650s, as in solar?



  • I have 18650s, and I have both new & old TP4056 boards. What has stopped me from proceeding is reading that 18650s don't "trickle charge". I take this to mean that you can't keep them up to voltage, topping them off. My goal is to put sensors outside, and leave them.

    Not wanting to be in the local news, I've held off making a sensor with them that will allow me to keep them topped off.

    How are you using rechargeable LiPos with renewable energy charging?

    One example of data:


    Simple Guidelines for Charging Lithium-based Batteries

    -Turn off the device or disconnect the load on charge to allow the current to drop unhindered during saturation. A parasitic load confuses the charger.
    -Charge at a moderate temperature. Do not charge at freezing temperature. (See BU-410: Charging at High and Low Temperatures)
    -Lithium-ion does not need to be fully charged; a partial charge is better.
    -Not all chargers apply a full topping charge and the battery may not be fully charged when the “ready” signal appears; a 100 percent charge on a fuel gauge may be a lie.
    -Discontinue using charger and/or battery if the battery gets excessively warm.
    -Apply some charge to an empty battery before storing (40–50 percent SoC is ideal). (See BU-702: How to Store Batteries.)*


    source: BU-409: Charging Lithium-ion

    TIA!

    pat
    🙂

    P.S. Just clicked the 'emoji' icon in the WYSIWYG, and am shocked to find that people have copyrighted emojis. To quote #45: #sad


  • Mod

    That is why we have an open discussion on using supercaps for solar powered nodes as the lithium batteries do indeed store a lot of energy but they suffer from cold and hot so the outdoor conditions are not ideal for them.



  • @gohan That's great! I have a pile of super/ultra-caps just waiting to power a remote node!

    I've hesitated to date because the ones I've found are all cobbled together, and the presenter says nothing about whether their arrangement has lasted. I get the feeling they video as soon as they build it, but there is no data on what to expect.

    There is an exception, though, in a video I saw that went all the way into looking up the hours of daylight for an area, etc. by Andreas Spiess here. Well, the video is at the top of a reddit forum topic...

    I'd love to hear what components those deploying isolated sensors are using.


  • Mod

    If you look in openhardware there is a board that has a charge balancing controller and a voltage regulator for the output.



  • Have been using this for more than a year, without problems
    http://s.aliexpress.com/iAJRFfY3

    I was using a plain 5V solar cell at first, but later I used a rainproof solar LED light as a housing, after removing everything except the solar cell.
    http://s.aliexpress.com/MR7RjYb2

    The node has an NRF24L01 PA version (with the antenna), and communicates with the GW 6 stories below, sending the solar water heater temperature every minute.


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