Solar Regulator for the Dinghy

[janice142]

My dink uses a trolling motor for propulsion and last week I was gifted a small Uni-solar panel. Details follow. What I want/need is a regulator that I can hook up and leave in the dinghy (it will get wet, or ideas on how to protect same in a 7' hard dink)

Dinghy:


Solar Panel details:

• Maximum power 5W
• Current Max power .3A
• Voltage max power 16.5V (but I saw 19.5 on my multimeter)

Anyway, it's just a small flexible solar panel approximately 18 x 9"
What I don't want to do is cook a battery. BUT when I went over to Amazon the plethora of choices all appear to want the regulator stored inside in a nice dry location. What say the experts?

Oh, and it's got to be cheap too. (You knew this wouldn't be easy, didn't you?) Thanks for any advice you might have.

[Rapanui]

Great idea, I have the same plans for my perfect tender that rows, electric outboard and sails.
Get a small waterproof plastic box from your local electronics shop and put regulator inside and seal wire inlets and outlets. Stick it under a thwart out of the sun. At that sort of power, the worse heat dissipation should not be a problem.

[noelex 77]

It doesn't need a regulator with any moderate sized lead acid battery (which I presume is the case for a trolling motor) just hook it up directly, but with such a small panel it will contribute very little. Keeping up with the self discharge of the battery is as much as you can hope for with this small size.

Just hook it up directly to the battery with a fuse. If its likely to be out of the sun for long periods (say with a cover over the dingy, or upside down on deck) a blocking diode is worth considering

If its one of the lithium Torqueedo batteries rather than a lead acid battery then you need to be very careful as litium does not tolerate even a small amount of overcharge. For this you need a suitable regulator, but given the limited output and very slow self discharge of lithium it is probably not worth the trouble.

[svmariane]

Something like this? SunGuard4 Ref link: $30...

We use Morning Star controllers on our boat - happy with them.

[GordMay]

Originally Posted by noelex 77

It doesn't need a regulator with any moderate sized lead acid battery (which I presume is the case for a trolling motor) just hook it up directly ...

It is generally acknowledged that you can leave an unregulated solar panel connected to a battery, if the rated output of the panel is less than 2% of the battery's Amp-Hour rating.

[janice142]

Originally Posted by Rapanui

Get a small waterproof plastic box from your local electronics shop and put regulator inside and seal wire inlets and outlets. Stick it under a thwart out of the sun. At that sort of power, the worse heat dissipation should not be a problem.

Ah, that's the ticket then (thanks!) I am wondering though about condensation within the container??? Hmmm........

Originally Posted by noelex 77

It doesn't need a regulator with any moderate sized lead acid battery (which I presume is the case for a trolling motor) just hook it up directly, but with such a small panel it will contribute very little. Keeping up with the self discharge of the battery is as much as you can hope for with this small size.

Just hook it up directly to the battery with a fuse. If its likely to be out of the sun for long periods (say with a cover over the dingy, or upside down on deck) a blocking diode is worth considering

Therein lies the problem. The dink battery is a Walmart lawn mower battery (light weight, which is important to me) -- specifically this one:
EverStart U1P-7 Lawn & Garden Battery: Automotive : Walmart.com

Originally Posted by GordMay

It is generally acknowledged that you can leave an unregulated solar panel connected to a battery, if the rated output of the panel is less than 2% of the battery's Amp-Hour rating.

Thanks... I've looked around both walmart and everstart looking for the amp hours.
This site Everstart-batteries.com: The Best Search Links on the Net for me doesn't fully load. Is there a way to extrapolate amperage from the Cranking Amps (350) and Cold Cranking Amps (275) ??

[noelex 77]

The battery will be around 40AHrs.
That will still be OK without a regulator with that solar panel.

I am afraid the battery is a start, not a deep cycle battery so it is not an ideal choice for an electric trolling motor, especially in a small size like this. It is designed for shallow discharges.

If you specify what trolling motor you are using, some idea of the run time can be estimated.
The contribution of the solar panel can also be calculated, depending on how many days it sits between runs. It will only be small unfortunatly.

[Singleprop]

I am using this one, the 10 Amps version - you could use the 5 Amps:

Solar charge controller-Smart series-Products show-Lumiax

Its connected to a 30W solar panel and a 65A battery.

[Singleprop]

Here is the little waterproof controller on my spare battery:

[janice142]

Well, the plot thickens...

To back up a bit: I owned an ancient trolling motor. Twice it had been taken apart (lower end) and had the wires brushed off and essentially de-rusted and sprayed, then sealed and put back together. The bullet was rusting/corroding and occasionally the motor would spin slowly before picking up and working again. It was on it's last legs in any event.

Anyway, so, I was given the solar panel. I wired it directly to the battery, along with the old trolling motor and headed for home (about a 1/4 mile from the marina dock is where I'm anchored) ... on low speed (#1) and on the way I smelled burning. I looked up river and saw nothing. About 30' from the boat I saw smoke and, on the hot side, the first foot of insulation had burned off the wire.
One motor kaput.

First Mistake: I assumed (oh hush now) that this is because the motor was on it's last legs.

In the meantime a couple had gifted me a larger trolling motor. Age: vintage. The wires had been worked on ---- he'd replaced the wire from the top end to the batt with a Pacor 10-gauge shielded wire. He'd also hooked it up backwards. Specifically when I put her in forward on the switch she went backwards. Reverse was forward.

