Saturday, December 31, 2022

Re: [electricboats] Newbie looking for guidance

I concur with many here - go to thunderstruck-ev.com for complete kits. Their reduction/motor mount combo makes installation straight forward. 


if you have data - engine RPM - prop RPM - at the speeds you are looking for - this will help in choosing a reduction ratio. 

Once you choose operations time, then you can calculate batter size. I’m an advocate if building your battery from LiFePO4 cells with a suitable BMS  I did read about a US company selling complete batteries Trophy Battery that seem like quality products.

 

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Thursday, December 29, 2022

Re: [electricboats] Newbie looking for guidance

That is a good advise, in general !
Always put a thrust bearing in the drive line.
Anywhere, between the prop and the main shaft of the motor/engine.

Carsten


On Thursday, 29 December 2022 at 23:44:33 CET, kurtphone@gmail.com <kurtphone@gmail.com> wrote:


The prop has an optimum speed and the motor has an optimum speed. Proper ratio in the gear reduction is when they match. My initial installation at 2.5 to 1 was over propped and I could "overload" the motor. At 3 to 1 it drives the boat much like the old 30hp Volvo only more controllable. 
I noticed no significant change in the noise
level with my ratio changes. 

Thunderstruck advises to not use direct drive without some sort of thrust bearing to save the electric motor bearings from the thrust loads. 

Posted by at No comments:

Re: [electricboats] Newbie looking for guidance

The prop has an optimum speed and the motor has an optimum speed. Proper ratio in the gear reduction is when they match. My initial installation at 2.5 to 1 was over propped and I could “overload” the motor. At 3 to 1 it drives the boat much like the old 30hp Volvo only more controllable. 
I noticed no significant change in the noise
level with my ratio changes. 

Thunderstruck advises to not use direct drive without some sort of thrust bearing to save the electric motor bearings from the thrust loads. 

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Re: [electricboats] Newbie looking for guidance

Hi Tom,
Your boat looks great!
If you're considering something low power on the order of 3 HP and have more time than money, you might get a motor and controller for $100-$200.  Study the torque charts and your propeller geometry to see if you need to modify the prop for higher RPM.  Get a set of 12V (nominal) LiFePO4 batteries for another $100.  You may have an iteration or three to resolve the differences between theory and water.  Once you have it working, buy additional batteries according to how long you want it to run before you switch to oars.
Cheers
Halden
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Re: [electricboats] Newbie looking for guidance

What kind of boat do you have, Tom ?
Here we have all kinds of boats...

What is an "A4" engine (please describe), and what kind of connection do you have between the engine and the prop ?

If you strip the fossile engine, it will be hell to put it back. Good thing is - you will never want to go back !

Carsten


On Thursday, 29 December 2022 at 23:09:42 CET, Tom@saltyachts.com <tom@saltyachts.com> wrote:


Thank You All,
It is the 30hp A4 currently installed
I know converting from a good running A4 to electric isn't exactly logical but what in boating is?  I do want to try going electric, it suites the way we use her.
If I do it I will use the existing running gear, as easy as it to acess the A4, I may want to put it back in at times.
The hull is very efficent up to 4-6kts (it gets there at idle now) 
Currently if I want to run a trot line I need to drag two 5 gal buckets to go slow enough...The electric will allow for that slow troll.


Tom
Posted by at No comments:

Re: [electricboats] Newbie looking for guidance

Thank You All,
It is the 30hp A4 currently installed
I know converting from a good running A4 to electric isn't exactly logical but what in boating is?  I do want to try going electric, it suites the way we use her.
If I do it I will use the existing running gear, as easy as it to acess the A4, I may want to put it back in at times.
The hull is very efficent up to 4-6kts (it gets there at idle now) 
Currently if I want to run a trot line I need to drag two 5 gal buckets to go slow enough...The electric will allow for that slow troll.


Tom
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Re: [electricboats] Newbie looking for guidance

I have to disagree with ONE thing Matt said. The one penalty for oversizing may only be economic but it is real and could be significant between 3 and 10 HP.

