Solar powered kayak bilge pump and device charger system.

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
  • RTV
  • 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 ( *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.


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  • Les says:

    @at = @
    If the battery is 14.8 V, then it must be a 4-cell Li IOn – right? If so, the max charge voltage (V @ full charge) is 16.8 V. If your panel only puts out 15.4 V, how can you expect it to fully charge the battery? I am in a similar situation.

    • Eric Kittell says:

      You can read more about the battery here: It says there are 12 cells.

      I don’t have the panel connected directly to the battery, it goes though this charger:

      It does say that the panel voltage “must be greater than battery voltage to charge” and I assume that is the rated voltage of 14.8V, and not the “Peak at 16.8V”. But now that you mention it I guess I’m not 100% sure about this. I imagine if it does not fully charge but can get close to fully charged then that should be good enough since the battery is very high capacity.

      Are you saying you have a similar setup and you experience that it does not fully charge? Neither my solar charger nor the AC charger have charge level indicators, they just indicate whether or not the battery is fully charged or not. I’m going to see if I can get it fully charged with the afternoon sun today or over the next few days and I’ll report back here.

      The only time I have used this system was on a 2 week trip when the panel was damaged early on (replaced under warranty now) and so I couldn’t tell how well it charged. Also 2 weeks wasn’t long enough to exhaust the initial charge on the battery even using the bilge pump a couple times and charging my smart phone twice.

      • Eric Kittell says:


        I really haven’t found a good place to leave this thing out in the sun for a number of days to see if it fully charges. After some recent use on the kayak the solar panel has become damaged and no longer works (this was my 2nd!) so I won’t be able to try it again this summer.

        I have tested the pump system a number of times while I was trying (unsuccessfully so far) to roll my new Feathercraft Heron. The pump worked very well to empty most of the water out of the boat after a number of wet exits.

        I can see now that the system isn’t nearly 100% waterproof. The DIY Delphi connector that I added to the pump leads got very wet inside and even the factory connectors from Powerfilm were a little damp inside. The box also had a number of tiny water droplets inside it. I don’t know how they got in there but I think it was from the lid and not from around the cables but I really can’t be sure. I don’t think the UK boxes are the best quality but they’re the only company who had one in the right size for this project.

        I realize now that if I want to practice a lot of rolls and wet exits then I really need to use the sea sock provided by Feathercraft instead of relying on this system which should be kept as dry as possible so that it is ready for a real emergency.

        I added NO-OX-ID conductive grease to the list of parts above. I had applied it liberally to all the metal contacts in the connectors before these wet tests. I’m not sure if that has helped but everything still works well (except for the damaged panel). I won’t be in any real wilderness this summer so the panel isn’t absolutely necessary though now I’ll have to make a point to find AC outlets I can use. Once a week on tour should be fine I think and I’ll probably stay at a campground at least that often.

  • Eric Kittell says:


    I eliminated the solar panel as it was no longer functional. I really want to try to use one again but I seem to keep breaking them so maybe I need to wait for someone to come out with a panel that’s more robust.

    I also decided to get rid of the Delphi connector between the pump and battery and just connect it directly. That was a very weak link in the most critical feature of this whole system. I used the pump many times this summer on an over one month long tour of parts of the Sardinian coast line. Even with a lot of pumping the battery was still going strong after a month with no recharges.

    Without the cable to the solar panel I now had room to add a separate cable just for device charging. For this I used a cable with a factory installed Delphi connector which is a lot more waterproof than the DIY connectors. In order to keep water out of it I cut the connector from the other end of the cable to plug into it while not in use. I also used some RTV to cover the exposed leads of the dummy connector to prevent possible short circuit from bilge water that could be bad for the battery since this cable is not connected to the switch and so is always on.

    Other minor improvements included using NO-OX-ID on all the connections inside the box and applying a thin film of silicone grease to the rubber seal for the box lid. I’m not sure but it seems like this helped a lot to eliminate the tiny water droplets I had found inside the box before rewiring it. After weeks of lying in the bottom of the boat I opened the box and found not a single trace of water inside it. I had also placed a small, used desiccant packet inside the box which may or may not have helped. I’m sure it would be a good idea to place a couple of fresh packets in there and change them regularly.

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