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Can Lithium batteries support an AGM installation for Solar Powered Catamaran

althemusicwizard said:
It's not the problem of building a 96V pack (though finding a BMS that is tried and tested may be) it's then charging that from the 48V (or the 230V AC) that will be coming from the panels / inverters / 48V LiFePO4 bank.
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REC BMS comes in 16s blocks and can be connected up to 128s.
It uses contactors.

How about two contactors, one on battery+, other on battery-
Connects two 48V battery chargers, one from middle to battery+, other from middle to battery-.
(This assumes BMS tolerates cell divergence, as the two 48V sections may not be same voltage. Should be adjustable parameter.)

Use four contactors total. One for each charging source, and one for each end of load. Well, maybe only one needed for load, so three contactors.
Need to isolate load from charging source to prevent excessive reverse-polarity voltage seen by charger.

This would be an all-lithium system, no AGM.
 
Q-Dog said:

96V Inverter Charger 15000 Watt 120/240Vac Pure Sine For Tesla Model 3 Lithium Battery Module – Sigineer Power

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Thanks for that......it just has to be the other way round. The input is 96V to 230V AC output. Now if it was 230V AC to 96V DC, then it would kind of work direct to the motors from the output of the inverters (paralleled), however you'd only get 10kW from the two inverters so would not be powerful enough as each motor can take a max of 21kW each. Thanks though.
 
Build 96 volt bank. Use 96 volt mppt to charge from solar and 96 volt inverters to provide house AC loads. Propulsion is 96 volt direct from batteries.
 
rhino said:
Have you also done calculations on how big of battery you'd need for that large of motor let alone two of them? Have you seen https://www.youtube.com/c/TheDigitalMermaid/videos ? She is converting her yacht to electric motor from diesel but will be using much smaller single motor and will have quite big battery bank.
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Hers is a sailboat isn't it? This is a power cat. She won't have a 60-90kWh battery bank on her yacht will she?
 
Thanks for the replies. The lack of 96V stuff and the fact that it IS 96V stuff, has made me decide that as far as electric is concerned, I'm sticking with 48V. The 48V stuff in the UK has come down in price to make this feasible and I haven't got the kind of budget that 'yacht owners' have. It will remain to be seen if the 48V motors will be able to drive the cat at hull speed (8 knots). If so, all well and good. As the petrol tanks have already been installed, a couple of smaller petrol outboards (20-30HP) might make sense as redundancy.
 
althemusicwizard said:
Thanks for the replies. The lack of 96V stuff and the fact that it IS 96V stuff, has made me decide that as far as electric is concerned, I'm sticking with 48V. The 48V stuff in the UK has come down in price to make this feasible and I haven't got the kind of budget that 'yacht owners' have. It will remain to be seen if the 48V motors will be able to drive the cat at hull speed (8 knots). If so, all well and good. As the petrol tanks have already been installed, a couple of smaller petrol outboards (20-30HP) might make sense as redundancy.
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I've just come across a brand new outboard from E-Propulsion, the X-40D. I've no idea how much it's going to cost, but it's almost like it was made for my cat. Back to the drawing board as it's 96V. I'm going to take a look at the EV forums and find outhow to build a 96V bank and how to charge it.
 
althemusicwizard said:
Thanks for those replies guys. I'm finding 96V stuff in the UK is non-existent. I've installed a 48V home system using solar inverters and it's been extremely successful. I do have a lead-acid bank. The need for 50HP motors is because the cat is 40ft, with a 20ft beam. It will weigh in around 4-5tonnes (depending on batteries, panels and motors......that lot alone could be 1.5tonnes). I'd like to be able to cruise at 6-8knots. The use of AGM batteries is really as a buffer between the 48V LiFePO4 bank. All the companies have battery solutions but they're probably at least twice the price of sourcing a solution myself.
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a few 300A 32S BMS in parallel