If cost is a minor consideration I'd say a nominal 5-6 kW system would be the sweet spot for most needs and bang/$$$. If your budget is tight, something in the 3 HP range should still push her with authority but might be lacking a little in heavy weather and strong currents. IMO

Capt. Carter
Www.shipofimagination.com


On Thu, Dec 29, 2022 at 9:54 AM, Matt Foley
<matt@sunlightconversions.com> wrote:
Assuming this was a 18hp Atomic? 

You could definitely gain by going with a larger prop. Since you cant go much bigger and you wont need much power at all to push this 6 knots its probably not worth it. 

Personally I think a 3kw motor would be plenty for this boat to putt around.  Since there isn't really any penalty in oversizing, I might go with a 10kw. This would match or exceed the performance of the Atomic. 

I would also try and go direct drive. It may overheat at top speed, but you wont have the battery capacity to keep it there long enough to be an issue. 

I typically don't recommend anything other than LFP for boats. I wouldn't be apposed to it here as long as its in a portable, waterproof enclosure. This will help keep the weight down and in turn have a larger capacity capable of pushing 10kw motor. 

Matt Foley 
Sunlight Conversions
Perpetual Energy, LLC
201-914-0466



On Wednesday, December 28, 2022 at 12:49:33 PM EST, twowheelinguy via groups.io <twowheelinguy=yahoo.com@groups.io> wrote:


I was thinking the same thing as Al. If that Atomic 4 is running good why convert?  A4s are super quiet and efficient ICEs. With the exception of using gasoline as its fuel, A4s are awesome and they would definitely be the best way to go 20 kts.
But if you have an aversion to gas on a boat , don't want to listen to and smell diesel and don't care of you ever go 20 knots again then that boat looks like it would be an excellent electric boat. 

I'd guess with a solar canopy it could cruise 5 kts just off solar on a sunny day.

If you're sure  electric is the best for you, Thunderstruck is a good place to look for an all inclusive kit for a good price but if you really have a tight budget I'd look at golf cart conversion  kits. I've been running one for 10 years. To say it's a little underpowered is an understatement but it will push the Arc 4 mph on nothing but sunshine and make 5 kits if I suck on the batteries hard.
It won't take much to get that boat up to 6 or 7 mph if that's all you want and if you do want to go much faster it won't do it for long unless you spend a fortune on batteries and a lot more on a motor and controller that you won't use most of the time.

Gas or electric though, it's a cool boat.

Capt. Carter
Www.shipofimagination.com


On Wed, Dec 28, 2022 at 11:16 AM, 63urban
<63urban@gmail.com> wrote:
But wouldn't that be far less efficient and a little more noise?

Nick



Sent from my Bell Samsung device over Canada's largest network.


-------- Original message --------
From: kurtphone@gmail.com
Date: 2022-12-28 10:35 a.m. (GMT-05:00)
To: electricboats@groups.io
Subject: Re: [electricboats] Newbie looking for guidance

i got my kit from Thunderstruck as well. Two thumbs up!
I just changed sprockets/ratios on the gear reduction until my existing prop worked. Much cheaper and easier than changing a prop. 
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Re: [electricboats] Newbie looking for guidance

Assuming this was a 18hp Atomic? 

You could definitely gain by going with a larger prop. Since you cant go much bigger and you wont need much power at all to push this 6 knots its probably not worth it. 

Personally I think a 3kw motor would be plenty for this boat to putt around.  Since there isn't really any penalty in oversizing, I might go with a 10kw. This would match or exceed the performance of the Atomic. 

I would also try and go direct drive. It may overheat at top speed, but you wont have the battery capacity to keep it there long enough to be an issue. 

I typically don't recommend anything other than LFP for boats. I wouldn't be apposed to it here as long as its in a portable, waterproof enclosure. This will help keep the weight down and in turn have a larger capacity capable of pushing 10kw motor. 

