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Discussion Starter · #1 ·
Starting this thread to document the full Solar Boat Conversion Project. Always looking for good advice.

The Concept

1) I will eventually be converting a nice 40 Cat or displacement Hull to Electric. Needed a project boat to experiment on first.

2) I found this 23 foot boat for $1800 + Trailer delivered to my house. It is a 1971 Uniflight. The early versions of the Uniflight are know for rock solid Fiberglass hulls. It will be stripped down to the Hull and Completely remodeled.
122395

Requirements

  • 50 to 100 mile range min at Cruise Speeds.
  • Charge from Solar when Moored or at sea. Targeting 3kWh array.
  • Charge from 50amp 240vac (or less) Shore Power when docked

Initial Research
This got interesting very fast. Here are some basics.

With current technology, you will not get a larger boat up on plane. This would require about 200hp for a 4300lb 23 foot boat.
1kW of electric motor appears to = ~1.34 HP Gas. However we need to acknowledge that Gas HP at the Prop is fractional of what most gas motors are rated for.

We would need a 149kWh motor (200hp) to get this on plane. if I did the math correct.
  • At 48v = 3000amps
  • At 96v = 1552amps
  • At 144v = 1034amps
Clearly this is not going to happen…. OK. Back to reality. Even if once on plane I would need less HP. I would never be able to get enough amps to get on plane and would chow battery to stay there. I will have to be happy at SUB plane speeds. Displacement only.

I had to learn about displacement max. Radically simplified. At a certain speed, a boat will just push water out of its way. This is your displacement hull speed. Above that speed the boat is trying to lift out of the water and get onto plane. Until on plane you only get 2ish miles per hour faster every time you double your current power. Very depressing. And this boat is not a displacement hull. I will be pulling lots of water behind me. May modify it. Found info on how to do this.

Found this calculator which let me start some calculations Vicprop - Prop calculator for Displacement and semi-displacement hulls

My 23 foot long boats Hull Speed is ~7mph. Assuming I would need a battery the size of a standard Electric Vehicle, did the math below with an 85kWh battery using the info from Vicprop.
  • 6.8kw motor -10hp = 7mph, 86 miles, 12 hours run time (more like 5mph to 6mph since not displacement hull)
  • 12kw motor - 16hp = 8.4mph, 60 miles, 7 hours run time (more like 6mph to 7mph since not displacement hull)
  • 24kw motor - 32hp = 10.4mph, 37 miles, 3.5 hours run time. (more like 7mph to 9mph since not displacement hull)
Decision time – 48v, 96v, 144v motor
Basic research shows that 48v, 96v and 144v EV motors are quite common the web. They come in Permeant Magnet and AC Induction.

One motor that kept on surfacing over and over was the Montgomery Motor 1616 (ME1616). It is a 55lb Beast that can run water cooled continuously at 250 amps up to 96v. This would get me a 24kWh motor (32hp). The same motor could be ran at 48v, 250amps for 12kWh (16hp)
There were several AC induction motors such as the AC50/51 that run at 144v. At 250amps continuous I could get 36kWh.

48v
PROS
  • Lots of Proven high end standard equipment for solar / shore charge / Inverter..
  • Safer
  • Will get almost any 30 foot boat up to Hull Speed
CONS
  • May be under power in wind or chop
  • No ability to blow thru battery for faster short trips
96v

PROS
  • Extra Power when needed in wind or chop
  • Ability to burn battery for short trips at faster speeds
  • You still can run at Hull Speed for long trips
  • May be necessary to get my final 40 foot boat to even Hull Speed
  • Smaller wires
CONS
  • Less Safe, Higher Voltages
  • Significantly more thought needs to go into Safe factor.
  • Very Little proven standard equipment
144v

PROS
  • Power…
CONS
  • Getting dangerous
  • Even with the extra power. Would still only be at 12mph Max
  • At max power only 1.5 hours to kill full 85kWh battery
  • While there are EV parts to charge the 144v. Could not find any Solar equipment or inverters to hook up to the battery. Became apparent fast this would be a Shore Power only charging boat.
The Verdict - 96v.
  • 48v – While it will get me to hull speed, it will be underpowered and not safe in anything but flat water. I would not feel confident for bigger trips on open water. I do believe this would be the no brainer choice for many though due to all the options available.
  • 144v will make going solar extremely complicated. I am also not willing to go this voltage in a marine environment
  • 96v - I have to figure out how to make 96v Work. It is the happy middle ground and will also be scalable for my final 40 foot boat. Sadly, I could not find any blogs about this. Hence this thread.
Let the Journey Begin
 

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Discussion Starter · #2 ·
Battery

I have already come to the conclusion that I would need ~85kWh to make the electric boat more than a toy for a small lake. This is on par with the size in many electric vehicles.

