LattePanda Sigma with big (100Ah) battery

Hi,
 

I'm planning to buy LattePanda Sigma, for a home server, and I'm thinking of attaching a DC UPS with a big 12V 100Ah, for extended periods of power outage.  So far, I was thinking of two options:

1. Use a 150W Mean Well AD-155A power source with UPS function - https://meanwell-ps.com/products/ad-155a
 or 2. Use the standard UPS Expansion HAT for LattePanda Sigma, with 100 or so of 18650 cells - https://wiki.dfrobot.com/SKU_DFR1095_LattePanda_Sigma_UPS.

 

I'm currently leaning toward option 1. 

Advantages:

  * Reliable and efficient power source  * Big and cheaper AGM lead-acid batteries may be found.

 

Disadvantages:

  * Battery charging level must be sensed and interfaced with the Sigma (through the on-board Arduino, most probably), for graceful shutdowns, which Mean Well lacks

 

When OnLine, the Mean Well will output approx. 13.8V, but when OnBattery it directly connects the battery to the output, and its cut-off current is 10V; so, it'll provide to Sigma 10 - 13.8V range. 

For option 2. I see as advantages:

  * Seamless hardware integration

  * The battery will be seen by OS, same as a laptop. The graceful shutdowns are trivial to implement.

 

As disadvantages:

  * Lithium-ion or LifePo4 cell packs are more expensive, and the bigger cycle count doesn't pose an advantage since they'll get discharged only when lacking power

  * For achieving the 100Ah equivalent, a lot of cells are needed, rendering a lot of soldering and careful cells stacking.

 

Questions:

1. I know that Sigma wants 12 - 20V as input, but will it actually work with just 10.2 - 10.4V?
 

2. The HAT needs to sense all the intermediary voltages from the 4s battery pack, or does it just care about the whole pack voltage?
 

3. I see lots of prismatic batteries with 3.2V cells. Can the HAT and/or firmware be adjusted for a max, let's say, of 13.8V and a 10V cut-off voltage?!

 

4. Are there any other simpler overlooked solutions for achieving this long OnBattery range for Sigma?

 

Thanks!