Matt Foley 
Sunlight Conversions
Perpetual Energy, LLC
201-914-0466



On Wednesday, December 28, 2022 at 12:49:33 PM EST, twowheelinguy via groups.io <twowheelinguy=yahoo.com@groups.io> wrote:


I was thinking the same thing as Al. If that Atomic 4 is running good why convert?  A4s are super quiet and efficient ICEs. With the exception of using gasoline as its fuel, A4s are awesome and they would definitely be the best way to go 20 kts.
But if you have an aversion to gas on a boat , don't want to listen to and smell diesel and don't care of you ever go 20 knots again then that boat looks like it would be an excellent electric boat. 

I'd guess with a solar canopy it could cruise 5 kts just off solar on a sunny day.

If you're sure  electric is the best for you, Thunderstruck is a good place to look for an all inclusive kit for a good price but if you really have a tight budget I'd look at golf cart conversion  kits. I've been running one for 10 years. To say it's a little underpowered is an understatement but it will push the Arc 4 mph on nothing but sunshine and make 5 kits if I suck on the batteries hard.
It won't take much to get that boat up to 6 or 7 mph if that's all you want and if you do want to go much faster it won't do it for long unless you spend a fortune on batteries and a lot more on a motor and controller that you won't use most of the time.

Gas or electric though, it's a cool boat.

Capt. Carter
Www.shipofimagination.com


On Wed, Dec 28, 2022 at 11:16 AM, 63urban
<63urban@gmail.com> wrote:
But wouldn't that be far less efficient and a little more noise?

Nick



Sent from my Bell Samsung device over Canada's largest network.


-------- Original message --------
From: kurtphone@gmail.com
Date: 2022-12-28 10:35 a.m. (GMT-05:00)
To: electricboats@groups.io
Subject: Re: [electricboats] Newbie looking for guidance

i got my kit from Thunderstruck as well. Two thumbs up!
I just changed sprockets/ratios on the gear reduction until my existing prop worked. Much cheaper and easier than changing a prop. 
Posted by at No comments:

Wednesday, December 28, 2022

Re: [electricboats] Newbie looking for guidance

I was thinking the same thing as Al. If that Atomic 4 is running good why convert?  A4s are super quiet and efficient ICEs. With the exception of using gasoline as its fuel, A4s are awesome and they would definitely be the best way to go 20 kts.
But if you have an aversion to gas on a boat , don't want to listen to and smell diesel and don't care of you ever go 20 knots again then that boat looks like it would be an excellent electric boat. 

I'd guess with a solar canopy it could cruise 5 kts just off solar on a sunny day.

If you're sure  electric is the best for you, Thunderstruck is a good place to look for an all inclusive kit for a good price but if you really have a tight budget I'd look at golf cart conversion  kits. I've been running one for 10 years. To say it's a little underpowered is an understatement but it will push the Arc 4 mph on nothing but sunshine and make 5 kits if I suck on the batteries hard.
It won't take much to get that boat up to 6 or 7 mph if that's all you want and if you do want to go much faster it won't do it for long unless you spend a fortune on batteries and a lot more on a motor and controller that you won't use most of the time.

Gas or electric though, it's a cool boat.

Capt. Carter
Www.shipofimagination.com


On Wed, Dec 28, 2022 at 11:16 AM, 63urban
<63urban@gmail.com> wrote:
But wouldn't that be far less efficient and a little more noise?

Nick



Sent from my Bell Samsung device over Canada's largest network.


-------- Original message --------
From: kurtphone@gmail.com
Date: 2022-12-28 10:35 a.m. (GMT-05:00)
To: electricboats@groups.io
Subject: Re: [electricboats] Newbie looking for guidance

i got my kit from Thunderstruck as well. Two thumbs up!
I just changed sprockets/ratios on the gear reduction until my existing prop worked. Much cheaper and easier than changing a prop. 
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Posted by at No comments:

Re: [electricboats] Newbie looking for guidance

But wouldn't that be far less efficient and a little more noise?

Nick



Sent from my Bell Samsung device over Canada's largest network.


