Multi layered questions about how to make a UPS compatible with Home Assistant

Big deep breath, I would like to make my UPS talk to Home Assistant via a Wemos, which I've already flashed with Tasmota, and is successfully measuring voltage only. I have a UPS which shows a green / flashing green charging LED, a yellow / flashing yellow low battery/(using) battery, and a red/flashing red overload / warning for information about the UPS. I have replaced the small 5ah battery with a large 50ah one, and would like to ensure it's not overloading the transformer if the battery isn't retaining a charge. I'd also like to read the warning LED signals to the Wemos. While I realise there may be UPSs which do this, they'd be much more expensive in the order of 100x. I've tried looking at the UPS circuit board, and discovered pin outs. Unfortunately the 5v output which I'd like to use to power the wemos d1 mini messes around with the operation of the UPS, so I can't use it. For convenience, I'll break down my various questions. 1. Can I pull the 12v down to 5v to use on the Wemos without having to buy a 12v-5v usb module? I do have some LM7805s but no capacitors. 2. What's the easiest way to measure current draw to the battery? I've considered a shunt, and have a clamp sensor, but it's not hall-effect and doesn't appear to work with a multiplex device (several analogue inputs) .... that is to say, I can't get anything meaningful from the fluctuating data -200 to 3000. 3. Is it possible to 'read' the input voltage to an LED on a digital pin (I'm using the analogue pin to measure the 12V via a voltage sensor which is working well) on a Wemos D1 Mini? I've discovered they're pulling 2.9v.

As mentioned the board pin outs are useful, and I was originally hoping to find a way to utilise them to see what's going on with the UPS, but I know almost nothing about SWIM which this has, and the 5V pin messes with the UPS operation.

I'm not expecting a comprehensive answer to any of the questions, but a pointer in the right direction would be great. Thanks in advance.

by DarthMonkey
February 26, 2024

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