This is under the best sunlight conditions, the solar panel is rated at 1.8W and the battery pack is 300W. The solar panel reads that it is a "trickle charger". My question is how long it would take such solar panel to recharge a completely empty battery pack.
With 12 hours of sunlight per day, it will take about 14 days.
However, since all rechargeable batteries self-discharge over time, it would take much longer, if it could be done at all. Many batteries give a figure of 1% per day loss, so that would be 3 W per day, or 1 h 40 m per day required just to recover to the level of the previous day. So, if there were only a 1% loss per day, you'd only get a net gain of 10 h 20 m per day. That would take a total of 16 days of 12 hours of sunlight.
If you lost 8% per day, you could never fully charge the battery...
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