Re: [Electric Boats] Re: solar assisted zodiac trip with torqeedo 1003

 

Hi Eric,

There's few other factors working against us harvesting as much solar power as might come from stationary panels...

Apart from what you mention there's also the way I arranged the panels around the dinghy.  The two on the bow were tilted up a little at the bow, more or less following the sheer of the dinghy.  This should be ok because we were going south with the sun in the north.

The panels on the sides were angled inwards, just the way the jury rigged attachment system worked out.  So the panels are all on the same plane, and I'm expecting that would lessen their effectiveness.

Because they were mounted low, if I sat on the seat I would shade the forward panels.  And even though sitting down in the zodiac's belly was ok, after an hour or two I ran out of different ways to sit comfortably so resorted to sitting on the seat for a while every now and then, and noticed when I did so that the watts coming from the battery would increase (ie less from the sun).  So we lost a bit that way.

And the other thing was most of the morning up till around 11 was overcast and so less than optimum.

But all things considered I think we had a good harvest.

One of the yachties around here made the comment that if your boat was sinking (the big boat that is) it could be good to take a solar panel and Torqeedo with you when you jump into the rubber dinghy/life raft.  Then, even though it might take a while, you could eventually get home.

And I'm impressed with your swimming speed  :)

Cheers

Chris

On 07/08/2011, at 7:57 AM, Eric wrote:

 

Hi Chris,

What a great experiment! I appreciate your perseverence to take the time to cover a long distance at a slow speed. It's interesting that the 160W (4 x 40W) of solar panels would just cover the 80W motor load on average during the day.

Doing a bit of the math, you used about 720Wh (80W x 9 hours), let round up to 800 for the "fast finish". You finished with about 70Wh in the battery so you used 330Wh from there. The remaining 470Wh would have come frm the panels. I've heard that a stationary panle will collect 4 to 6 times its rated capacity in Wh over the course of a day, depending on latitude and time of year. With 160W of rating, 480Wh would be a factor of three. This seems reasonable because of the moving boat and the fact that you didn't stay out for every trace of your winter daylight.

And I can really appreciate your comment about 1.5kts is not exactly a speed, I can swim 3000m in an hour (1.6kts), but not for 8 hours straight.

Congrats for a good day on the water.

Fair winds,
Eric
Marina del Rey, CA

--- In electricboats@yahoogroups.com, chris Baker <chris@...> wrote:
>
> I had been wondering for a while how far you can go with a torqeedo 1003 and its clip on battery. right where I'm based, at Pittwater near Sydney, is a short hop to Sydney Harbour and it seemed like it could be a fun adventure to do that trip one day in the zodiac. but its around 20 nautical miles and I'm not so sure that the battery would last.
>
> at the Sydney boat show I discovered some nice flexible solar panels from Italian company Solbian and now available downunder. so I borrowed four of the 40 watt panels to charge the 1003 battery as we went along. these panels put out about 9 volts so i needed to daisy chain them together to get the voltage needed by the lithium battery.
>
> the mother ship for this adventure was also electric powered—another inflatable of about the same size, 9ft, and fitted out with a Cruise 2 and couple of Optima 75ah's and two Optima 55s in reserve.
>
> we towed the test boat to starting point behind the mother ship. for those who know the area the start was behind palm beach, just near the entrance to Broken Bay. the sun was just coming up.
>
> we had the tide against us to begin with and we could do about 1.5 knots at 80 watts. both boats were showing about the same power requirement at that speed. (mind you, 'speed' is not such a good word to describe 1.5 knots :)
>
> the 1003 tiller has a readout of battery capacity, power being used, speed and range. the range till battery empty was showing up as 6 miles. on the mother ship the range was about 33 miles.
>
> the forecast was for a fine sunny day with light winds from the north, which should assist us. but it was actually overcast with rainy patches, so not much solar to begin with.
>
> as we got out of the heads and headed south we had a little bit of help from the 5 knot wind, and the tide effect reducing so the speed picked up to about 2 knots and the range increased to about 9 miles. which is about halfway there...
>
> after another half hour we noticed that the power needed on the 1003 had dropped to 50 watts while the mother ship was still on 80 watts. so despite the overcast we were getting 30 watts of assistance from the solar panels. i had a long narrow panel on each side on side tube, and two square ones on the bow. and range was improving to about 12 miles.
>
> as the morning progressed the clouds mostly cleared and it was cool to see zero watts as the power needed to take her along at 2.5 to 3 knots. the battery had got down to around 55% and for the next few hours in the middle of the day it hung around here. sometimes rising a little as power was put back into the battery and sometimes falling again as a big cloud passed over the sun.
>
> we got to sydney heads at 3pm with 37% remaining in the battery and so we were confident to make it the next two miles to our destination. i gave it a little more throttle on the final leg against the tide again and finished with 17% remaining in the 400 watthr battery.
>
> the mother ship still had 60% remaining in its batteries and we hadn't touched the two spares. the time taken for the trip was about 9 hours, the distance covered 19.5 nautical miles, and the average speed 2.3 knots
>
> for some photos you can see my blog at http://thetorqeedoshop.com.au/
>
> cheers
>
> chris
>

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