Review on 🌞 USB+AA Solar Charger by PowerFilm by Marcus Britton

I bought this to always have a good battery in my GPS (uses two AAs) and mobile phone (uses 3.7v 850mah ) for work during the week. Bike tours like GOBA. It turns out it's so small I keep it in my emergency repair kit all the time. I leave the batteries out of the unit as the USB charger draws ½mA with no load. This will drain the batteries in about six months. You should probably do some math before you buy. The product description lacks detailed specifications (why only four stars), so here's what you need to know: The USB charger is rated at 5V with a maximum load of 1 amp. If your application requires more than that, it won't work. The solar charger is rated at 3.6V at 400mA in bright sunlight, which is optimized for charging the batteries supplied with the device. To determine if a USB device is overcharging a battery, look at the battery's current and voltage to calculate Vah (Volts/Amp Hour). For example; my phone battery is 3.7V at 850mAh = 3.145Wh. It takes at least 20% longer to charge the battery due to losses. So in my case I am estimating that it takes 4Wh to charge this battery. The AA batteries supplied with the device have a nominal voltage of 2.5 V (per pair) at 2000 mAh = 5 Wh. That turns out to be almost correct, because the AA batteries still have enough power after the battery of my mobile phone has been fully charged to power the GPS for about two hours. sunbeam. Charge the USB rechargeable battery with fully charged AA batteries and expose the solar panel to sunlight.