Musings on Solar Power and USB Batteries

When I started this project I naively bought some 3 watt solar panels from a supplier who advertised them as being capable of charging iPhones, and the latest Android smartphones, etc. As the e-readers, the Kindles, require less power than these devices I hoped these panels would be able to easily provide sufficient power to charge the Kindles, even in the UK.

Cutting a long story short, the panels wouldn’t charge the Kindles except occasionally to keep me on-the-hook so I kept going for much longer than I otherwise would or should have done. They didn’t even charge the devices in the peak of the day in Kenya, on the equator. Also their voltage regulators were unreliable, and lost about 1 watt of the 3 watts the panels were claimed to deliver.

To make matters worse, the kindles often froze because the voltage (at around 4v via the regulator) was borderline to trigger the charging circuit which drew current and caused the voltage to drop, then the charging stopped. This allowed the voltage from the panel to increase which restarted the cycle. Eventually these cycles seemed to cause the kindle to freeze.

I discovered Solar panels are considered constant current devices while we want something closer to constant voltage at a given minimum current. Although I considered creating my own homebrew regulators with large capacitors to even out the power delivery, etc. I abandoned the idea as others had tried better solutions and mine was unlikely to work.

Indirectly I was encouraged to try connecting the solar panel, without a voltage regulator to an inexpensive USB battery reserve power device intended to provide portable emergency recharging for mobile phones. Internally their electronics enables them to charge their internal battery @3.6 volts DC while delivering a steady 5V DC output once they’d been sufficiently charged. These devices seemed to do just what I needed for this project and my initial tests are promising. I’ve tried a variety of these portable battery units, including several with integral small solar panels rated at 0.7 watts, which isn’t enough in practice.

I also discovered an innovative business for concert goers who want to keep their smart phones and iPads, etc. charged beyond the reach of mains power.

Overall, the combination of an external 3 watt solar panel  and a smallish USB battery unit seem to be a practical solution for recharging the other electronic devices we’re using, including the Kindles and the 3G WiFi routers.

Kindles and WiFi passwords

We noticed the Kindles sometimes fail to connect when we configure them with the correct WiFi password for the 3G Huawei routers. We’re not sure why this happens yet. The workaround is to repeat the registration several times (once you are sure you have entered the password correctly).

Some tips

  • If you have a smartphone, tablet computer, or a laptop, that has WiFi, try registering it on the network. Once you know it works, disable this WiFi network (or ‘forget it’ as Android phones say) otherwise you risk using lots of the network traffic inadvertently.
  • Double-check the password is entered correctly. Perhaps someone else can read out the password so you can check it. Then swap responsibilities.
  • Enter any letters in the correct case e.g. one of our WiFi passwords was a series of numbers followed by a single capital letter. Enter the capital letter as a capital letter.

3 passwords for Huawei WiFi routers

There are various passwords involved when configuring the Huawei routers we are using to provide rural WiFi for schools. You may be confused by which password is which and when do you need to use them.

Each password serves a specific purpose.

  1. The first, and the only one that’s commonly needed in the school, is the WiFi password. This is written on the inside of the cover on the WiFi device. We use this password when configuring e-readers, including Kindles, to connect to the WiFi. You also need the name of the network, this is also printed on the router.
  2. The second is the administrative password to  configure and manage the WiFi router. This is generally only needed for technical work; however some schools may want to monitor the usage of the mobile (3G) network, and they will need this password to do so. You also need the username of the administrator account. Details of the username and password are provided in the manual.
  3. The third password is actually a number, called the PIN. This is needed to unlock and enable the 3G SIM card fitted in the router. This PIN is generally configured by whoever is configuring the WiFi router (using the details of the administrative username and password).


Getting Started for a new School

This article helps get a new school up-and-running with e-readers. There are various things to take care of if you want to use the e-readers effectively and for long periods. We will cover the various topics to help you do so.

Keep the e-reader safe, charged, and protect it. Otherwise you might not have a working kindle when you want to use it. Cases are provided to protect the e-reader. When not using the e-reader, please make sure the case is closed, and fastened if it includes a fastener.

The e-reader can often be charged using a solar charger that includes a small battery to store the power from the solar panel and that provides power over a USB connection. Alternatively use the mains USB charger where you have mains power. Sometimes you may need to travel to a suitable location if your school doesn’t have power available.

For Amazon Kindles, one of the benefits is being able to download and buy electronic materials from the Amazon store. First you need an Amazon account, and the Kindle needs to be registered to this account. An account, and the electronic materials, can be shared across several Kindles. The most common recommendation is up to 5 Kindles can share an account. Doing so keeps the costs down as each purchase can be shared across the various registered Kindles.

Any purchases need to be paid for, the most practical way at the moment is to use Amazon Gift Certificates. These also need to be paid for by somebody, and added to the relevant Amazon account for this school. When you spend money, for instance by buying an electronic copy of a newspaper or a book, the money is gone from the account, unless you decide to cancel the purchase within a few minutes. A purchase by one person affects the entire account, so any purchase needs to be carefully considered and done wisely, otherwise you waste the limited money in the account.

Trap: We have noticed several schools have bought irrelevant or inappropriate books during the pilot phase of the project. In some cases purchases have wasted much of the budget for that school and meant they were not able to buy more relevant books when they needed to. Please clearly explain to whoever uses the Kindle what sorts of books are suitable to purchase and read. Also encourage them to use the following practices for any book they are interested in reading, especially if the item costs money.


Amazon provides several facilities to help you manage your purchases wisely:

  • You can ‘try a sample’ of a Kindle book. Please do so before you consider actually buying the book.
  • You can add books and other items to a wish list, then ask others to review the wish list to decide which items to buy this time. Other items then remain on the wish list so we can consider paying for them later on.

There are many thousands of books that are free to download and read. These include many ‘classics’. 

There needs to be a way to connect to the Amazon store, and to the Internet, from Amazon Kindles. The choices depend on the model of Kindle you have and what connection options it includes. Connection options are:

  • WiFi (for the less expensive models)
  • 3G (for old Kindle 2 devices)
  • 3G + WiFi (for the more expensive Kindle Keyboard 3, Kindle Touch, Kindle Paperwhite, etc.)

You need a WiFi connection for WiFi Kindles to connect. There are several options, which include:

  • Visiting a local Internet / Cyber cafe or another location where you are permitted to use their WiFi
  • Installing and using a local WiFi router. In rural Kenya we currently use 3G WiFi routers from a company called Huawei. These accept a 3G SIM card, similar to the ones used in a mobile phone. The 3G SIM card needs credit on the account and it’s cheaper if the credit is used to pre-pay for Internet access, for instance for 100MB of data. Like your mobile phone account, when you use the service, it costs money. This means you need to check the balance for the SIM card occasionally and top-up the account if it is running low on Internet credit. In this article we assume you have someone who is able to configure and commission the 3G WiFi router.

Find ways to learn from each other in your school, and from nearby schools who also use a similar service. That way you will be able to use the e-readers more effectively, share recommendations on how to use them for teaching, and share recommendations on good electronic materials to download and use.