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Posted: 2023-04-0406:39 AM. Last Modified: 2023-04-0406:48 AM
You will find several videos explaining how to do it but in short the external connector has 3 terminals: one is positive, one is negative and the third one tells the UPS that a external battery pack is hooked and then the UPS will increase it's displayed reserve time. Basically the external Battery Pack has two 12 Volt 9 Ah hooked in series plus another two 12 Volt 9 Ah also in series and then both are hooked in parallel so you will have a external battery pack rated at 24 Volt 18 Ah. The signal wire inside the external battery pack as I recall has 50K resistor wired to the negative pole. So instead of using the 12 Ah I would hook a couple of 18 Ah in series which will give you a lot more of reserve time and will match this UPS charging capability. Keep in mind you HAVE to connect the external battery pack signal wire to the negative pole because if not, the ups logic circuit will turn off the UPS at the factory setting no matter how much charge you still have on the external batteries