Conversion project - documented

[Shaneesprit]

When you finally test it, you need to remove 20% possibly more from your range.
Not because you need to keep some in reserve, but because you have to size a battery on what you need at end of life - normally based on 10 years although rarely make it to 10 years. Lithium might or even should last
We are not seeing piles of scrap Tesla cars yet, so a very good sign for Lithium.

Weight wise ability to shift batteries forward is a goog advantage

[SaylorMade]

Originally Posted by Shaneesprit

When you finally test it, you need to remove 20% possibly more from your range.
Not because you need to keep some in reserve, but because you have to size a battery on what you need at end of life - normally based on 10 years although rarely make it to 10 years. Lithium might or even should last
We are not seeing piles of scrap Tesla cars yet, so a very good sign for Lithium.

Weight wise ability to shift batteries forward is a goog advantage

I don't think that is how that works.
Never seen age being a part of the equation - cycles are though.
Assuming the use of Grade A cells, you can expect at least 4,000 cycles (to 80% DOD) before 20% capacity is lost.

That is never ever going to happen in my life-time on my boat.
In a car you get cycles like that (80% DOD) much much faster.

Anyway if that would be an issue I don't see why you would intially deduct 20 percent? Makes no sense to me.
Even if you do lose 20 percent in x years, just add a 50Ah spare battery to swith over to in the rare event you need to full original capacity.
Heck I might even do that any way, just to have a spare to get into a harbour if the big pack dies while underway.


Maybe I misunderstood your post, if so, I am sorry.

[SaylorMade]

Went to the battery pusher today, to pick up the battery.

12 KWh LiFePo4 with Bluetooth BMS.

Even though it was a total of 5 hours driving, it was nice to go myself and pick it up.
I got to see the inside of the batteries, and see the assembly line.
Seems like they run a nice shop.

Dimensionwise it's really compact for the amount of energy:
Length x Width x Height is: 50 x 37 x 26 (centimeters, you have do the math yourself )

Weight: 73 kg. (160 lbs).

[Statistical]

Originally Posted by SaylorMade

I don't think that is how that works.
Never seen age being a part of the equation - cycles are though.
Assuming the use of Grade A cells, you can expect at least 4,000 cycles (to 80% DOD) before 20% capacity is lost.

That is never ever going to happen in my life-time on my boat.
In a car you get cycles like that (80% DOD) much much faster.

LFP batteries (well all batteries) suffer from both calender aging and cycle aging. Calender aging is slow on the order of 1% a year depending on conditions but it is unavoidable even if the battery is never used and kept at a constant ideal 70% SoC.

The quoted cycle life is usually at a temperature controlled constant 25C. In your neck of the woods that might actually be possible for most cruisers their batteries will run a lot hotter than 25C and so effective cycle life is lower.

Combine the two plus the harsh environment of being on a boat and if you get a decade of usable life out of an LFP pack that is pretty damn good. Could you get more? Sure but I wouldn't count on it. It would be a bonus.

Anyway if that would be an issue I don't see why you would intially deduct 20 percent? Makes no sense to me.
Even if you do lose 20 percent in x years, just add a 50Ah spare battery to swith over to in the rare event you need to full original capacity.
Heck I might even do that any way, just to have a spare to get into a harbour if the big pack dies while underway.

Maybe I misunderstood your post, if so, I am sorry.

That part is true. Worry about the reducing in capacity when it happens.

[Statistical]

Originally Posted by SaylorMade

Went to the battery pusher today, to pick up the battery.

12 KWh LiFePo4 with Bluetooth BMS.

Even though it was a total of 5 hours driving, it was nice to go myself and pick it up.
I got to see the inside of the batteries, and see the assembly line.
Seems like they run a nice shop.

Dimensionwise it's really compact for the amount of energy:
Length x Width x Height is: 50 x 37 x 26 (centimeters, you have do the math yourself )

Weight: 73 kg. (160 lbs).

That is a nice looking battery. If you ever needed more range could go with a pair of them.

[SaylorMade]

Originally Posted by Statistical

If you get a decade of usable life out of an LFP pack that is pretty damn good. Could you get more? Sure but I wouldn't count on it.