Tanfon 96v mppt
 
Last edited:
pollenface said:
a few 300A 32S BMS in parallel

Tanfon 96v mppt
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Thanks for that link. I'll have to find out how much the E-Propulsion X40 are going to cost and work from there. Their own G-Series batteries are
rated at a maximum charge / discharge of 100A, therefore to run the 40kW motor at peak you'd need four batteries in parallel, I think. Most BMS for lithium batteries can usually handle at least 100A can't they?
I just Googled and found this company who seem to offer bespoke solutions:

www.ctsbattery.com

Quality E Scooter Battery Pack, Solar Battery Storage System factory, E Scooter Battery Pack manufacturer, Solar Battery Storage System from China

China leading provider of E Scooter Battery Pack and Solar Battery Storage System, Hunan CTS Technology Co,.ltd is Solar Battery Storage System factory.
www.ctsbattery.com

Lots to think about.
 
I'm planning a 96v setup for my boat too. So interesting discussion.

Looking at other eboat conversations, the tend to need very little power at displacement speeds, and that's hull dependant. After that power requirements are exponential.

Good displacement hulls are long and thin (higher displacement speeds), so a cat is likely to be the perfect choice!

My boat isn't a cat, it does 5 knots with 5hp and 8 knots at 40hp. That last 3 knots really uses a stack of energy. So electrification for me is displacement mode, max 6 knots, and a 10kw motor, running at around 5kw, is my goal.

I'd be surprised if you need any more than 10kw in each pontoon to hit your displacement speed. Thoughts?

See Candela C-8 for a high speed eboat!
 
I have thought about that as well.

I use a Batrium BMS in my MotorHome and like it. I believe you can make a 96v or 144v battery with that bms.

If at all possible drop the Elco motor down to a 48v model. It will make life better (and cheaper).
 
agm's a re a terrible idea for electric propulsion, 300 cycles? that's one year
i Mix 1045ah of AGM at 12v and 2kw of lithium also at 12v on a sailboat because I can't risk a BMS failure killing all communications, navigation, nav lights etc, and I have that amount of storage because I like to run the air conditioning in silence, I use the generator every few days to supplement the 2kw of solar.
I'd recommend 32prismatic Lifepo4 in series with a 32S BMS rated for the amperage of both motors, but truthfully you should have 2 p6v banks incase one fails.
I beleieve one of the ev's maybe a leaf has 96v batteries that could be adapted. Jehu Garcia probably has something that would work, but you have more to consider, 12v batteries charge at around 14v 48v batteries charge at around 52v so 96v will charge in the 104v range, most MPPT chrgers need 20-30% higher voltage so you'll need enough solar panels in series to give say 150v.
I don't know who makes MPPT chargers in that range.
the gas outboards are starting to look better to me.
 
Joe Delaney said:
agm's a re a terrible idea for electric propulsion, 300 cycles? that's one year
i Mix 1045ah of AGM at 12v and 2kw of lithium also at 12v on a sailboat because I can't risk a BMS failure killing all communications, navigation, nav lights etc, and I have that amount of storage because I like to run the air conditioning in silence, I use the generator every few days to supplement the 2kw of solar.
I'd recommend 32prismatic Lifepo4 in series with a 32S BMS rated for the amperage of both motors, but truthfully you should have 2 p6v banks incase one fails.
I beleieve one of the ev's maybe a leaf has 96v batteries that could be adapted. Jehu Garcia probably has something that would work, but you have more to consider, 12v batteries charge at around 14v 48v batteries charge at around 52v so 96v will charge in the 104v range, most MPPT chrgers need 20-30% higher voltage so you'll need enough solar panels in series to give say 150v.
I don't know who makes MPPT chargers in that range.
the gas outboards are starting to look better to me.
Click to expand...
This idea is terrible. Sailor here. Electric is ok as an aux with sails. But if you want to do more than a planned circuit route of limited range this idea is doomed. Sailboats converted to electric aux power lose value. You dont have sails.
Say you have a range if 50 miles. You leave and go 40 miles. Weather changes, storm ahead. Not enough power to get to port. No sails. No solar.
What do you do?
 
