Solar charging 90AH deep cycle battery

[OutOfBounds]

So I'm a total noob when it comes to electronics, batteries etc. I'm slowly learning though. The main reason I got into overlanding is because I'm a fly fishing addict and love exploring the remote backcountry of northern Alberta and BC in search of more and bigger fish.

Part of that pursuit involves an electric trolling motor and a deep cycle battery. I'm often without power hook ups for a week or more at a time however I still want to use my trolling motor every day. I'm starting to research ways to keep my battery powered for extended trips.

My battery is a 90ah deep cycle. I'm wondering if there's a way to solar charge this thing. I have 3 ideas:

1. Some sort of compact solar powered trickle charger that can keep the battery topped off while I'm out on the water. The motor primarily is used to get me to a spot on the lake and then I anchor down. I don't generally troll continuously for more than an hour.

2. A slightly larger solar system I can use in camp on shore during the mid day when I'm not fishing to top up the battery

3. My least favorite idea is a system that I can connect to my truck so I can idle the truck for a bit and top up the battery. I'm not a fan of this idea since it burns fuel and an idling truck in camp is irritating.


I'm not trying to bring the battery up to full charge from completely dead. I just want to top it up from the day's usage or supplement it's range with trickle charging. If I can bring it up from say 75% to 95% in 3 - 4 hours I'd be happy.

Am I nuts? Is there a way to make one of these ideas happening?

 

[AndrewP]

Northern Canada?

Not a ton of available solar that far north.

So for a solar only system, you'll need a lot of panel power to capture the low angle sun as best you can. Do you know the watts or amp-hours your system uses in a typical fishing day?

I'd consider charging from your truck or better, bring a small generator.

 

[john61ct]

Get two batts, charge one up while using the other then swap.

A Victron 75/15 controller gives you some flexibility.

Ideal match for a panel would be "24V nominal", say 40V up to 60V max.

Wattage varies with size, that SC could do 2x 100w up to 150w, either start with one then expand later if you need it, or look for one big 250-300w to start with.

At full capacity you could run a 12V fridge/freezer as well.

The goal for batt longevity is get to 100% full each cycle, in your case 2-day cycles, and don't go below 50%.

A genny won't be run long enough, you'd need some solar anyway, so I reckon shoot for solar-only first.

 

[rkj__]

So I'm a total noob when it comes to electronics, batteries etc. I'm slowly learning though. The main reason I got into overlanding is because I'm a fly fishing addict and love exploring the remote backcountry of northern Alberta and BC in search of more and bigger fish.

Part of that pursuit involves an electric trolling motor and a deep cycle battery. I'm often without power hook ups for a week or more at a time however I still want to use my trolling motor every day. I'm starting to research ways to keep my battery powered for extended trips.

My battery is a 90ah deep cycle. I'm wondering if there's a way to solar charge this thing. I have 3 ideas:

1. Some sort of compact solar powered trickle charger that can keep the battery topped off while I'm out on the water. The motor primarily is used to get me to a spot on the lake and then I anchor down. I don't generally troll continuously for more than an hour.

2. A slightly larger solar system I can use in camp on shore during the mid day when I'm not fishing to top up the battery

3. My least favorite idea is a system that I can connect to my truck so I can idle the truck for a bit and top up the battery. I'm not a fan of this idea since it burns fuel and an idling truck in camp is irritating.


I'm not trying to bring the battery up to full charge from completely dead. I just want to top it up from the day's usage or supplement it's range with trickle charging. If I can bring it up from say 75% to 95% in 3 - 4 hours I'd be happy.

Am I nuts? Is there a way to make one of these ideas happening?

What do you consider compact for option 1?

I bought a kit at Canadian Tire that included a 40W panel, and 7A charge controller. It was on sale for $99 most of the summer. It measures 14x31 inches, or 35x79 centimeters.

It looks like an average trolling motor on max speed draws near 40A. So, if you run it for even one hour total, you will need to re-charge 40Ah.

Using my 40W panel as an example, you could see maybe 2A charging. So, even if you got 5 hours of good sunlight, you are still only recharging about 25% of your usage.


