Solar Pontoon Boat Controller Parameters

[Crabby R]

Hi. I'm new but very interested in figuring this out. I have watched William Prowse's videos and I got inspired to make my own solar pontoon boat. I have a big flat roof on the boat that is perfect for solar panels so I put 8 of them up there. I have it all wired now but I have questions on setting the Solar Controller Parameters for deep cycle lead acid batteries. (I'm not going to buy lithium yet.) It's not in my budget. Maybe in 5 years.

So.....
Solar Controller Parameters for my electric solar pontoon boat project:
I have eight 100 watt solar panels on the roof. 4 panels wired in a series for a 48 volt system. The other 4 panels wired the same and then connected in parallel to the other 4.
I live in Central Florida so I have full sun most of the day (and the temperature can get as high as 95 degrees F for several months straight. (35 Celsius)
I have a 60 amp MPPT Solar Controller mounted in a waterproof box with a vent and a fan.
I have four 75 ah DEEP CYCLE flooded lead acid “Energizer” brand batteries wired in a series to be a 48 Volt. Since I am using Deep Cycle (not starting or combo marine batteries) does that mean I can discharge them to a lower voltage without damaging them? This is where I'm most confused.
I have an electric boat motor on order that is 48 volts and will draw a lot of amps. I will limit it at 60 amps because my goal is to troll with it at around 5-6 mph about once a week and have the solar panels recharge the batteries during the week. (I have everything wired with 6 gauge wire and a 70 amp breaker.) It would be great if I could get 3-5 years out of these batteries so I don’t want to damage them. I think I will only actually be running at 30-40 amps but I'm not sure yet.
Solar controller options that I need help with:
I set the controller as 48 volt 60 amp max.
So now I need to program the rest because I don’t trust the default settings.
Charge Voltage Settings:
Floating ____V
Equalizing ___V

Discharging Limit Vol. Set
Voltage Value ____V
Set Limit Value ____V

Low Voltage Protecton ___V
High Voltage Protection___V

There might also be some settings that ask for voltages under load. I’m not at the controller right now.

Any help is much appreciated!
I will post pictures when I get it operating.

Crabby R

 

[SolarRat]

This is probably in the ballpark for charging (It's very close to what my on-board mains marine charger puts out). I expect a lot of voltage sag on that battery bank at the amps you are talking about drawing, so the low voltage cutoff will probably have to be tweaked after testing under load. I think you are quickly going to want more battery capacity...5mph on a pontoon requires much more juice than I expected.

I'm going to be starting a similar project soon so please keep me up to date with your progress and findings!

What motor did you order, a Torqeedo?

 

[Crabby R]

This is probably in the ballpark for charging (It's very close to what my on-board mains marine charger puts out). I expect a lot of voltage sag on that battery bank at the amps you are talking about drawing, so the low voltage cutoff will probably have to be tweaked after testing under load. I think you are quickly going to want more battery capacity...5mph on a pontoon requires much more juice than I expected.

I'm going to be starting a similar project soon so please keep me up to date with your progress and findings!

What motor did you order, a Torqeedo?

Hi thank you for the help. I ordered what is supposed to be a 20 horsepower electric outboard from Goldenmotor.com. it was about $3,500 total instead of the $9,000 that the big torqeedo cost. Chinese made so hopefully it holds up. I'll let you know how it works when I get it installed. I read about it and it has an amp limiting feature when you set it up via Bluetooth and an app on your phone.

 

[SolarRat]

I just looked up that motor, nice! I'll be very interested in what you have to say about it. I'm wondering how the "gearless transmission" works? Belt drive? I'm also wondering about the speed control, resistors?

Just thinking out loud here, for my own understanding as much as anything...

Since it's 10kw and only 3 speeds we can assume the 3rd speed draws 10kw, and guess 3kw and 6kw for the others. So, on low speed it'll draw 3kw @ 48v or 62.5 amps. Just a guess, it could be higher or lower.

You have a 48v 75ah bank. Keeping it to 50% DOD you have ~38 AH usable....or about 35 minutes of run time on low speed, whatever that may be.

These calculations are why I haven't started my boat yet...the batterie$ are the huge limiting factor on practicality.

In the future you may want to add a PWM speed control to give you infinite speeds, allowing you to go below 1kw for slower speeds and greatly increase run time. For example, my 21' pontoon does 2.5mph using "only" 600w (probably more like 3.5mph with a clean bottom, but mine has been in the water 14 straight months and has some growth). I'm guessing it will take me about 5kw to do 5mph (it takes a lot more power for a little more speed). I'm only running 12v, so that 600w is 50 amps for me, but you'd only be drawing 12.5a. And your panels can probably supply that most of the day.

If my math is wrong, someone please correct it (boy I hope it's wrong).

 

[Crabby R]

I just looked up that motor, nice! I'll be very interested in what you have to say about it. I'm wondering how the "gearless transmission" works? Belt drive? I'm also wondering about the speed control, resistors?

Just thinking out loud here, for my own understanding as much as anything...

