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96v Solar Cabin Cruiser Project - Full Solar/Shore/Inverter/LifePO4 - Discussion and Progress

carterjohnsons25

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Mar 26, 2021
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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 from Gas 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.
2021-03-15 11.19.39.jpg

Requirements

50 to 100 mile range min at Cruise Speeds.
Charge from Solar when Moored or at sea. Targeting 2kWh array.
Charge from Shore Power when docked – utilizing full capacity of a standard 30amp RV/Marine hookup. No reason to go above this.



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 https://vicprop.com/displacement_size_new.php

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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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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Clearly this is not going to happen….
You are throwing a lot of numbers around here. My seat of the pants numbers from my time in boats:

1 - a 23' full cabin boat is going to plane off at about 16-18 mph and probably need at least 150hp to get on plane. Your cruise speed will be about 22mph. Sustained cruise speed will use at least 50hp. 50hp x 745 W/hp = 37kW sustained power. Again, seat of the pants numbers.
  • 6.8kw motor -10hp = 7mph, 86 miles, 12 hours run time
  • 12kw motor - 16hp = 8.4mph, 60 miles, 7 hours run time
  • 24kw motor - 32hp = 10.4mph, 37 miles, 3.5 hours run time.
2 - I don't see these numbers working in an actual situation. At 10HP gas trolling motor will push you at maybe 4mph downwind.
1kWh = ~1.34 HP
3 - You are mixing up Watts (W) and Watt-hours (Wh)

4 - Motor voltage is a secondary consideration after determining your max power consumption (W) and battery storage requirements (Wh or Ah).

5 - Running on plane/cruise speed is going to be an expensive proposition.
 
awesome project concept

following this thread

be careful about bumps with 280Ah cells. for marine applications that have sudden plops onto water, the inside of the cells can be damaged. be careful. i think 280Ah cells might be workable but if you continue with them, be very careful about getting up to speed and plopping down onto the water
 
You pulled the trigger on $10k of batteries an hour asking this forum for help?
Yep - Fake it till you make it. I am putting a lot of weight into the knowledge of this community to guide me :) Batteries in route. Worst case scenario, I use them for my off grid home solar and scrap the boat project.
 
You have planing hull ...buy displacement or semidisplacement hull for start
Agree, and looked for a long time. But round 1 is a complete experiment. $1800 was about all I was willing to spend on the boat since hull will likely be a throw away. (Electrical will get re-used in final project) All the Cats I found were $20 to $30k on the cheap. The final 40 foot boat will be a Cat or other variety of semi-displacement.

So for now. it is what it is. Good feedback though. Absolutely correct. Your comment truly reminds me on what is needed for V2.

Other food for thought - I have found people that added 2.5 additional feet to Cabin Cruisers (Basically make them terminate like a sail boat) so they do not pull water behind the flat surface at slow speeds. If this project turns out. I have a fiberglass guy who already agreed to do this work for me.

Spot on! Thanks.
 
Why don't you add a skeg ,keel ..it will go then straight in slow displacement speeds
 
Oh boy. Before you put a single dime into this particular project, make sure you check that hull out for moisture. You need to know if the stringers and transom were made with wood because if that's the case, I'd recommend you start by tearing that hull down and rebuilding with composites. Otherwise you risk a very expensive project sitting at the lake floor.

Also, make sure you don't use any dissimilar metals in your terminal connections. Galvanic corrosion can stick a nut on permanently. Ask me how I know, lol.
 
You are throwing a lot of numbers around here. My seat of the pants numbers from my time in boats:

1 - a 23' full cabin boat is going to plane off at about 16-18 mph and probably need at least 150hp to get on plane. Your cruise speed will be about 22mph. Sustained cruise speed will use at least 50hp. 50hp x 745 W/hp = 37kW sustained power. Again, seat of the pants numbers.

2 - I don't see these numbers working in an actual situation. At 10HP gas trolling motor will push you at maybe 4mph downwind.

