Trolling Motor Solar Panel Install

[Joe I]

I currently have 2 batteries for my trolling motor that connect to a Sportsman Series Dual Pro Two Amp Bank (see attached) which used to get plugged into an electical outlet at my dock. Since my new dock does not have an outlet I am looking to install a solar panel. My question is, can my existing Amp bank be plugged into from a solar panel or do I need to replace it with something else?

 

[hwy17]

In general, batteries can be charged from solar, yes.

But we'd have a lot more questions about the application. A trolling motor is a large load. How long do you want it to run per day?

 

[Joe I]

In general, batteries can be charged from solar, yes.

But we'd have a lot more questions about the application. A trolling motor is a large load. How long do you want it to run per day?

Ideally a full day of fishing, approx 8hrs

 

[wholybee]

Assuming your current batteries can run your motor for 8 hours, it would take about 300W of solar to charge them from 50% to 100% if left on charge for a full day. If your plan is to fish for one day per week, and let them sit charging for 6 days, I would recommend a 100W panel.

If you want to go fishing more often, or consecutive days, then the best option is to buy an LFP battery (smaller, lighter, and more run time) and take it home to charge overnight. And if your current batteries don't last 8 hours, then for sure, get LFP.

 

[HarryN]

I have the dual pro version of that charger - fantastic setup and really does a nice job of charging and keeping everything in balance.

The trick with solar charging is that it happens during the daytime only, while that charger plugged in charges 24 / 7, so you can go fishing during the day and have it ready to go by morning. Solar alone cannot easily do that.

So that gives you a couple of options:
- Put enough solar near the dock to charge as quickly as possible during the day hours
- Put some solar + battery + inverter near the dock to charge that up at a modest pace, and then just plug your existing boat setup into it like you are doing now.

Right now, you are getting a nominal ( 10 amps ) x ( 2 charge ports ) x ( 13 volts) ~ 300 watt charge rate, both day and night.

If you wanted to "make it behave the same way", you could use a 1 kW inverter, 2 each 100 amp-hr batteries, and perhaps 400 watts of solar at the dock to do it.

If you want to do it with just solar panels only, and be ready quickly, then you will need something more like:

- 30 amp solar charge controller
- 600 watts of solar, possibly some facing morning and some facing later in the day

It looks like you have 10 awg wire in most of it. Perhaps add some fuses.

 

[HarryN]

Here is a little goof around project I am doing in my garage that you can use for ideas if you like. Not too far off from what you are doing.

Small test fixture

Sometimes it is easier to show people things in photos than to describe them. So I made a little test fixture from left over parts, nothing fancy. In this case, some people asked about methods of dealing with pre-charging the capacitors on the input stage of inverters, and I had suggested that...

diysolarforum.com

 

[tpenfield]

Looks like the Sportman charger needs 120v AC input. So the short answer is no, you need something else.

To go with solar charging, you will want a solar charge controller to manage the charging of the batteries from the solar panel.

As mentioned, other questions would be:

> How often do you plan to use the boat/trolling motor? Back-to-back usage may be a problem as there would be little time to re-charge the batteries from solar.

> I assume it is a power boat? The engine alternator could provide some power for charging the trolling motor batteries while going to/from the fishing spot, but it may not be enough.

> Do the batteries need to stay independent of each other?, or are they combined? 12Volt or 24Volt trolling motor?

> How much space do you have to put a solar panel? T-top, deck, etc? That will determine how much solar charging you can get.

 

[Joe I]

In general, batteries can be charged from solar, yes.

But we'd have a lot more questions about the application. A trolling motor is a large load. How long do you want it to run per re

Looks like the Sportman charger needs 120v AC input. So the short answer is no, you need something else.

To go with solar charging, you will want a solar charge controller to manage the charging of the batteries from the solar panel.

As mentioned, other questions would be:

> How often do you plan to use the boat/trolling motor? Back-to-back usage may be a problem as there would be little time to re-charge the batteries from solar.

> I assume it is a power boat? The engine alternator could provide some power for charging the trolling motor batteries while going to/from the fishing spot, but it may not be enough.

> Do the batteries need to stay independent of each other?, or are they combined? 12Volt or 24Volt trolling motor?

> How much space do you have to put a solar panel? T-top, deck, etc? That will determine how much solar charging you can get.

Thank you for the insight...

I would be using the boat/trolling motor on back to back days over the weekend.

I don't think the batteries need to stay independent of each other.

There isn't a ton of space on the dock as it's shared. My thought was to mount it on an arm to the boat lift.

 

[Joe I]

Assuming your current batteries can run your motor for 8 hours, it would take about 300W of solar to charge them from 50% to 100% if left on charge for a full day. If your plan is to fish for one day per week, and let them sit charging for 6 days, I would recommend a 100W panel.

If you want to go fishing more often, or consecutive days, then the best option is to buy an LFP battery (smaller, lighter, and more run time) and take it home to charge overnight. And if your current batteries don't last 8 hours, then for sure, get LFP.

Thank you, might need to consider the LFPs. I do t know much about those, so will need to look into it as an alternative.

 

[Joe I]

I have the dual pro version of that charger - fantastic setup and really does a nice job of charging and keeping everything in balance.

The trick with solar charging is that it happens during the daytime only, while that charger plugged in charges 24 / 7, so you can go fishing during the day and have it ready to go by morning. Solar alone cannot easily do that.

So that gives you a couple of options:
- Put enough solar near the dock to charge as quickly as possible during the day hours
- Put some solar + battery + inverter near the dock to charge that up at a modest pace, and then just plug your existing boat setup into it like you are doing now.

Right now, you are getting a nominal ( 10 amps ) x ( 2 charge ports ) x ( 13 volts) ~ 300 watt charge rate, both day and night.