Since it's 10kw and only 3 speeds we can assume the 3rd speed draws 10kw, and guess 3kw and 6kw for the others. So, on low speed it'll draw 3kw @ 48v or 62.5 amps. Just a guess, it could be higher or lower.

You have a 48v 75ah bank. Keeping it to 50% DOD you have ~38 AH usable....or about 35 minutes of run time on low speed, whatever that may be.

These calculations are why I haven't started my boat yet...the batterie$ are the huge limiting factor on practicality.

In the future you may want to add a PWM speed control to give you infinite speeds, allowing you to go below 1kw for slower speeds and greatly increase run time. For example, my 21' pontoon does 2.5mph using "only" 600w (probably more like 3.5mph with a clean bottom, but mine has been in the water 14 straight months and has some growth). I'm guessing it will take me about 5kw to do 5mph (it takes a lot more power for a little more speed). I'm only running 12v, so that 600w is 50 amps for me, but you'd only be drawing 12.5a. And your panels can probably supply that most of the day.

If my math is wrong, someone please correct it (boy I hope it's wrong).

That is very good info! Thank you. Yes I thought it was strange it only had 3 speeds instead of infinite. Anyway yes if it draws that many amps I'll definitely be looking at better batteries. I appreciate you doing all that math for me. I'll let you know how it works out in real life when it shows up. I actually have 4 12 volt batteries in a series (each battery 75 ah.) Does that mean I have only 75 ah total or 300? (I just looked that up on the internet and now I understand I have a 75 ah bank.)

 

[SolarRat]

Yup, 75ah and 3.6kw (1.8kw usable). With your motor and battery you could probably make a 65mph golf cart....or a 5mph boat

I'm really hoping, for both our sakes, that your toon will hit your target 5-6mph speeds on low speed. If it does and it were me, I'd probably install a PWM speed control ASAP, maybe even before more batteries. You have to decide how much you want to spend on a battery system that you'll be stuck with for a long time...ie, is it worth buying 4 or 8 or 12 more identical FLA's, or is it time to cut bait and start looking for a crashed Tesla, Leaf or Bolt. That's my hardest decision right now, because I know the right answer and it's an investment.

 

[Crabby R]

So it took forever for the 20hp electric outboard to come in. (From Goldenmotor.com) I got it hooked up and yes SolarRat is right. I've got too much electric motor for my 4 deep cycle lead acid batteries and 6 awg wires. Fortunately the motor connects to an app that lets me set the max percentage of motor power in eco mode. When I set it 20% of max power I can move the throttle lever slowly all the way up to full throttle and it limits itself to about 1000 watts which pushes my 24 foot pontoon boat at 3.5 mph. ? This appears to be the limit because when I put it on regular mode and push the throttle up past 1000 watts my voltage drops below 45 and the motor cuts itself off to save my batteries. (It immediately resets so I guess it's just a warning to slow down or quit discharging the batteries.)
Imagine if I had a big lithium battery setup. I could access the other 80% of the motor power.
Anyway I'm glad I have excess motor capacity. Unfortunately it'll be next to impossible to match that capacity with the batteries. I'll have to be happy with 3.5 mph for now. ?

 

[SolarRat]

Thanks for the update! Since my earlier posts I removed my 12v 50amp motor and installed a 36v motor I got for basically free. On the same pontoon boat (with still dirty pontoons) I am now getting a max of 4mph at 32 amps (1150w), but 3.5-3.7mph is more realistic. When I set my PWM to just 20 amps (720w) I get a reliable 3.2mph and almost 3 hours run time (no solar installed yet) from my 3x 105ah deep cycles before hitting 50% DOD.

What I noticed is that when I back it down to 600w I'm still at about 3mph reliably compared to the 12v motor's iffy 2.5mph speed at the same 600w draw. Not sure if that is due to a more efficient motor (both are Minn Kota) or because of the larger prop. Wind and tide doesn't seem to change my max speed much so I assume the prop is made for 3.5mph and is maxed out...so I should be able to install a higher pitched prop to get another MPH or so (the motor is rated to 46 amps which i can't hit with this prop).

It seems our speed vs. watt #'s jive pretty close with each other, so I'm really interested to see what your motor can do with some bigger batteries or with your solar helping out your current bank (or is it already?).

How do you like the motor so far? Quality? Noise level?

 

[starpowered]

When I set it 20% of max power I can move the throttle lever slowly all the way up to full throttle and it limits itself to about 1000 watts which pushes my 24 foot pontoon boat at 3.5 mph.

Great project! Very interested in a similar project at some point.

At 3.5 mph what is the run time?

 

[SolarRat]

I'm probably going to install a simple 120v to 36v 40 amp power supply OR golf cart type battery charger on my battery bank, so if I want to take a longer trip out to the Gulf I can bring along my little 2000w inverter generator and turn it into a hybrid system. If you have a little genny and charger lying around maybe you could do something similar in order to fully test that motor's capability?

 

[Crabby R]

Great project! Very interested in a similar project at some point.

At 3.5 mph what is the run time?

