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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...

https://www.ebay.co.uk/itm/404039387204?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=xSQy3lEsReG&sssrc=4429486&ssuid=&var=&widget_ver=artemis&media=EMAIL

Are 300v DC solar inverters a bad idea for a catamaran? I've just been reading some other posts about electric boats and I've decided to limit my own project to 48v batteries and electric motors. I have twelve 500w panels that I was going to wire in two banks of 3kw per side of the cat, running...

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...

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...

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...

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.

WOW, for a sailboat? Just found that video....indeed a might battery bank.

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...

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 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...

Thanks for those replies. I'd have to look into diodes etc. as it's above my pay-grade :).......but the combination of separate AGM banks and separate solar inverter for the AGM bank so I could hit it hard when needed, might be a solution.

For anyone who's looked into this problem before (solar boat), I compiled what video history I could find of 'Solarwave 42'. This was the boat that Heike and Micheal Kohler designed and built and now they run Silent Yachts. https://www.silent-yachts.com/ In one shot, it shows the nav station...

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.

Oh sorry....I won't have a problem getting a 12V or 24V supply from the 48V bank for running 'boaty' stuff, nor for 230V AC which will come straight from the inverters, it's the 96V DC supply to the inverters that I'm having difficulty with.

The problem is being able to create a 96V supply for the motors from a 48V supply. AFAIK you can't just hook up two 48V lithium packs like the Gobel I listed in series. Fine for parallel and a bigger bank, but not for series. 48V stuff is abundant and relatively cheap these days.

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.

Thanks for the link, but I think they're only good to 600W. Each motor at maximum might draw 21kW if the batteries allow it.

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...

Hi pollenface, I've just posted a similar thread to this and wondered if you had a spare minute so have a look at the circuit diagram? https://diysolarforum.com/threads/can-lithium-batteries-support-an-agm-installation-for-solar-powered-catamaran.72545/#post-919876 Thanks, Al

I've just found a similar thread to this and a poster called 'pollenface' suggested a similar solution as to the one I've posted here. I've redone the schematic to show switches that could switch the AGM bank between being a 48V bank and a 96V bank. The AGM bank couldn't be charged as well as...

I've just created a new thread but on the same subject. After reading the thread here, I see that my idea has already been suggested by 'pollenface'.

I think I see it now....thanks. I'll have another look

Could you explain why?

Thanks for your thoughts. I may have this wrong, but why do you think the busbar will be at 96V? I've kind of taken what I've learned from installing my home solar system and come up with this. In my 48V home system, I have 28, 12V batteries connected in series / parallel. They are connected in...

I'm like Martin Luther King.......'I have a dream'. Only by this time next week, hopefully I'll be the owner of a 40foot mulithull catamaran. The cat has been partially completed, about 70% and I'll be hopefully finishing it. The build has been based around a twin outboard setup, with twin...

I came upon this thread as I may be completing a power catamaran. I would like to install electric pod drives for the propulsion and found these AQUAMOT motors: https://www.greenboatsolutions.com/shop/motor/pod/aquamot-trend-25-0-fm They are 96V pod drives with a maximum draw of 260A. I would...

Great looking boat and project. I've been looking at a similar thing for a power catamaran. I've been mulling over two old 40-60HP outboards that might be renovated to use 96V electric motors like this. http://www.motenergy.com/mepmwaco.html or this: http://www.motenergy.com/mepmwacomo.html...

I fitted my system in Dec 2022. I have 32 x sealed lead-acid VARTA LFD230 batteries, a kind of hybrid starter / habitation battery. They weigh 56kg (123.5 lbs) each. I have two tonne of lead in my garage. I sized it so big (c. 90kWh) so that I would only use around 30% of it over 2-3 days (my...

Thanks Steve_S and Quatrohead for that great advice. I'll check out your links Steve. Regards, Al

Hi guys, As we head into winter in the UK, I've decided to replace the huge lead-acid battery bank I installed nine months ago for a MASON 280L 15kWh battery bank containing Grade B Envision 304Ah prismatic cells. Fogstar, in the UK are offering the 'build your own battery' for £1999, which is...

Thanks for those replies eggo. With all that info I feel much more confident now to know what I'm looking at re. charging, depletion and the idiosyncracies of the Juncktek. Cheers, Al

Great, I think what you have just indicated is what I saw today. What may have also happened is that the meter may have misaligned over the last few charges and that the 100% SOC might not have been reflected in the reality of the bank charge. I daren't tell you the 'Junk tek' model of monitor...

Interestingly, today we had some good solar and the bank did something I hadn't seen before. I had charged it up overnight so that by 7.30am it was sitting at 99% and around 52.6V. The solar lasted for five or six hours (between 9am and 3pm) at a really good output from 2-5.5kW per hour. After...

'When pulling 200A, what is the current passing through each of the 8 strings?' I'd have to check that. As you can imagine, having 32 x 240Ah batteries (each weighing 56kgs) was an engineering feat in itself, if I do say so myself. Getting a clamp meter in place is a little difficult but doable...