Why would it be unusable after 10 years, even if you are right that it will only yield 10,2 KWh of the original 12 KWh?

Maybe I am missing something here.

Anyway, let's keep it about documenting the project in this particular thread

[SaylorMade]

Originally Posted by Statistical

That is a nice looking battery. If you ever needed more range could go with a pair of them.

Thanks.

Yep I can stack one more on top in the old engine compartment, but I highly doubt that I will ever need to do that.

And if I did that, the weight in that area of the boat would approach the weight of the old engine

[Shaneesprit]

Originally Posted by SaylorMade

I don't think that is how that works.
Never seen age being a part of the equation - cycles are though.
Assuming the use of Grade A cells, you can expect at least 4,000 cycles (to 80% DOD) before 20% capacity is lost.

That is never ever going to happen in my life-time on my boat.
In a car you get cycles like that (80% DOD) much much faster.

Anyway if that would be an issue I don't see why you would intially deduct 20 percent? Makes no sense to me.
Even if you do lose 20 percent in x years, just add a 50Ah spare battery to swith over to in the rare event you need to full original capacity.
Heck I might even do that any way, just to have a spare to get into a harbour if the big pack dies while underway.


Maybe I misunderstood your post, if so, I am sorry.

You didn’t misunderstand, I sign off battery systems as part of my job, what I said is correct as you understood it, I didn’t explain why.
Reason is you should design a system for your minimum requirements, and as they are the minimum requirements, this is actually at the point you have to replace the batteries. So in the theoretical 10 years time. (Around 6 or 7 in practice) depending on battery type and all manner of variables.
Like the following post points out battery temperature is critical to battery life.

Above 25C battery life expectancy is drastically reduced, by 30C it’s likely to be halved. Funnily enough battery supplies / installers like to quote battery ratings at 25C. This is because they can claim a higher battery output than is actually reasonable.
Sweet spot is 21-22C for output Vs life.

the temperature degradation applies even when not in use. I would always review the manufactures literature for figures. Assuming a reputable manufacturer.
Also would carry out 1 full battery cycle at maximum load, to prove the battery / system can deliver what the supplier quoted.

So you see the EV boat industry is in its infancy, not including the end of life.

[PineyWoodsPete]

Originally Posted by SaylorMade

Went to the battery pusher today, to pick up the battery.

12 KWh LiFePo4 with Bluetooth BMS.

Even though it was a total of 5 hours driving, it was nice to go myself and pick it up.
I got to see the inside of the batteries, and see the assembly line.
Seems like they run a nice shop.

Dimensionwise it's really compact for the amount of energy:
Length x Width x Height is: 50 x 37 x 26 (centimeters, you have do the math yourself )

Weight: 73 kg. (160 lbs).

That's a huge capacity for it's size and weight! Generally 48V LFP batts. are significantly larger and heavier than LiPo's - which I have of very similar output. I haven't measured my 11.5 kWh - 9 years old and showing no signs of aging I can detect - but it weighs a bit more @ 80kg, and is definitely larger in at least length and width - ~80 x 50 cm L & W. Heat degredation in our area is not a problem, as ambient air temps rarely get to 77F on the coast with water temps in the 52-60F only with the cold Humboldt current sweeping doen the Pacific coast.

[SaylorMade]

Originally Posted by PineyWoodsPete

That's a huge capacity for it's size and weight! Generally 48V LFP batts. are significantly larger and heavier than LiPo's - which I have of very similar output. I haven't measured my 11.5 kWh - 9 years old and showing no signs of aging I can detect - but it weighs a bit more @ 80kg, and is definitely larger in at least length and width - ~80 x 50 cm L & W. Heat degredation in our area is not a problem, as ambient air temps rarely get to 77F on the coast with water temps in the 52-60F only with the cold Humboldt current sweeping doen the Pacific coast.

Yeah they do seem to still make some progress on energy density/volume, so that's good.

I don't know why this ageing factor is an issue all of a sudden?
I mean everything degrades over time, it's not like the interior of an ICE, let alone it's hoses, manifold, compression ratio etc does not degrade in a decade.
Everything does, it is quite obvious, and not something that only affects a certain kind of propulsion in my mind.

