[PSUBS-MAILIST] Repackaged LifePo4?

Mon Jun 6 15:49:46 EDT 2022

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
>
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