I am disturbed by my initial findings.

Food for thought
  • Premium batteries such as Victron at the time of writing this go for about $1 per kWh. 85Kwh would cost you $85,000
  • Used Batteries. Mind blown. 85kWh of used Tesla Modules would be about $50k to $90k depending on age / source.
  • Even Amazon “Cheapos” LifePO4 cost about ~$0.60 per kWh.
Ponder this: A brand new standard Tesla Model 3 cost about $55,000. You could hire a mechanic and electrician for $30,000. They could strip the Battery, Motor, Controller, Charger, BMS and more. You would have every part you need and it would be better than anything you can buy.
And when the Cyber truck is release for $35k, there would be 0 reason to ever buy “EV” parts again. Just get a new cyber truck and a mechanic to strip all parts for your EV for ½ the cost.

My Brain just exploded. The cheapest way to make and EV is to buy a new Tesla and hire a mechanic to strip the parts. I hope reality will catch up to EV part pricing soon.

Where to go ☹

Since this is an experiment. I need to find a reasonable LifePO4 option. After days of searching the web, I found good reviews for these massive 280ah cells. They are sold by following brands. Just search this forum for much discussion. From China so you mileage may vary....
  • Lishen,
  • CATL
  • EVE.
They are cheap and don’t look durable. Regardless, shipped to my Door, I could get 85kWh for under $9000.

The Deed is done – HELP PLEASE

For good, bad or worse, I purchased 100 Lishen 280ah cells. 96 of these will be about 85kWhs and weight 1200lbs.

They will be shipped with
  • 3x the number of bus bars
  • Double posted stainless Studs vs Screws
I will use Loctite and recommended torque to fasten double sided studs. Many posts on this topic but always Open for discussion. It is ok that Loctite will insulate studs where inserted. 1) Studs are stainless and not much conductivity 2) The bus bar on the terminal is where the connection happens. I will also use Silver grease on terminals 3) Never coming loose and creating a firm connection is paramount for safety.

Decision time – Need Feedback
I need the ability to do 250amps from final 96v pack sustained and 400amps peak surge

Option 1
  • Create 6 16s 48v banks and put them in 2s3p (3 96vbanks in parallel once done)
  • Each bank would weight about 200lbs.
  • Each 48v pack would need a 150amp BMS to get the 400 for the full pack
Pros
  • More BMS options
  • Smaller packs
  • Easier to compress – Lots of info on youtube and this forum on doing this.
Cons
  • Would need 6 BMS monitoring screens. Unless somebody has a solution where one screen can monitor 6 separate BMS vis wifi or Bluetooth. Thus far I cannot find this. - any recommendations?
Option 2
  • Create 3 32s 96v Banks and put them in 3p. Each pack would weight 400lbs.
Pros
  • Only 3 BMS required. Each would still need to be able to handle 150 amps - any recommendations?
Cons
  • Massive packs would need to be assembled in the boat.
  • Harder to compress
More questions
Would love feedback on
  • BMS for 150amp 48v and 96v. Industrial is better, needs the ability to monitor. Any recommendations?
  • Regardless of size. Each pack will have its own ON/OFF 150amp breaker switch. Any recommendations?
  • Any other advice please.
  • Battery Boxes??? Any recommendations?
 

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Discussion Starter · #3 ·
96v BMS and Charging system - Need Help / Advice

As all my past experience have been with House Solar, I have been gravitating to similar equipment, I am quickly learning though there is an entirely new world in the EV space better suited.
  1. There will be 85kWh of LifePo4 Batteries. 96 cells
  2. I was gravitating to 3 32s 96v Batteries that would be ran in parallel. Would allow 3x redundant. 2 packs could be taken off line if needed. (THIS CAN BE CHANGED)
  3. The EV will have a standard Split Phase 50amp 240vac Shore inlet as power source.
    1. NOTE: Depending on where parked. Shore power may only offer 30amp 120v or 15amp 120v service.
    2. Charger needs the ability to work with both.
This is where I am lost and fear my Solar experience is leading me down the wrong path. HELP!!!

