diy solar

diy solar

Can Lithium batteries support an AGM installation for Solar Powered Catamaran

One point is that 96v inverters really aren't that uncommon- at least in Australia
72v and 96v have pretty much overtaken the offgrid housing market here , with 48v being relegated to 'small bush shacks' and DIY setups lol
(indeed when I bought my own 48v, 12kw inverter- it was being sold as 'obsolete stock' at a bargain price...)
The company that made mine sells a 15kw 96v inverter as its replacement for example
And seconded on AGM being a poor choice (they are for anything these days, but buggy whip manufacturers stick with what they know lol)- good quality LFP are simply a far better choice economically and power storage versus weight/size (plus they last so much longer than any L/A chemistry battery...)
 
The first thing that I noticed between AGM’s and LFP is how easily the lithium soaks up power. With the AGM it seems that when there’s only a small amount of charge current available, nothing was being taken in. You had to have a reasonable rate of charge for it to be worth while.
 
Skypower said:
The first thing that I noticed between AGM’s and LFP is how easily the lithium soaks up power. With the AGM it seems that when there’s only a small amount of charge current available, nothing was being taken in. You had to have a reasonable rate of charge for it to be worth while.
Click to expand...
That is mostly due to AGMs electrolyte inefficiency- because it is literally 'soaked into a glass mat (AGM- absorbent glass mat) their 'round trip' performance effeciency and charge/discharge rates are lower than other L/A cells...
They really are a bad idea- but have gained traction because of their sealed nature ie 'fit and forget' compared to flooded L/A cells
 
I think I would consider an asymmetric solution. Use one electric outboard of your choice and one 60 HP four stroke outboard. If you are content going 7 Knots in the first place, 4 Knots won't be any worse. The 60 HP could save your bacon if you get in a jam.
 
justgary said:
I think I would consider an asymmetric solution. Use one electric outboard of your choice and one 60 HP four stroke outboard. If you are content going 7 Knots in the first place, 4 Knots won't be any worse. The 60 HP could save your bacon if you get in a jam.
Click to expand...
It’s a catamaran so while it will run one engine, it will run cattywampus with one engine. Two electrics and one small 4 stroke backup would probably work.
 
  • Like
Reactions: Bop
Just a short update.
I've been working on the catamaran for about five months now. The 6kW solar roof is on and awaiting connection. I settled on a 48V system with twin 15kW electric outboard motors from an Austrian company called Aquamot. They're due to be delivered in the next month. As far as batteries go, I settled on SEPLOS vertical battery cases (6), EVE 304LF Grade A prismatic cells (96) and domestic type solar inverters (2) with a maximum of 11kW @ 220V. I am not going to have a 'house' battery and 'motor' battery, but will run everything from two banks with a maximum of 45kW available per hull / motor. I also have two petrol 'suitcase' type generators from Hyundai that will give emergency backup of 2.2kW per generator. I will probably carry a petrol outboard for use with the dinghy, something small like a 5HP.
As all of this is experimental, I fully expect to make some changes along the way. I have set my sights around a coastal cruising capability for the catamaran of between 20-30 miles, which at 4-5knots should consume 15-25kW or better. We shall see!
 
althemusicwizard said:
Just a short update.
I've been working on the catamaran for about five months now. The 6kW solar roof is on and awaiting connection. I settled on a 48V system with twin 15kW electric outboard motors from an Austrian company called Aquamot. They're due to be delivered in the next month. As far as batteries go, I settled on SEPLOS vertical battery cases (6), EVE 304LF Grade A prismatic cells (96) and domestic type solar inverters (2) with a maximum of 11kW @ 220V. I am not going to have a 'house' battery and 'motor' battery, but will run everything from two banks with a maximum of 45kW available per hull / motor. I also have two petrol 'suitcase' type generators from Hyundai that will give emergency backup of 2.2kW per generator. I will probably carry a petrol outboard for use with the dinghy, something small like a 5HP.
As all of this is experimental, I fully expect to make some changes along the way. I have set my sights around a coastal cruising capability for the catamaran of between 20-30 miles, which at 4-5knots should consume 15-25kW or better. We shall see!
Click to expand...
Prop selection is paramount in any marine situation. Even though you can use the outboard for small tender or a small work barge, the prop that’s best for the tender will be dismal for the barge and vice versa. I didn’t see any power curve or prop selection guide, sizing or props available for that matter for Aquamot. Did you speak with them about compatibility for your project? If they didn’t ask displacement, hull(s) type, beam(s) and length, I’d be concerned. What’s typically seen is the more displacement moved, the bigger the prop diameter, shallow pitch and and sometimes more blades. There are on line calculators that get you in the ballpark if you have all the data to put in the blanks
 
Last edited:
Thanks for that.
By the time I get to experimenting with different prop shapes and sizes / cavitation / pitch etc, the cat will be practically complete. Don't forget, I'm told the torque of electric outboards / motors will be totally different than their ICE equivalents. I have told Aquamot what the cat is like (dimensions etc) and they have also seen some video footage. The original cat design was for petrol outboards, although the size of the outboards is up to the builder. Some put 60HP outboards on them, some put 200+HP outboards on them. Here are some examples:





The cat is 40ft in length, with the waterline being similar as the hulls are practically vertical at the ends. The beam at the waterline is probably around 18ft as the whole beam is around 20ft. The draft is probably going to be around 1.5ft-2ft depending on total finished weight, which I think is going to be around 5 tonnes or 11000 lbs. The cat is being built as much as a liveaboard / houseboat as it is a boat. I see myself being at anchor for 90-95% of the time, with journeys in the beginning only being 4-8 hours and all probably during daylight. I will be 61 this year, and am tired of the same vista that I have woken up to for the last 25 years. Like most people, you 'settle down' and end up living out your days in the same place. The last four years should have changed everyone. I was already head of everyone in this respect and the recent past has made this much more acute.
 
  • Like
Reactions: Bop
althemusicwizard said:
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.
Click to expand...
Al, any updates from last year? I’m curious how your project is going, especially in regards to the BatteryEnergyStorageSystem. I’m currently designing a similar size boat around PV and batteries for zero emission liveaboard boating and I decided to build the banks myself.
 
althemusicwizard said:
Thanks for that.
By the time I get to experimenting with different prop shapes and sizes / cavitation / pitch etc, the cat will be practically complete. Don't forget, I'm told the torque of electric outboards / motors will be totally different than their ICE equivalents. I have told Aquamot what the cat is like (dimensions etc) and they have also seen some video footage. The original cat design was for petrol outboards, although the size of the outboards is up to the builder. Some put 60HP outboards on them, some put 200+HP outboards on them. Here are some examples:





The cat is 40ft in length, with the waterline being similar as the hulls are practically vertical at the ends. The beam at the waterline is probably around 18ft as the whole beam is around 20ft. The draft is probably going to be around 1.5ft-2ft depending on total finished weight, which I think is going to be around 5 tonnes or 11000 lbs. The cat is being built as much as a liveaboard / houseboat as it is a boat. I see myself being at anchor for 90-95% of the time, with journeys in the beginning only being 4-8 hours and all probably during daylight. I will be 61 this year, and am tired of the same vista that I have woken up to for the last 25 years. Like most people, you 'settle down' and end up living out your days in the same place. The last four years should have changed everyone. I was already head of everyone in this respect and the recent past has made this much more acute.
Click to expand...
This post from May’24 was not visible a minute ago….
 
You must log in or register to reply here.

diy solar

diy solar
Back
Top