3 - You are mixing up Watts (W) and Watt-hours (Wh)

4 - Motor voltage is a secondary consideration after determining your max power consumption (W) and battery storage requirements (Wh or Ah).

5 - Running on plane/cruise speed is going to be an expensive proposition.
Agree - Not a displace hull, My numbers will be worse
Also Agree - Cannot keep this boat on plane. will not get the 150hp to get there or 50 to maintain. Just not going to happen.
And Agree again. Had typo on kW vs kWh.. fixed. Think the math and number are still correct for DISPLACMENT hull (which this is not) based on Vicprops.

Your numbers and estimate are probably more spot on for a Cabin Cruiser such as this vs displacement as vicprop calculates. Thank you. No amount of surface knowledge will replace actual Experience which you seem to have a lot of. I Updated thread to suggest such. Much appreciated.
 
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Oh boy. Before you put a single dime into this particular project, make sure you check that hull out for moisture. You need to know if the stringers and transom were made with wood because if that's the case, I'd recommend you start by tearing that hull down and rebuilding with composites. Otherwise you risk a very expensive project sitting at the lake floor.

Also, make sure you don't use any dissimilar metals in your terminal connections. Galvanic corrosion can stick a nut on permanently. Ask me how I know, lol.
Yes. Great advice on all accounts.

1) Terminal is aluminum and Studs are Stainless and Bus bars are Nickle plated Copper :( For this reason I am using the Silver Grease. But agree. Possibly Downhill battle. Will have to maintain and keep track of. thank you for reminding me of this.

Will need a robust Sealed Battery Box Current plan is to get these fabricated. May cost more than the batteries. Need suggestions for this.

2) Sadly, I suspect prefabbed batteries may have the same issue. But perhaps not. If I see corrosion, the batteries will get pulled and go into my Home Solar. if the project seems successfully will likely have to bite the bullet on Expensive completely sealed Batteries.

3) Agree, will need to do full once over on the hull. Batteries will be low as possible down the center for stability. Will need Extensive and reliable Bilge Pumps and similar in case of leakage.

Truly appreciate your reminding me of this important but subtle point. NOTED :)
 
96v Solar Charger - DONE

After much research and contacting companies. I went with this iPanda 96v Solar Charger. No idea if it is good or not.

It is getting shipped as I type.

PROS – 96v, “Industrial” IP67 Waterproof, Configurable via PC, Has Wifi APP to monitor. Has great name. iPanda. who does not like pandas.
CONS – Unknown product. Else will be perfect. Expensive Product.


Talked with reps several times from iPanda. Seem knowledgeable, and willing to work with me. Answered emails and more. We will see. ~$700 Shipped from China to the USA.


Panel Suggestions? Was looking at 400watt 48v options. 6 total.???
Note: I am not delusional. Solar is for charging while docked. It will provide not much to anything to the 15,000 to 20,000 watts I will be drawing from Battery at 5 to 8mph..... 2k array will also take a week to charge the boat here in the PNW.

96v Waterproof Charge Controller.jpg
 
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96v Inverter chargers – HELP

So Far, I have found these. They all scare the heck out of me.


https://www.inverter.com/6000-watt-off-grid-solar-inverter
  • 6000 watt inverter runs on 96v Battery
  • Do not believe there is monitoring?
  • Can charge Battery at 30amps from Shore
  • I cannot find much info at all about the product
  • Unclear on how it switches between shore and Battery
  • Thus far, the company has proven to have little to no knowledge about their product.
  • Looks very cheap
  • Expensive
Inverter 2.jpg

Then there is this one. May even be the same, but from China OEM for ½ the cost

https://www.dhgate.com/product/ft-5...=760025624312856586#s1-4-1;searl|4217576637:8

  • No info at all
  • Looks Dirt Cheap
  • Does seem to have a PC out monitoring port. option. unclear. Scary.
  • Scaryinverter-charger 1.jpg
 

nordkyn is ur friend

280Ah might be safe in boat. the ratio of jelly to outside support structure gets important depending on what sort of chop you really expect to see.

that page has a section on mechanical damage
I am only aware of one instance where marine lithium batteries may have failed following mechanical damage on a yacht: the crash of the Volvo 70 racer Team Vestas Windon offshore coral reefs in the Indian Ocean in 2014. The investigation report only contains two very succinct mentions of the Mastervolt lithium battery packs present on board, one to indicate that the batteries started venting following the accident and were transported to a nearby beach, and the second to mention that they were later found to have burned themselves out.

