100% Solar-Powered Boat - How Would You Build it ?

[LiFeTech Energy]

Originally Posted by cburger

Very interesting regarding the Lithium Iron Phosphate batteries (LiFePO4). Is this the type of battery that to the lay person is generally referred to as Lithium batteries, similar to what is in my camera and cell phone?

Lithium batteries is a generic name which covers several families/chemistries just as with lead acid batteries there are also variations- for example sealed lead acid, wet cell, AGM, gel, etc.

Similarly with lithium batteries there are also several different types each with its own characteristics. For example a few of the most common types are lithium cobalt, lithium polymer, lithium manganese and lithium iron phosphate. All of these are broadly termed "lithium ion" batteries.

Lithium cobalt and polymer types are potentially hazardous in large format packs and should never be considered for a boat (if your boat burns to the water line as a result of a defective battery I don't think your insurance company would be too impressed!). Lithium cobalt is the type used in cell phones, cameras, lap tops, etc. You may recall the Dell computer battery recall when several batteries caught on fire a few years ago.
Lithium manganese are used in some applications since they are somewhat safer but their draw back is their relatively short cycle life.
Lithium Iron Phosphate (LiFePO4) is the lithium battery of choice since it is the safest type of lithium battery (safer than lead acid) as well has by far the longest cycle life (thousands of cycles rather than hundreds).

There is some more info and comparison on the Boatweb website-
Lithium Iron Phosphate (LiFePO4) Batteries For Boats | Boatweb

[Adambomb]

My suggestion: Something like this

[zGerman]

Most highly energy efficient vehicles focus much on reducing weight for a reason. Moving mass requires energy, more mass needs more energy. Due to this fact a traditional monohull with a heavy keel is out. So that steers towards a cat. Reducing mass is only one requirement. Drag is the second requirement. If you do not have any sails you should consider a dagger board designed cat as the donor hull. That will be likely the least expensive light weight low drag donor you can find.

I would also strongly advise to plan on having propulsion 24/7 with some energy to spare. To design a system that kinda runs most of the time when the sun is shining is in my view a dangerous proposition. I would not want to be on board of such vessel in offshore conditions.