The above is just a rough example as a starting point. Maybe you have a little motor, and only run it on low, for about an hour. That could use as little as 5-10Ah, which could potentially be recovered by a small-ish 40-60W panel, if you have good sun.

 

[OutOfBounds]

Thanks for the info so far guys.

My motor draws a max of 42A, so rkj's estimates look pretty close. I only run at max speed for maybe 15 - 20 minutes a day though, just to get out to my spot and when moving to a new one. When trolling, I'm usually running on the lowest speed or close to it and not usually for more than an hour. The kit you mention is compact enough for me, so I'll keep an eye on that for when it comes on sale again.

I'm open to buying a second battery and having it charge while I use the other one which would give me more charge time. Contrary to what was mentioned with daylight hours up here, from about may - october (fishing season) we get between 10 and 14 hours of daylight give or take a bit. It's not like we're down to 6 hours of daylight during fishing season.

A generator is also another option, but much more expensive. I could buy 3 or 4 batteries for the cost of a generator. Add to that I head out in the bush to get away from that kind of racket. I don't really want a generator running all day in camp.

 

[rkj__]

Contrary to what was mentioned with daylight hours up here, from about may - october (fishing season) we get between 10 and 14 hours of daylight give or take a bit. It's not like we're down to 6 hours of daylight during fishing season.

I think the comment regarding limited solar up north was more a comment on the sun's intensity far away from the equator, not the daylight hours.

"The angle formed by rays of sunlight hitting the Earth is technically known as the angle of incidence. Rays striking the planet's surface from directly overhead -- that is, at a 90 degree angle measured from the horizon -- are the most intense. At most times and locations, the sun forms an angle with the horizon less than 90 degrees -- that is, usually the sun sits lower in the sky. The smaller the angle, the greater the surface area over which the sun's rays spread. This effect reduces the sun's intensity in any one place. For example, at a 45 degree angle of incidence, solar radiation covers a 40 percent greater area and is 30 percent less intense than at the maximum angle of incidence of 90 degrees.

Only locations lying along one line of latitude on the surface of the Earth can receive sunlight at a 90 degree angle on a given day. All other places receive sunlight at lesser intensities. In general, the sun's rays are the most intense at the equator and the least intense at the poles."
Source: https://sciencing.com/sun-intensity-vs-angle-23529.html

 

[OutOfBounds]

Gotcha. That makes sense. I was forgetting my high school science. LOL

 

[dwh]

Yea, but with a portable solar panel he can face it toward the sun, thereby making the angle of incidence close to 90 degrees.

But 40w won't be enough. Lot of guys around here use Renogy 100w kits. Good rule of thumb is 100w solar (minimum) per 100ah of battery capacity.

Figure you'll get 5a or so out of a 100w panel. If the battery is down 25% - 25ah - then you'll need 5 hours MINIMUM to replace that. Plus lead-acid batteries are only 80% efficient, so add another 20% - an hour - to that. Now you need 6 hours minimum with a 100w panel facing the sun dead on to recharge that battery 25%.

 

[SoCal Tom]

You can only count on about 4 good hours of sun that far north
https://www.wholesalesolar.com/solar-information/sun-hours-us-map
To get 40 amps of power in four hours means 10 amps per hour, which would take 200 or 250 watts. That’s a bit over 300$ USD, and you still need the sun to come out . A small generator would be a better plan in this case.
Tom


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[OutOfBounds]

Darn. That's what I was afraid of. I think at this point I'll pick up 2 more batteries to use on extended trips. That's still much cheaper than the $700 - $1000 a small Honda generator will run me

Thanks for all the info. Even though my idea isn't really practical, you all gave me info that has furthered my understanding.

 

[SoCal Tom]

Look at the harbor freight / wen inverter generators. Good reviews less than $500


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[OutOfBounds]

Look at the harbor freight / wen inverter generators. Good reviews less than $500


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Those look nice. Unfortunately finding a source in Canada is tough. Plus, once you figure in the fact that I have to pay in CAD, I'm not far off the price of a Honda. I'd rather buy once, cry once and have a generator for life with solid post-sale resources.

On an update note, we just got back from a 4 day trip and I got 3.5 days of fishing out of my battery. The battery level indicator on the motor still shows roughly a 50% charge. I'm pretty impressed with that.