[PSUBS-MAILIST] Personal_Submersibles Digest, Vol 107, Issue 2
via Personal_Submersibles
personal_submersibles at psubs.org
Mon Jun 6 18:15:40 EDT 2022
Hi Jon, Hank, et co.
I have been repackaging LiFePO4 for 10 years now since I started.
This is the main thing that has kept me from getting my sub in the water.
First thing you need to decide on is the Life PO4 type. Either cylindrical
or Prismatic. Cylindrical batteries have better performance. I am using 15
Ah cells (headway 40152S 15Ah )which have a 10C discharge i.e. 150 amps. We
have made a test circuit where we discharge them at 150 amps and see what
the current drops to in each cell. I have 560 cells. The problem with them
is that you need multiple CMU (cell management Units) to balance them and
then report via CAN to the BMS. These cells are 40mm diam x mounted in
hexagonal plastic interlocking mounts and you can build different shapes. I
have a number of different strings of 8 cells (24v) in parallel and series.
The idea of these is to have an air space around each cell and to provide
good cooling.
Due to the pain in my butt from having all these CMU's to deal with I am now
changing over to Prismatic which are rectangular. The ones I am using are
120Ah and I am able to get 1.5 times the total energy for the sub. i.e.
32kwh instead of 22 kwh. Now I am able to use far fewer CMU's and simplify
the system and packaging but only able to get 2C discharge (240 amps per
cell). These cells are a lot cheaper and easier to manage and
package/service etc..
The problem with sub batteries is the length of time between uses and
keeping the system charged.
This is a lengthy subject and I have a fair bit of experience in problems
that I have had.
I suggest you put together the wish list you have and the operating voltage
and total amphours you are wanting to achieve.
I would not recommend removing the BMS and CMU's from the packs.
Jon if you can tell me where I can drop a bunch of documents I am sure I can
assist with my experience in these. I have had some cells let go and others
punctured. Both types.
I am also importing electric vehicles with lead acid and going to convert to
LiFePo4.
Cheers to all,
Hugh
-----Original Message-----
From: Personal_Submersibles <personal_submersibles-bounces at psubs.org> On
Behalf Of via Personal_Submersibles
Sent: Tuesday, 7 June 2022 7:50 AM
To: personal_submersibles at psubs.org
Subject: Personal_Submersibles Digest, Vol 107, Issue 2
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Today's Topics:
1. Re: Repackaged LifePo4? (Jon Wallace via Personal_Submersibles)
2. Re: Repackaged LifePo4? (hank pronk via Personal_Submersibles)
3. Re: Repackaged LifePo4? (David Colombo via Personal_Submersibles)
----------------------------------------------------------------------
Message: 1
Date: Mon, 6 Jun 2022 11:27:39 +0000 (UTC)
From: Jon Wallace via Personal_Submersibles
<personal_submersibles at psubs.org>
To: Personal Submersibles General Discussion
<personal_submersibles at psubs.org>
Subject: Re: [PSUBS-MAILIST] Repackaged LifePo4?
Message-ID: <1768746693.7700625.1654514859732 at mail.yahoo.com>
Content-Type: text/plain; charset="utf-8"
I agree, buoyancy is a factor but can be addressed by filling the battery
pods with lead or concrete weight in replacement of the original battery
weight.? I believe I can literally power the entire submarine with just two
LiFePo4 batteries if I wanted to.? That's attractive to me in terms of
maintenance.
Jon
On Monday, June 6, 2022, 07:06:11 AM EDT, Rick Patton via
Personal_Submersibles <personal_submersibles at psubs.org> wrote:
The one thing that comes to mind Jon is that the Ksubs buoyancy is designed
using the wet cell batteries which may not be an issue but worth
considering.?Batteries have come so far since the Captain designed his three
models and I have wanted to upgrade to a more efficient battery myself but
have decided to stick with what?s on the plans due to space limitations and
possible weight differences.?Rick ?
