My BIG apc 2500XL Is my favorite. It was a monster huge unit about 30” tall, and weighed a ton.I have a UPS fetish with four different systems, three are APC. Show & Tell. This is what I’ve learned so far:
- Only the APC “XL” models are rated for continuous operation. You can easily identify by the rear external battery connector.
- Most other consumer UPS’s are designed to overheat shortly after the internal batteries are depleted. Running the non-XL UPS at minimal power, or adding fans to get around the heat issue won’t work. As stated above, the UPS will still shutdown based on a timer.
- The XL will automatically recalculate expanded battery capacity when using AGM. I have no experience (yet) powering with LiPo.
- The APC battery display is expecting a normal AGM voltage range. If you connect to solar, the higher battery voltage will manifest as one blinking bar. It's not indicating low battery. Show & Tell.
- Higher battery voltage can affect the APC capacitors (the little ones, not the big H-bridge ones). This affected my 2700W unit that will no longer boot. My to-do list is to replace them and see if it works.
- If you want a reliable pure-sine, low-frequency inverter a used UPS is your cheapest method.
I ripped the thing apart, put the board in a little suitcase, and am working on setting it up for more portable use.