Tuesday, February 6, 2018

Re: [Electric Boats] #18650 Batteries

 

Anyone who claimed to have a 6000mah 18650 cell is lying to you. Even Tesla isn't there in that form factor. The best 18650s commercially available are from Panasonic (Tesla's partner in lithium joy) and have a capacity of 3400mah. And they are not cheap. 


I would so very much like to be proved wrong in this. 

For fun, I purchased 30 similar 18650 cells, black shrink wrap, no branding, marked 6000mah capacity. There was a mush-mash or capacities, mostly around 1200mah. I was able to build a few small packs for my son's Halloween costume and other toys, but I would never want to depend on them for my safety (like powering a dinghy or such). 

If your goal is a small diy pack, I would suggest buying surplus laptop packs and ripping them apart and repacking to your needs. Count on about 3000mah per cell. 
For a 48v nominal, go for a 15-series pack. There are BMS boards readily available for that size. 

Best of luck,

/Jason

--
Jason Taylor
v:514-815-8204

On Feb 6, 2018, at 08:40, Chris Morriss chris.morriss@ouroboros.myzen.co.uk [electricboats] <electricboats@yahoogroups.com> wrote:

 

I use 18650 cells (salvaged from an old laptop PC battery pack) for two high-power LED torches I have.  Chargers are available from Amazon to charge two of the cells in parallel.  Unfortunately they are difficult to charge in series (unlike lead-acid batteries) without sophisticated charge-equalisation circuitry.

Tesla use this size of cell in huge battery packs in their electric vehicles!

18650 cells are usually up to about 3.7 amp-hours, so I certainly wouldn't trust the 6 A-hr specs you've seen.


On 06/02/2018 12:56, oak oak_box@yahoo.com [electricboats] wrote:
I saw AA Energizer Lithium batteries at the grocery store, and was thinking about the past a year (or two or three?) ago where someone said they were going to put together a bank from a whole bunch of small cells.

It seemed odd that they had plenty of lithium AA batteries, but no chargers.  Looking the internet, it kinda' seems like these aren't meant to be recharged - just used as a higher capacity disposable??  Is that really true?

Then, I came across #18650 batteries.  Just looking at the internet, they appeared to be very close to the AA battery form factor, but on closer inspection, longer and thicker - but also higher capacity?  And higher voltage - these were rated as 3.7V cells, not 1.5 like AA's.

Many of the 18650 batteries were about 3000mAh, but some by Garberiel, seemed reasonably priced (on Amazon), and claimed to be 6000mAh.   I haven't done the math yet, but it looked like it would be a cheap way to get a 48V bank quickly, and then as I wanted to put more $$ into it and as the experiments went forward, I could always add more capacity in parallel (which at that point would probably be more expensive than just buying higher capacity cells to begin with).

Anyway, I was curious if anyone has played with these cells?  Is the 6000mAh rating likely to be real?

Sounds like it would take about 221 of these to make a 48V, 100Ah battery - is that right?
13 x 3.7=48V   17x6Ah>100Ah, so 221 cells to make up the bank...   @ about $15/10, about $330 for the bank???   That sounds way too good to be true.  Of course, there would need to be monitors and battery boxes, etc...   But does this math sound at all close???


John





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Re: [Electric Boats] #18650 Batteries

 

I use 18650 cells (salvaged from an old laptop PC battery pack) for two high-power LED torches I have.  Chargers are available from Amazon to charge two of the cells in parallel.  Unfortunately they are difficult to charge in series (unlike lead-acid batteries) without sophisticated charge-equalisation circuitry.

Tesla use this size of cell in huge battery packs in their electric vehicles!

18650 cells are usually up to about 3.7 amp-hours, so I certainly wouldn't trust the 6 A-hr specs you've seen.


On 06/02/2018 12:56, oak oak_box@yahoo.com [electricboats] wrote:
I saw AA Energizer Lithium batteries at the grocery store, and was thinking about the past a year (or two or three?) ago where someone said they were going to put together a bank from a whole bunch of small cells.

It seemed odd that they had plenty of lithium AA batteries, but no chargers.  Looking the internet, it kinda' seems like these aren't meant to be recharged - just used as a higher capacity disposable??  Is that really true?

Then, I came across #18650 batteries.  Just looking at the internet, they appeared to be very close to the AA battery form factor, but on closer inspection, longer and thicker - but also higher capacity?  And higher voltage - these were rated as 3.7V cells, not 1.5 like AA's.

Many of the 18650 batteries were about 3000mAh, but some by Garberiel, seemed reasonably priced (on Amazon), and claimed to be 6000mAh.   I haven't done the math yet, but it looked like it would be a cheap way to get a 48V bank quickly, and then as I wanted to put more $$ into it and as the experiments went forward, I could always add more capacity in parallel (which at that point would probably be more expensive than just buying higher capacity cells to begin with).