My knee jerk was Each 32s Battery would have its own 32s 200amp BMS. The 3 packs would then be hooked up to a 96v Inverter/Charger. This is current Plan.


Concerns - Would love your advice
  • These are unproven likely not very robust parts made for Solar setups
  • I feel like there are robust proven EV solutions for 96v
  • Will not utilize the full 50amp 240vac Shore hookup - will max out at ~2500 ish Watts charging
Would love to get feedback on 96v BMS / Charging setups
  • Sadly, I do not even know where to begin help me!!!
  • Basic research suggest there are systems where the charger talks to each Battery BMS.
  • How would the charger hook up to a 50amp 240v split phase breaker box vs Charging station inlet
  • Would the charger be able to handle power if it was only 120v. (30amp shore power or 15amp shore power) how would it know to step down?
  • See such great potential here and do not want to try to re-invent the wheel as this 96v setup must be basic in the EV world

Thanks
 

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Discussion Starter · #4 ·
96v Motors - More Advice Needed

Scenario

On perfectly Flat water with no wind, I will only need about 10kW to keep Hull Speed.
  • But.. when is it ever perfectly flat with no wind.
  • I will have a 85kWh Battery that can do 500amps at less than 1C.
  • Most trips will be under 20 miles so not afraid to just chow thru battery for small speed gains
  • Want the ability to maintain hull speed even in wind / chop
  • This is a test system for a much larger boat
  • I can re-gear to get 1900 RPM (Belt system)
Due to the above, I am looking for the most powerful 96v motor/controller that can run continuously at 250 amps. 96v * 250amps = 24Kw motor.

Preliminary research is leading me to these options. But I may be missing a lot. Any feed back on AC induction vs Water cooled Permeant Magnet?
  • What runs better at sustained load
  • what are more robust

ME1616
Motors DC and PMAC :: ME1616 - would be coupled with a large Curtis controller.

AC-50 / AC-51 AC Induction Motor Drive

Would love your feedback

Thanks
 

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I think you've made some mistakes in your calculations, and you would've been well served to ask questions before committing to battery purchases. I'm not sure you would've made the same choices had you gotten some of this a bit more correct.

You've made some interesting choices and limitations, atypical ones I would say.

Lots of detail, I'll try to fill in later if no one else has.
 

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Discussion Starter · #6 ·
I think you've made some mistakes in your calculations, and you would've been well served to ask questions before committing to battery purchases. I'm not sure you would've made the same choices had you gotten some of this a bit more correct.

You've made some interesting choices and limitations, atypical ones I would say.

Lots of detail, I'll try to fill in later if no one else has.
You have my full attention. Would love to hear your thoughts. Here to learn. Thank you. Very new to EV world and likely stuck in solar realm. Better EV specific stuff likely exists.
 

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2) I found this 23 foot boat for $1800 + Trailer delivered to my house.
The cheapest way to build something is to buy someone else's abandoned project. You bought a trailer and it came with a free boat.

At 144v = 1034amps Clearly this is not going to happen…. OK. Back to reality. Even if once on plane I would need less HP. I would never be able to get enough amps to get on plane and would chow battery to stay there.


1034 amps is not outrageous. 144v is low for an EV (and, double the voltage, half the amps for the same power).

Decision time – 48v, 96v, 144v motor Basic research shows that 48v, 96v and 144v EV motors are quite common the web.
Yeah, but I don't think that's a cost effective way of going about it.

They come in Permeant Magnet and AC Induction.
Odd, usually you see Series Wound DC (not Permanent magnet) or AC Induction, or Brushless DC in EVs.

48v PROS Lots of Proven high end standard equipment for solar / shore charge / Inverter..
Almost all the builds I see have people swearing at stupid marine voltage (or RV voltage) equipment and being so happy when they went to a normal 120v or 240v inverter system and just used regular appliances.

I wouldn't let it affect my decision to stick with lower voltage stuff. You should be able to find plenty of options at any voltage.

The Verdict - 96v.


