RE: [Paddlewise] A last turn on Global Warning -> exercise and power -> rechargeable batteries for kayak equipment - will they work?

Jennifer & Peter make good points about power use on longer kayak trips.
 
Eight years ago, I standardised on AAs (camera, LED head-torch & backup VHF)
then later added GPS to that. These all work acceptably well with
rechargeable (NiMH) AAs.

On modern Eneloop 2000 AAs (newer low-self-discharge NiMH) my Garmin Legend
HCx lasts 15 hours (screen lighting off - it just logs my track and gives an
rare answer to WTF am I). It seemed like I might be exaggerating that, so I
just checked the logs for the past weekend. It did two days of 7.5 hours and
the 2 AAs have power left.

The VHF I liked in 2001 (HX-460S) uses a custom Lithium battery. This was a
trade-off I accepted because it was much lighter & more compact than the
AA-powered alternatives; as well as having better battery life, less charge
decay and better (IMO) water-resistance. I also paid $15 for the 2xAA
battery case for the VHF - as a last-resort backup. I still like it and
would make the same choices.

I don't remember a cellphone ever using AAs. All mine have had a custom
battery - first NiCad, then NiMH, now Lithium - but they all last quite a
while if turned off ;)

To cope with multiday trips, I carry a (big & heavy) 12V gel-cell (7200 mAh)
to recharge the other devices via their 12v power cords. This has worked
very well. Every week, I find somewhere (eg: ranger's house or cafe) to
recharge the gel-cell overnight. (I also carry its power-brick charger
along.) Battery & charger are a weight penalty no worse than a big bottle of
water.

This practice has worked well over the years and many trips. The VHF gets
topped up every night and the others are recharged when necessary.

So, now in 2009, my camera (XG-9) also works off custom Lithium cells - but
much more efficiently than my first digital camera (which ate AAs). The
XG-9's batteries are cheap & light enough that I bought 3 of them - which
will usually last for 10 days. The charger is also light & tiny and runs
from the gel-cell if I need to recharge.

I should replace the big gel-cell with a smaller & lighter-weight 13.6 v
Lithium RC (radio-control) power pack. These are popular with the night-time
runners and mountain-bikers (for use with very powerful headlamps). At
around $150, they are amazing tech - but care is needed with recharging -
they can explode! (Nothing too daunting - we've all safely survived igniting
little pots of gas & petrol for years ;-)

The addition of a decent deck-mounted solar-cell would add a whole new
dimension of independence. I would love to try this as soon as it's ready
for that ultimately challenging environment - the deck of a kayak. Every now
& again, I have looked at the progress being made with the panels and - as
others have commented - been pleased at the improvement. Some early problems
: 
- waterproofness & fragility	
- serious & rapid panel degradation - cells still 'worked', but output fell
badly. 
- output seriously reduced if something like a rope (sailing sheet) lay
across any part of the panel

I'd love to hear stories of people using the new flexible panels on kayak
decks and getting useful power out of them. I've considered bringing panels
along for use in camp - but camp is usually dark or stormy. 

I still don't like the idea of plugging in devices (to solar) on deck. I
imagine I'd prefer to keep a 'master battery' - maybe a smaller RC pack -
under constant charge (maybe in my dry day-hatch) and then take its 12-14 V
output to charge one of the other devices. Say a spare camera battery by day
and the VHF at night. I know this is grossly wasteful - every step has
pretty bad efficiency losses - but there are cost & safety issues to balance
against 'maximum efficiency'. 

Best Regards
Paul Hayward, Auckland, New Zealand
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