The accessory genre of portable battery pack is well established, of course - the Proporta ones are best known. But a twist on the concept is to have solar input as well, giving extra flexibility when away from computers and power sources. The Scosche solBAT II Solar is a recent example, so I got it in for review, only to find a showstopping problem almost immediately. It's interesting tech though, so do please read on...

Ideally, the battery would charge while you're out during the day, perhaps hiking or cycling, and then you'd use it to recharge your smartphone each night. Ideally. In practice, the solar cell area is relatively small and it takes a couple of days of direct sunshine (at the very least) to fully recharge the unit - and even then, that 1500mAh isn't transferred to your greedy smartphone with anything near perfect efficiency. As is usual with these devices, you lose up to half the capacity in performing the transfer. So you'd need four days (minimum) of sunshine to fully charge your phone in two stints, 48 hours apart! 

So we're not talking about a full standalone, practical solution here. Consider accessories like the solBAT II more of an emergency top-up - you leave it in a window in your car or caravan or similar, so that it's always kept topped up and then you grab it for a quick 700mAh (approx) fix if your mobile device gets caught short.

Sadly, at least in the Nokia world, even that's just a theoretical plan - the (micro)USB output from the solBat II Solar is geared towards the vanilla 5V USB charging of the wider phone and iPod world. Nokia phones have always demanded a slightly higher quality charging source (so enough volts and enough milliamps) and plugging in the solBAT II Solar doesn't register on any of my Nokia smartphones. 

Plugging in an Android device worked fine though, as shown below. The same USB to microUSB cable supplied with the device works for both charging the solBAT II and also discharging it to a device. No other tips or adapters are supplied, somewhat disappointingly.

When discharging, a green LED lights up and a red one lights when charging. And, at the press of a button, a rough guide as to the voltage of the internal battery is shown - mainly useful to check if the accessory is full yet. During discharging, the voltage 'meter' shows low because of the drain on the internal cell, as is normal with battery technology:

This being All About Symbian, it's hard to recommend the solBAT II Solar charger, though it will find uses in the wider phone world, especially where extreme outdoor activities are involved (away from 12V and/or mains power). And even then, expectations will have to be kept low.

There are bigger and better solar charging solutions out there, several of which have the higher quality output which Nokia smartphones seem to need. In the meantime, the solBAT II Solar Charger is too expensive (£24), too low in capacity, underspecified in terms of output voltage and ill equipped in terms of charging adapters. Sorry, Scosche, back to the drawing board with this product.

Steve Litchfield, All About Symbian, 11 April 2011