.Samo. said:
I'm planning a 96v setup for my boat too. So interesting discussion.

Looking at other eboat conversations, the tend to need very little power at displacement speeds, and that's hull dependant. After that power requirements are exponential.

Good displacement hulls are long and thin (higher displacement speeds), so a cat is likely to be the perfect choice!

My boat isn't a cat, it does 5 knots with 5hp and 8 knots at 40hp. That last 3 knots really uses a stack of energy. So electrification for me is displacement mode, max 6 knots, and a 10kw motor, running at around 5kw, is my goal.

I'd be surprised if you need any more than 10kw in each pontoon to hit your displacement speed. Thoughts?

See Candela C-8 for a high speed eboat!
Click to expand...
Many thanks for the reply.
I've been so busy with the cat that I haven't checked in here for a while. I've decided to go with a 48v system as the EPropulsion X series are just too expensive for me. I have ordered six Seplos Mason 15kWh batteries and will use three for each side of the cat. I have been talking to YouTuber Patrick from 'Sailing Elektra' channel. His cat is a 9m one and he uses two EPropulsion Navy 6.0 electric outboards. I'd previously discounted this idea but was reading an article about petrolheads who use two, three and four ICE outboards on their speedboats and I suddenly thought, why don't I use two Navy 6.0 outboards PER SIDE of the cat ie. four in total. The max current draw at 6kw per motor is 125A. My batteries are each capable of at least 200A continuous so should be able to manage even on full throttle. I've emailed EPropulsion this weekend to see what they think, but this could be a real solution as there is space on each transom to fit two. The real test would be in the water as I don't think there is any definitive answer as to how the two would perform as against one bigger one, but the benefits (redundancy, smaller voltage, manageable current, cable size) all look favourable as being the solution.
 
Dave911 said:
This idea is terrible. Sailor here. Electric is ok as an aux with sails. But if you want to do more than a planned circuit route of limited range this idea is doomed. Sailboats converted to electric aux power lose value. You dont have sails.
Say you have a range if 50 miles. You leave and go 40 miles. Weather changes, storm ahead. Not enough power to get to port. No sails. No solar.
What do you do?
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Drop anchor? Drift? Sorry, I couldn't resist. You have to forgive my naiveity as my only sailing experience was a 'pot luck' fortnight in Greece 30 years ago. I have now bought the cat. It's a power cat so there are no sails. It already has two 250litre fuel tanks so I'm thinking of fitting two 5kw petrol generators as a back up system to the electric. The real answer to your concerns is that only through experience will I be able to guage what the range will be, what sea state / weather puts a spanner in these calculations and to err on the side of caution when starting out. Thanks for your thoughts.
 
althemusicwizard said:
Drop anchor? Drift? Sorry, I couldn't resist. You have to forgive my naiveity as my only sailing experience was a 'pot luck' fortnight in Greece 30 years ago. I have now bought the cat. It's a power cat so there are no sails. It already has two 250litre fuel tanks so I'm thinking of fitting two 5kw petrol generators as a back up system to the electric. The real answer to your concerns is that only through experience will I be able to guage what the range will be, what sea state / weather puts a spanner in these calculations and to err on the side of caution when starting out. Thanks for your thoughts.
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Keep in mind that pushing a boat through flat water is entirely different that pushing a boat into storm waves and wind.

Hp requirements can be 2-3x. My sail boat can do 6 knots via the engine in flat water. I had to go directly into the wind in a blow for a few miles and I could only do 2-3 knots at full power as we got beat up from the wind, waves, and spray.
 
Dave911 said:
Keep in mind that pushing a boat through flat water is entirely different that pushing a boat into storm waves and wind.

