How To: Solar Charge a Mobile Phone
Click on the image to the left or visit our solar powered mobile phone charger section.
Charging your mobile phone ...
with solar power works in one of two ways:
A solar panel charges a rechargeable battery, that in turn charges your mobile. This means you can charge your phone even when there is no sunlight - at night for example - so long as you’ve charged your battery during the day. The battery can be an internal Lithium-ion (eg. the Suntrica or the Ipower) or removable AA NiCads or NiMHs (eg. the Powerfilm USB charger or the Violetta).
With this type of arrangement, the capacity (mAh) of the battery will determine the number of times you can recharge your phone before you need to use the solar panel again.
Internal Li-ion batteries are an excellent lightweight, high capacity option, but it may be useful to have removable AA/AAA batteries if you can use these for other devices.
The power (W) of the solar panel will determine how quickly the internal battery is charged. The speed at which your phone is charged from the batteries will not change.
Beware, many chargers do not have a blocking diode to stop power draining back from the phone into the (empty) battery. You should always monitor charging and disconnect your phone from an empty battery.
Some solar chargers with integrated batteries come with a set of connectors to fit directly into your phone. The Freeloader and the iPower come with a range of connectors for phones and other mobile devices. However, as mobile phone manufacturers regularly change the types of connector used, there may be compatibility issues, especially with newer models. The phone manufacturers are starting to standardise around a mini USB port which should help to reduce these problems.The Violetta and the Powerfilm chargers come with USB ports, so you'll need a USB to mini USB or USB to your phone connection to use them.
You can also recharge your phone directly from a solar panel, usually via a 12V cigarette lighter plug adapter socket, much the same arrangement as you have in a car. Folding and rollable solar panels such as the MMP, Sunlinq and Powerfilm panels are supplied with a cigarette lighter socket attachment into which you plug your in-car charger (12V cigarette lighter plug). You will need to purchase this separately for your particular make of phone, but they are available from any good travel store, phone or electronic shop. The 12V cigarette lighter socket gives you great flexibility, but there are still issues to be aware of.
Phones can only accept charge up to a maximum rate of around 0.5A@5V. This means that over around 2.5W a larger panel will not charge your phone faster in bright sunlight. However, in poor light conditions a larger panel will continue to generate sufficient power when a less powerful panel will not.
Some phones will only accept power over a certain rate – in other words you can't trickle charge them with a very low current. Nokia phones, for example, need at least 120mAh before they will begin to charge.
If you charge directly from a solar panel, a passing cloud could reduce the power output to practically zero. Many phones in this situation will stop accepting a charge until they are reset. Thus they will no longer charge even though the panel is producing enough power. To reset them you just need to disconnect and reconnect them to the panel.
As USB ports have become increasingly prevalent as a means of charging in recent years, more solar panels have come onto the market with a USB connection. Examples include the MMP USB charger , MMP and Sunlinq panels, and the Powerfilm USB charger.
NOTE: If you are charging an iPhone there are some extra things to watch out for. If you are charging via a 12V socket, please ensure that the12V plug you use is compatible with your particlar model - this seems to be one of the biggest factors in success or failure!
Text is copyright Select Solar Ltd. No part of this text may be reproduced or copied without written permission from Select Solar Ltd.
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