Solar Power

In the December 2003 issue of Sea Kayaker Magazine a D-I-Y article was published by Robert Walker about an "Expedition-Capacity Waterproof Solar Battery Charger". I quickly assembled one for my 2004 Faeroe trip.

The idea being that during the day, from the back deck of my kayak, I could charge a 10-pack of 1.2V 1800 mAh AA NiMh batteries (making 12V). During the evening and night I would take the battery pack into my tent to re-charge (for instance) my hand-held VHF radio. And I always would have charged AA batteries to power my then new digital camera, head torch, GPS, etc. Unfortunately the system did not work as planned and I did not have the technical knowledge to figure a way out of this at the time. After the first night of recharging my VHF from the battery pack, it appeared that the batteries would not charge again. At home I found out that when the battery pack is drained below 10.7V, the charge controller would not charge the batteries. Worse, the whole system would not give any voltage, despite the solar panel delivering 20V; Bummer! There are charge controllers that have a 'Voltage Load Disconnect' (VLD) circuit, but these charge controllers tend to be much bulkier. To date I have not found a small size charge controller with VLD. Anyway, I could not figure out to make this system bullet-proof on trips where I do not have access to a normal AA battery charger to 'reset' the system to a 12V battery pack. At about the same time Fiona Whitehead enthusiastically talked about charging her mobile phone directly off a solar panel. To my astonishment she used the same solar panel as I did. Thus directly feeding a car battery adapter from the solar panel. But being focussed on charging AA batteries, I did not continue to use the solar battery charger. Today I took my solar charger out of storage and with a small adaptation put it back into service. Instead of only allowing to recharge from the battery pack, I made an extra connection directly from the solar panel leads. The solar panel can give up to 20V and the charge controller converts this to about 12V. Reading the small print on my mobile phone car charger revealed '12-24V'. The only draw-back is that the waterproof box I use now is too small to hold any equipment other than the battery pack. And other boxes might be too big to carry on the back deck. We'll see how this works for a start.

Mentioning 'Solar Power', the term 'Girl Power' comes to mind... Or is my associative memory playing tricks on me? ;-) Lots of ENERGY there !