Anyway, I was curious if anyone has played with these cells?  Is the 6000mAh rating likely to be real?

Sounds like it would take about 221 of these to make a 48V, 100Ah battery - is that right?
13 x 3.7=48V   17x6Ah>100Ah, so 221 cells to make up the bank...   @ about $15/10, about $330 for the bank???   That sounds way too good to be true.  Of course, there would need to be monitors and battery boxes, etc...   But does this math sound at all close???


John





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[Electric Boats] #18650 Batteries

 

I saw AA Energizer Lithium batteries at the grocery store, and was thinking about the past a year (or two or three?) ago where someone said they were going to put together a bank from a whole bunch of small cells.

It seemed odd that they had plenty of lithium AA batteries, but no chargers.  Looking the internet, it kinda' seems like these aren't meant to be recharged - just used as a higher capacity disposable??  Is that really true?

Then, I came across #18650 batteries.  Just looking at the internet, they appeared to be very close to the AA battery form factor, but on closer inspection, longer and thicker - but also higher capacity?  And higher voltage - these were rated as 3.7V cells, not 1.5 like AA's.

Many of the 18650 batteries were about 3000mAh, but some by Garberiel, seemed reasonably priced (on Amazon), and claimed to be 6000mAh.   I haven't done the math yet, but it looked like it would be a cheap way to get a 48V bank quickly, and then as I wanted to put more $$ into it and as the experiments went forward, I could always add more capacity in parallel (which at that point would probably be more expensive than just buying higher capacity cells to begin with).

Anyway, I was curious if anyone has played with these cells?  Is the 6000mAh rating likely to be real?

Sounds like it would take about 221 of these to make a 48V, 100Ah battery - is that right?
13 x 3.7=48V   17x6Ah>100Ah, so 221 cells to make up the bank...   @ about $15/10, about $330 for the bank???   That sounds way too good to be true.  Of course, there would need to be monitors and battery boxes, etc...   But does this math sound at all close???


John




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Wednesday, January 31, 2018

Re: [Electric Boats] Perfect sailors motor boat

 

I have a 3.75 Kw. golf cart motor modified to fit directly onto a gear box or drive shaft. I also have a Curtis motor controller never used $1100 firm. Photos to follow .

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Tuesday, January 30, 2018

Re: [Electric Boats] Perfect sailors motor boat

 

Thank you for your reply. It gives me the confidence to keep developing this idea.
Your concerns about the panels acting like a sail I think is not a problem as the majority of the panels are going to be on the roof of the cabin . I am planning on making it a trimaran for stability so some of the panels will extend out over the amas. I will look into the structural strength of the supports more. I like the idea of retracting a row of panels. I will look into this more.

Thanks again.

Chris P

On 31 Jan 2018, at 1:57 AM, Hannu Venermo gcode.fi@gmail.com [electricboats] <electricboats@yahoogroups.com> wrote:

 

On 40ft loa, you probably need 2 kW - 2.5 or so on a cat/tri for 5 knots+.

Feasible yes, maths great, plan great.
5 kW is huge and will give you great power and even some airco if you want.

One comment/issue maybe:
The very large 32 sq m panel will have huge wracking and tilting and pushing loads in heavy winds - since it is high up and has a big moment arm.
Think 10-20-++ tons, metric, twisting the boat.

A thick torsion box is probably best.
Thick means the vertical-direction sides and stiffeners / ribs need to be tall, not necessarily thick or heavy.
Criss-cross honeycomb, perhaps 25 cm tall.
Plywood would work fine, and you could even have it with large holes for air passage.
Laser-cut, cheap, epoxy impregnated.

Air spacers or gaps might be good in the top structure.
I would plan for main support pillars in say == 150x8 (-6) mm steel tube.
Any steel blasted, and properly painted, or 316L if You can afford it.

If at all possible try to have low free unsupported span, or a central support.
And very very strong mounts well-tied to the structure.

Consider a gust tilting the boat, and the top structures edge going into the water at 6 knots.
You would want the structure to be streamlined and not a ram.
Even then, probably 5 tons++ of force acting on the edge of the structure in a twisting action.

Alternatively, struss structure like construction cranes.
You could use commercial steel prefab pieces, cheap and strong.
Air would pass, and a water contact would have less load.

It might be possible to have somewhat different heights on the panels, perhaps allowing most of the air to pass instead of acting like a big wing or sail.

I would probably use linear guides, and have some, maybe 1 outermost set, of the panels be retractable on the edges.
Just sliding below the other panels.
316L supported rod, igus plastic linear bearings, ideal for this.
They will resist salt water, salt grit, etc and not rust.

