Adding External Batteries to APC UPS for Longer Runtime.

Here's how I added extra battery capacity to an APC Smart-UPS 750 uninterrupted power supply (model SMT750). This process applies to any of the common home or workstation use UPS units that use 12V Lead Acid batteries (SLA or VRLA).

Stuff I used or recommended in this video:

IDEAL Stripmaster 45-092 Automatic Wire Stripper for #10 to #22 AWG:
https://amzn.to/44vuKkz

iCrimp Wire Crimping Tool for Anderson Powerpole 15, 30, and 45 Amp Contacts:
https://amzn.to/4lb7ehG

30 Amp Anderson Powerpole Connectors PP15-45, w/Retention Clips, 12-16 AWG (10 Sets):
https://amzn.to/3Tu1UKo

30 Pcs Rubber Boots Covers Flame Retardant Sleeve For Powerpole connectors 15, 30, and 45 Amp:
https://amzn.to/4kP8wiH

Powerwerx Genuine Anderson Powerpole Parts and Accessories:
https://powerwerx.com/anderson-power-...

650pcs Heat Shrink Tubing Black Wire Shrink Wrap UL Approved Ratio 2:1:
https://amzn.to/4e51xPT

200pcs Adhesive Lined Heat Shrink Tubing Black, Red Wire Shrink Wrap - 3:1 Ratio:
https://amzn.to/45obshj

100pcs Heat Shrink Spade Connectors Kit 22-10 AWG Female and Male Fully Insulated Wire Crimp Quick Disconnect:
https://amzn.to/3ZBej2R

Mighty Max Battery ML12-12 - 12 Volt 12 AH Non-Spillable SLA Battery (also available as 2-pack):
https://amzn.to/4jVbC38
(I used the same size batteries from a used lawnmower battery pack)

GearIT 10/2 Outdoor Direct Burial CL3 CL2 Rated 10AWG Gauge 2 Conductors Oxygen-Free Copper, Black 50ft:
https://amzn.to/440tgwx
(This is the cabling I used because I already had it from another project, but you can absolutely use 12 Gauge instead)