-------- Original message --------
From: kurtphone@gmail.com
Date: 2022-12-28 10:35 a.m. (GMT-05:00)
To: electricboats@groups.io
Subject: Re: [electricboats] Newbie looking for guidance

i got my kit from Thunderstruck as well. Two thumbs up!
I just changed sprockets/ratios on the gear reduction until my existing prop worked. Much cheaper and easier than changing a prop. 
Posted by at No comments:

Re: [electricboats] Newbie looking for guidance

i got my kit from Thunderstruck as well. Two thumbs up!
I just changed sprockets/ratios on the gear reduction until my existing prop worked. Much cheaper and easier than changing a prop. 
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Tuesday, December 27, 2022

Re: [electricboats] Newbie looking for guidance

Nicely done! If it were me I would be happy with the current speeds that you are getting, but my boat is electric and the only way it will go that fast is on the trailer.
Have fun with your boat. Best Regards Al Hartley

On Tue, Dec 27, 2022 at 10:15 AM Michael Schiller via groups.io <captainmike454=yahoo.com@groups.io> wrote:
Thunderstruck EV is where my kit came from there is a lot of information on the site.


On Dec 27, 2022, at 9:39 AM, Tom@saltyachts.com wrote:

Hello friends,
i just stumbled upon this site and looks like a wealth of information.
I built a little crab skiff during Covid, 21' narrow and pretty light. Power is currently an Atomic 4 gas engine.  It is a tunnel drive and turning a 12"- 3 blade cupped "indigo" prop, specifically designed for A4's. I believe the prop was meant to allow the A4 to turn up and run at 1400 rpm.
the boat currently runs about 14knts wot but is used mostly at 2 to 7 knots which guessing is 500- 1000 rpm.
I can only go an inch bigger prop due to tunnel.

I guess my question is where does one start picking the components?
Can I expect any efficiency with existing prop?
thank you for any feedback
tom
<2EACD22E-788D-44D1-AB1B-1D32B6CF87D1.jpeg>
<A1E5DB80-AE76-457C-AE58-48E58F40EC01.jpeg>
<162A3583-DB8C-405E-910B-E9814647F6A6.jpeg>

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Posted by at No comments:

Re: [electricboats] Newbie looking for guidance

Thunderstruck EV is where my kit came from there is a lot of information on the site.


On Dec 27, 2022, at 9:39 AM, Tom@saltyachts.com wrote:

Hello friends,
i just stumbled upon this site and looks like a wealth of information.
I built a little crab skiff during Covid, 21' narrow and pretty light. Power is currently an Atomic 4 gas engine.  It is a tunnel drive and turning a 12"- 3 blade cupped "indigo" prop, specifically designed for A4's. I believe the prop was meant to allow the A4 to turn up and run at 1400 rpm.
the boat currently runs about 14knts wot but is used mostly at 2 to 7 knots which guessing is 500- 1000 rpm.
I can only go an inch bigger prop due to tunnel.

I guess my question is where does one start picking the components?
Can I expect any efficiency with existing prop?
thank you for any feedback
tom
<2EACD22E-788D-44D1-AB1B-1D32B6CF87D1.jpeg>
<A1E5DB80-AE76-457C-AE58-48E58F40EC01.jpeg>
<162A3583-DB8C-405E-910B-E9814647F6A6.jpeg>
Posted by at No comments:

[electricboats] Newbie looking for guidance

Hello friends,
i just stumbled upon this site and looks like a wealth of information.
I built a little crab skiff during Covid, 21’ narrow and pretty light. Power is currently an Atomic 4 gas engine.  It is a tunnel drive and turning a 12”- 3 blade cupped “indigo” prop, specifically designed for A4’s. I believe the prop was meant to allow the A4 to turn up and run at 1400 rpm.
the boat currently runs about 14knts wot but is used mostly at 2 to 7 knots which guessing is 500- 1000 rpm.
I can only go an inch bigger prop due to tunnel.

