I bought a new 2000VA UPS to kind of, upgrade the old one i had modded. When i got back home, i powered it on, to note that nothing would happen. Like it was dead. After a small inspection i realised that the battery's inside the unit where "dead" and the thing must have bin in the shellfs for a good 2 year or so. Since i threw away the reciept while having a coffee at starbucks, i stumbled upon refilling of UPS battery's. Bottom point: battery's dry out over time and the capacity / voltage gets worse to the point they die. Since this thing has'nt bin used and just depleted itself for over 2 years being in stock i kind of had a chance to revive those 2x 9A battery's hooked up in serie (24V).
Opening them up was fairly easy, pop off the plastic cap and the rubber caps and you'll get this:
Looked pretty dry to me, so i went towards the store to get distilled water and due to the lack of a proper pipet a simple ketchup bottle with nozzle, lol.
I think per battery around 170ml of fluid went in, and some more after shaking the battery's and halfway charging them up.
At various points i measured the voltages; before filling it up it woud'nt pass the 7 volts really, but now they where actually at around 11v and a very tiny bubbling noise coming from the battery's. There's life! So after another hour the voltage measured 12.05v - which is around 3.6v or so. After cleaning them up, putting things back together and slapping back the cover on, it was time for a leak test, which is to prevent any fluids coming out or so, but as i suspected nothing happend which is a good sign.
They still need a bit of charge - the thing is'nt really fast, takes approx 7 hours to get 'm at 90% of their capacity. Proberly a full night for being at 100%. I managed to run a 1000W toaster so far for a minute which is'nt bad. I guess the recovery of such battery's depends on the sulfation that happens on the plates once they are exposed with air or so. Proberly because they are sealed.
. it started as a standard cuk mantis case. 