Not long. I only have four 75 ah deep cycle lead acid batteries. At 3.5 mph it will push the boat for about 2.5 miles before the batteries are getting down close to 50-60% charge. Which is not bad for a sunset cruise. Plus the 8 100 watt panels on the roof charge it back up the next day. I really could use at least four more of the same batteries. My goal is to get 5 mph and I'm sure the outboard motor could do it however I'm going to need an expensive lithium battery bank to do it. I'll probably use what I have for a couple years and then look for a lithium battery next.

 

[Crabby R]

I'm probably going to install a simple 120v to 36v 40 amp power supply OR golf cart type battery charger on my battery bank, so if I want to take a longer trip out to the Gulf I can bring along my little 2000w inverter generator and turn it into a hybrid system. If you have a little genny and charger lying around maybe you could do something similar in order to fully test that motor's capability?

That's a great idea. I already have a 2000w honda generator. I might be going hybrid too!

 

[Supervstech]

This is great info. Let’s me know how crazy important batteries are to the moving of a boat... I watch some videos of guys that built their boats, but hadn’t seen any math or descriptions of the requirements.
can you post some pictures of your build? Motors? Etc... I’m a dry sponge on this stuff, and would love to have more info for my distant plans.

thanks!

 

[Crabby R]

I'm probably going to install a simple 120v to 36v 40 amp power supply OR golf cart type battery charger on my battery bank, so if I want to take a longer trip out to the Gulf I can bring along my little 2000w inverter generator and turn it into a hybrid system. If you have a little genny and charger lying around maybe you could do something similar in order to fully test that motor's capability?

SolarRat, I was just browsing ebay and I saw this batch of nissan leaf lithium batteries. They would provide 7 kwh at 48 volts. (I calculate that to be 146 amp hours) The listing states that these batteries are at 60%???? Anyway my current lead acid setup is 4 75ah batteries in a series so I only have 75 amp hours at 48 volts.

Nissan Leaf 48v Battery G1 Lithium Ion 7 kWh 500 watt per module Lot of 14 | eBay

Find many great new & used options and get the best deals for Nissan Leaf 48v Battery G1 Lithium Ion 7 kWh 500 watt per module Lot of 14 at the best online prices at eBay! Free shipping for many products!

www.ebay.com

Am I correct in assuming that the nissan leaf batteries would be 1. lighter in weight. 2. provide more current when needed with less voltage drop. 3. provide double the amount of run time because there are more amp hours AND lithium can be drained to 90% of battery capacity without hurting the batteries????
I just want to verify my thinking on this.
Thank you!!!
Crabby R

 

[Supervstech]

SolarRat, I was just browsing ebay and I saw this batch of nissan leaf lithium batteries. They would provide 7 kwh at 48 volts. (I calculate that to be 146 amp hours) The listing states that these batteries are at 60%???? Anyway my current lead acid setup is 4 75ah batteries in a series so I only have 75 amp hours at 48 volts.

Nissan Leaf 48v Battery G1 Lithium Ion 7 kWh 500 watt per module Lot of 14 | eBay

Find many great new & used options and get the best deals for Nissan Leaf 48v Battery G1 Lithium Ion 7 kWh 500 watt per module Lot of 14 at the best online prices at eBay! Free shipping for many products!

www.ebay.com

Am I correct in assuming that the nissan leaf batteries would be 1. lighter in weight. 2. provide more current when needed with less voltage drop. 3. provide double the amount of run time because there are more amp hours AND lithium can be drained to 90% of battery capacity without hurting the batteries????
I just want to verify my thinking on this.
Thank you!!!
Crabby R

yes to all your points, but leaf are lithium ion, so charge parameters are CRITICAL... fire out on a boat is a bad thing to be sure!

 

[SolarRat]

I've been keeping a close eye on the used EV batteries, and they are getting cheaper and cheaper every few months. I've seen some good deals on the Leaf batteries but I would stay away from the Leaf generation 1's (2012 I believe). They had many problems with lifespan and also had many lawsuits. I"d stay away from any battery that only has 60% capacity remaining because that will quickly diminish to 50%, then 40& etc...

$765 for those batteries seams like a great deal but at 60% capacity they are only a 4.2kw battery and getting smaller by the day. Still probably a better deal than some mystery ShunBin battery, but I think the longer we can wait the more options we will have. I don't mind spending a few hundred on good lead acids while waiting.

I've seen some crashed 2013+ Leafs sell in the $2500 range with decent batteries. When I pull the trigger on lithium to replace my trusty FLAs, I want to do it all at once and get a pack that will last me a decade. I'm thinking 40kw+. I don't want to piecemeal it with 10 cells from one car, 5 from another, 14 from another etc. I don't hear much about the Chevy Bolt batteries but I think they are better than the Leaf cells, and can be watercooled (may be important on my boat in Florida when I install larger draw motors, and may be easy to rig a cooling system using seawater through a heat exchanger).

As more and more electric cars hit the road, more and more also end up in the scrap yard. So the future looks good for cheap batteries...we're just not quite there yet.