Man its been a bit since I blogged. But back into the breach! A week ago while on my way to hang out with some friends I bought a Hottips Solar charger from 7-11. I know I know I probably paid way too much, 19.99, compaired to whatever they’re selling them for on ebay. But I impulse bought a motorcycle once so there!
Since its some random convenient store brand from a far away country finding information about it was rather hard. But I did manage to figure out from an ebay posting the rating on the solar panel. Looks to be it is a 5v panel that produces 100ma of current. If that’s true then it should charge the 1200mah battery in 12 hours of “optimal” sun. Thats of course assuming 100 efficiency so in reality I would expect a little longer. Since lithium ion batterys have a max terminal voltage of 4.2 volts and a minimum of 3.2 when its dead it must have some sort of step up circuit to bump that to the 5v it outputs. That would eat some current. This was evident when I tried to charge my phone with it from a dead state on the phone. It took it to a 68% charge. since my phones battery is 1150mah and the solar charger has a 1200 mah capacity theres definately some losses. Charging battery’s is usually around 80% efficent your mileage will of course vary given types and brands. I do suspect if you charge a phone while the charger is setting in the sun the panel will assist which might make up for the shortfall. Definately something I need to test.
The power supply on the panel seems to maintain a high enough voltage to charge the battery even when its indoors in ambient light. This would mean that the you would be getting alot less than 100ma but so long as the voltage is higher than what the battery is currently outputing it will charge. I had this at work in the light and after it sat for 8 hours I got 20% charge out of it. It also has an integrated led flashlight which uses tiny amounts of power because even when the thing is near dead it will still power it. The charger has a green light that will illuminate when its charging and shut off when it done. Though in the light its always on. Probably to provide a trickle charge to the battery.
The solar charger came with a few removable ends you can of course buy more. One for the Iphone, one with mini usb and a normal A usb connector for charging the device from a pc. It also came with a wall charger but the rating on its only 500ma so i’ve been using my tmobile charger which outputs 1000ma to charge it quicker for testing. I am a bit dissapointed it takes so long to charge with just the sun, but if you leave it in a car while your at work with would be perfect for an emergancy charge and it doubles as a flashlight. It would also be perfect for camping as you can just attach it to a back pack with velcro and probably get a decent charge after a hike. Its very light and tiny which keeps your options open. Also since it uses mini usb which is supposed to be the new charging standard for alot of devices it will pretty much work with anything. All in all its not bad. Especially if you have a non smart phone with a tiny battery.