The problem with a big flat rigid plane up top is wind catching it ..
and the more it tilts the more force it has.
This has the potential to flip the boat in a second until the top edges touch water, even in calm conditions, with a moderate gust.



On 17/01/2018 07:25, chrispurkiss@bigpond.com [electricboats] wrote:
 

Hi all.  First post. I'm a sailor from Australia.  Currently own a nice sailing catamaran that i built. As i get old it is too hard to hoist the main sail and all the trimming and reefing gets too hard.  I am planning on building the perfect sailors motor boat basically i am looking at replacing the sails with solar panels.  The design will be a trimaran for stability and to make a hull shape that is very slippery.  Looking at approx 40 foot LOA with 16 foot BOA.  

I hope you guys can check the maths to see if i am being too optimistic in my assumptions.

Area of solar panels 32 sq meters - gives 5 kW system - in low tropics gives 20+ kWH per day.

Propulsion by twin motors in the amas say 10 hp = 7.5 kW gives cruising speed 5 to 6 knots.

Battery pack similar to the one in a tesla car 75 kWH weight of batteries 540 kg. Total weight of boat 3 ton with back up 10 kWH generator for extended cruising.


Does this seem feasible? Does my maths add up?


Chris P




--   -hanermo (cnc designs)

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Re: [Electric Boats] Perfect sailors motor boat

 

On 40ft loa, you probably need 2 kW - 2.5 or so on a cat/tri for 5 knots+.

Feasible yes, maths great, plan great.
5 kW is huge and will give you great power and even some airco if you want.

One comment/issue maybe:
The very large 32 sq m panel will have huge wracking and tilting and pushing loads in heavy winds - since it is high up and has a big moment arm.
Think 10-20-++ tons, metric, twisting the boat.

A thick torsion box is probably best.
Thick means the vertical-direction sides and stiffeners / ribs need to be tall, not necessarily thick or heavy.
Criss-cross honeycomb, perhaps 25 cm tall.
Plywood would work fine, and you could even have it with large holes for air passage.
Laser-cut, cheap, epoxy impregnated.

Air spacers or gaps might be good in the top structure.
I would plan for main support pillars in say == 150x8 (-6) mm steel tube.
Any steel blasted, and properly painted, or 316L if You can afford it.

If at all possible try to have low free unsupported span, or a central support.
And very very strong mounts well-tied to the structure.

Consider a gust tilting the boat, and the top structures edge going into the water at 6 knots.
You would want the structure to be streamlined and not a ram.
Even then, probably 5 tons++ of force acting on the edge of the structure in a twisting action.

Alternatively, struss structure like construction cranes.
You could use commercial steel prefab pieces, cheap and strong.
Air would pass, and a water contact would have less load.

It might be possible to have somewhat different heights on the panels, perhaps allowing most of the air to pass instead of acting like a big wing or sail.

I would probably use linear guides, and have some, maybe 1 outermost set, of the panels be retractable on the edges.
Just sliding below the other panels.
316L supported rod, igus plastic linear bearings, ideal for this.
They will resist salt water, salt grit, etc and not rust.

The problem with a big flat rigid plane up top is wind catching it ..
and the more it tilts the more force it has.
This has the potential to flip the boat in a second until the top edges touch water, even in calm conditions, with a moderate gust.



On 17/01/2018 07:25, chrispurkiss@bigpond.com [electricboats] wrote:
 

Hi all.  First post. I'm a sailor from Australia.  Currently own a nice sailing catamaran that i built. As i get old it is too hard to hoist the main sail and all the trimming and reefing gets too hard.  I am planning on building the perfect sailors motor boat basically i am looking at replacing the sails with solar panels.  The design will be a trimaran for stability and to make a hull shape that is very slippery.  Looking at approx 40 foot LOA with 16 foot BOA.  

I hope you guys can check the maths to see if i am being too optimistic in my assumptions.

Area of solar panels 32 sq meters - gives 5 kW system - in low tropics gives 20+ kWH per day.

Propulsion by twin motors in the amas say 10 hp = 7.5 kW gives cruising speed 5 to 6 knots.

Battery pack similar to the one in a tesla car 75 kWH weight of batteries 540 kg. Total weight of boat 3 ton with back up 10 kWH generator for extended cruising.


Does this seem feasible? Does my maths add up?


Chris P




--   -hanermo (cnc designs)

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Posted by: Hannu Venermo <gcode.fi@gmail.com>
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.

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Friday, January 26, 2018

[Electric Boats] Re: bldc motors

 

King,

I run most windows things in XP in a VM, Oracle Virtual Box, on Linux Mint.  If you contact me I will give you the details.There are a couple of obscure steps to getting USB to work.  Or can post to the list if you think others would be interested.

John A
jcacord(at)gmail(dot)com

--
Flatwater Electronics
www.flatwaterfarm.com
"Neurosurgery for computer looms."

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