I guess my question is where does one start picking the components?
Can I expect any efficiency with existing prop?
thank you for any feedback
tom
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Saturday, December 10, 2022

Re: [electricboats] Li-ion battery designer commentary

I've heard good things about NorthStar batteries, and I've used the Trojan "carbon infused" batteries but I wasn't that impressed. Sure, they worked a lot better, but they still don't hold a candle to Lithium chemistry. And carbon infused lead batteries are a lot more expensive so that cancels out any cost advantage they might offer.   

The problem with lead chemistry is not it's capacity to store energy, it actually provides a pretty good value for that. The problem is you lose your ass putting the energy in and taking it out, especially if you want to do it in a hurry. If you have a system where you can charge slowly and only do low current draws with low depth of discharge, you could have argued that lead was a better value than lithium until recently. But now that you can buy a ready to use kWhr of lithium storage capacity for $250, lead has just about lost any price advantage it had and once it hit's $150/kWhr it will pretty much be game over for the lead battery industry. I don't think lead will ever completely be dead but it will soon be relegated to only very specialized applications imo. 

I'm on a cruise right now running my new lithium batteries hard for the first time and I can state UNEQUIVELENTLY they are definitely in another league than ANY lead batteries I've ever used or heard of and I've cruised the Arc over 5000 miles using various lead batteries over the last 12 years. As a long time holdout for using lead acid chemistry, I have to agree with Elon Musk now when he said, "lead sucks". 

You can still debate the cost benefit ratio of lead for some specialty applications but comparing the performance of lead to lithium is like comparing little league baseball to the major league.  Lithium is that much better, imo.

Capt. Carter
www.shipofimagination.com


On Saturday, December 10, 2022 at 06:57:55 AM EST, F. Neil <fneilss@gmail.com> wrote:


At >60 pounds per kWh, and limited 50% depth of discharge (for maximum lifespan), these Northstar carbon lead batteries are not really in the same class as Lifepo4 batteries for applications where energy density is an issue... 
Posted by at No comments:

Re: [electricboats] Li-ion battery designer commentary

At >60 pounds per kWh, and limited 50% depth of discharge (for maximum lifespan), these Northstar carbon lead batteries are not really in the same class as Lifepo4 batteries for applications where energy density is an issue... 
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Thursday, December 8, 2022

Re: [electricboats] Li-ion battery designer commentary

I was on the fence about LiFePo, but I have completely abandoned them. 

They can work well in conjunction with one of the many super capacitor 12v boards out there that will handle CCA,  but...

Story:

I have installed several RV solar installations using lithium, but recently I was introduced to a carbon lead battery that has more (greater) cycle life than LiFePo, and has the ability to supply large loads. 

The name of the battery is Northstar, and the series is the blue series. It is under the outback umbrella. Before you waste any more of your resources on polluting the earth, producing lithium products, download the manual for the blue series of batteries from there website. 

In answer to your future questions!  Yes I am using them on my system, and yes I am recommending them. 

On Wed, Dec 7, 2022, 8:12 PM sw via groups.io <v1opps=yahoo.com@groups.io> wrote:
Buy li then make u hang around so they die first





On Wednesday, December 7, 2022, 14:22, Daniel Wolf <danielhwolf@gmail.com> wrote:

These are great points. For instance, I'd not thought of having an Li-ion house bank while keeping an AGM for starting. Makes a lot of sense. 

I would urge people to click through to the Quora author's master page, he covers a lot of topics, some of which may help inform the discussions here rather than taking it abroad into cars and so on.

Best regards,

Dan 

Daniel H. Wolf, Esq.
Founder, CEO
Democracy Counts!
San Diego, CA 92104 USA
619.270.6434 Mobile

Act always as if the future of the universe depends on what you do, while laughing at yourself for thinking that anything you do makes any difference.

                                                                                                  A Buddhist saying


On Wed, Nov 30, 2022 at 12:53 PM Myles Twete <matwete@comcast.net> wrote:

John and Cap'n Carter offer great points and advice to consider.