I think 96v is silly. I wouldn't be scared off by higher the voltage, you're not scared off it in a house. Most EVs run near 400V. It's far easier and cheaper to make controllers that way. I don't know if I've ever seen a 96v build that wasn't a golf-cart speed vehicle or a motorbike.

Premium batteries such as Victron at the time of writing this go for about $1 per kWh. 85Kwh would cost you $85,000
Typo, you meant $1000/kWh.

And, I'm not sure why you'd think this. I've never seen anything close to this. You come up with this conclusion about it being cheaper to buy a whole new car than to buy battery. Definitely not true.

Random non-endorsed ebay option for an 85kwh pack: TESLA S 2015 Battery 247606 | eBay

$17k, buy it now. 20% the price you quoted.

Since this is an experiment. I need to find a reasonable LifePO4 option. They are cheap and don’t look durable. Regardless, shipped to my Door, I could get 85kWh for under $9000. The Deed is done – HELP PLEASE
Good deal, for probably not great batteries.

Most people usually their batteries last, as it's the biggest expense and the thing you take the most time to shop for.

BMS for 150amp 48v and 96v. Industrial is better, needs the ability to monitor. Any recommendations?
400V (or, 316 or whatever LiFe adds up to) and run a standard EV controller and use their BMS.

NOTE: Depending on where parked. Shore power may only offer 30amp 120v or 15amp 120v service. Charger needs the ability to work with both.
I think just about any EV charger could run on almost any controller and be configurable for whatever power limits you want. 240v, 120v, 10a, 15a, 30a, 50a, whatever. A 240v 50a is just a standard EV level 2 charger. Fairly cheap and rather universal.

You seem more like a spend-it kind of guy than a save-it kind of guy, but there are starting to be some really cheap repurposed hybrid controllers to perform charging duty. Like, $150 + a few hundred for the controller cheap.

My knee jerk was Each 32s Battery would have its own 32s 200amp BMS. The 3 packs would then be hooked up to a 96v Inverter/Charger. This is current Plan.


You shouldn't, but if you insist, hook up each of the 3 batteries in parallel before connecting those up in series, and you would only need a single BMS. The cells in parallel will be balanced automatically by virtue of being in parallel.

On perfectly Flat water with no wind, I will only need about 10kW to keep Hull Speed.
This is light duty for an EV. That's only 13 horsepower. Almost any EV should have no problem sustaining double that, indefinitely, let alone sprints. By the time they heat up enough to be a concern, the battery would be dead anyway. Heck even forklift motors are rated higher than that for continuous duty, and that's at their default voltage.

You could run a tiny little Prius drivetrain to plentifully meet your needs. (Good for hundreds of horsepower short term).

I have no recommendations for a 96v 250A motor. I don't think I've seen anyone pursue something that minor.
 

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Don't have much to add other than to say I really enjoy these boat builds. For your project since the vessel will only be powered by batteries and nothing else (no sails or ICE) then I agree you should look into repurposing an EV car because of the way higher power and efficiency. You should also probably buy a cheap trolling motor and 10 gallons of gas before your maiden voyage too haha! :D

As for charging, solar is the obvious option, but a less obvious choice is wind power! There are tons of small wind turbines from 500W on up to several KW that might work great for this project. Wind is usually plentifu near water and also sometimes goes through the night!
 

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Another option for wind, is to use the propeller as a generator. When wind is high, move a little and recharge the batteries. When wind is gone, use the batteries.

Probably not practical for this boat, but you mentioned this is just a stepping stone to some eventual future project.
 

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this thread over here at Endless Sphere seems like it might be sort of relevant given the size/weight of both of your watercraft : Shamrock, 25 foot sailboat electric conversion with an ebike hub motor - Endless Sphere
Just FYI... Justin is not "just" some guy.

He is a pioneer in the E-bike scene, runs or ran or owns or owned Canada's largest e-bike shop, volunteers at the Makerfaire there every year, has done a ton of EV outreach and PR. And when Endless-Sphere was looking to be bought out, he pitched in and paid for it all himself so that it could stay owned by the community and didn't even really let anyone know, didn't want credit for saving the community. Hell of a guy.

... That said, this is a gimmick build, he wants to test out his ebike stuff in weird situations. No one should copy this build.
 
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