If you wanted to "make it behave the same way", you could use a 1 kW inverter, 2 each 100 amp-hr batteries, and perhaps 400 watts of solar at the dock to do it.

If you want to do it with just solar panels only, and be ready quickly, then you will need something more like:

- 30 amp solar charge controller
- 600 watts of solar, possibly some facing morning and some facing later in the day

It looks like you have 10 awg wire in most of it. Perhaps add some fuses.

Thank you for the information. I don't have much dock space and I don't know if a 600 watt panel could be mounted to the boat lift so maybe I need to reconsider my options.

 

[Supervstech]

If it were me, i would order a chins 24v LFP battery, 1 or 200Ah put a 200W or so panel and a good charge controller onboard, and have a battery that can handle two days without charging, then leave it on the dock charging during the week.

 

[wholybee]

If it were me, i would order a chins 24v LFP battery, 1 or 200Ah put a 200W or so panel and a good charge controller onboard, and have a battery that can handle two days without charging, then leave it on the dock charging during the week.

I agree. This is the direction the OP needs to consider.

 

[Joe I]

Thanks. A little expensive but seems like a workable solution. Would using the existing batteries with a panel and controller not work? Why a Chins? Any recommendations for the panel or controller?

 

[wpns]

Can you put the solar panels on the boat?

 

[Joe I]

It has a cover on it and a canopy so it would get much sun (see attached)

 

[wpns]

It has a cover on it and a canopy so it would get much sun (see attached)

So mount the panels on the top of the cover and have a (weatherproof) DC disconnect.

 

[SparkyGage]

How does the boat lift get power? (opps, scratch that, I see the crank wheel now)

For reference, I get about 10-14 hours of ACTUAL run time on a 86lb thrust motor varying between 2/5-4/5ths throttle on my sailboat. I carry the battery home and charge there. I have quick disconnects to just plug it at home and boat. While the battery isn't exactly light, I've not gotten tired of lugging it back and forth. It weighs less than that 12v Interstate (I have the same one for other purposes).

When you say 8 hours, is that 8 hours running it constantly, or 8 hours with maybe 4 hours usage and much of that usage part throttle?

 

[tpenfield]

What @wpns said . . . looks like the boat lift awning is plenty large for good solar. Getting some LiFePO4 batteries will get you the most capacity vs. the lead acid batteries so you can go for 2 days between re-charging. You'll need to figure out how many solar panels you will need to get decent charging during the weekdays.

I think you are talking . . .

> Solar panels
> Solar controller
> 2-LFP batteries (looks like you have the batteries in series with a 12v tap, so getting both 24 & 12 volts from the batteries.)

Is it a 24 volt trolling motor?

 

[HarryN]

It looks like you are using it for both an engine start and electric trolling motor battery pair ?

So 12 volt for each one ?

So as long as the charge / discharge amps works, you can pick a variety of batteries.

Don't under estimate how much current an engine uses to start. If the motor's alternator disconnects from the battery pack for some reasons, then it will blow out most alternators. ( for example if the BMS trips )

It might be possible to pull it all off with one battle born game changer battery.

Depending on how much you are using the gas engine vs trolling, it might even be possible to get enough solar charge out on the water by putting a panel across the flat area at the bow.

 

[Joe I]

What @wpns said . . . looks like the boat lift awning is plenty large for good solar. Getting some LiFePO4 batteries will get you the most capacity vs. the lead acid batteries so you can go for 2 days between re-charging. You'll need to figure out how many solar panels you will need to get decent charging during the weekdays.

I think you are talking . . .

> Solar panels
> Solar controller
> 2-LFP batteries (looks like you have the batteries in series with a 12v tap, so getting both 24 & 12 volts from the batteries.)

Is it a 24 volt trolling motor?

It is a 24v trolling motor

 

[tpenfield]

It is a 24v trolling motor

Thx . . .

One complexity that you may want to consider is that LiFePO4 batteries will be good for having enough power to run for 2 days, . . . but . . . The boat motor (looks like an outboard ? ) may not be LiFePO4 'friendly'. Some of the newer boat motors have smart alternators, yet most in operation at this point do not. Some of the LiFePO4 batteries claim to be 'drop-in' compatible . . . perhaps debatable .

You may find that 2 separate battery banks may be the way to go . . . a 'standard' (lead-acid) battery for the outboard and the remaining 12 volt systems and the LiFePO4 (24 volt) bank for the trolling motor.

Otherwise . . . you would need about 2 - 3 times the battery capacity that you have now in a lead-acid configuration and use solar charging, but it could be simpler in the long run.

 

[HarryN]

Since you have:
- A 12 volt starter battery requirement.
- 24 volt trolling motor requirement
- A dual out put, 12 volt / 24 volt charger that is pretty nice
- Just want to add a way to charge the trolling motor aspect

_________________

Basically what you are doing now is using the dual output charger to make up for your setup going out of balance every time you use the boat.

_________

I would be tempted to keep one of the existing batteries as the motor starter battery

Since you are in IL and probably go fishing until the lakes are frozen over, I am mixed about suggesting LiFe batteries as they loose the ability to charge below freezing.

The battle born batteries allow discharge below freezing down to ~ 10 F even when charging is blocked by the internal BMS, so that might be a useful feature.

It is kind of a pain if the engine won't start due to a low starter battery charge. There are some modest rate 24 - 12 volt DC chargers on the market that can help to keep it charged up from the 24 volt trolling motor battery arrangement.

Or if you use a pair of 12 volt batteries wired in series ( AGM or Li ) it might be possible to jump start the motor. The sportsman will re-balance as needed.

 

[HarryN]

There are some roll up solar panels that potentially could hang from your boat cover and charge a battery on the dock in a box.

Use a battery to battery charger to charge the boat at night.