Sent from my iPhone
On Jun 6, 2022, at 6:34 AM, Jon Wallace via Personal_Submersibles
<personal_submersibles at psubs.org> wrote:
?Looking for some brain-power deductive reasoning.? I've been following some
of these youtube channels that teardown LiFePo4 batteries to see what's
inside and also test various functions of them.? I've notice with all of
them that the actual Lifepo packs are significantly smaller than the
container they are inserted into and use padding keep them centered.? At
first I assumed this was to prevent chafing of the cells against the
container but also noticed that padding is not used on the bottom which
seems to me where most movement that might cause chafing would occur.? So
I'm left to assume manufactures are simply using padding so they can provide
LifePo batteries in industry standard battery group sizes.
Given that the battery pods on K-Subs do not lend themselves well to current
battery groups I'm curious what you guys think about repackaging current
market LifePO batteries into smaller containers.? I can't see any reason not
to do it but am sure there are some opinions out there I would want to hear.
Jon
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Message: 2
Date: Mon, 6 Jun 2022 08:25:20 -0600
From: hank pronk via Personal_Submersibles
<personal_submersibles at psubs.org>
To: Personal Submersibles General Discussion
<personal_submersibles at psubs.org>
Subject: Re: [PSUBS-MAILIST] Repackaged LifePo4?
Message-ID: <E937B7EF-67DE-429B-9F2A-92E5AC3A33A4 at yahoo.ca>
Content-Type: text/plain; charset="utf-8"
Jon, I had the same idea and cut the top off one of my batteries. In my case
there is little space saving height wise but there could be savings on the
width. The BMS sits on top of the cells. There is no significant padding
under the cells. If you are willing to remove the BMS board, you could
reduce the heigh by about 2 inches. This would be very doable if you built
a cage.
Hank
Sent from my iPhone
> On Jun 6, 2022, at 5:28 AM, Jon Wallace via Personal_Submersibles
<personal_submersibles at psubs.org> wrote:
>
> ?
> I agree, buoyancy is a factor but can be addressed by filling the battery
pods with lead or concrete weight in replacement of the original battery
weight. I believe I can literally power the entire submarine with just two
LiFePo4 batteries if I wanted to. That's attractive to me in terms of
maintenance.
>
> Jon
>
>
>> On Monday, June 6, 2022, 07:06:11 AM EDT, Rick Patton via
Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>>
>>
>> The one thing that comes to mind Jon is that the Ksubs buoyancy is
designed using the wet cell batteries which may not be an issue but worth
considering.
>> Batteries have come so far since the Captain designed his three models
and I have wanted to upgrade to a more efficient battery myself but have
decided to stick with what?s on the plans due to space limitations and
possible weight differences.
>> Rick
>>
>> Sent from my iPhone
>>
>>> On Jun 6, 2022, at 6:34 AM, Jon Wallace via Personal_Submersibles
<personal_submersibles at psubs.org> wrote:
>>>
>> ?
>> Looking for some brain-power deductive reasoning. I've been following
some of these youtube channels that teardown LiFePo4 batteries to see what's
inside and also test various functions of them. I've notice with all of
them that the actual Lifepo packs are significantly smaller than the
container they are inserted into and use padding keep them centered. At
first I assumed this was to prevent chafing of the cells against the
container but also noticed that padding is not used on the bottom which
seems to me where most movement that might cause chafing would occur. So
I'm left to assume manufactures are simply using padding so they can provide
LifePo batteries in industry standard battery group sizes.
>>
>> Given that the battery pods on K-Subs do not lend themselves well to
current battery groups I'm curious what you guys think about repackaging
current market LifePO batteries into smaller containers. I can't see any
reason not to do it but am sure there are some opinions out there I would
want to hear.
>>
>> Jon
>>
>> _______________________________________________
>> Personal_Submersibles mailing list
>> Personal_Submersibles at psubs.org
>> http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles
>>
> _______________________________________________
> Personal_Submersibles mailing list
> Personal_Submersibles at psubs.org
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Message: 3
Date: Mon, 6 Jun 2022 12:49:46 -0700
From: David Colombo via Personal_Submersibles
<personal_submersibles at psubs.org>
To: Personal Submersibles General Discussion
<personal_submersibles at psubs.org>
Subject: Re: [PSUBS-MAILIST] Repackaged LifePo4?