This year I had had enough with lead acid starting batteries on my Vanagon, which only gets driven really a few times a year.  I looked at available lithium options that might work to replace the starting battery, but except for "maybe" one that checked at least most of the boxes, the price was in the higher hundred$ for a Lithium Ion option.  Sure, LiFePo options are out there, but as pointed out earlier, there are BMS and other reasons they can't handle this application.

What did I do?

I made my own Lithium Ion starter battery.  It was a lot of work and ended up not fitting, so I had to carve out some metal to get it to fit, but what an amazing starter battery I have now.  Tested CCA (Battery Analyzer): 3000 CCA.

While it didn't cost me a whole lot to do, it was a lot of work.

In my case, I started with a known lithium ion cell stack I have used on my boat for 31-48v use (nom. 42v, 35ah, 12S2P config).  I then disassembled all the interconnects and carefully made new ones to make a nom. 14v (4S6P) 105ah battery.  I took the existing BMS card and made custom cabling, using just 4 of the monitoring channels.  I already use these batteries and BMS cards on my boat pack (20P(12S(2P)) configuration for 700ah capacity) where I can monitor (and bypass if needed) any of the 240 cell pairs in the pack.  For my Vanagon, there's just 4 cell hextets to monitor.

In either case, no active BMS is really needed given the operating conditions I have.  In the boat's case, I almost never take the pack voltage below 36v and check and balance the pack about once a year (only maybe 4-7 charge cycles).

In the Vanagon's case, I measured the BMS readings at rest, during start and after charging and after a couple trips and have seen no change in differential cell voltages.

 

Performance: Rock solid starting (3000CCA vs maybe 250 or less with what I typically ended up with).  Ability to disconnect and float the battery (and cells) for months or years at a time without lead-acid worry of "sulfation".  Cost was under $300 total.

 

I still need to get the thing completely parked in place.  I do have a new battery compartment lid I made, but still need to hammer out a replacement side wall.  I also finally invested in a "house power" or auxiliary battery.  In that case, I bought some of the lower cost nom. 12v LFP 25ah(?) boxes out there.  The price was right, and they fit in the cavity nicely, but boy I really do hate that these battery manufacturers get away with embedding BMS electronics that cannot be disabled or won't self-disable during times of no discharge.  Probably every one of these out there will "self-brick" within months if left alone.  When these LFP batteries I got arrived, each one of them only read under 2volts!!!  Fortunately, literature shows that most lithium chemistries will survive "self-discharge", just not reverse polarity (which is what you get when you serially discharge a series of cells).  Still some of these LFP manufacturers (e.g. NEC) make batteries which, like laptop smart batteries, will blow an internal fuse or otherwise lock out the battery terminals from being charged or discharged if the voltage drops, say, below 10v.  These may be recoverable as I found with the NEC batteries, but your mileage may vary…

 

One last thing: You might be thinking "Wow, you must have one heck of a beefy BMS if it can work as a starter battery!"  Actually, no.  The BMS cards I use is only good to bypass about 1amp around cell pairs.  It's such a trickle that it can take days or longer to balance differentials of any significance.   And that's okay.  As configured, a 420amp starting current will draw just 70amps per cell with my battery.  Now, that is not exactly insignificant as these are 17ah cells, so this is about a 4C draw.  However, it's just for a very short time and the amount of amp-hours drawn during a start episode is miniscule---I measured drop in the low millivolts at the cell level during a start.

 

Anyway, long wind here, but for me, very happy with lithium ion for a starter battery.

 

-Myles

 

 

From: electricboats@groups.io [mailto:electricboats@groups.io] On Behalf Of twowheelinguy via groups.io
Sent: Wednesday, November 30, 2022 12:00 PM
To: electricboats@groups.io
Subject: Re: [electricboats] Li-ion battery designer commentary

 

I checked out the post and the guy left out one simple yet important detail. You can't use a battery with a 100amp BMS for starting your car, which is what all of the cheaper prismatic cell lithium batteries come with. Thankfully most of them will point blank tell you not to use on your car but usually it's buried in the finer print that most people don't read or even follow half the time when they do.  

