Hull Design Choices for Very Fuel Efficient Live-aboard

[gonzo]

Setting aside cost differences, how roughly do you think the Practical lifespan of AGM batteries compares to Li Ion batteries for this sort of application? That is to say, would one expect to need to replace one much sooner than the other? Also, would I be right to assume AGM would be generally safer?

The quality of each battery matters. Within the same technology there is a huge variation. Johnson Controls manufactures the best AGM available, and sell them under a variety of brands like Varta and Interstate. As far as Li Ion, besides the quality there is a variety of chemistries too. One of the advantages of AGM batteries is that they don't need a sophisticated power management system. I worked on research on both types and the life expectancy is similar. The temperature range of the AGM is much larger so that should be taken into account too.

 

[montero]

Yes. My feeling is basically that Lion batteries are this generation's thalidomide and DDT. But our parents were able to fix thalidomide and DDT in about 50 years. We won't be so lucky. Or rather our kids won't be so lucky. It is possible to make reasonably safe Lion batteries, but then they are only about twice a good as lead and cost more than ten times as much, so nobody makes them that way. There is no way to control a lithium battery fire on land, let alone on the water. They will collapse a parking garage with a two hour fire rating in ten minutes. They don't need outside air to burn, they will burn just fine under water or encased in concrete. And I don't want to think what a boat built with Gas Group IIC or IIB+H2 certified enclosures would cost. A full EV-sized battery pack can vent up to 50,000 liters of total gas, with approximately 13,000 liters consisting of highly explosive hydrogen. In a 44' cruiser, about half the volume of the hull would be battery gasses, and 20% would be hydrogen. The lower explosive limit for hydrogen is 4%. A lead battery can evolve about 6 cc per minute per amp of overcharge. At 30 amps, it would take 50 days to gas off the hydrogen that a lion EV battery can produce in about a minute during runaway.

I've been using LiFePO4 for many years without a BMS.
The greatest achievement with this battery was starting a Y60
(2.8 D six inline) with just a wrench and the person holding it.

How do you imagine a Milwaukee screwdriver without Li-something?

I want to buy a Milwaukee SDS Max for mooring or keeping my car from sinking in the sea.

 

[gonzo]

How do you imagine a Milwaukee screwdriver without Li-something?

They used to be NiCad and other chemistries.

 

[skaraborgcraft]

An (100amp for example) AGM battery from a local store costs more than double the imported LiFeP04 from Germany. The AGM has an expected life of 1000 cycles at 50% discharge, while the LiFeP04 has 10,000 cycles at 80% discharge.
I liken it to continually topping up your fuel tank to full, when you only drive a short distance once a week, it is a lot of extra weight to carry around that is not used.
LiFeP04 is not as bigger a fire risk as Li-on. It is like comparing gasoline to diesel. Biggest risk i see is an internal BMS problem, but that is just as likely as an external charger having the same problem.

 

[philSweet]

How do you imagine a Milwaukee screwdriver without Li-something?

We have a bunch of cordless tools at the shop at work - Dewalt, Kobalt, and Porter Cable 20 volt systems. I special-order the 2Ah batteries since 3s have become standard at Lowes etc. I keep the chargers all ten feet apart and on different circuits and located in safe places. I only keep one battery near or on each charger. There hasn't been many major fires attributable to batteries 2Ah and smaller.

An often overlooked aspect of this is that it doesn't have to be the batteries that are the point of ignition. Something else can start the fire. But once the batteries become involved, it's game over.

This is a fire involving a lead-acid battery-

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This is a fire involving lithium battery golf carts. We don't know how it started. Chapel Ridge Golf Course in Pittsboro

 

[skaraborgcraft]

This is a fire involving a lead-acid battery-

The 2 lead acid battery fires i have seen also involved an explosion, i see part of that battery top is missing, but may have just melted. True that one is easier to put out than some others. Given that some short haul ferries are LiFePO4 powered, I do not fear the battery, only that it is installed correctly with the appropriate safety circuit breakers.

 

[gonzo]

LiFeP04 is not as bigger a fire risk as Li-on.

LiFePO4 is a type of Li Ion.

 

[gonzo]

The 2 lead acid battery fires i have seen also involved an explosion, i see part of that battery top is missing, but may have just melted.

Were those flooded acid or AGM? They are very different. AGM are also valve regulated (VRLA) to prevent pressure build up. Further, explosions in lead acid batteries are usually caused by external fires or sparks.

 

[rxcomposite]

This long for efficiency

 

[skaraborgcraft]

LiFePO4 is a type of Li Ion.

Petrol/gas is a type of oil. Not all have the same ignition factors, same Li lon or Li Fe Po4.

 

[skaraborgcraft]

Were those flooded acid or AGM? T

Flooded. I know the first explosion/fire was caused by someone using a grinder in the engine room, and im pretty sure the other was spark related. Both may have been avoided with good air extraction of battery gas and perhaps less aggressive bulk charging.

I do prefer AGM over FLA on my own boats. Hard to ignore the capacity and weight benefits of LiFePo4 on a smaller boat. I can lift a 25kg battery, i cant lift one of 85kg of the same capacity, but different chemistry.

 

[gonzo]

Petrol/gas is a type of oil. Not all have the same ignition factors, same Li lon or Li Fe Po4.

That is not correct. You state the Li Fe Po4 is not Li Ion. Li Ion is the generic family which includes Li Fe Po4.

 

[skaraborgcraft]

That is not correct. You state the Li Fe Po4 is not Li Ion. Li Ion is the generic family which includes Li Fe Po4.

Like gasoline and diesel is the same generic family that comes from oil, but with different BOOM values. If LiFePo4 was the same as Li ion why the name change if not for differences?

Difference​

bing:

The main differences between Li-ion and LiFePO4 batteries are their chemical composition, performance characteristics, and intended applications. Li-ion batteries are known for their high energy density and are commonly used in consumer electronics like smartphones and laptops. They are also suitable for applications requiring quick power bursts, such as electric vehicles and portable devices.
LiFePO4 batteries, on the other hand, are prized for their safety, durability, and longevity. They are often preferred for applications where safety is a major concern, such as solar power systems, electric vehicles, and industrial equipment. LiFePO4 batteries are also known for their superior thermal stability and resistance to degradation, making them ideal for long-term use in stationary or grid applications.
In summary, the choice between Li-ion and LiFePO4 batteries depends on the specific requirements of the application. For high energy density and quick power delivery, Li-ion batteries are the better choice. For safety, longevity, and cost-effectiveness, LiFePO4 batteries are the preferred option

If you want to argue semantics, I can message Carlos. Im done here......

 

[OrionSailor]

Just see this fellow. From Finnland.
Sailing now from Finland to Spain.
DIY Electric Solar Yacht Prototype at 7 knots

TRUE NORTH

Let's explore the world and build an absolutely free way of life. Contact for collaborations beyond 3k upfront only.

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https://www.instagram.com/lukas.seaman/

 

[gonzo]

Like gasoline and diesel is the same generic family that comes from oil, but with different BOOM values.

They are very different molecular structures, even though they are hydrocarbons. The engines that use them as fuel have different operating modes.

If LiFePo4 was the same as Li ion why the name change if not for differences?

Because the first is a particular chemistry and the second is a family of chemistries and construction.

Difference​

bing:

If you want to argue semantics, I can message Carlos. Im done here......

Sarcasm is the last resort to hide the lack of facts to win an argument.