Started a thread a couple weeks ago looking for electrolyte or contact process sulfuric acid to DIY my own battery and measure its performance empirically. Still no luck.
Had an AC technician recently "vacuum" my home split air conditioner for ten minutes using an old refrigerator compressor. Vacuum micron rating? Please, we're listening for the sound of the compressor struggling to indicate the vacuum is complete. The same guy filled the system with outside air using the same compressor.
"Vacuum pump derh lakh rupay ka hay. Kaun le kar ghoomay ga?"
"Nitrogen kaun le kar ghoomay ga?"
He's not wrong. Electricians and HVAC technicians are struggling just like everyone else, cutting costs and lying, even if it doesn't come naturally to them, so that they can survive.
It would be valuable information to anyone interested in protecting their equipment to know where to get well-prepared lead-acid batteries or the materials to prepare them, as well as HVAC technicians who won't mess your system up forcing you into another ~Rs. 200,000 air conditioner purchase that'll inevitably end up being a cheaply manufactured piece of trash.