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Solar charging Li-Ion battery pack

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  • Solar charging Li-Ion battery pack

    Hello all,

    First off: let me apologise for my ignorance, this is all new to me..

    Recently I bought a set of a 10W solar panel with a 12V 6800MaH battery pack on Ebay advertised as being 'all you need' for a simple solar set up.

    The battery pack is protected with an over charge controller and over discharge protection.

    The pack charged nicely with the charger it came with, but did very little charging while connected to the solar panel.
    I contacted the supplier who kindly is sending me a new solar panel under the assumption that this is the fault. Even though I was measuring voltages up to 17V coming from the panel. I haven't received the new panel yet, so I cannot tell you if the first panel is different or not.

    Personally I though that a solar charge controller would be better as this would level out the charging voltage to the battery. So I went ahead and bought a PWM charge controller. However when I opened the package and read the manual I saw that the charger was described as not being suitable for Li-Ion batteries. Which got me wondering...

    After doing a bit of reading online I found a lot of pages that said that you cannot float charge a Li-Ion battery, some tell of dire consequences like exploding batteries and toxic fumes.. Obviously we want to avoid this! We want to use this solar panel battery pack set up during a camping/road trip and will be mostly charging the battery during driving. The last thing we want of course is the battery catching fire or exploding while driving or even worse while the car is parked up somewhere while we are on a long hike only to come back to a torched down car

    So: to make a long story a bit longer: What is your take on this?
    As far as I can see Li-Ion batteries only explode when overcharged, so would the over-charge controller in the battery pack prevent this from happening?
    Also what would be better charging the batteries directly from the solar panel or through the charge controller?
    And finally, as I am getting a second 10W solar panel: would it be harmful to connect these panels in parallel and connect this to the charge controller or the battery?

    Thanks a lot!

  • #2
    If you are worried about fire then get a Safety Bag like ...

    How long did you leave the Solar Panel in [B][I]FULL Direct Sunlight[/I][/B] ?
    I am thinking you need about 8-9-10 hours of [I][B]Full Direct Sunlight[/B][/I] to fully recharge a fully drained battery.

    Where & how are you mounting a 10 Watt Solar Panel in your car, while driving?

    You should not use the PWM Charger your the Lithium Ion battery pack.
    Last edited by NEOH; 09-14-2017, 09:39 AM.


    • #3
      If you are driving a car, and want to charge a tiny 6.8Ah battery pack, an hour of power from a cigarette lighter outlet would do it, Ask the seller for a car power adapter.
      And yes, when the battery is full, you STOP charging Li batteries
      You could even charge it while you are parked overnight, your car 80Ah battery will hardly notice it. Almost like leaving the door open (and dome light on for half hour).
      Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
      || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
      || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A



      • #4
        Thanks for the feedback.

        The solar panel fits nicely on the back window of the car, wouldn't be in the way at all. I wouldn't be too worried about the charging time. The only thing we use the batteries for is to light some 12V LEDs and maybe charge an old type nokia phone, so the battery will hardly be empty. I was thinking of just topping it up every day, a couple of hours daylight in the south-east of France should do.

        Can you explain to me why I shouldn't use the PWM charge controller, Neoh?

        And thanks for the tip of charging the batteries with the cigarette outlet, Mike. There is actually a cigarette outlet adapter with the battery pack. However I would like to work with the solar, just to see if it works. But if/when it comes to it we can always use this option.