My First Solar Powered Boat Project

[SunEagle]

Using solar panels on a moving boat will not get you the power need to properly charge your battery due to the constant movement of the boat and sun.

It would be better to have them mounted on a permanent structure properly aimed at the sun for best absorption of light. You can then charge your battery on land and then move it to your boat for use. This way you can also have a second charger powered by a generator to charge your battery if the solar panels don't get you to full charge. If you hadn't already ordered your solar panels I would have suggested you don't and just use a stand battery charger on your battery. Using solar to charge batteries is the most expensive way to do so.

Also before you size your charge controller you need to properly size your battery based on the number of hours you want to run your motor. The manufacturer should be able to help you size your battery based on their motor specs but I don't think the 75AH size that mentioned will get you very much in the way of use. The battery should be much bigger.

[Wy_White_Wolf]

1. Parralel/series would be better. More efficient and smaller wiring.

2. I'll let the others more knowledgeable than me answer.

3. Batteries have minimum/maximum charge/discharge rates. FLA - C/8 to C/12, AGM - C/4 to c/12
With thw 40 Amp load possible you need at least a 320AH FLA or 160AHAGM.

WWW

[SolarCanoe]

Hello All!

I am in the early stages of putting together an electric boat. I have searched the net to get some answers to questions I have but I am still not sure I am on the right track. I am an electronics technologist so I do understand the basics of Ohm's Law etc. I finally decided I would have to join a forum and outline my plans and get some feedback on my plans so far.

Background Info: My wife and I purchased a trailer in a seasonal campground and now have access to a very nice lake to go canoing on. We have a little 12 ft canoe that has been in the garage for 15 or more years. While we liked the opportunity to spend some time on the water we found the canoe less stable than we remember and decided to make some sort of outriggers. While researching that I ran across examples of people using trolling motors to power their canoes. Thus began this new project.

My plan is to make a very light weight canopy to keep the sun off of us, so naturally I started looking into solar panels. Long story short, I made a very low offer for 8 50 watt semi-flexible solar panels off of ebay and much to my surprise it was accepted so now I have 400 watts worth of solar panels for my canopy.

I plan to get a Minn Kota Enduro Max 40 trolling motor. It can produce 40 lbs of thrust and given 1 amp per lb thrust could draw as much as 40 amps full out. The current drops off quite quickly and at more moderate speeds will be down around 10 amps or less. This motor employs a maximizer circuit (ie, PWM) speed control that can extend battery life significantly over a conventional speed control on lower speeds. At full speed the currentt draw is the same.

I have found a 40 amp MPPT Solar Charge Controller on ebay, Tracer 4210RN, that is rated at 40 amp maximum battery current and 20 amps maximum load current. This does not seem like it is adequate since the motor can draw up to 40 amps and the max load current is only 20 amps.

I have also found some nice retro round analog amp and volt meters on ebay. I thought I would go for a nostalgic aircraft cockpit look and have an amp meter on the solar panels, battery, and load. The battery meter will have to be a +/- 0-50A meter and the other two can be 0-50. I know I probably don't need 50A range but the next range down is 20 amp which is probably too low. I would also add three voltmeters.

Equipment Summary:

Solar Panels 400 watts (8 x 50 watt).

Minn Kota Enduro Max 40 Trolling Motor (40 lbs thrust, max 40 amps).

Tracer 4210RN 40 Amp MPPT Solar Charge Controller.

Some retro round meters to monitor current draw and voltages.


My Questions:

1. I have already ordered the solar panels. 8 50 watt panels. I decided to go this way so that a panel failure represents less of the total. Vm=18V Im=2.78A (Voc=22.19 Isc=3A). Should I simply connect them all in parallel, or would there be an advantage in connecting them as 4 groups of 2 in series then all the groups in parallel to up the Vm to 36V? If I stick with the 18v parallel arrangement will a regular charge controller be almost as good as a MPPT type?

2. Should I connect the trolling motor to the battery or the load connectors on the charge controller. If the motor is connected to the battery will the panels supply current to the motor once the battery is dead? If the battery is fully charged and the solar panels can supply enough current to drive the motor will the battery remain unused until the solar panel power drops due to a lack of sunlight? Should I try to find a charge controller that can handle a 40 amp load?

3. Give the overkill of solar panels I am thinking I won't need a very large battery, maybe a 75 Amp Hour deep cycle battery would be enough. Assuming a battery rated at 75 AH is really only good for about 40 amp hours and that I would keep the motor current under 20 amps I assume that gives us about two hours to get home if we stay out after dark. Are these reasonable assumptions?

4. I'm sure I have forgotten something so please bring anything else I should consider to my attention.

Thanks in advance for any answers and comments

Todd