Okay, I know from taking apart these beasts that the two wires (Red and Black) to the lower end are for forward. They are a heavier gauge (12) than the two for reverse (16, a blue hot and yellow ground) ... so
When I put the wires on the battery I put the black to hot and the red to ground. Now, when I switched on the motor and put it in forward it went forward.

Okay, you're with me now. I also hooked up (direct) the solar panel (the proper way) and at night via my multi-meter I saw 12.7 or 12.8... I wondered if I would lose power overnight. The following morning about 1.5 hours after dawn I checked the voltage and it was at the 12.7-8 point.

Good to go!

The Skipper and I head to shore. When I put the motor on the voltage dipped to 12.5 but all was well. At approximately 100' from the dock the wires started smoking. They both melted up into the motor head and again I rowed. I'd attached everything together with 1/4 bolts using a wing nut. The doggone nut was so hot it took me a bit to get the thing off and disconnect.

Mistake Two: toasting a second motor.
And yes, I took it apart (why not?, it's already not working right) and every wire inside the top was melted or damaged. The wires leading down however looked pretty good.

I removed the Pacor duo and using my own power supply (male cigarette lighter with two clips at the end) hooked up to the side of the switch. The propeller did turn in both directions, at least until that switch gave up the ghost.

So, I rowed home.
A bit more exploring and I decided to chop off the head. That's done. When I put power to the red/black the prop spins but it seems to be too fast? And the red sparks at my battery. Reverse works too incidentally when I use those two wires.

I believe the solar is the cause of my difficulties -- in that the failure was essentially in the same place and without said solar the old motor was working well, well, except for the slowing down/getting ready to die part. (whew)

A friend took the bullet end and I'm waiting his verdict and the salvage potential of the motor end. It works so I'm thinking if I can cut down the amount of power it may actually not cost me $100 for a new one on Amazon.

HOWEVER that leaves me with the solar issue. Am I correct in theorizing that the solar is what caused the melt-downs? And is the regulator going to solve that for me? Any other ideas welcome. Thanks for your patience in reading my tale of woe. (smile)

[nimblemotors]

Agree those lawn tractor start batteries will be killed off very quickly running a trolling motor. The cheap ones particularly are light because they have little capacity, got one right here I use to test 12v electronics, I like how lightweight they are (the cheap ones). I would suggest you go to a junkyard and get a used car start battery for like $20, they will last a bit longer just because they are bigger, but eventually will die too.

I doubt a 5w solar panel will cause these kinds of problems if its connected to a battery.
Melting wires are usually from too much resistance somewhere, usually the connections get corroded so, in highly technical terms, they make the electricity work too hard to get where it is supposed to go and generate heat like a toaster instead of move down the wire into the motor.
The wires themselves can be corroded too and cause them to heat up.
I'd see if you can replace them with some really thick ones, like big battery cables, hey that junkyard again might have some connected to the battery.

[GILow]

I think that you will find the 5 watt panel is not even enough to prevent the battery from sulphating up, let alone cooking it. The open circuit voltage you read on the multi would drop off the instant there was any load. Try it and I bet you will find it won't even drive a 5 watt globe

Not wanting to insult the panel, but the reg would be a waste of money. Those flexible panels are easily damaged and I have yet to meet one putting out 80% capacity after a year of use.

As for the melted wires, at 5 watts that panel is not even remotely the culprit.

But from your description I would not know where to start so I am not much good!

[janice142]

Thanks fellas... as far as resistance/corrosion in my ends, well, for my original motor that's not true. Guaranteed. I'd just replaced them within the past month -- thought it couldn't hurt and as the motor was occasionally taking its time to catch....

The newest motor (second to be murdered by self) also had new ends -- I'd replaced them the day before. Size 10, heat shrink variety circa Harbor Freight (not Ancor) -- and the wires got hot from the battery up to the motor in both cases although with the second motor the connections inside the case were not the best.

Anyway, it is possible of course that timing was the same and both motors would fail in identical ways at essentially the same point in the river.
Via multimeter in sunlight I was seeing 19.8 volts on the solar panel ends -- I don't know the amperage though.

So I'm at anchor (good thing) however without my wheels (motor) at present. Of course I can row -- that gets real old in 90 degree weather. Besides, I'm spoilt. Thanks for the suggestions. I am hopeful, and frankly a bit afraid too -- don't want to ruin another motor!
The next plan it to get a motor and only attach the solar when the motor is off. That should eliminate any difficulties. I hope.

[janice142]

Addition: I've got the "better" of the two lawn mower batteries sold by Walmart and generally run on #1 (according to Minn-kota, that's 6 amp hours) so a few trips back and forth are the norm.

Second side note, generally one round trip takes my battery down .1 volt (from 12.7 to 12.6 for instance) and I am very careful to not take it down below 12.4. The lawn mower batts generally last over a year and for me, that's a good value. Buying a larger "more appropriate" sized battery, well, I'd be tempted to put it in the boat (Seaweed) versus in Algae.

This works, at least when everything is cooperating.

Second side note re the 30 pound thrust Minn-kota (which I might end up buying if I can't make mine go)
And their customer service is very responsive. This is the message I received from Ryan when asking power draws for their smallest unit:

While we do not have exact amp draws at speeds 1-4, but I can give you some estimates. Speed 1 will draw about 6 amps, 2 will be about 10, 3 about 14 and 4 about 18. It takes a big jump from there; when it is on speed 5, the motor will draw up to 30 amps. In reverse, speed 3 is about equal to 5 in forward. I really do not have any information about speeds 1 and 2 in reverse, but you can make some estimates based on the forward speed.