I originally got the idea for this from Rogue Paddler and also Gnarly Dog. You can purchase a ready made system from BlueWater Kayak but as of this writing their solar panel option is not ready, their battery capacity is only 2200 mAh and the system isn’t setup to charge other devices though that would be an easy modification.
These are all the major parts that I used:
- PowerFilm 7W 15.4V Rollable Solar Charger $127 (buy)
- Tenergy Li-Ion 18650 14.8V 7800mAh PCB Protected Rechargeable Battery Pack $133 (buy)
- MPPT Solar Charge Controller for 14.8V Li-Ion battery pack $110 (buy)
- TLP-2000 Tenergy Universal Smart Charger for Li-Ion/Polymer battery Pack $22 (buy)
- Underwater Kinetics 406 UltraBox $17 (buy)
- CPI Waterproof Switch $60 (buy)
- Rule 500gph 12V Bilge Pump $30 (buy)
Small items used:
- Power Film RA-7 15 ft. Extension Cord (to connect the panel to charger input)
- Ancor Marine liquid tight wire seal 765002
- Tamiya Kyosho power connector (found on ebay)
- Delphi 2 pin weatherpack connector (found on ebay)
- 2.5 Amp fuse
- twist on wire connectors
- 12V to USB adapter
- heat shrink tubing (to hold the 2 pump leads together as one cable)
- bilge pump hose
- NO-OX-ID (http://www.sanchem.com/aSpecialE.html *added May 29, 2012)
Since the solar panel and included cables use Delphi connectors I used those for the connection to the bilge pump as well. This way you can unplug the bilge pump and plug the PowerFilm cigarette lighter adapter into the same connector. I didn’t think about what would happen with these connectors sitting unplugged inside the hull of the kayak while the battery unit is removed to charge other devices. Luckily the plug for the cable leading to the panel is female and the one for the pump is male and they can be plugged together so you don’t have to worry about bilge water getting in and corroding the contacts while the system is disconnected. The corresponding plugs that come out of the box can be plugged together to protect them also.
For the connection between the solar charger and the battery inside the box I used Tamiya Kyosho connectors so the battery can be unplugged at home and plugged into the AC charger to top off the pack before you head out. I used one medium sized cable seal instead of 3 smaller ones to keep things simple. It can’t create a watertight seal on all 3 cable at once so I used RTV to seal the gaps between and around them and also where the seal housing is screwed down on to the box. As per the instructions for the pump I installed a 2.5 amp fuse inside the box on the negative lead going to the power output. The switch leads are wired inside the box to connect the positive output lead. PowerFilm solar panels can be daisy chained, so you could easily add another one to the system to really up your solar power gathering capacity if you have deck space for them
I used the system recently on a 2 week tour of Long Island, New York. I did get to use the bilge pump twice, once was after landing in surf. I did not get to charge my VHF radio because that device failed on the first day! I did, however, recharge my phone twice while watching 2 movies on it. I don’t know for sure how much of the battery capacity was used each time, or how long it took the the solar panel to fully charge the battery again each time. The control unit only indicates if either the battery is fully charged or how much current it’s getting from the panel at the moment. There’s no charge level indicator. I couldn’t find one as an extra add on either. I’m hoping that the combination of high capacity battery, efficient charger and high quality panel will be more than adequate for the needs of small electronics and occasional bilge pumping. It could charge a laptop with a car adapter but it would take much longer to recover the lost potential and you always want to have enough power left for emergency bilge pumping! Of course I also carried a hand operated bilge pump just in case. I think I might reduce the chance of electric pump failure by using a dedicated cable without a detachable connector and have a separate cable for charging devices. I don’t want to have to open the box for anything in the field so an external connection is necessary for that part.