Hp requirements can be 2-3x. My sail boat can do 6 knots via the engine in flat water. I had to go directly into the wind in a blow for a few miles and I could only do 2-3 knots at full power as we got beat up from the wind, waves, and spray.
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I've been told by the designer of the cat (Richard Woods) that the hull speed is probably 7-8 knots. To get it to plane you would need to increase the speed to around 12 knots and it would require 10hp more per knot increase in speed. If I could do 5 knots on 2-3kwh of battery I would consider the project a resounding success.
 
althemusicwizard said:
Sorry I should have added, this is a power catamaran. There are no sails. Propulsion is solely via engine and in this case, the design was for two, 60HP outboard engines minimum, although if money was no object you could install a couple of 300HP outboards presuming you could afford the fuel.
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My 47ft Monohull sailboat is about 15 tonnes, and motors at 7kts with a 40hp diesel, I thinkyour weight looks low and power looks like overkill unless it's a planing hull. If you need 96v then buid the biggest 96v Lifepo4 bank you can, then build another 12v lifepo4 bank that can power all marine needs, lights refrigeration, windlass etc. you can get 230v volts for ac etc with a victron from the 12v bank
you need 96v for the motor, 12v for marine, no need to add a 48v bank.
I's recommend a diesel generator dedicated to charging batteries when the sun isn't cooperating.
 
I was just chatting with two guys who did an electric conversion to a conventional 33 ft and 36ft sloop.
One has 13 KWHR of batteries and the other about 15 KWHR. The one boat can do 19 miles and the other 25 miles on electric motor alone. This is not against or running with the wind. This is also in fairly calm water and at quite a bit less than hull speed.
That won't work for me on my 33 ft sloop. More than once I have had to motor a good part of the day (36 miles or so) to get someplace when the wind died. With 20 gallons of gas onboard, at a bit less than 1 gallon per hour, I am good for over 100 miles easy with a significant reserve for when things go sideways.

I'd probably be ok if I could jam 80-100 kwhr worth of batteries in my boat but there wouldn't be room for much else. But then there is the problem of charging all of that. I would need to be able to access a 50 amp, 240 volt power source at the dock to recharge in a reasonable time. That isn't a reasonable request at most marinas. I could carry a diesel or gas generator, but then that defeats the purpose of the electric conversion. Perhaps a fuel cell would be the answer? Someday, but not today.
 
Dave911 said:
This idea is terrible. Sailor here. Electric is ok as an aux with sails. But if you want to do more than a planned circuit route of limited range this idea is doomed. Sailboats converted to electric aux power lose value. You dont have sails.
Say you have a range if 50 miles. You leave and go 40 miles. Weather changes, storm ahead. Not enough power to get to port. No sails. No solar.
What do you do?
Click to expand...
run the generator
 
I had a 43” fiberglass houseboat with a planing hull. It had twin 330hp fuel injected gasoline engines. It had two fuel efficient speeds 9mph and 20mph ( comfortably,on plane). At top speed it passed everything but the fuel dock. The crazy thing is if you were moving 9mph and shut one engine off it would only drop down to 8mph.
I’ve rescued many boats or moved boats around by “side tying”, my preferred method. If it’s a short distance or tight quarters, I’ve even used my little 12 foot RIB with a 25hp efi Suzuki outboard with this method on motor yachts to 45’. With my biggest problem being visibility(tied close to stern), but maneuverability once in Harbor was an asset with such a small boat. I had no problem moving a yacht of that size up to 7 mph at 3/4 throttle unless it’s windy, then forget bout it. The most important thing that I must convey to you is prop selection. Tho that little RIB could go 32mph with just me in it, there’s no way that same prop is any good for pulling a yacht around so I always swapped it out for a bigger diameter, low pitch four blade for grunt power and less strain on the engine. I can’t overstate how important the right propeller selection is. The OP needs to consider this regarding the electric outboards. Visually, it looks like the props on those are for a runabout. Lastly, two outboards will probably be plenty. Reality, plan on a good displacement speed, otherwise the power consumption would be massive and range extremely limited.
 
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