[Statistical]

Originally Posted by SaylorMade

Yeah they do seem to still make some progress on energy density/volume, so that's good.

I don't know why this ageing factor is an issue all of a sudden?
I mean everything degrades over time, it's not like the interior of an ICE, let alone it's hoses, manifold, compression ratio etc does not degrade in a decade.
Everything does, it is quite obvious, and not something that only affects a certain kind of propulsion in my mind.

Nobody said it was a problem please don't put words in my mouth. I am a huge proponent of electric propulsion. The reality is though outside of a climate controlled lab with liquid cooling it is unlikely your battery will last 20 years. That isn't a problem it will be even cheaper to replace the batteries 10+ years from now compared to prices today. Batteries are only going to get cheaper and bettery.

Now maybe your battery will last 20-30 years I really hope it does and you give us an update then. It could happen but it doesn't make 20 years a realistic timeframe for average longevity of LFP pack in a boat any more than someone saying they knew some guy that got 14,000 hours on a marine diesel once so the average longevity of a marine diesel is at least 14,000 hours before rebuild.

I won't say anything further on it though.

[SaylorMade]

Originally Posted by Statistical

Nobody said it was a problem please don't put words in my mouth. I am a huge proponent of electric propulsion. The reality is though outside of a climate controlled lab with liquid cooling it is unlikely your battery will last 20 years. That isn't a problem it will be even cheaper to replace the batteries 10+ years from now compared to prices today. Batteries are only going to get cheaper and bettery.

Now maybe your battery will last 20-30 years I really hope it does and you give us an update then. It could happen but it doesn't make 20 years a realistic timeframe for average longevity of LFP pack in a boat any more than someone saying they knew some guy that got 14,000 hours on a marine diesel once so the average longevity of a marine diesel is at least 14,000 hours before rebuild.

I won't say anything further on it though.

If I put words in your mouth I am sorry - not my intention.
It's all good, we agree that nothing lasts forever, and in 20 years I am probably ready to stay on shore anyway

[GrowleyMonster]

Originally Posted by SaylorMade

Went to the battery pusher today, to pick up the battery.

12 KWh LiFePo4 with Bluetooth BMS.

Even though it was a total of 5 hours driving, it was nice to go myself and pick it up.
I got to see the inside of the batteries, and see the assembly line.
Seems like they run a nice shop.

Dimensionwise it's really compact for the amount of energy:
Length x Width x Height is: 50 x 37 x 26 (centimeters, you have do the math yourself )

Weight: 73 kg. (160 lbs).

That's one sweet looking battery! Hate to think what it costs compared to my golf cart batteries, but that is a tidy little package you got there. I would have gone for a pair of them, funds permitting. Maybe three of them! You could electro-motor all day and all night and into the next day! Maybe even pull a shrimp trawl! Okay, a small one, yeah.

[SaylorMade]

Originally Posted by GrowleyMonster

That's one sweet looking battery! Hate to think what it costs compared to my golf cart batteries, but that is a tidy little package you got there. I would have gone for a pair of them, funds permitting. Maybe three of them! You could electro-motor all day and all night and into the next day! Maybe even pull a shrimp trawl! Okay, a small one, yeah.

Yeah, well I can always slap one more on top, if I need it. I don't think I will be needing it.

It was 5,000 USD, including our horrendous 25 percent VAT we deal with in this country

You would have to buy what corresponds to 24 KWh of LeadAcid to effectively have the same capacity. That would not be cheap either. Plus my boat would sink

[PineyWoodsPete]

Originally Posted by SaylorMade

Yeah, well I can always slap one more on top, if I need it. I don't think I will be needing it.

It was 5,000 USD, including our horrendous 25 percent VAT we deal with in this country

You would have to buy what corresponds to 24 KWh of LeadAcid to effectively have the same capacity. That would not be cheap either. Plus my boat would sink

My four AGM 12V batts - 3x100Ah + 1-120Ah - weigh right at 50% more than the 80kg 240Ah @ 48V LiPo. I've replaced two of them so far in the 2014 boat - engine start and stern-thruster - and carry a spare, which I'll replace the bow-thruster/windlass one with before our next little cruise down to the Channel Is. as it's a bear to get to...