The document blames the failure on immersion in seawater, but a simple calculation based on the conductivity of sea water shows that this would only result in discharge currents of a few amps. Water ingress within the cells is also unlikely due to their sealed nature, the lack of water pressure and the fact that the relief valve is designed to open on internal over-pressure. A tentative explanation is that the shock from the sudden impact at speed caused the elements within the cell casings to shift, bruising the edges of the plates and creating a short-circuit. The cells themselves were of standard prismatic construction, 180Ah/3.2V LiFePO4. If the violent impact indeed caused them to short-circuit internally, then it illustrates the foolishness of using large format LFP cells for building marine house banks as some have already done, sometimes resorting to 400Ah or even 700Ah individual units.
 

nordkyn is ur friend

280Ah might be safe in boat. the ratio of jelly to outside support structure gets important depending on what sort of chop you really expect to see.

that page has a section on mechanical damage
Scary. The cells I have are cheapo...... Doubt much consideration for bump / chop. over time.
 
Scary. The cells I have are cheapo...... Doubt much consideration for bump / chop. over time.
Cool, sorry to harp on that topic. If you don’t expect big chop and drops onto water then using the 280Ah cells in this mobile application seems in the realm of possible safe execution to me. I genuinely interested in your experiment and hope you’ll share more on the forum as it goes.

I really wanted to go with the 280Ah cells because of cost per kWh, and went with 100Ah cells for my project in part because of the structural strength, also the terminal studs. But that’s because I don’t want to deal with aluminum tapped hole.

Cheers best wishes for your project
 
Cool, sorry to harp on that topic. If you don’t expect big chop and drops onto water then using the 280Ah cells in this mobile application seems in the realm of possible safe execution to me. I genuinely interested in your experiment and hope you’ll share more on the forum as it goes.

I really wanted to go with the 280Ah cells because of cost per kWh, and went with 100Ah cells for my project in part because of the structural strength, also the terminal studs. But that’s because I don’t want to deal with aluminum tapped hole.

Cheers best wishes for your project
I share your concern. Some of the 100ah Cells are bomber. 85kWh would have cost $20k though before BMS, breakers and case :(.

I hope to make the Packs as safe as possible using these ideas

1) Locktite on studs
2) Each pack compressed so no stress on the Terminals
3) Each pack on a breaker, Fuse and on off switch
4) Each pack in a insulated metal case.
5) Each pack has its own BMS for High and Low voltage and temp shut off. Seems overcharging is biggest concern.

We will see. Nervous for sure. but committed.
 
At displacement speed there will be little or no chop/wave slamming.

Glacier Bay made a ton of semi displacement catamarans in WA state. We can even find old ones in Ohio easily at decent prices.

IMHO you would get much further along (see what I did there) with a better hull to start with.
 
At displacement speed there will be little or no chop/wave slamming.

Glacier Bay made a ton of semi displacement catamarans in WA state. We can even find old ones in Ohio easily at decent prices.

IMHO you would get much further along (see what I did there) with a better hull to start with.
You are Absolutely correct. Cat is better on all accounts. Find me a Glacier Bay for $5000 and I'm in :)

30 min web search so far and even 20 year old ones are $30k. If I sell the motors for $10k. which is a long stretch for a 2 20 year old motors, and I am still $20k or more deep in the Hull for this experiment.

Send me these cheep 26foot catamaran listing you speak of please.



Cat.jpg
 
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