 

As long as you shell out for the upgraded BMS and cells that will give you the CCA capacity you need then lithium is great but I don't think it's a better value because  the batteries that can do that are much more expensive and that brings into questions the cost effectiveness of the extra investment, especially when you can pretty much count on a decent FLA to crank your car for 6 years or more. The lithium chemistry definitely outperforms Lead by leaps and bounds but it's the long-term reliability of the BMS I worry about. If you're paying 5 times more for a Lithium battery do you really think you'll get 5 times longer life? Do you even need 5 times longer life?

 

I'm a total Lithium convert and won't deny it's the near term future of energy storage. With the recent precipitous price drops, I finally converted the Arc from FLAs to  LiFePo this year and am flabbergasted at how much better they are but I think it's safe to say lead is not quite dead. Yet. 

 

Capt. Carter

 

On Wednesday, November 30, 2022 at 09:08:24 AM EST, Daniel Wolf <danielhwolf@gmail.com> wrote:

 

 

Lurker here who enjoys all the informative info you all post.

 

This came down my Quora feed, I thought it might be of interest to you. It's by a Li-ion battery designer and he provides a lot of practical knowledge.

 

Best regards,

 

Dan

 

Daniel H. Wolf, Esq.

Founder, CEO

Democracy Counts!

San Diego, CA 92104 USA

619.270.6434 Mobile

 

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Wednesday, December 7, 2022

Re: [electricboats] Li-ion battery designer commentary

Buy li then make u hang around so they die first





On Wednesday, December 7, 2022, 14:22, Daniel Wolf <danielhwolf@gmail.com> wrote:

These are great points. For instance, I'd not thought of having an Li-ion house bank while keeping an AGM for starting. Makes a lot of sense. 

I would urge people to click through to the Quora author's master page, he covers a lot of topics, some of which may help inform the discussions here rather than taking it abroad into cars and so on.

Best regards,

Dan 

Daniel H. Wolf, Esq.
Founder, CEO
Democracy Counts!
San Diego, CA 92104 USA
619.270.6434 Mobile

Act always as if the future of the universe depends on what you do, while laughing at yourself for thinking that anything you do makes any difference.

                                                                                                  A Buddhist saying


On Wed, Nov 30, 2022 at 12:53 PM Myles Twete <matwete@comcast.net> wrote:

John and Cap'n Carter offer great points and advice to consider.

This year I had had enough with lead acid starting batteries on my Vanagon, which only gets driven really a few times a year.  I looked at available lithium options that might work to replace the starting battery, but except for "maybe" one that checked at least most of the boxes, the price was in the higher hundred$ for a Lithium Ion option.  Sure, LiFePo options are out there, but as pointed out earlier, there are BMS and other reasons they can't handle this application.

What did I do?

I made my own Lithium Ion starter battery.  It was a lot of work and ended up not fitting, so I had to carve out some metal to get it to fit, but what an amazing starter battery I have now.  Tested CCA (Battery Analyzer): 3000 CCA.

While it didn't cost me a whole lot to do, it was a lot of work.

In my case, I started with a known lithium ion cell stack I have used on my boat for 31-48v use (nom. 42v, 35ah, 12S2P config).  I then disassembled all the interconnects and carefully made new ones to make a nom. 14v (4S6P) 105ah battery.  I took the existing BMS card and made custom cabling, using just 4 of the monitoring channels.  I already use these batteries and BMS cards on my boat pack (20P(12S(2P)) configuration for 700ah capacity) where I can monitor (and bypass if needed) any of the 240 cell pairs in the pack.  For my Vanagon, there's just 4 cell hextets to monitor.

In either case, no active BMS is really needed given the operating conditions I have.  In the boat's case, I almost never take the pack voltage below 36v and check and balance the pack about once a year (only maybe 4-7 charge cycles).

In the Vanagon's case, I measured the BMS readings at rest, during start and after charging and after a couple trips and have seen no change in differential cell voltages.