Message-ID:
<CAHHFyEGjyRy2TnWcQHLWWH8xnJsrC2z+ciy1Y=VeNY-PqvG7LA at mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
Hi Jon, I am currently using a single battery in the VAST interior AGM,
weight of 58 lbs, dim 13.3x6.875x8.5" tall, 92 AH. My replacement lipo4 is
43.1 lbs, dim 19.02x6.7x9.45" tall, and 200AH.
This battery I will be laying on its side which gives me an additional 2
inches of vertical height, which will give me better access to the scrubber
location.The loss of weight of 14.3 lbs will be cast as a lead weight and
placed in my drop weight tray. Better center of gravity and less weight in
the aft section.
I have played with the idea of having the cells placed as an arc between the
internal t ribs as an alternative by building my own lipo4 battery pack. It
would certainly give back valuable space in the VAST with such a design,
just not sure I have the bandwidth to add another design project to my
current schedule, but you never know.
My thoughts on the battery pods, are to use the lipo4 as they come, figure
out how to add lead weights in the hollow area beneath the batteries for
some cast lead strips. At a cost $500 per battery or more depending on the
AH desired, I wouldn't cut them open. Might be cheaper to build your own.
David
On Mon, Jun 6, 2022, 7:26 AM hank pronk via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:
> Jon, I had the same idea and cut the top off one of my batteries. In
> my case there is little space saving height wise but there could be
savings on
> the width. The BMS sits on top of the cells. There is no significant
> padding under the cells. If you are willing to remove the BMS board,
> you could reduce the heigh by about 2 inches. This would be very
> doable if you built a cage.
> Hank
>
>
> Sent from my iPhone
>
> On Jun 6, 2022, at 5:28 AM, Jon Wallace via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> ?
> I agree, buoyancy is a factor but can be addressed by filling the
> battery pods with lead or concrete weight in replacement of the
> original battery weight. I believe I can literally power the entire
> submarine with just two
> LiFePo4 batteries if I wanted to. That's attractive to me in terms of
> maintenance.
>
> Jon
>
>
> On Monday, June 6, 2022, 07:06:11 AM EDT, Rick Patton via
> Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
>
> The one thing that comes to mind Jon is that the Ksubs buoyancy is
> designed using the wet cell batteries which may not be an issue but
> worth considering.
> Batteries have come so far since the Captain designed his three models
> and I have wanted to upgrade to a more efficient battery myself but
> have decided to stick with what?s on the plans due to space
> limitations and possible weight differences.
> Rick
>
> Sent from my iPhone
>
> On Jun 6, 2022, at 6:34 AM, Jon Wallace via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> ?
> Looking for some brain-power deductive reasoning. I've been following
> some of these youtube channels that teardown LiFePo4 batteries to see
> what's inside and also test various functions of them. I've notice
> with all of them that the actual Lifepo packs are significantly
> smaller than the container they are inserted into and use padding keep
> them centered. At first I assumed this was to prevent chafing of the
> cells against the container but also noticed that padding is not used
> on the bottom which seems to me where most movement that might cause
> chafing would occur. So I'm left to assume manufactures are simply
> using padding so they can provide LifePo batteries in industry standard
battery group sizes.
>
> Given that the battery pods on K-Subs do not lend themselves well to
> current battery groups I'm curious what you guys think about
> repackaging current market LifePO batteries into smaller containers.
> I can't see any reason not to do it but am sure there are some
> opinions out there I would want to hear.
>
> Jon
>
> _______________________________________________
> Personal_Submersibles mailing list
> Personal_Submersibles at psubs.org
> http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles
>
> _______________________________________________
> Personal_Submersibles mailing list
> Personal_Submersibles at psubs.org
> http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles
>
> _______________________________________________
> Personal_Submersibles mailing list
> Personal_Submersibles at psubs.org
> http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles
>
> _______________________________________________
> Personal_Submersibles mailing list
> Personal_Submersibles at psubs.org
> http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles
>
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