Kodak Solar Charger KS100-C

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Florent Alzieu
Test date: July 6, 2010

Charge AA batteries or an in-built product battery

Kodak's Solar Charger is supplied with two rechargeable AA batteries with an advertised capacity of 2100 mAh for 1.2 V. To charge both AA batteries together, an input of 2.4 V will therefore be needed. At this voltage, the Solar Charger can provide 85 mA. As no system is 100% efficient, we can assume losses of around 20% during the charging process. With this taken into account, the KS100-C will take just over 29 hours to charge the two batteries included. You'd better not need them in a hurry, then!

So 29 hours later, let's try charging a mobile phone. The HTC Hero, for example, has a battery capacity of 1300 mAh. When charging, we measured an output of 4.4 Volts from the KS100-C. At this voltage, the charger can supply around 500 mA. So if we once again factor in the 20% loss, the charger should take a little over 3 hours to charge this particular mobile. The problem is that at 500 mA and 4.4 Volts, the power produced is 2.2 Watts. This means that during the charger's three hours' use, the total power consumed by the phone will be 6.6 Watts. However, as the batteries can only provide 4.8 Watts/hour, the batteries will run flat before the phone has been fully charged.

The Kodak Solar Charger KS100-C is a solar powered battery charger. It can recharge two 2100 mAh 1.2 V AA batteries (supplied), which can in turn be used to charge a device. It can also directly power and/or charge an external device via a USB cable.

Without the AA batteries the KS100-C weighs 70 g and the surface of the solar panel measures 28 cm² (8 x 3.5 cm). So just how much power can it provide? We first of all measured the output from the solar panel alone in optimal conditions (i.e. bright sunlight). We then measured the output with the AA batteries fully charged and the solar panel switched off.

Figure 1: Output using energy directly from the sun (brightness over 40,000 lux)

Figure 2: Output from the batteries alone (solar panel off)

In figure 1, output peaks at around 3 Volts and 0.24 Watts. These results are much lower than those obtained with the powermonkey-eXplorer, which generates 0.5 Watts at 3 Volts. Then again, that's not really so surprising, as the surface of its solar panels is twice as large as that of the Kodak Solar Charger.

In figure 2, the line shows output from the batteries alone. To charge a 5 Volt in-built product battery, the two NiMH AA batteries can provide an output of 166 mA and 0.85 Watts. The power output shows a sharp increase at around 3.9 Volts, and even manages to hit 3 Watts.

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Pluses

Compact design

Charges NiMH AA batteries

Pair of rechargeable AA batteries included

USB output for direct connection to an external device

Minuses

Takes over 29 hours the recharge the AA batteries supplied

0.24 W max. output from the solar panel alone

Few adapters supplied, just a USB cable

Very limited ability to charge external devices directly

The Kodak KS100-C is a compact solar charger that recharges two NiMH AA batteries. Its main drawback is the lack of power provided by its small solar panel. Even in the best possible conditions (bright sunlight) it'll take over 29 hours to charge the two NiMH AA batteries supplied!