Pond Boss Forums GENERAL QUESTIONS Product sources Solar Charger for Trolling Motor

We overhauled our paddle boat to put a trolling motor on it. Does anyone have a recommendation for a solar charger for the battery?

[img]http://imgur.com/a/2f2UBmT[/img]

How big is the battery? What is the voltage of the trolling motor and battery? How often do you use the boat? How long do you use the boat (hours per day)?

Let's start with those questions.

The battery is 550 cold cranking amps and it's a category 27 deep cycle marine battery so like 85 amp hours. On average the boat is going to be used probably once or twice a week. Average time of usage is probably no more than 2 hours at a time.

A solar charger that maintained or charged the batteries while the solar panels were actively providing power, and then stopped when it got dark would be a plus.

Poorly worded question. Corrected it in my second post.

Are you willing to attach the panel(s) and charge controller to the boat? If so, can you dock the boat with the panel(s) pointed at the sun? If you can say yes to all that, I would go with an 80-100 watt panel and a Midnite Brat PWM charge controller and enjoy. Your math is as follows: 50% usage on the battery, 42 AH. To replace those AHs, you need to add them back and account for the internal resistance. You will see three amps replaced continuous during peek solar production and account for the internal resistance, that means you need 14 hours of peek charging. Since you don't have peek charging all day long, you charging will take around two days. Add cloudy conditions and you will need longer recovery times. Hit your batteries harder, and you will not be able to recover with less than a 120 watt setup.

My experience has been that the solar charger is great for maintaining a charged battery, but not so great for charging it up in the first place. But I have a small system.

Yup it will keep it charged but won’t bring it up if it’s down very much. I found that out the hard way

I was looking for the exact same information, wanting to put aboat and trolling motor with battery set up at my farm a little distance away and wondering about a system I could leave in place and be ready and charged when I decide to do a few loops around the pond, probably even less usage then jludwig was proposing.
Thanks for your inputs!

When I didn't have electricity at the dock, I used a small Honda portable generator. Not ideal by any means, but better than trying to take out huge battery and lugging it to and from the house.

If there are two 12 batteries wired with a parrallel connection, will the Brat charge them both, or would you need to charge the batteries separately? Also, as long as I pair a 12 volt panel to a 12 volt battery, or a 24 volt panel to a 24 volt battery, I'm assuming I can go as big as I want with a solar panel. I'm thinking about a semi-permanent charger on my dock.

I've read that some cheaper controllers can actually pull a charge from a battery if left connected after the solar panels quit charging. Fake news?

Al, you ask good questions but I don't know the answers. I'm sure there are people here who do.

I do think a charger on the dock is a good idea, as relying 100 percent on solar seems risky, especially for hours of use in windy conditions.

Anthropic...I have a Minn-Kota 80lb thrust trolling motor

Solar Battery Charger...I believe is 5-Watt

Optima Blue Top 12 Volt Battery

The solar works ok, maybe because I only use it once a week...if that.

But after cloudy days it seems rather weak.

Maybe it's not near enough wattage... it would seem from what HighFlyer stated.

So I bought a marine charger I throw on the battery when I arrive at property.

Anthropic, I'm just wanting to maintain batteries when I'm spraying weeds, or my wife and I want to fish for an hour or two in the evenings. My spray rig is powered by a gas engine, so there's no battery load there. I usually spray an acre or two at a time, wait a week, then spray a different area. Pulling the boat out just to recharge the batteries, then having to relaunch it again is a pain in the rear. Being able to just leave it in the water, tied to my dock for a week, would be perfect for me.

I'm thinking a pipe driven into the ground for the base, so I can store the panel and it's mount when it's not needed is where I want to go. A Brat would also let me throw it and all the cables into a cheap battery box.

In order,

Frank, if your solar system is undersized, you are right, it will not keep up with the internal resistance of the battery.

Geha, If your battery is a single deep cycle battery, what I posted above will work for you as well.

Allen, If the batteries are used in parallel, one Brat can supply enough amps to charge them both. I would recommend 120-200 watts worth of solar panels for optimum service. Cheep chargers will not have the correct diode sizing and current could flow backwards from the battery through the controller to the panels, heating them up some, and draining your batteries. Go With Quality.

Frank rev 2, Solar is not risky, improper solar is risky. Sized appropriately, solar is a good choice for remote needs.

Mark, you are using a thin film panel and it can loose as much as 30% of its capability in six to nine months. At five watts, you are not putting enough energy into a deep cycle battery to keep up with its internal resistance. You really need poly or mono crystal panels and 80-100 watts per battery if you want to rely on solar for any recharge (50 watts worth of solar would be the minimum I would recommend). It is all about the math.

Allen rev2, I got your back it is doable and mounting it on the dock would make it very convenient. The only thing we will have to make sure of is that the panel is "turned off" before disconnecting the batteries so as to not hurt the Brat.

I say go bigger than you think you will need, but that's just how I roll. If a 120 watt panel will get the job done, but a 250 watt panel would take up basically the same footprint, use the same mount, cost insignificantly more, etc go with the 250! You will be happy you did on those cloudy days or when you want to take the boat out two days in a row, etc. Basically, if I am doing it, I am getting the highest wattage panel I can get that the brat can handle and won't charge my battery at too high of a rate.

Gotcha....thanks Brian.

So much information here. Thanks for the recommendations highflyer! Sounds like you kept us from making an expensive mistake.

Does anyone have recommendations for individual parts or a kit?

My research shows Northern Tool has a kit for sale online.

The charge controller they were talking about above is the Midnite Solar Brat. After that you would need a solar panel, wire and a way to mount the panel. Northern Arizona Wind and Sun sells all those components.

Thanks, Brian! My solar charger is original equipment with the pontoon boat & the panel is about the same size as the ones on my TH fish feeders. WIthout it, the battery loses charge faster than I'd like. But it is too weak to recharge it much. That's the risk factor.

Frank,
If you would like to "right size" your charger, let me know and I'll see what you have and what I would recommend, but I don't do kits for things like this.

Thanks, Brian. Now that I have electricity on the dock, will probably stick with solar just to maintain charge.

Thanks a million guys for the info, great information! highflyer, I would like to consult with you when I do this setup, at the present I have nothing so I basically need recommendations all the way thru as to what battery is best to purchase and a charging system for said battery, I would only be using a single battery, 12V system, with maybe a 55lb thrust motor.

Jake,

Others will most likely ID a best value battery. After that I got you covered. I would still recommend the Brat for the PWM charge controller. I would go with a Mono or Poly crystalline panel in the 80-100 watt range if you have the room. A 50 watt panel is as small as I would go for light use. Use good multi-strand wire and enjoy. Don't cheep out on the connectors and install. Using cheep components here equals lost energy.

Hi....if you just expect 7-10 hours of max speed out of your savaging engine seven days a 50 watt board and regulator would work. 50 watt board is $200-250, and a fundamental charge regulator is $50. Morningstar makes great modest regulators and there are quite a few boards, google look for 50 watt sun powered board. PM on the off chance that you need more point by point data.

https://www.7pcb.com/