Replacing a 12V 7Ah SLA battery with 14.4V 12Ah keeping SLA's dimensions

[powersupply]

Hi all,
my first attempt to put together some batteries, so please be helpful and kind.
I was looking to replace a 12V 7Ah SLA battery and found ready made batteries but with low Power or other issues.

This should replace a standard 12V 7Ah SLA battery and has eight 32700 6Ah LiFePo4 batteries in a 4S 2P configuration resulting in 14.4V 12Ah.
It has a simple "smart" BMS and fits tightly in the same footprint/dimensions as the mentioned 12V SLA battery.

Here is the Sketchup drawing
https://3dwarehouse.sketchup.com/model/04f2a667-ce18-44a2-a83e-6ea5b027ccf3/Replacing-a-12V-7Ah-SLA-battery-with-144V-12Ah-keeping-SLAs-dimensions

Components
Batteries: 8 x LiFePo4 32700 3,2v 6Ah
BMS: Daly Smart BMS R05T1-Gl19, 4S, "12V", 30A
Some 2mm sheet LASER CNC'd

Alternately the case of an old SLA battery + Credit Cards as separators

I hope to learn from your kind actionable and constructive inputs, I am then looking to LASER CNC some 2mm thick plastic sheet somewhere.
Depending if it's not OK to solder right onto the batteries, I might need to borrow or go to a place for a point welder also.

Thank you all!

 

[Chalo]

One of my buddies did that for a big portable speaker. He used a Bluetooth BMS, though, and taped the batteries into a pack. He gets much better run time than with the heavier SLA battery.

Your solution seems a little overengineered, but effective. If it entertains you, press on.

 

[powersupply]

Which is the "Bluetooth BMS"? Is your friend happy with it?

Contrary to your friends speaker use, this is not for entertainment.
This battery will power a weather station and some other sensors.

Does anybody have suggestions before I start building my very first cell based battery?
Thanks!

 

[Chalo]

Which is the "Bluetooth BMS"? Is your friend happy with it?

I don't know what he used. He likes Bluetooth BMSes because he likes to keep track of the pack from his phone. I'm good with checking things with a voltmeter when I want to know what's up.

I'm not suggesting that your battery is for entertainment. I am suggesting that making special cell holders will be only of entertainment value. With so few cells and a stationary application, you can simply tape or hot glue the cells into a pack. Don't let that stop you from fabricating something if you're into it.

 

[powersupply]

That was valuable info, thank you!
I thought the batteries must be spaced so they don't short in worst case scenarios.
And also leave room for stretching (if they do stretch).
Now I understand your "overengineered" comment.

I designed it so that regular credit cards can be (heat) bent to act as some spacer.
I rather not do LASER cutting, so your input was great news!

The BMS to be used has a bluetooth dongle, though I'll rather set things up wired (has also serial->USB).
We might communicate with the BMS serially via Arduino later, if needed.

Please keep it coming.
Thanks!

 

[Chalo]

If you reckon there will be vibration, you can give each cell a turn of Gorilla Tape or the like before you bind them together. But that's not usually necessary for a stationary pack.

 

[powersupply]

Yes, violent (shock) vibrations due to windsock on top of the mast.
Removing the lead stuff from the old SLA is a real pain so far, will order one of those containers next time.
Will have to solder the cells together, wish there were a hobby place here in West Los Angeles where I could spot weld the batteries.