 

Performance: Rock solid starting (3000CCA vs maybe 250 or less with what I typically ended up with).  Ability to disconnect and float the battery (and cells) for months or years at a time without lead-acid worry of "sulfation".  Cost was under $300 total.

 

I still need to get the thing completely parked in place.  I do have a new battery compartment lid I made, but still need to hammer out a replacement side wall.  I also finally invested in a "house power" or auxiliary battery.  In that case, I bought some of the lower cost nom. 12v LFP 25ah(?) boxes out there.  The price was right, and they fit in the cavity nicely, but boy I really do hate that these battery manufacturers get away with embedding BMS electronics that cannot be disabled or won't self-disable during times of no discharge.  Probably every one of these out there will "self-brick" within months if left alone.  When these LFP batteries I got arrived, each one of them only read under 2volts!!!  Fortunately, literature shows that most lithium chemistries will survive "self-discharge", just not reverse polarity (which is what you get when you serially discharge a series of cells).  Still some of these LFP manufacturers (e.g. NEC) make batteries which, like laptop smart batteries, will blow an internal fuse or otherwise lock out the battery terminals from being charged or discharged if the voltage drops, say, below 10v.  These may be recoverable as I found with the NEC batteries, but your mileage may vary…

 

One last thing: You might be thinking "Wow, you must have one heck of a beefy BMS if it can work as a starter battery!"  Actually, no.  The BMS cards I use is only good to bypass about 1amp around cell pairs.  It's such a trickle that it can take days or longer to balance differentials of any significance.   And that's okay.  As configured, a 420amp starting current will draw just 70amps per cell with my battery.  Now, that is not exactly insignificant as these are 17ah cells, so this is about a 4C draw.  However, it's just for a very short time and the amount of amp-hours drawn during a start episode is miniscule---I measured drop in the low millivolts at the cell level during a start.

 

Anyway, long wind here, but for me, very happy with lithium ion for a starter battery.

 

-Myles

 

 

From: electricboats@groups.io [mailto:electricboats@groups.io] On Behalf Of twowheelinguy via groups.io
Sent: Wednesday, November 30, 2022 12:00 PM
To: electricboats@groups.io
Subject: Re: [electricboats] Li-ion battery designer commentary

 

I checked out the post and the guy left out one simple yet important detail. You can't use a battery with a 100amp BMS for starting your car, which is what all of the cheaper prismatic cell lithium batteries come with. Thankfully most of them will point blank tell you not to use on your car but usually it's buried in the finer print that most people don't read or even follow half the time when they do.  

 

As long as you shell out for the upgraded BMS and cells that will give you the CCA capacity you need then lithium is great but I don't think it's a better value because  the batteries that can do that are much more expensive and that brings into questions the cost effectiveness of the extra investment, especially when you can pretty much count on a decent FLA to crank your car for 6 years or more. The lithium chemistry definitely outperforms Lead by leaps and bounds but it's the long-term reliability of the BMS I worry about. If you're paying 5 times more for a Lithium battery do you really think you'll get 5 times longer life? Do you even need 5 times longer life?

 

I'm a total Lithium convert and won't deny it's the near term future of energy storage. With the recent precipitous price drops, I finally converted the Arc from FLAs to  LiFePo this year and am flabbergasted at how much better they are but I think it's safe to say lead is not quite dead. Yet. 

 

Capt. Carter

 

On Wednesday, November 30, 2022 at 09:08:24 AM EST, Daniel Wolf <danielhwolf@gmail.com> wrote:

 

 

Lurker here who enjoys all the informative info you all post.

 

This came down my Quora feed, I thought it might be of interest to you. It's by a Li-ion battery designer and he provides a lot of practical knowledge.

 

Best regards,

 

Dan

 

Daniel H. Wolf, Esq.

Founder, CEO

Democracy Counts!

San Diego, CA 92104 USA

619.270.6434 Mobile

 

Act always as if the future of the universe depends on what you do, while laughing at yourself for thinking that anything you do makes any difference.

                                                                                                  A Buddhist saying

 

 

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